Casopisni svet/Publishing Council Barbara Simoncic, predsednica/President Katja Burger, Univerza v Ljubljani Silvo Hribernik, Univerza v Mariboru Tatjana Kreže, Univerza v Mariboru Gašper Lesjak, Predilnica Litija, d. o. o. Nataša Peršuh, Univerza v Ljubljani Petra Prebil Bašin, Gospodarska zbornica Slovenije Melita Rebic, Odeja, d. o. o. Tatjana Rijavec, Univerza v Ljubljani Daniela Zavec, ZITTS Helena Zidaric Kožar, Inplet pletiva d. o. o. Vera Žlabravec, Predilnica Litija, d. o. o. Glavna in odgovorna urednica/ Editor-in-Chief Tatjana Rijavec Namestnica glavne in odgovorne urednice/Assistant Editor Tatjana Kreže Podrocni uredniki/Associate Editors Matejka Bizjak, Katja Burger, Andrej Demšar, Alenka Pavko Cuden, Andreja Rudolf, Barbara Simoncic, Sonja Šterman, Brigita Tomšic, Zoran Stjepanovic Izvršna urednica za podatkovne baze/ Executive Editor for Databases Irena Sajovic Mednarodni uredniški odbor/ International Editorial Board Arun Aneja, Greenville, US Andrea Ehrmann, Bielefeld, DE Aleš Hladnik, Ljubljana, SI Petra Forte Tavcer, Ljubljana, SI Darinka Fakin, Maribor, SI Jelka Geršak, Maribor, SI Karl Gotlih, Maribor, SI Memon Hafeezullah, Shanghai, CN Abu Naser Md. Ahsanul Haque, Daka, BD Geelong, AU Ilda Kazani, Tirana, AL Svjetlana Janjic, Banja Luka, BA Igor Jordanov, Skopje, MK Petra Komarkova, Liberec, CZ Mirjana Kostic, Beograd, RS Manja Kurecic, Maribor, SI Rimvydas Milasius, Kaunas, LT Olga Paraska, Khmelnytskyi, UA Irena Petrinic, Maribor, SI Željko Penava, Zagreb, HR Tanja Pušic, Zagreb, HR Zenun Skenderi, Zagreb, HR Snežana Stankovic, Beograd, RS Jovan Stepanovic, Leskovac, RS Zoran Stjepanovic, Maribor, SI Simona Strnad, Maribor, SI Jani Toroš, Ljubljana, SI Mariana Ursache, Iai, RO Antoneta Tomljenovic, Zagreb, HR Dušan Trajkovic, Leskovac, RS Hidekazu Yasunaga, Kyoto, JP (ISSN: 0351-3386 tiskano, 2350-3696 elektronsko) je znanstvena revija, ki podaja temeljne in aplikativne znanstvene informacije v fizikalni, kemijski in tehnološki znanosti, vezani na tekstilno in oblacilno tehnologijo, oblikovanje in trženje tekstilij in oblacil. V prilogah so v slovenskem jeziku objavljeni strokovni clanki in prispevki o novostih v tekstilni tehnologiji iz Slovenije in sveta, prispevki s podrocja oblikovanja tekstilij in oblacil, informacije o raziskovalnih projektih ipd. (ISSN: 0351-3386 printed, 2350-3696 online) the scientific journal gives fundamental and applied scientific information in the physical, chemical and engineering sciences related to the textile and clothing industry, design and marketing. In the appendices written in Slovene language, are published technical and short articles about the textile-technology novelties from Slovenia and the world, articles on textile and clothing design, information about research projects etc. Dosegljivo na svetovnem spletu/Available Online at www.tekstilec.si Tekstilec je indeksiran v naslednjih bazah/Tekstilec is indexed in Emerging Sources Citation Index – ESCI (by Clarivate Analytics) Leiden University's Center for Science & Technology Studies (2019: SNIP 0.496) SCOPUS/Elsevier (2019: Q3, SJR 0.19, Cite Score 0.45, H Index 10) Ei Compendex DOAJ WTI Frankfurt/TEMA® Technology and Management/ TOGA® Textile Database World Textiles/EBSCO Information Services Textile Technology Complete/EBSCO Information Services Textile Technology Index/EBSCO Information Services Chemical Abstracts/ACS ULRICHWEB – global serials directory LIBRARY OF THE TECHNICAL UNIVERSITY OF LODZ dLIB SICRIS: 1A3 (Z, A', A1/2); Scopus (d) Ustanovitelja / Founded by • Zveza inženirjev in tehnikov tekstilcev Slovenije / Association of Slovene Textile Engineers and Technicians • Gospodarska zbornica Slovenije – Združenje za tekstilno, oblacilno in usnjarsko predelovalno industrijo / Chamber of Commerce and Industry of Slovenia – Textiles, Clothing and Leather Processing Association Revijo sofinancirajo / Journal is Financially Supported • Univerza v Ljubljani, Naravoslovnotehniška fakulteta / University of Ljubljana, Faculty of Natural Sciences and Engineering • Univerza v Mariboru, Fakulteta za strojništvo / University of Maribor, Faculty for Mechanical Engineering • Javna agencija za raziskovalno dejavnost Republike Slovenije / Slovenian Research Agency Izdajatelj / Publisher Univerza v Ljubljani, Naravoslovnotehniška fakulteta / University of Ljubljana, Faculty of Natural Sciences and Engineering Sponzor / Sponsor Predilnica Litija, d. o. o. Naslov uredništva / Editorial Office Address Uredništvo Tekstilec, Snežniška 5, SI–1000 Ljubljana Tel./Tel.: + 386 1 200 32 00, +386 1 200 32 24 Faks/Fax: + 386 1 200 32 70 E–pošta/E–mail: tekstilec@ntf.uni–lj.si Spletni naslov / Internet page: http://www.tekstilec.si Lektor za slovenšcino / Slovenian Language Editor Milojka Mansoor Lektor za anglešcino / English Language Editor Glen David Champaigne, Barbara Luštek-Preskar Oblikovanje platnice / Design of the Cover Tanja Nuša Kocevar Oblikovanje / Design Miha Golob Oblikovanje spletnih strani / Website Design Jure Ahtik Tisk / Printed by PRIMITUS, d. o. o. Copyright © 2021 by Univerza v Ljubljani, Naravoslovnotehniška fakulteta, Oddelek za tekstilstvo, grafiko in oblikovanje Noben del revije se ne sme reproducirati brez predhodnega pisnega dovoljenja izdajatelja / No part of this publication may be reproduced without the prior written permission of the publisher. Revija Tekstilec izhaja štirikrat letno / Journal Tekstilec appears quarterly Revija je pri Ministrstvu za kulturo vpisana v razvid medijev pod številko 583. Letna naroc­nina za clane Društev inženirjev in tehnikov tekstilcev je vkljucena v clanarino. Letna narocnina za posameznike 38 € za študente 22 € za mala podjetja 90 € za velika podjetja 180 € za tujino 110 € Cena posamezne številke 10 € Na podlagi Zakona o davku na dodano vrednost sodi revija Tekstilec med proizvode, od katerih se obracunava DDV po stopnji 5 %. Transakcijski racun 01100–6030708186 Bank Account No. SI56 01100–6030708186 Nova Ljubljanska banka d. d., Trg Republike 2, SI–1000 Ljubljana, Slovenija, SWIFT Code: LJBA SI 2X. VOLUME 64 • TEKSTILEC 3 2021 UDK 677 + 687 (05) ISSN 0351-3386 (tiskano/printed) SCIENTIFIC ARTICLES/Znanstveni clanki 188 Desalegn Atalie, Gashaw Ashagre Performance Properties of Half-bleached Weft Knitted Fabrics Made of 100% Cotton Ring Yarns with Different Parameters Ucinkovitost lastnosti polbeljenih votkovnih pletiv, izdelanih iz 100-odstotnih bombažnih prstanskih prej z razlicnimi parametri 197 Xinfeng Yan, Shakhrukh Madjidov, Habiba Halepoto, Lihong Chen Optimisation in the Logistics and Management of Supply Chains in Production by Textile Enterprises Optimizacija v logistiki in upravljanju dobavnih verig proizvodnje v tekstilnih podjetjih 206 Špela Kumer, Gregor Radonjic Analiza okoljskih kriterijev v porocilih o trajnostnem razvoju podjetij v tekstilnem in oblacilnem sektorju Analysis of Environmental Criteria in Sustainability Reports of Companies in the Textile and Apparel Sector 221 Gregor Lavric, Igor Karlovits, Deja Muck, Eva Petra Forte Tavcer, Urška Kavcic Influence of Ink Curing in UV LED Inkjet Printing on Colour Differences, Ink Bleeding and Abrasion Resistance of Prints on Textile Vpliv sušenja tiskarske barve v UV LED kapljicnem tisku na barvne razlike, razlivanje tiskarske barve in odpornost proti drgnjenju potiskanih tkanin 230 A. N. M. Masudur Rahman, Shah Alimuzzaman, Ruhul A. Khan Performance Evaluation of PLA Based Biocomposites Reinforced with Photografted PALF Ocena ucinkovitosti biokompozitov na osnovi polimlecne kisline, ojacenih s fotoinducirano cepljenimi ananasovimi listnimi vlakni 247 Mustafijur Rahman, Mohammad Abbas Uddin, Md. Moynul Hassan Shibly, Nusrat Binta Hossain, Mohammad Forhad Hossain, Muriel Rigout Synthesis and Characterisation of Azo-Based Dichlorotriazine Reactive Dye with Halochromic Behaviour Sinteza in karakterizacija diklorotriazinskega reakcijskega barvila na azoosnovi s halokromnim odzivom 260 Marta Stjepic, Sabina Bracko Colour Memory Analysis for Selected Associative Colours Analiza barvnega spomina za izbrane asociativne barve 188 Tekstilec, 2021, Vol. 64(3), 188–196 | DOI: 10.14502/Tekstilec2021.64.188-196 Desalegn Atalie, Gashaw Ashagre Bahir Dar University, Ethiopian Institute of Textile and Fashion Technology, Textile Production Research and Innovation Centre, 1037, Bahir Dar, Ethiopia Performance Properties of Half-bleached Weft Knitted Fabrics Made of 100% Cotton Ring Yarns with Different Parameters Ucinkovitost lastnosti polbeljenih votkovnih pletiv, izdelanih iz 100-odstotnih bombažnih prstanskih prej z razlicnimi parametri Original scientific article/Izvirni znanstveni clanek Received/Prispelo 8-2020 • Accepted/Sprejeto 2-2021 Corresponding author/Korespondencna avtorica: Desalegn Atalie E-mail: desalegnatalie@gmail.com ORCID: 000-0002-6127-9979 Abstract Knitted fabrics are distinguished by their outstanding comfort for clothing and for their rapid mass production. Though cotton knitted fabrics can provide better comfort, their physical appearance and service life are affected by many factors, and they have a propensity for pilling, abrasion and snagging. The main goal of this research work was to investigate the effect of yarn parameters on the abrasion, pilling and snagging resistance of half-bleached knitted fabrics. Six knitted fabrics were manufactured from 100% cotton carded ring yarn with a linear density of 21, 25, and 30 tex, with two yarn twist levels for each linear density. Except for yarn linear density and twist, the remaining yarn and machine parameters were constant, including fabric manufacturing. The knitted fabrics were treated using a half-bleach treatment before property evaluation. The results showed that knitted fabric made from a finer count of 21 tex with a higher yarn twist of 920 m-1 had the highest mass loss ratio of 2.12–10.76%, and the lowest abrasion resistance of 89–97.88% between 5,000 to 20000 abrasion cycles. The highest abrasion resistance of 96.4–98.9% (mass loss ratio of 1–3.5%) was recorded for a single jersey knitted fabric made from coarser yarn (30 tex) with the lower twist of 826 m-1. The abrasion resistance of knitted fabrics was significantly affected by the thickness of the fabric, while regression analysis proved that fabric thickness and mass loss ratio had very good correlation, with an adjusted R2 value of 93.8%. The snagging resistance of knitted fabrics increased as yarn twist and fineness increased. Pilling propensity increased as yarn linear density increased and twist decreased. Linear regression results revealed that yarn linear density and twist were highly correlated to abrasion resistance (mass loss method) at an adjusted R2 value of 98.6% or 0.986 after 20,000 rubs. Keywords: yarn parameters, knitted fabrics, half-bleached, abrasion, pilling, snagging resistance Izvlecek Izjemna udobnost pletenih oblacil in hitra masovna proizvodnja pletiv sta znani. Ceprav bombažna pletiva zagota­vljajo udobje, pa sta njihov estetski videz in doba trajanja odvisna od številnih dejavnikov, ki vodijo v nastanek pilinga, drgnjenje in izvlecenje zank. Glavni cilj te raziskave je bil prouciti vplive parametrov preje na odpornost proti drgnjenju, pilingu in izvlecenju zank polbeljenih pletiv. Izdelanih je bilo šest pletiv iz 100-odstotnih bombažnih mikanih prstanskih prej s finoco 21 tex, 25 tex in 30 tex z dvema razlicnima stopnjama vitja. Preostali parametri izdelave prej in pletiv so bili enaki. Pletiva so bila pred oceno lastnosti polbeljena. Rezultati so pokazali, da je pletivo, izdelano iz finejše preje 21 tex z višjim vitjem 920 m-1, pri 5000 do 20.000 ciklih drgnjenja izgubilo najvec mase, in sicer 2,12–10,76 %, ter imelo najnižjo, 89–97,88-odstotno odpornost proti obrabi. Najvišja, 96,4–98,9-odstotna odpornost proti drgnjenju (masa zmanjšana za 1–3,5 %), je bila zabeležena pri enojnem jerseju, izdelanem iz preje 30 tex z vitjem 826 m-1. Na odpornost proti drgnjenju je mocno vplivala debelina pletiv. Regresijska analiza je pokazala, da sta debelina in zmanjšanje mase med seboj mocno soodvisna, kar je potrdil 93,8-odstotni korelacijski koeficient, R2. Odpornost pletiva proti izvlecenju zank se je povecala z vitjem in finoco preje. Nagnjenost k pilingu se je povecala, ko se je finoca preje zvišala in se je vitje znižalo. Rezultati linearne regresije po 20.000 drgnjenjih (metoda zmanjšanja mase) so pokazali korelacijo finoce in vitja preje z odpornostjo proti drgnjenju, saj je korelacijski koeficient, R2, znašal 98,6 odstotka ali 0,986. Kljucne besede: parametri preje, pletivo, polbeljeno pletivo, drgnjenje, piling, odpornost proti izvlecenju zank 1 Introduction Abrasion resistance and pilling performance are two of the most important mechanical characteristics of fabrics [1] and a factor in virtually every textile appli­cation. They are also a major purchasing requirement from the consumer’s viewpoint. The abrasion resist­ance of textile materials is affected by many factors in a very complex and poorly understood manner [2]. Market studies have shown that evaluations of con­sumer quality requirements are related to abrasion resistance [3]. Abrasion is the gradual removal of fi­bres from yarns, and is influenced by fibre cohesion in yarns [4]. Kalaoglu et al. and McCord [3, 5] stated that the abrasion resistance of textile materials is af­fected by many factors, such as fibre content, fibre fineness, yarn linear density, yarn type, weave, fabric thickness, finishes, etc. Abrasion first modifies the fabric surface and then affects the internal structure. Similarly, the pilling of knitted fabrics is a persistent and serious problem for the clothing industry [6]. Many parts of clothing, such as collar, cuffs, and pockets are subjected to wear in use, which limits their serviceability. Pilling not only reduces ap­pearance and comfort properties, but also affects the service life of textile products [7]. Uyanik and Topalbekiroglu studied the effects of knit structures on the pilling resistance of knitted fabrics made from the same cotton yarn. The results revealed that sin­gle jersey has a lower pilling resistance than fabrics with tuck stitches, while knit structures with larger pores show higher a resistance to pilling. Some au­thors studied the relationship between fibre, yarn and wool single jersey and rib knitted fabrics on pilling property. The prediction of the pilling tendency of those wool knits was developed by artificial neural network modelling (ANN) [8, 9]. In addition, dyeing and finishing processes reduce the pilling resistance of knitted fabrics [10]. Other authors have researched the effect of wet processing on cellulosic knitted fabrics, and the model suggests that the ends of fibres come out from yarns by me­chanical abrasion due to low fibre-fibre friction [11]. Candan studied the pilling and abrasion properties of different knitted fabrics made from ring and open-end spun cotton yarns, and 50/50 cotton/polyester yarns. The results showed that, unlike plain jersey fabrics, Lacoste fabrics perform very well and that fabrics knitted from open-end spun yarns generally have a lower propensity to pilling [12]. Akaydin and Can stated that the abrasion resistance and pilling performance of interlock fabrics were higher than jersey fabrics, those of dyed fabrics higher than raw fabrics, and those fabrics produced from compact yarns were higher than fabrics produced from ring yarns [13]. Another researcher investigated the effects of fibre type, and single and ply yarns on the abrasion and pilling resistance of socks. The results indicated that the abrasion resistance of socks increased with use of coarser yarn or thicker yarn, the addition of polyester, and the addition of polyamide or elastic yarns to the structure [14]. Knitted fabrics with in­terlock, rib and single jersey structures made from compact and conventional ring yarns and their phys­ical properties were investigated, and compared with each other before and after printing processes. It was found that no statistical differences were observed with regard to weight, abrasion resistance, colour efficiency and rubbing fastness [1]. A previous study reported that the fibrous composi­tion and thickness of materials (up to 6%), as well as washing and softening (from 33% to 67%) change the pilling resistance of knitted fabrics [15]. Daiva stud­ied the pilling resistance of single jersey, rib and in­terlock knitted fabrics made from PES yarns, cotton yarns and cotton yarns combined with PU yarns. The results found that 2×2 rib knitted fabric has a better pilling resistance than interlock, 1×1 rib and plain knitted fabric because of the reduced operating sur­face area. Fabrics knitted from PES (polyester) yarns or those PES yards blended with cotton yarns have a worse visual appearance than fabrics knitted from pure cotton yarns because PES fibres are resistant to malformed pills due to their exceptional strength [6]. A 100% cotton single jersey knitted fabric made from a combed ring yarn with a linear density of 19.7 tex, and a different stitch position and length, was stud­ied, and the results revealed that stitch density (wales/cm and course/cm) and mass per unit area, burst­ing, pilling and abrasion resistance decrease as stitch length increases [16, 17]. Single jersey knitted fabrics with various numbers and position of tuck stitch­es were made from glass yarn using a flat knitting machine. The findings proved that fabric thickness increased and air permeability decreased as tuck stitches increased [18]. The effect of rubbing fastness on single jersey knitted fabrics made of combed ring-spun and compact cotton yarns was researched. The reports showed that knitted fabrics made from com­pact and comb yarn were similar in terms of rubbing property in a dry state. However, single jersey knitted fabrics made from ring yarn have a greater rubbing resistance in a wet state due to the high porosity of the ring yarn fabrics, which allows water molecules to penetrate [19, 20]. Numerous researchers have stated that the end-use properties of clothing, such as pilling effect and abrasion resistance, are influenced by material type, fibre fineness, yarn linear density, yarn strength, yarn hairiness, fabric structure and surface densi­ty [2, 21–24]. A comparison of pilling and abrasion properties of knitted fabrics was performed for differ­ent spinning yarns, such as ring, compact and rotor yarns [25–30]. The effects of washing and drying [1] as well as finishing and dying [31, 32], were also in­vestigated. Knitted fabrics from compact yarns have a higher pilling and abrasion resistance than ring and rotor yarns, while the abrasion resistance of knitted fabrics from ring-spun yarns was slightly better than open-end spun yarns [33]. As shown in a review of literature, many research­ers have studied the effects of yarn structure, linear density, twist and knitted structure on the abrasion, pilling, tensile and tear strength properties of fabrics. Most of the studies were done at the greige fabric level and based on a comparison based on different spinning methods. However, the effects of yarn prop­erties on fabric snagging resistance have not been thoroughly addressed. The aim of this study was to investigate the influence of ring yarn parameters (by varying yarn linear density and twist) on the pilling, abrasion and snagging resistance of half-bleached knitted fabrics. 2 Materials and methods 2.1 Materials Six single jersey knitted fabrics were produced from 100% cotton carded ring yarn counts of 21 tex with two twist levels of 920 m-1 and 905 m-1, 25 tex with twist levels of 890 m-1 and 860 m-1, and 30 tex with twist levels of 847 m-1 and 826 m-1. 2.2 Methods Each of the three yarns with two different twist levels were produced using a ring spinning system (RIETER-G35) manufactured by Bahir Dar Textile Share Company. All yarns were spun from the same fibre mix with a micronaire value of 4.23, a maturity of 0.85, an upper half mean length (UHML) of 29.86 mm, a uniformity index (UI) of 84.5%, a strength of 30.4 cN/tex, an elongation of 7.4%, a short fibre content of 6.7% and a trash grade of three. Yarn lin­ear density and yarn twist were measured according to the ES ISO 2060 and ASTM D1422 test methods, respectively. Six knitted fabrics were manufactured using those developed yarns with incremental twist levels. Except for yarn linear density with different twist levels, the remaining parameters were con­stant and the knitted fabrics were produced on the same SHIMA SEIKI® (model – SES 122 FF, gauge 7) flat knitting machine at the Technical University of Liberec in the Czech Republic. The machine settings, such as machine speed, loop length, and horizontal and vertical density per centimetre were kept con­stant for all fabrics. The yarn and fabric characteris­tics are presented in Table 1. Chemical treatments Hydrogen peroxide (H2O2) based half-bleach com­bined treatment was carried out for knitted fabrics using a winch machine. The fabric and water solution were prepared at a material to liquor ratio (MLR) of 1:5, and hydrogen peroxide (H2O2), sodium silicate (Na2SiO3), sodium hydroxide (NaOH) and a wetting agent of 4%, 2%, 3%, and 0.5% of fabric weight, re­spectively. Knitted fabrics were treated at a temper­ature of 95 °C for 90 minutes at a machine working speed of 40 m/minutes. Abrasion resistance The abrasion resistance of the knitted fabrics was measured using two methods according to ES ISO 12947-1 (appearance change method) at 5,000 cy­cles and ES ISO 12947-3 (mass loss method) using a Martindale Abrasion and Pilling device (Mesdan-Lab, Model 2568). The mass loss ratios of knitted fab­rics were recorded after 5,000, 7,500, 10,000, 15,000 and 20,000 cycles of the Martindale Abrasion and Pilling device. Pressure loading of 9 kPa was used during testing for both methods (1 and 3). Pilling resistance The pilling properties of knitted fabrics were meas­ured using two different methods according to ES ISO 12945-2 after 5,000 cycles using a Martindale Abrasion and Pilling device. The second evaluation was based on ES ISO 12945-1 at 18,000 cycles according to the ICI Pilling-Box method using a Mesdan-Lab device, model no. 1006). Finally, the pilling grade was rated using the EMPA (SN 19825) photographic standard. Snagging resistance A snagging test was evaluated according to ASTM D3939 after 600 revolutions using an SDL ICI Mace snagging tester (model no. P22668). The test speci­mens were graded using the relevant photographic standard. Statistical analysis To determine the analysis of variance and significant test, SPSS version 25 for Windows statistical software was used. Regression analysis was performed using Origin Lab software (version 9.6.5) to determine the correlation of factors (yarn parameters) and response (fabric properties). 3 Results and discussion Table 1 presents the properties and characteristics of the yarns used and the developed knitted fabrics. Except for yarn count and twist levels, all knitted fabrics were produced using the same yarn property, knit type and thread density. Structural properties of knitted fabrics The structural parameters of the knitted fabrics, such as stitch density, loop length, cover factor, thickness and fabric weight were tested and the results are pre­sented in Table 1. The fabric cover factor K is defined as the propor­tion of the fabric area covered by actual yarn and expressed using equation 1. (1) where Tt represents linear density (tex) and l repre­sents loop length. Effects of yarn parameters on abrasion resistance (appearance change) As seen in Figure 1, the abrasion resistance (appear­ance change) of knitted fabrics declined from fabric K1 to K6. This is probably because individual fibres and neps were not firmly held in the yarn cross-sec­tion as turns per meter were decreased. Knitted fabrics made from lower twist yarns had a signifi­cant abrasion effect (appearance change) since the ­presence of hairiness and neps were high in lower twist yarns. As is evident from Figure 1, fabrics K4, K5 and K6 from coarser yarn counts of 25 tex and 30 tex with lower twists of 860 m-1, 847 m-1and 826 m-1 had a slightly poor abrasion resistance grade in surface appearance. As stated above, this is because fibres in the yarn cross-section are not held firmly and are thus easily pulled by the abradant. As seen in Table 2, the statistical analysis also confirmed that abrasion resistance in the appearance change meth­od resulted in a significant change at an F-value of 13.000 and P-value of 0.033. If the P-value is greater than 0.05, this means the samples have similar prop­erties, while the opposite is true if the P-value is less than a value of 0.05. Figure 1: Abrasion resistance of knitted fabrics using the appearance change method Twist is an important parameter affecting abrasion. At low twist levels, it was observed that fibres can be easily pulled from the yarn cross-section and that the resistance grade was reduced at 5,000 rubs. At high twist levels, however, the fibres are held more tightly, but the yarn is stiffer, so it is unable to distort under pressure when it is abraded. The findings of this study are in line with Saville’s report [4]. Multiple regression analysis showed that the studied yarn pa­rameters have a positive correlation with the abrasion resistance (appearance change) of knitted fabrics at an adjusted R2 of 0.801. The adjusted R2 value is an indication of the correlation of yarn properties (fac­tors) and fabric characteristics (responses). When the adjusted R2 value increases or decreases to 1 or –1, this indicates a strong correlation between them [34]. Effects of yarn parameters on abrasion resistance (mass loss) As is evident from Figure 2, the knitted fabric weight mass loss ratio was increased as abrasion cycles in­creased in all fabrics. Nevertheless, the abrasion resistance increased as yarn count (tex) increased and yarn twist decreased. On the other hand, fin­er counts and higher twist yarns resulted in fabrics with thinner thickness, which had a high tendency to be abraded quickly. This, in turn, this led to higher mass loss ratio. As seen in Figure 2, knitted fabrics made from 30 tex with a yarn twist of 847 m-1 have a higher abrasion resistance of 96.4-98.9% (mass loss ratio of 1-3.5%) between 5,000 to 20,000 abrasion cycles than other developed fabrics. Knitted fabrics made of 25 tex with a twist per meter (TPM) of 890 m-1 and 860 m-1 demonstrated moderate abrasion resistance, while knitted fabrics made from a finer yarn count of 21 tex with the highest yarn twist of 920 TPM demonstrated the highest mass loss ratio of 2.12-10.76% or an abrasion resistance of 89-97.88%. For this reason, fabrics from coarser yarn are thicker and bulky, and will require a great deal of time and a higher number of abrasion cycles to lose their origi­nal mass. These findings inveterate an earlier report by Kalaoglu and Onder [5]. As illustrated in Table 2, the statistical analysis proves that the abrasion resistance (mass loss method) of knitted fabric resulted in a insignificant change at a P-value of 0.660 after 5,000 rubs, and a significant change at P-values of 0.038, 0.000, 0.010 and 0.008 af­ter 7,500, 10,000, 15,000 and 20,000 rubs, respectively. The results showed that the correlation of yarn param­eters and abrasion resistance (mass loss method) was low at an adjusted R2 value of 0.242 after 5,000 rubs. On the other hand, yarn twist and count were highly correlated with abrasion resistance at an adjusted R2 value of 98.6% or 0.986 after 20,000 rubs. As observed from Table 1 and Figure 2, fabric thickness affects the abrasion resistance of knitted fabrics because thin fabrics withstand damage during friction for an ex­tended period, and vice versa for thicker fabrics. The regression analysis proves that fabric thickness and abrasion mass loss are directly proportionate and cor­related with an adjusted R2 value of 84.3%. Effects of yarn parameters on pilling resistance Table 3 illustrates the pilling resistance of knitted fabrics using the Martindale and ICI Pilling Box methods. The results obtained from the ICI Pilling Box method demonstrated a higher pilling resistance than the pilling grade using the Martindale method for all knitted fabrics. This is because the ICI Pilling Box method was performed at a low mechanical force, while test specimens were dropped randomly on a wooden board during rotations. However, me­chanical force is higher in the Martindale tester than in the ICI Pilling Box method because consistent friction is formed by the Lissajous pattern form on the fabric (ISO 12947-1: 1998). In both test methods, knitted fabrics made from finer ring yarns had a higher pilling resistance than fabrics from coarser yarns. The reason for this is that the coarser yarns had less twist and fibres are easily pulled from the yarn cross-sec­tion. On the contrary, knitted fabrics from finer yarns had a compact structure, which means fibres would be hidden by twist and are hard to raise by the piler. The researchers Omeroglu and Ulku also reported a similar concept [2]. As is evident from Table 2, the pilling resistance of knitted fabrics in the ICI Pilling Box method resulted in a significant change at an F-value of 13.500 and P-value of 0.004. On the other hand, knitted fabrics did not show a significant difference after the pill­ing property test using a Martindale Abrasion and Pilling device with an F-value of 1.333 and P-value of 0.385. In previous studies, some researchers reported a similar concept, i.e. pilling tendency increased as mass per unit area of polyester-cotton blended fab­rics increased. [35, 36]. As mentioned above, multiple regression results proved that the pilling resistance of knitted fabrics (ICI Pilling Box method) had a neg­ative correlation with studied yarn parameters with an adjusted R2 value of -0.760. Effect of yarn parameters on snagging resistance Snagging resistance was evaluated using ICI photo­graphic snagging standards, which consists of five incremental photo replicas, grades 5 to 1. Grade 5 indicates no snagging, grade 4 indicates slight snag­ging grade 3 indicates moderate snagging, grade 2 indicates sever snagging and grade 1 indicates very severe snagging. As shown in Figure 3, the snagging resistance of knitted fabrics decreased as yarn linear density (tex) increased and twist decreased. Knitted fabrics K1 and K2 made from 21 and 25 tex had a higher snagging resistance (grade 4-5), followed by fabric from 30 tex. The snagging grade also declined as yarn twist decreased. This is because knitted fab­rics from higher twist yarns are very strong and fibres are held firmly in the yarn cross-section, meaning they are not easily snagged by sharp and rough ob­jects. As stated in a previous study, yarn strength gen­erally increases as yarn twist increases (19). However, fabrics made from coarser yarn with a lower twist demonstrated a poor snagging grade because yarns with less yarn twists have low turns per meter in the yarn cross-section, and are more easily snagged by sharp materials. These findings confirm an earlier study by Paek [7]. Figure 3: Snagging resistance As shown in Table 2, the snagging resistance of knitted fabrics was affected by yarn parameters at an F-value of 18.500 and P-value of 0.021. Multiple linear regression proved that yarn parameters had very good correlation with the snagging resistance of fabrics at an adjusted R2 value of 0.949 (94.9%). In addition, yarn count and fabric thickness were highly correlated with the snagging resistance of knitted fabrics at an adjusted R2 value of 0.898 (89.8%) and 0.955 (95.5%), respectively. Textile materials, such as knitted fabrics and military cloths, are subjected to snagging. Rough objects, fingernails or toenails are some initiators of the snagging effect for knit­ted fabrics. Therefore, knitted fabric manufacturers should consider yarn count and twist for the desired snagging resistance of fabrics. 4 Conclusion Six 100% cotton single jersey knitted fabrics were produced from 21, 25 and 30 tex ring-spun yarns with different twist levels. The knitted fabrics underwent half-bleach treatment and drying. The abrasion, pill­ing and snagging properties of knitted fabrics were evaluated using a Martindale Abrasion and Pilling tester, the ICI Pilling Box method and a Mace snag­ging tester. The results obtained showed that knitted fabric made from a finer count of 21 tex with high­est yarn twist of 920 TPM demonstrated the highest mass loss ratio of 2.12-10.76% (poor abrasion resist­ance 89-97.88%) between 5,000 to 20,000 abrasion cycles. On the contrary, single jersey knitted fabrics made from coarser yarn (30 tex) with the lowest twist (826 TPM) demonstrated a higher abrasion resistance of 96.4-98.9% (mass loss 1-3.5%). The pilling pro­pensity increased as yarn count (tex) increased and twist decreased. Linear regression results revealed that yarn count and twist were highly correlated with abrasion resistance (mass loss method) at an adjust­ed R2 value of 98.6% or 0.986 after 20,000 rubs. The snagging resistance of knitted fabrics increased as yarn twist and yarn fineness increased. Generally, abrasion resistance was highly affected by the thick­ness of the fabric, while regression analysis proved that fabric thickness and mass loss ratio had very high correlation with an adjusted R2 value of 93.8%. References 1. ÖZGÜNEY, A.T., DÖNMEZ, Kretzschmar S., ÖZÇELIK, G., ÖZERDEM, A. The comparison of cotton knitted fabric properties made of compact and conventional ring yarns before and after the printing process. Textile Research Journal, 2008, 78(2), 138–147, doi: 10.1177/0040517507080249. 2. OMEROGLU, S., ULKU, S. An investigation about tensile strength, piling and abrasion prop­erties of woven fabrics made from conventional and compact ring-spun yarns. Fibres and Textiles in Eastern Europe, 2007, 15(1), 39–42. 3. MCCORD, J.P.M. Cotton quality study: V: Resistance to abrasion. Textile Research Journal, 1960, 30(10), 715–751, doi: 10.1177/004051756003001001. 4. SAVILLE, B.P. Physical testing of textiles. Cambridge : Woodhead Publishing, 1999. 5. KALAOGLU, F., ONDER, E., ÖZIPEK, B. Influence of varying structural parameters on abrasion char­acteristics of 50/50 wool/polyester blended fabric. Textile Research Journal, 2003, 73(11), 980–984, doi: 10.1177%2F004051750307301108. 6. DAIVA, M. The influence of structure parameters of weft knitted fabrics on propensity to pilling the influence of structure parameters of weft knitted fabrics on propensity to pilling. Materials Science (Medžiagotyra), 2009, 15(4), 335–338. 7. PAEK, S.L. Pilling, abrasion, and tensile prop­erties of fabrics from open-end and ring spun yarns 1. Textile Research Journal, 1989, 59(10), 577–583, doi: 10.1177/004051758905901004. 8. KAYSERI, G.Ö., KIRTAY, E. Predicting the pill­ing tendency of the cotton interlock knitted fab­rics by artificial neural network: part II. Journal of Engineered Fibres and Fabrics, 10(4), 2015, 62–71, doi: 10.1177/155892501501000417. 9. BELTRAN, R., WANG, L., WANG, X. Predicting the pilling tendency of wool knits. The Journal of The Textile Institute, 2006, 97(2), 129–136, doi: 10.1533/joti.2005.0135. 10. UYANIK, S., TOPALBEKIROGLU, M. The ef­fect of knit structures with tuck stitches on fabric properties and pilling resistance. The Journal of The Textile Institute, 2017, 108(9), 1584-1589, doi: 10.1080/00405000.2016.1269394. 11. OKUBAYASHI, S., CAMPOS, R., ROHRER, C., BECHTOLD, T. A pilling mechanism for cellu­losic knit fabrics – effects of wet processing. The Journal of The Textile Institute, 2005, 96(1), 37–41, doi: 10.1533/joti.2004.0055. 12. CANDAN, C., ÖNAL, L. Dimensional, pill­ing, and abrasion properties of weft knits made from open-end and ring spun yarns. Textile Research Journal, 2002, 72(2), 164–169, doi: 10.1177/004051750207200213. 13. AKAYDIN, M., CAN, Y. Pilling performance and abrasion characteristics of selected basic weft knitted fabrics. Fibres and Textiles in Eastern Europe, 2010, 18(2), 51–54. 14. EL-DESSOUKI, H.A.A. Study on abrasion character­istics and pilling performance of socks. International Design Journal, 2010, 4(2), 229–234, https://www.faa-design.com/files/4/10/4-2-desoki.pdf. 15. BUSILIENE, G., LEKECKAS, K., URBELIS, V. Pilling resistance of knitted fabrics pilling resistance of knitted fabrics. Materials Science (Medžiagotyra), 2011, 17(3), 297–301, doi: 10.5755/j01.ms.17.3.597. 16. AKTER, S., Al FARUQUE, M.A., ISLAM, M.M. Effect of stitch length on different properties of plain single jersey fabric. International Journal of Modern Engineering Research, 2017, 7(3), 71-75. 17. ASSEFA, A., GOVINDAN, N. Physical prop­erties of single jersey derivative knitted cotton fabric with tuck and miss stitches. Journal of Engineered Fibres and Fabrics, 2020, 15, doi: 10.1177/1558925020928532. 18. INCE, M.E. The effect of number and position of tuck stitches within the pattern repeat on air permeability of weft-knitted fabrics from glass yarn. Academic Perspective Procedia, 2019, 2(3), 317-323, doi: 10.33793/acperpro.02.03.2. 19. SHAHID, M.A., HOSSAIN, M.D., NAKIB-UL-HASAN, M., ISLAM, M.A. Comparative study of ring and compact yarn-based knitted fabric. Procedia Engineering, 2014, 90(1), 154-159, doi: 10.1016/j.proeng.2014.11.829. 20. SIDDIKA, A., UDDIN, M.N., JALIL, M.A., AKTER, N.N., SAHA, K. Effects of carded and combed yarn on pilling and abrasion resistance of single jersey knit fabric. IOSR Journal of Polymer and Textile Engineering, 2017, 4(2), 39-43, doi: 10.9790/019X-04023943. 21. KANE, C.D., PATIL, U.J., SUDHAKAR, P. Studies on the influence of knit structure and stitch length on ring and compact yarn single jersey fabric properties. Textile Research Journal, 2007, 77(8), 572–582, doi: 10.1177/0040517507078023. 22. MILAŠIUS, V., MILAŠIUS, R., KUMPIKAITÉ, E., OLŠAUSKIENÉ, A. Influence of fabric structure on some technological and end-use properties. Fibres & Textiles in Eastern Europe, 2003, 41(2), 48–51. 23. ATALIE, D., GIDEON, R. K., FEREDE, A., TESINOVA, P., LENFELDOVA, I. Tactile com­fort and low-stress mechanical properties of half-bleached knitted fabrics made from cotton yarns with different parameters. Journal of Natural Fibres, 2019, in press, doi: 10.1080/15440478.2019.1697989. 24. ORTLEK, H.G., TUTAK, M., YOLACAN, G. Assessing colour differences of viscose fabrics knitted from vortex-, ring- and open-end ro­tor-spun yarns after abrasion. The Journal of The Textile Institute, 2010, 101(4), 310–314, doi: 10.1080/00405000802399528. 25. MOHAMED, M.H., LORD, P.R. Comparison of physical properties of fabrics woven from open-end and ring spun yarn. Textile Research Journal, 1973, 43(3), 154–166, doi: 10.1177%2F004051757304300306. 26. BECEREN, Y., NERGIS, B.U. Comparison of the effects of cotton yarns produced by new, modified and conventional spinning systems on yarn and knitted fabric performance. Textile Research Journal, 2008, 78(4), 297–303, doi: 10.1177/0040517507084434. 27. ALTAS, S., KADOGLU, H. Comparison of con­ventional ring mechanical compact and pneu­matic compact yarn spinning systems. Journal of Engineered Fibres and Fabrics, 2012, 7(1), 87–100, doi: 10.1177/155892501200700110. 28. BLACK, D.H. Knitting with cotton and cotton blend open-end spun yarns. Textile Research Journal, 1975, 45(1), 48–53, doi: 10.1177%2F004051757504500109. 29. ORTLEK, H.G., ONAL, L. Comparative study on the characteristics of knitted fabrics made of vor­tex-spun viscose yarns. Fibres and Polymers, 2008, 9(2), 194–199, doi: 10.1007/s12221-008-0031-3. 30. KRETZSCHMAR, S.D., ÖZGÜNEY, A.T., ÖZÇELIK, G., ÖZERDEM, A. The comparison of cotton knitted fabric properties made of com­pact and conventional ring yarns before and after the dyeing process. Textile Research Journal, 2007, 77(4), 233–241, doi: 10.1177/0040517507076745. 31. YANG, C.Q., ZHOU, W., LICKFIELD, G.C., PARACHURA, K. Cellulase treatment of dura­ble press finished cotton fabric: effects on fabric strength, abrasion resistance, and handle. Textile Research Journal, 2003, 73(12), 1057–1062, doi: 10.1177/004051750307301205. 32. CANDAN, C., NERGIS, U.B., IRIDAG, Y. Performance of open-end and ring spun yarns in weft knitted fabrics. Textile Research Journal, 2000, 70(2), 177–181, doi: 10.1177/004051750007000215. 33. ATALIE, D., GIDEON, R. Prediction of psycho­logical comfort properties of 100% cotton plain woven fabrics made from yarns with different parameters. Tekstilec, 2020, 63(1), 60-67, doi: 10.14502/Tekstilec2020.63.60-67. 34. ISO12947-1. Textiles – Determination of the abrasion resistance of fabrics by the Martindale method – Part 1: Martindale abrasion testing apparatus. Geneva : ISO Copyright Office, 1998. 35. AKTER, Smriti S., ISLAM, Md. Azharul. An ex­ploration on pilling attitudes of cotton polyester blended single jersey knit fabric after mechanical singeing. Science Innovation, 2015, 3(1), 18–21, doi: 10.11648/j.si.20150301.12. 36. ASIF, A., RAHMAN, M., FARHA, F.I. Effect of knitted structure on the properties of knitted fab­ric. International Journal of Science and Research (IJSR), 2015, 4(1), 1231–1235, . Table 1: Yarn and knitted fabric characteristics Fabric code Yarn linear density (tex) Twist (m-1) Knit type Loop length (mm) Cover factor (K) Stitch densi­ty (stitch/cm) (horizontal/vertical) Thickness (cm) Mass per unit area (g/m2) K1 21 920 Plain 4.10 0.96 9/12 0.071 184 K2 21 905 Plain 4.10 0.98 9/12 0.075 189 K3 25 890 Plain 4.12 1.21 9/12 0.082 196 K4 25 860 Plain 4.11 1.26 9/12 0.086 203 K5 30 847 Plain 4.10 1.37 9/12 0.091 211 K6 30 826 Plain 4.08 1.44 9/12 0.096 224 Figure 2: Abrasion results of knitted fabrics using the mass loss method (at 5,000, 7,500, 10,000, 15,000 and 20,000 rubs) Table 2: Analysis of variance of knitted properties Fabric properties Sum of squares Df Mean square F Sig. Pilling (Martindale method) Between groups 0.333 5 0.167 1.333 0.385 Within groups 0.375 3 0.125 Pilling (ICI Box method) Between groups 0.583 5 0.292 13.500 0.004 Within groups 0.250 3 0.083 Abrasion resistance (appearance change) Between groups 1.083 5 0.542 13.000 0.033 Within groups 0.125 3 0.042 Abrasion mass loss (at 5,000 rubs) Between groups 0.336 5 0.168 0.478 0.660 Within groups 1.054 3 0.351 Abrasion mass loss (at 7,500 rubs) Between groups 4.606 5 2.303 11.589 0.038 Within groups 4.348 3 1.449 Abrasion mass loss (at 10,000 rubs) Between groups 7.293 5 3.646 12.006 0.000 Within groups 5.454 3 1.818 Abrasion mass loss (at 15,000 rubs) Between groups 16.427 5 8.214 8.773 0.010 Within groups 13.896 3 4.632 Abrasion mass los (at 20,000 rubs) Between groups 16.695 5 8.347 11.102 0.008 Within groups 22.724 3 7.575 Snagging resistance Between groups 3.083 5 1.542 18.500 0.021 Within groups 0.250 3 0.083 Table 3: Pilling resistance of knitted fabrics Yarn linear density (tex) Fabric code Evaluation methods Martindale method ICI Pilling Box 21 K1 3/4 4-5 K2 3 4 25 K3 3 4 K4 3/4 3-4 30 K5 3 3-4 K6 2/3 3-4 197 Tekstilec, 2021, Vol. 64(3), 197–205 | DOI: 10.14502/Tekstilec2021.64.197-205 Xinfeng Yan1, Shakhrukh Madjidov2, Habiba Halepoto3,4, Lihong Chen5 1 ICES of Donghua University, No. 1882, West Yan’an Road, Shanghai 200051, China 2 Changshu Institute of Technology, 99 South Third Ring Road, Suzhou, Jiangsu 215500, China 3 Donghua University, University, Engineering Research Center of Digitized Textile and Fashion Technology, Shanghai 201620, China 4 Donghua University, College of Information Science and Technology, Shanghai 201620, China 5 Donghua University, Shanghai International Fashion Innovation Center, 200051, China Optimisation in the Logistics and Management of Supply Chains in Production by Textile Enterprises Optimizacija v logistiki in upravljanju dobavnih verig proizvodnje v tekstilnih podjetjih Original Scientific Article/Izvirni znanstveni clanek Received/Prispelo 6-2020 • Accepted/Sprejeto 3-2021 Corresponding author/Korespondencni avtor: Lihong Chen E-mail: lchkxyy@163.com Abstract This article is devoted to questions regarding the analysis of the implementation of logistics and supply chain management conditions in textile production. Based on delivery optimisation, the authors offer a model of multimodal transportation of textile products produced in Uzbekistan. The importance of optimising the supply chain of the logistics business processes in order to decrease costs is demonstrated in this article. A mathemat­ical model of optimisation for placement textile enterprises to stimulate the reduction of supply chain costs is recommended. However, this research would be beneficial for the textile and fashion industries. The approach might be further extended to other similar industries. Keywords: logistics, transportation management, multimodal transportation, optimisation, supply chain management Izvlecek V clanku so obravnavana vprašanja, povezana z analizo pogojev izvedbe logistike in upravljanja dobavne verige v tekstilni proizvodnji. Na podlagi optimizacije dostave avtorji predlagajo kombinirane prevoze tekstilnih izdelkov, izdelanih v Uzbekistanu. V clanku je dokazan pomen optimizacije dobavne verige logisticnih poslovnih procesov za zmanjšanje stroškov. Priporocen matematicni model optimizacije plasiranja tekstilnih podjetij spodbuja zmanjšanje stroškov dobavne verige. Raziskava se nanaša na tekstilno in modno industrijo, vendar je pristop mogoce razširiti na druge podobne industrije. Kljucne besede: logistika, upravljanje prevoza, kombinirani prevozi, optimizacija, upravljanje dobavne verige 1 Introduction The globalisation of the world economy, the develop­ment of information technologies, means and ways of delivering products, the outsourcing of business processes, and services have a considerable impact on the way administrative decisions are adopted in all components of the business processes of production, marketing, commerce and logistics [1]. Adopting op­timal administrative solutions in difficult economic situations has always been a constant in the practical activities of textile sectors throughout the world [2]. Moreover, their role has increased considerably re­cently as the dynamism of the external and internal environment has increased. The period required to make decisions has been reduced. The development of science and technologies has resulted in the emer­gence of many alternative options and interdepend­ence. Different administrative decisions and their consequences have been amplified. The labour input required to adopt and implement challenging and multi-criteria decisions has increased significantly [3]. In these conditions, establishing rational and optimal solutions is the main focus of developing textile enterprises’ logistics and organisations’ busi­ness processes at the strategic and operational levels to improve supply chain management and logistics methods [4, 5]. The need for the high-quality growth of Uzbekistan’s economy assumes that textile enter­prise managers make better use of the entire range of methods and models of adopting optimal solutions in the supply, production and distribution of goods and services in the logistics and supply chain. A diagnostic analysis of the administrative decisions made by the managers of textile enterprises and sup­ply chain participants allowed us to establish that adopting logistic decisions used in practice is char­acterised by utility and subjectivity, and a lack of modern computer technologies (software products). The conducted research can be deemed the further development of the theory and methodical bases of supply chain management, and an opportunity for the broader application of mathematical models and methods for adopting optimal logistic solutions in the performance of management functions and the business processes of production, distribution, transportation and consumption of intermediate and readymade products [6-10]. Despite the extensive and practical application of logistics and supply chain management in the or­ganisation of the transportation and production of goods, it is still not fully implemented in Uzbekistan. There is a lack of exhaustive scientific research suc­cessfully carried out in these areas. The importance of optimising logistics business processes to cut costs is demonstrated in this article using a mathematical model. Though different models have been proposed for other industries, the textile and fashion industry has not considered them. We have developed a meth­od for optimising the business process of distribution and sales (supply) of a textile enterprise’s finished products based on an economic and mathematical model for optimising the sales structure. Thus, this research practically presents a practical solution for both the textile and fashion industries. 2 Methods 2.1 Analysis of conditions in the textile industry in Uzbekistan Uzbekistan is one of the largest global cotton-fibre suppliers, while it also pays a great deal of attention to the deep processing of raw cotton [11]. For in­stance, the current coefficient of processing is 40%. The adopted modernisation programme of the textile industry is expected to bring the processing volume to 70% by 2020 [5]. In the modern world, the textile industry possesses a high rating among the other exports. It has the broadest range of exported goods’ nomenclature, from yarn to readymade goods (ap­parel and knitted products; see Figure 1). The textile industry is an essential, versatile and innovatively attractive sector of the economy of Uzbekistan. Its role is a macroeconomic complex that can be assessed from the following data: the textile in­dustry accounts for 2.7% of Uzbekistan’s GDP, 26.2% of industrial output in terms of volume, and more than 34% of the production of non-food consumer goods. Four hundred textile companies equipped with modern conditions are included in the UZTEX Group. Of those, 130 are joint ventures created with the participation of foreign partners from the world’s leading countries. The group records annual increas­es in production and exports of more than 18% and 10%, respectively. The annual combined output of group companies is around 480 thousand tonnes of yarn, 290 million square meters of cotton fabrics, 101 thousand tonnes of knitted cloth, 275 million pairs of stitched-knitted products, 53.1 million pairs of socks and hosiery, and 2.1 thousand tonnes of raw silk threads. Group companies also make products for medical use, nonwoven fabrics, batting products, uniforms and fashion apparel, and eiderdown prod­ucts. Companies operate continuously using mod­ern and efficient equipment. More than 1.6 million spinning spindles and 100 thousand cabinets are commissioned for operation, accounting for 89.3% of existing technological equipment. Products pro­duced by the textile industry are exported to more than 50 countries, including European countries, China, the Commonwealth of Independent States, Latin America, the Republic of Korea, Singapore, Israel, Iran, the USA and others. In this regard, tex­tile enterprises’ supply chain management issues are crucial today. The formation of textile supply chains has some so­phisticated and distinctive influencing factors. They include the need for technological associativity based on a material stream that defines the contractors’ choice, providing the delivery of and ability to ren­der additional services. They also include the physi­cal characteristics of a material stream that define a means of transportation and storage conditions, with the choice of the transport scheme and the warehous­ing method, respectively (refer, Figure 2). One of the primary operating conditions of a tex­tile enterprise’s supply chain management is its in­terconnected system, which streams of goods and services and the labour force, and moves within the market system under the influence of market stim­ulus [12-17]. 2.2 Model formulation An analysis of scientific literature over the last ten years regarding developments and the functioning of supply chains allowed us to formulate the following basic principles for carrying out the optimisation of supply chains and logistics business processes [18]: I. The purposes of optimisation must be measur­able and correspond to the optimality criteria of the actual logistic decision. This must be reflected in the statement of the corresponding task (the administra­tive decision). The following optimality criteria can be sued to create the general economic-mathematical model of optimisation of the sales of a manufacturer’s finished goods: to maximise sales and profit, while minimising used resources and costs. Thus, various statements of problems of optimisation and the im­plementation of the associated economic-mathemat­ical models can be developed. Thus, if the global pur­pose of business management lies in the hierarchy, then its purpose is about maximising overall profit, while the optimisation of supply is carried out for commodity groups of finished goods. To that end, the economic regulations of the sales dynamics of finished goods in natural units of measurement (O), proceeds from the sales of finished goods (R) and the dependence of price on sales of finished goods are used (C) in the implementation of these tasks. The graphs of these dependencies are shown in Figure 3. (1) (2) Consequently, a textile enterprise’s profit as the dif­ference between revenue and total costs (I) takes the form of a second-degree polynomial (P), which should be reflected in the profit maximisation prob­lem statement. Therefore, the profit of a textile enterprise, as a variety of procedures and general costs, has the aspect of a second-degree polynomial that must be reflected in a problem statement of maximising profit. The development of an economic-mathematical model for optimising the delivery of finished goods to com­modity groups is based on the textile UZTEX Group. Optimality criteria result in the statement and solu­tion of optimising the sales structure and delivery of finished goods to maximise a textile company’s profit. Thus, the regression dependence of the profit of in one thousand US dollars from sales of t-shirts in one thousand pieces has the following aspect: (3) The regression dependence of the profit of in one thousand US dollars from sales of sportswear in one thousand pieces has the following aspect: (4) The regression dependence of the profit of in one thousand US dollars from sales of hosiery in one thousand pieces has the following aspect: (5) The graphs of these regression dependences of profit from sales are shown in Figure 4. Graphical model­ling allows us to conclude that there are maximum profit values at the optimal sales of the indicated types of finished products of a textile company. It is possi­ble to optimize the structure of its sales and supply. The economic-mathematical modelling of the sales structure of finished goods of three main types consists of the formation additive function, which maximises the general profit from sales of t-shirts, sportswear and hosiery. The statement and solution of the optimising task are given below: (6) (7) Given (8) (9) Thus, an optimal volume of the sale and supply of t-shirts to consumers is 25 thousand pieces, while that figure is 38 thousand pieces for sportswear and 46 thousand piecesfor hosiery. The UZTEX Group’s overall maximum profit will be equal to $10.17 million. II. Models of optimisation must be adequate, and accurately illustrate the logistics business pro­cesses and functions of supply chain management. Economic-mathematical optimisation models must be designed using concrete figures for logistics busi­ness processes and contain quantitatively measurable conditions for their implementation. They must be expressed in a system of restrictions of the model in terms of the size of used resources and reasonable assumptions on the scope of variation. In these terms, the research of operations applied in optimising lo­gistics business processes should be supplemented with mathematic-statistical characteristics that take into account the probability of realisation under the established law of parameter distribution of these processes as random sizes. III. The external conditions and parameters of the internal environment of supply chains and logistics business processes vary. While carrying out the opti­misation, it is necessary to consider possible changes in the external conditions and parameters of logistic decisions. Similar changes are made periodically or in the process of detection to the developed econom­ic-mathematical models of optimisation. Previous practice with optimising models shows that they can be applied in an imitating form [19]. This assumes the automatic recalculation of optimisation results when there is a change of factorial signs and system parameters of the restrictions imposed on the used resources in supply chains. IV. Data regarding the parameters of supply chains must be exact, timely and quick. This requirement is due to the use of that data in optimisation models, whose results significantly vary depending on the values of factorial signs and system of restrictions. Testing the results of the optimisation parameters of supply chains is obligatory. Such testing is carried out by verifying developed models and the results obtained via other economic-mathematical process­ing. The large number of records regarding supply chain parameters requires the preliminary analysis of those records, in a subsequence of integration and the use of new software products for optimisation by the chosen optimality criteria. V. Optimising calculations of supply chain pa­rameters must be presented in a form convenient for use. The form of representing results of optimisation must facilitate the adoption and implementation of administrative decisions by managers. The develop­ment and application of unique decision-making algorithms are needed where applied supply chain optimisation parameters are one of the key factors [20]. Though it is still an essential element, the algo­rithm used to develop the optimal solution in supply chains must be flexible, adaptable and confirmable. This will facilitate the implementation of manage­ment decisions regarding supply chains. VI. Optimisation requires the qualified profes­sionals of companies to search for the best logistics decision [21]. This principle and requirement pro­vide scientific and almost reasonable optimisation objectives, including intentional function, optimal­ity criteria, a system of restrictions of the econom­ic-mathematical model of the logistics decision, and modern software. It is not necessary to assu­me the correct objective definition of optimisation and the effective use of computer programs. This is particularly true for workers who do not posses the necessary knowledge in this area or experience in optimising calculations. VII. Monitoring supply chains and logistics busi­ness processes subject to optimisation. The busi­ness processes for which optimisation is carried out must be supported according to goals and developed algorithms. However, this does not ex­clude their continuous improvement by managing changes and the emergence of more effective soft­ware products. 3 Results and discussion The monitoring of optimised supply chains is sup­plemented with an assessment and analysis of opti­misation costs. The maintenance of and changes to initial optimised parameters, as the improvement of supply chains, demand considerable technology and personnel costs. Also necessary are the assessment of the total costs of optimisation and the comparison of a previous decision with control alternatives. The definition of the impact of the optimisation of tech­nology on the economic indicators of an organisation requires benchmarking. This might relate to crucial indicators of efficiency before technological imple­mentation, the comparison of optimisation results with control indicators and the performance of reg­ular audits of optimised business processes. A critical place in supply chain management is taken by the optimisation of the arrangements of a ware­house chain in the territory served. The optimisa­tion of a logistics chain includes analysing data and logistics strategy elements for the definition of quan­tity and delivery volumes, and the arrangement of distribution centres to achieve an optimum balance between the level of service and logistics costs. The optimisation of a chain allows us to increase service quality and achieve significant efficiency in terms of the maintenance costs of a warehouse, the transpor­tation of goods and investment. Growing interest in the optimisation of chains among professional logis­tics providers has caused significant growth in the software market for optimisation over the last five years. However, many companies mistakenly car­rying out optimisation based only on the analysis of data. By paying too much attention to econom­ic-mathematical modelling, companies miss the stra­tegic and practical contexts of optimisation, which may lead to a severe reduction in their client base. The characteristics of the shipment of goods through optimisation software may consider these critical, but less operational factors. The optimisation possibilities of software have im­proved considerably over the last five years and now allow us to carry out complex factorial analysis [22]. However, logistics specialists must rely not only on the modelling instruments of decision-making support, but also on the defining factors of creating a distribu­tive chain. The best approach consists of the optimum combination of these tools that facilitate the econom­ic-mathematical modelling of a distributive chain. This includes practical questions regarding a logistic chain’s arrangement and objective statements, and the development of the corresponding strategy. Initially, it is necessary to consider the shortcom­ings of the specific optimisation of a chain. It is then possible to offer a modern approach to carrying out similar optimisation. This considers the strategic and practical questions regarding the placement of a logistic chain and their integration with optimisation results. Companies wishing to optimise logistics net­works spend most of the time collecting and develop­ing accurate operational estimates of costs to satisfy data software package requirements. Considerable efforts are necessary for processing, analysing and verifying data to accurately understand their general corporate strategy with regard to their impact on the supply chain. Meetings with clients to plan future service parameters of the chain using data serve as secondary sources for analysis. A company can af­ford or delay optimising a chain or consider potential supply chain harmonisation without optimising the needs of its supply chain participants due to the high probability of the need to purchase assets for the de­velopment and optimisation of the chain. This is not less important than the practical strategic objective of achieving logistics chain optimisation. Support for the adoption of the logistics decision to optimise a network is provided using modern software [18], which gives significant assistance for assessing collected data regarding the quantitative and qualitative parameters of a network and the pro­ductive parameters obtained from economic-mathe­matical modelling. 3.1 Application and implication of the model In the integrated supply chain management world, the textile companies seek to optimise supply chains and the functional area of logistics, and the business processes of transportation, warehousing and dis­tribution to achieve the maximum results while op­timising current costs and resources [23]. In order to optimise economic streams at companies and in supply chains, the managers of foreign textile com­panies use well-known methods and ways that might include six sigma, economical production, integrat­ed quality control, complicated computer modelling instruments, and the planning of deliveries, the use of modern technologies of management, and other numerous optimisation methods [24]. In the broadest terms, optimisation means balancing several factors to achieve the best overall result. In planning, for example, optimisation means balancing the use of transport and operational costs, i.e. the reserve rate, including customer service. The prices of finished goods and raw materials, outputs or a combi­nation of business processes are balanced to achieve cooperation. In the processing mode, transaction optimisation means using modern software to choose the best alternative processes, such as the routing of shipment or distribution of production [25]. We must, however, take into account the best pos­sible decision that provides the maximum result in each specific situation. This is impractical as its achievement requires high implementation costs. For example, textile companies develop an optimal distributive chain variant. Computer modelling can build an optimum chain of similar distribution on several markets and place the distributor’s primary distribution centre on several markets. From a prac­tical point of view, however, a better approach is to implement a decision on only one market. In other words, instead of looking for the ideal decision, it is better to choose the practical decision for each spe­cific situation. We can add to the central questions of optimising logistics business processes and supply chain man­agement the definition of its purpose, optimality cri­teria, and the corresponding restrictions regarding time and resources. In strict economic-mathemat­ical terms, optimisation represents the process of searching for parameters, such as economic streams, logistics business processes and supply chain man­agement. By using them, the extreme (minimum or maximum) value of the indicator (vector) chosen by the optimality criteria is achieved [18]. Companies took a huge step forward in data pro­cessing automation, deliveries connected with a par­ticular chain and logistics operations. While these innovations reduced costs due to decreased labour skills, their most significant impact is expected in the future. The automation of data processing is an essential subsystem of optimising the supply chain, and allows most textile companies to reduce their costs and increase efficiency significantly. There is an opportunity to reduce costs by 10 to 40% through more effective logistics decisions for many supply chains. 4 Conclusion Findings This research suggests that optimising and managing the supply chains of textile producers requires the optimisation of other costs and transport expens­es, including optimal placement when establishing new textile enterprises. Thus, the satisfaction of the need for the effective control and management of all logistic chains, i.e., supply, production, transporta­tion and textile production will lead to positive re­sults when penetrating the organisational structure of a new business that is technologically adjacent to an existing production and marketing chain. It was also highlighted that optimisation models must be adequate and correctly illustrate the logistics business processes and functions of supply chain management. Limitations This research focused on only one country, i.e., Uzbekistan, and thus might not apply to some other countries. This research deals with well-established models and lacks the latest statistical or mathematical models. More care should be taken to ensure that data regarding logistics, supply chains and business processes are exact, timely and quick due to their use in optimisation models, which results in a significant variation depending on the values of factorial signs and system of restrictions. Future suggestions The purposes of optimisation must to be measura­ble and correspond to the optimality criteria of the actual logistic decision that it has to be reflected in the statement of the related task. For example, the economic-mathematical model of sales optimisation of finished goods can be carried out using the opti­mality criteria to maximise sales and profit, while minimising used resources and costs. The use of artificial neural networks and artificial intelligence might be applied in the future. Funding This research was funded by Humanities and Social Science Pre-research Project of Donghua University (218-10-0108019). References 1. COHEN, S., ROUSSEL, J. Strategic supply chain management: the five core disciplines for top performance. 2nd ed. New York : McGraw-Hill Education, 2013, 321 p. 2. KHOSO, A.N., MEMON, H., HUSSAIN, M., SANBHAL, A.N., ABRO, A.Z. Production and characterization of wool and hair fibers in high­lands of Baluchistan, an economic and sustain­able approach for Pakistan. Key Engineering Materials, 2015, 671, 473-482, doi: 10.4028/www.scientific.net/KEM.671.473. 3. BAKHSH, N., KHAN, M.Q., AHMAD, A., HASSAN, T. Recent advancements in cotton spinning. In Cotton Science and Processing Technology. Edited by H. Wang and H. Memon. (Textile Science and Clothing Technology). Singapore : Springer, 2020, 143-164, doi: 10.1007/978-981-15-9169-3_8. 4. CHRISTOPHER, Martin, TOWILL, Denis R. Supply chain migration from lean and functional to agile and customised. Supply Chain Management, 2020, 5(4), 206-213, doi: 10.1108/13598540010347334. 5. MADJIDOV, S., KHAKIMOV, B. Viewpoints about potential stimulation and possibilities of investments on textile industry Uzbekistan. European Journal of Business and Economics, 2012, 6, 22-24, doi: 10.12955/ejbe.v6i0.138. 6. BHATEJA, Ashish Kumar, BABBAR, Rajesh, SINGH, Sarbjit, SACHDEVA, Anish. Study of green supply chain management in the Indian manufacturing industries: a literature review cum an analytical approach for the measurement of performance. IJCEM International Journal of Computational Engineering & Management, 2011, 13, 84-99. 7. BEAMON, B.M. Supply chain design and analy­sis: models and methods. International Journal of Production Economics, 1998, 55(3), 281-294, doi: 10.1016/S0925-5273(98)00079-6. 8. FERNIE, J., SPARKS, L. Logistics and retail man­agement: insights into current practice and trends from leading experts. Boca Raton : CRC Press, 1999, 214 p. 9. FISHER, M.L. What is the right supply chain for your product. In Operations management. Edited by Michael. A Lewis and Nigel Slack. (Critical perspectives on business and management). London: Routledge, 2003, 73-88. 10. LOWSON, B., KING, R., HUNTER, A. Quick response: managing the supply chain to meet con­sumer demand. West Sussex : John Wiley & Sons, 1999, 304 p. 11. KHANKHADJAEVA, N.R. Role of cotton fib­er in knitting industry. In Cotton science and processing technology. Edited by Hua Wang and Memon Hafeezullah.. (Textile Science and Clothing Technology). Singapore : Springer, 2020, 247-303. 12. CHEN, Ming-Kuen, LIN, Yen-Ling, FANG, Chun-Pin, CHEN, Kuo-Hsuan. Supply chain strategic structure in the taiwan textile indus­try. International Journal of Electronic Business Management, 2013, 11(2), 73-87. 13. KRITCHANCHAI, D., WASUSRI, T. Implementing supply chain management in Thailand textile indus­try. International Journal of Information Systems for Logistics and Management, 2007, 2(2), 107-116. 14. KAYA, Ö., ÖZTÜRK, F.A. Research on the ap­plications of supply chain in textile-clothing industry. International Journal of Innovation, Management and Technology, 2014, 5(5), 334-338. 15. SŘNDERGĹRD, B., HANSEN, O.E., HOLM, J. Ecological modernisation and institutional trans­formations in the Danish textile industry. Journal of Cleaner Production, 2004, 12(4), 337-352, doi: 10.1016/S0959-6526(03)00049-0. 16. GIRI, S., RAI, S.S. Dynamics of garment sup­ply chain. International Journal of Managing Value and Supply Chains, 2013, 4(4), 29-42, doi: 10.5121/ijmvsc.2013.4403. 17. VANATHI, R., SWAMYNATHAN, R. Competitive advantage through supply chain col­laboration – an empirical study of the Indian tex­tile industry. Fibres & Textiles in Eastern Europe, 2014, 4(106), 8-13. 18. HUI P.C.L., TSE K., CHOI TM., LIU N. Enterprise resource planning systems for the tex­tiles and clothing industry. In Innovative quick response programs in logistics and supply chain management. Edited by Cheng T. and Choi T.M. Berlin, Heidelberg : Springer, 2010, 279-295, doi: 10.1007/978-3-642-04313-0_14. 19. CANIATO, F., CARIDI, M., CRIPPA, L., MORETTO, A. Environmental sustainability in fashion supply chains: an exploratory case based research. International Journal of Production Economics, 2012, 135(2), 659-670, doi: 10.1016/j.ijpe.2011.06.001. 20. WANG, H., MEMON, H., SHAH, S.H.H., SHAKHRUKH, M. Development of a quantita­tive model for the analysis of the functioning of integrated textile supply chains. Mathematics, 2019, 7(10), 1-14, doi: 10.3390/math7100929. 21. HERBERT, I.P., ROTHWELL, A.T., GLOVER, J.L., LAMBERT, S.A. Graduate employabili­ty, employment prospects and work-readiness in the changing field of professional work. The International Journal of Management Education, 2020, 18(2), 1-13, doi: 10.1016/j.ijme.2020.100378. 22. GUNASEKARAN, A., NGAI, E.W.T. Information systems in supply chain integration and man­agement. European Journal of Operational Research, 2004, 159(2), 269-295, doi: 10.1016/j.ejor.2003.08.016. 23. DUTTA, P., MISHRA, A., KHANDELWAL, S., KATTHAWALA, I. A multiobjective optimization model for sustainable reverse logistics in Indian E-commerce market. Journal of Cleaner Production, 2020, 249, 1-13, doi: 10.1016/j.jclepro.2019.119348. 24. STAMATIS, D.H. Six sigma fundamentals: a complete introduction to the system, methods, and tools. Boca Raton : CRC Press, 2019. 25. GAYIALIS, S.P., TATSIOPOULOS, I.P. Design of an IT-driven decision support system for ve­hicle routing and scheduling. European Journal of Operational Research, 2004, 152(2), 382-398, doi: 10.1016/S0377-2217(03)00031-6. Figure 1: Structure of exports of textile products of Uzbekistan Figure 2: Formation of supply chains in a textile complex Figure 3: Dependence of the profit of a textile enterprise on product sales Figure 4: Regression dependences of profit from sales of finished products 206 Tekstilec, 2021, Vol. 64(3), 206–220 | DOI: 10.14502/Tekstilec2021.64.206-220 Špela Kumer, Gregor Radonjic Univerza v Mariboru, Ekonomsko-poslovna fakulteta, Katedra za tehnologijo in podjetniško varstvo okolja, Razlagova 14, 2000 Maribor, Slovenija Analiza okoljskih kriterijev v porocilih o trajnostnem razvoju podjetij v tekstilnem in oblacilnem sektorju Analysis of Environmental Criteria in Sustainability Reports of Companies in the Textile and Apparel Sector Izvirni znanstveni clanek/Original Scientific Article Prispelo/Received 08-2020 • Sprejeto/Accepted 02-2021 Korespondencni avtor/Corresponding author: Prof. dr. Gregor Radonjic E-pošta: gregor.radonjic@um.si ORCID: 0000-0003-2621-5045 Izvlecek Tekstilna panoga je pogosto deležna kritik, ker zelo negativno vpliva na okolje in ker so delovne razmere v njej v državah v razvoju zelo nehumane. Eden od ciljev odgovornega in trajnostnega ravnanja je tudi transparentnost pri porocanju o vplivih podjetja na okolje in izvajanju ukrepov okoljske politike, pri cemer imajo pomembno vlogo porocila o trajnostnem razvoju. V ta namen smo z analizo vsebine proucili porocila o trajnostnem razvoju izbranih podjetij tekstilne in oblacilne panoge s poudarkom na okoljskih kriterijih. Raziskali smo, o katerih okoljskih kriterijih in ukrepih porocajo izbrana podjetja in ali se je zavedanje o okoljskih problemih in o številu ukrepov, ki jih proucevana podjetja povzrocajo s svojo dejavnostjo, v opazovanem casovnem obdobju poglobilo. Rezultati so potrdili, da ogljicni in vodni odtis v zadnjih letih mocno pridobivata na pomenu. V okviru življenjskega cikla oblacil v proucevanih podjetjih najpogosteje namenjajo najvecjo pozornost ukrepom v fazi proizvodnje in pridobivanja surovin, najmanj pa v fazi uporabe. Vsa so v svojih porocilih navajala zgolj pozitivne informacije, le v majhni meri so bili navedeni tudi neuspehi pri doseganju dolocenih ciljev trajnostnega razvoja. Kljucne besede: tekstilna panoga, oblacilna industrija, porocila o trajnostnem razvoju, okoljski kriteriji, ogljicni odtis Abstract The textile industry is often criticized for its enormous negative impact on the environment and non-human work­ing conditions, especially in third-world countries. One of the goals of sustainability measures is the transparency of communications regarding environmental impacts and the policy measures of companies. So-called sustainability reports have become one of the most popular ways to communicate with stakeholders regarding the sustainability efforts of companies. In this paper, we analysed the content of the sustainability reports of textile industry and apparel companies with an emphasis on environmental criteria. We focused on the number of environmental criteria and ana­lysed the measures taken in a given period. The results revealed that, in all cases, more detailed information regarding the carbon and water footprint were reported every year. In general, companies reported the most about measures taken in the production and raw material extraction phases, and the least about the consumption stage. However, mostly positive information about environmental aspects were included in the analysed sustainability reports. Failures regarding sustainable development programmes were rarely mentioned. Keywords: textile sector, apparel industry, sustainability reports, environmental criteria, carbon footprint 1 Uvod Trajnostni vidiki so se prebili med pomembnejše vidike v tekstilni industriji [1–4]. Zahteve po zmanj­ševanju negativnih vplivov na okolje in cloveku primernih delovnih razmerah prihajajo od kupcev, konkurence, neprofitnih organizacij in iz državnih ustanov [2, 5]. Kupci v zadnjih letih skupaj z mediji, nevladnimi organizacijami in lokalnimi skupnostmi pritiskajo na podjetja tekstilne in oblacilne industri­je, da zacnejo delovati v smeri trajnostnega razvoja [6–8]. Samo oblacilna industrija naj bi bila odgovorna za 2–10 odstotkov vseh vplivov na okolje v okoljskih življenjskih ciklih izdelkov v EU [9]. Proizvodnja tekstilnega izdelka zajema veliko proi­zvodnih faz, ki se pogosto izvajajo v razlicnih delih sveta. Posledicno imajo tekstilna podjetja zapletene globalne dobavne verige [10–11], ki vkljucujejo veli­ko razlicnih faz in udeležencev [12–13]. Še posebno resna so opozorila v povezavi s proizvodnjo oblacil, kjer je za vsako fazo življenjskega cikla mogoce naj­ti skrb zbujajoce podatke bodisi o onesnaževanju glede velike porabe vode, škodljivih kemikalij, fo­silnih goriv in nastajanja razlicnih vrst odpadkov [7, 12, 14–15] bodisi o delovnih razmerah v t. i. državah tretjega sveta [5, 16–17]. Zaradi globalnih in kompleksnih dobavnih verig oblacila prepotuje­jo velike razdalje od zacetka svojega življenjskega cikla do koncnih uporabnikov, kar znatno pove­cuje njihov ogljicni odtis [10]. K resnim okoljskim vplivom pripomore tudi prodobivanje bombaža. Po nekaterih podatkih bombaž zaseda 2,4 odstotka celotne obdelovalne površine na svetu, povecanje števila nasadov pa zmanjšuje biotsko raznovrstnost narave [18–19]. Za pridelovanje bombaža se porabi kar šest odstotkov vseh pesticidov in 16 odstotkov vseh insekticidov na svetu [20]. Tekstilna industrija je tudi sicer velik porabnik kemikalij, kar je tudi eden osrednjih virov onesnaženja vode v tekstil­ni proizvodnji, ki je posebej evidenten v državah z nizkimi okoljevarstvenimi standardi in zakonodajo [21–22]. Ob tem je oblacilna industrija pod velikimi pritiski tudi zato, ker povzroca velikanske kolicine trdnih odpadkov, ko se oblacila zavržejo [23]. To je posledica poslovnega modela, ki temelji na pretiranem potro­šništvu oziroma na t. i. trendu hitre mode, kar pome­ni, da oblacila cim hitreje pridejo iz proizvodnje na trg, in to po cim nižji ceni, ob nenehnem spodbujanju novih nakupov. V ta namen se proizvodnja preseli v države z nižjimi stroški dela. Tako so oblacila cenejša in jih odjemalci lahko kupijo v vecjih kolicinah [24]. Vendar velika kolicina kupljenih oblacil slabše kako­vosti posledicno povzroci, da jih uporabniki hitreje zavržejo [14]. Kot navaja Draper s soavtorji [10], so prav razpršene in nepregledne dobavne verige ter hitra moda glavni problemi te panoge. Zaradi neod­visnih raziskav in raznih škandalov, v katere so bila vpletena velika podjetja oblacilne industrije, se zau­panje javnosti v ta podjetja zmanjšuje, kar zmanjšuje ugled celotne panoge [4]. Ne glede na kompleksnost problema tudi v tej panogi že obstajajo premiki glede implementacije trajnostnih vidikov [25] in rast pro­aktivnih praks [26]. Zato je postala eden od ciljev trajnostnega razvoja tudi transparentnost pri porocanju o vplivih podjetja na okolje in izvajanju ukrepov okoljske politike [4, 6, 8, 11], kar vkljucuje tudi pripravo in objavljanje poro­cil o trajnostnem razvoju. Le-ta postajajo v številnih panogah cedalje pomembnejša za komuniciranje z javnostjo o aktivnostih podjetja, ki pripomorejo k trajnostnemu razvoju [27–31]. Porocila o trajnostnem razvoju omogocajo podjetjem, da predstavijo svoje aktivnosti na podrocju okolja in družbe, hkrati pa javnosti omogocajo vpogled v poslovanje podjetja in nacin prispevanja k trajnostnemu razvoju. Porocanje o trajnostnem razvoju je v zadnjem desetletju v izra­zitem porastu v razlicnih panogah [27, 32]. To lahko pripišemo tudi povecani uporabi smernic porocanja Global Reporting Initiative (GRI), ki so priporocila za porocanje o ekonomskih, socialnih in okoljskih vidikih poslovanja podjetja. Upoštevanje smernic porocanja GRI poveca primerljivost, kakovost in po­enotenost informacij podjetij o njihovih (pozitivnih in negativnih) prispevkih k trajnostnemu razvoju [29, 33]. Ceprav število podjetij s podrocja tekstilne panoge v svetu, ki se odlocajo, da bodo delila trajno­stne podatke z javnostjo, raste, pa je delež tovrstnih podjetij v dolocenih državah še vedno razmeroma majhen [34]. Pregled spletnih bibliografskih baz je pokazal, da je število raziskav, v katerih je bilo sistematicno pro­uceno, kateri trajnostni indikatorji so najpogosteje predstavljeni na podrocju tekstilne panoge (in na kakšen nacin), še vedno zelo omejeno tudi v medna­rodnem merilu, na kar opozarjajo avtorji sami [26, 35]. Ceprav so dosedanje objave zagotovo pripomogle k boljši preglednosti in razumevanju trendov ter pris­topov podjetij v tekstilni panogi glede trajnostnega porocanja, pa je še vedno na voljo premalo podatkov za razumevanje celovite slike v kompleksnih dobav­nih verigah te panoge in potrošniških navadah. Na splošno je takšno porocanje ponavadi kombinacija kvantitativnih in kvalitativnih kazalnikov, bodisi na spletnih straneh [35] bodisi v okviru trajnostnih po­rocil [11, 36], med katerimi prevladujejo okoljski vidi­ki in opisi delovnih razmer [26]. Vec avtorjev poroca, da se trajnostni indikatorji najpogosteje nanašajo na ukrepe v dobavnih verigah, manj pa na porocanje o poslovnih inovacijah in spreminjanju potrošniških navad [11, 37]. Ob tem obstajajo še številna odprta vprašanja glede standardizacije, verifikacije in ve­rodostojnosti trajnostnih porocil ter s tem njihove medsebojne primerljivosti, kar sicer ni znacilno le za tekstilno oz. oblacilno panogo [38]. To potrjuje­jo izsledki študij, o katerih porocajo Kozlowski in soavtorji [37] ter Garcia-Torres in soavtorji [39], ki nakazujejo na vrzeli v konsistentnosti in verodostoj­nosti pri trajnostnem porocanju podjetij tekstilne panoge v svetu. Zaradi omenjenih razlogov postajajo analize obja­vljenih okoljskih in trajnostnih porocil v zadnjih letih pomembno podrocje raziskav trendov trajno­stnega razvoja [30, 36, 40–42]. Z njimi želimo prido­biti informacije o strukturi porocil, nacinih komu­niciranja, izbranih trajnostnih kriterijih, razvojnih dosežkih in razlikah med panogami. Spoznanja iz raziskav o trajnostnem porocanju so pomembna tudi z vidika objektivnosti porocanja v prihodnje, saj so objavljeni podatki žal velikokrat zavajajoci in nepopolni [43, 44]. Namen raziskave je opraviti primerjalno analizo porocil o trajnostnem razvoju izbranih podjetij tek­stilne panoge in ugotoviti, o katerih okoljevarstvenih kriterijih in izvedenih okoljskih ukrepih proucevana podjetja porocajo. Ob tem želimo raziskati, ali se traj­nostno porocanje in s tem zavedanje podjetij tekstilne panoge o okoljskih problemih, ki jih povzrocajo s svojo dejavnostjo, povecuje ali ne. S tem želimo pri­spevati k spoznavanju dinamike trajnostnega poro­canja v dolocenih casovnih obdobjih, kjer so podatki še zelo pomanjkljivi. Znanstvenih prispevkov, ki bi v slovenski prostor prinašali spoznanja o pomenu, znacilnostih in po­manjkljivostih trajnostnega porocanja, za podjetja ni veliko. Rezultati raziskave so namenjeni podjetjem slovenske tekstilne panoge, a tudi drugih panog slo­venskega gospodarstva v zvezi s trajnostnim poroca­njem. Disipacija tovrstnih informacij in spoznanj je pomembna in nujna za implementacijo objektivnega trajnostnega porocanja tako v slovenski industrijski kot tudi trgovinski dejavnosti. Razumevanje pro­blema vplivov na okolje, ki jih povzrocajo (velika) podjetja, in razumevanje pravilnega informiranja in porocanja o tem je pomembno tudi za vzpostavitev trajnostnih politik malih in srednje velikih podjetij (ki so pogosto dobavitelji velikim podjetjem), saj jim velika podjetja postavljajo dolocene zahteve, ki jih morajo izpolniti. Brez tega razumevanja bodo tudi mala in srednje velika podjetja v vseh gospodarskih panogah, vkljucno s tekstilno, v prihodnosti zagotovo manj konkurencna. 2 Metodologija raziskave 2.1 Opis vzorca raziskave Kriterij za izbor podjetij za raziskavo je bilo jav­no dostopno porocilo o trajnostnem razvoju (angl. Sustainability report), objavljeno na spletni strani podjetja. V raziskavo smo vkljucili trajnostna po­rocila naslednjih podjetij: Adidas Group, C&A, Gap Inc., H&M in Nike Inc. V porocilih teh podjetij so informacije za celotno tekstilno panogo, od prido­bivanja tekstilnih surovin do plemenitenja tekstilij. Podatki se nanašajo na dobaviteljska podjetja, ki jih uvršcamo v ožji pomen tekstilne panoge, saj se ukvarjajo s proizvodnjo tekstilnih materialov kot koncnih tekstilnih izdelkov. Zavedamo se, da gre za specificen vzorec podjetij tako glede izdelkov, ki jih ponujajo na trgu (oblacila, obutev), kot glede na poslovne modele in korporacijsko organizira­nost. Uporabili smo tiste informacije iz porocil, ki se nanašajo na oblacilne izdelke, ki jih sicer vsa ta podjetja ponujajo na trgu. Dejstvo pa je, da imajo tekstilni izdelki v obliki oblacil za izbrana podje­tja pomemben tržni delež in da so podjetja vpe­ta v vse faze dobavne verige, vkljucno s tekstilno proizvodnjo (tekstilnih materialov in ploskovnih tekstilnih izdelkov), na katero mocno vplivajo ter o zbranih okoljskih podatkih svojih dobaviteljev iz tekstilne panoge tudi porocajo. Njihova trajno­stna porocila so informacijska baza, v kateri so na enem mestu zbrani podatki o njihovih dobavite­ljih v celotni tekstilni verigi, vkljucno s pridobiva­njem oz. proizvodnjo tekstilnih materialov, prej, ploskovnih tekstilnih izdelkov s plemenitenjem in konfekcioniranjem. Izbor podjetij dodatno utemeljujemo z naslednjim: (1) Velika podjetja imajo na splošno laže dostop­na in obsežnejša porocila o trajnostnem razvoju kot mala in srednje velika. (2) Imajo veliko tržno moc in s tem veliko družbeno odgovornost. Velika globalna podjetja (lastniki mod­nih znamk) imajo najvecji vpliv na to, kakšne izdelke bodo izdelovali in pod kakšnimi pogoji. (3) So pod vecjim pritiskom javnosti. (4) Mocno vplivajo na spremembe v dobavnih verigah zaradi zahtev, ki jih lahko postavljajo do­baviteljem. So tista, ki pogosto sprožijo trajnostne spremembe in v to prisilijo tudi mala in srednje velika podjetja, ki so njihovi dobavitelji ali odjemalci. (5) Trendom, ki so trenutno prepoznani za velika podjetja, se pozneje marsikdaj pridružijo tudi mala in srednje velika podjetja. Trajnostne zahteve, ki se tako prenašajo z vecjih na manjša podjetja, so gibalo sprememb v smeri trajnostnega razvoja v panogi. (6) Razpolagajo z vec kadrovskimi, raziskovalni­mi in financnimi potenciali, ki jih lahko vložijo v ekoinovacije. 2.2 Analiza porocil in uporabljene metode Raziskava temelji na kvalitativni analizi porocil, ki so izrecno ocenjena kot trajnostna (angl. sustainability report). V ta namen smo marca leta 2019 pregleda­li spletne strani izbranih podjetij. Za proucevanje napredka pri trajnostnem porocanju smo se omejili na porocila, izdana v zadnjih treh do petih letih za vsako izbrano podjetje. Za vsako od izbranih podjetij smo pregledali tri najnovejša dostopna porocila o trajnostnem razvoju, pri cemer so dolocena poroci­la izdana za eno leto, nekatera pa za dve leti skupaj (preglednica 1). Pri trajnostnih kriterijih (okoljski, socialni, ekonom­ski) se v raziskavi omejujemo na okoljske kriterije: izvor surovin tekstilnih materialov, uporaba kemi­kalij, raba energije, vodni odtis, ogljicni odtis in trdni odpadki. Kot navaja vec avtorjev, prav ti vidiki pome­nijo podrocja, ki najvec prispevajo k okoljskim obre­menitvam v celotnem življenjskem ciklu tekstilnih izdelkov [14, 19, 21]. Kot posebej pomembne za tek­stilno industrijo jih omenjajo tudi porocila Evropske unije in nevladne organizacije [1–2, 14]. Za proucevanje porocil o trajnostnem razvoju izbra­nih podjetij smo uporabili metodologijo, ki je znana kot ‚analiza vsebine‘ (angl. Content analysis), katere metodološki raziskovalni standard je delo avtorja Klausa Krippendorfa [60] in je pogosto uporabljena za raziskave trajnostnih porocil tekstilnih oziroma oblacilnih podjetij [26, 37, 39]. Krippendorf opre­deljuje analizo vsebine kot raziskovalno metodo za pridobitev ponovljivih in verodostojnih tekstovnih informacij glede na kontekst njihove uporabe, in sicer za dolocanje podobnosti in razlik med proucevani­mi tekstovnimi podatki, pa tudi za iskanje povezav med njimi. Metodologija analize vsebine pomaga zmanjšati kolicino zbranih podatkov in jih razvrstiti v dolocene skupine. Analiza vsebine poteka tako, da najprej zberemo relevantne podatke, jih sistematicno pregledamo z uporabo izbranih kriterijev ter doloci­mo podobnosti in razlike med proucevanimi podat­ki, pa tudi povezave med njimi [61]. Analizo vsebine smo uporabili, ker je široko uporabljan metodološki okvir pri raziskovanju trajnostnih in sorodnih po­rocil [62-65]. Pri analizi besedil smo bili pozorni na to, da izbrani kriteriji niso bili zgolj omenjeni v besedilu, ampak da so bili zanje podani dejanski opisni in številski podatki. Za vsak okoljski kriterij smo preverili in analizirali kvalitativne in kvantitativne podatke. Pristop, ki smo ga uporabili, ne razvršca pojmov gle­de na njihovo relativno pomembnost, temvec glede na njihovo pogostnost. Ob tem smo dodatno proucili, kako izbrana podjetja v svojih porocilih porocajo o ukrepih v razlicnih fazah okoljskega življenjskega cikla. Prav tako smo proucili, kako podjetja v svojih porocilih porocajo o ukrepih za zmanjševanje vpli­vov na okolje. 3 Rezultati in razprava V preglednicah 2 in 3 so prikazani rezultati analize vsebine porocil o trajnostnem razvoju za izbrana pod­jetja (preglednica 1). Treba je poudariti, da v okviru uporabljene metodologije v preglednicah 2 in 3 nave­dene ukrepe podjetij predstavljamo v enaki termino­loški obliki, kot so zapisani v porocilih, se pravi z de­janskimi izrazi, kot so jih navajala podjetja. Posledicno to pomeni, da se v porocilih lahko pojavljajo drugacni oz. sorodni termini za iste ukrepe. V tabeli 2 so nave­deni ukrepi za vsak proucevani okoljski kriterij pose­bej in kvantitativne vrednosti zmanjševanja vplivov na okolje. Velikosti zmanjšanja vplivov se razlikujejo glede na posamezni okoljski vpliv oziroma glede na fazo okoljskega življenjskega cikla izdelkov. Opazne razlike so tudi med posameznimi podjetji. Videti je, da podjetja o nekaterih ukrepih pogosteje porocajo. Na primer, vsa proucevana podjetja porocajo o zmanjše­vanju porabe vode v proizvodnji. Prav tako skoraj vsa porocajo o ukrepih za zmanjševanje izpustov toplo­grednih plinov (kar je povezano z ogljicnim odtisom). V vseh pregledanih porocilih je bilo opaziti velik pou­darek na izboru surovin, vendar nikjer nismo zasledili konkretnih podatkov o ravnanju z vodo in uporabi ke­mikalij pri pridelavi bombaža, kar je do dolocene mere skladno s spoznanji nekaterih drugih avtorjev [26]. Vsa izbrana podjetja porocajo o rabi vode v proizvod­nih procesih dobaviteljev, ne porocajo pa o ravnanju z odpadno vodo. Prav tako vsa podjetja omenjajo, da iz proizvodnih procesov izlocajo zdravju nevarne kemi­kalije, nismo pa zasledili podatkov o ravnanju z upora­bljenimi kemikalijami, ki se marsikdaj izpušcajo v bli­žnje reke, na kar opozarjajo nevladne organizacije [3]. Tudi Kozlowski in soavtorji [37] porocajo, da se okoljski kazalniki v trajnostnih porocilih tekstilnih podjetij sicer nanašajo na vse faze življenjskega cikla, vendar so ukrepi neenakomerno porazdeljeni po po­sameznih fazah. S primerjavo teh spoznanj z našimi se zdi, da dajejo podjetja v tem trenutku vecji pouda­rek tistim ukrepom, ki so povezani z najveckrat jim ocitanimi vplivi na okolje v širši javnosti in v medijih. Za dejansko primerljivost podatkov glede zmanjše­vanja vplivov na okolje in s tem primerljivostjo med podjetji samimi bi bile potrebne enotne in jasne med­narodno standardizirane zahteve glede trajnostnega porocanja. Ob tem želimo poudariti, da v skladu z namenom in cilji raziskave proucujemo, kaj in kako podjetja porocajo, ne pa tudi, s cim in na kakšen na­cin te ukrepe dosegajo (npr. s katerimi procesnimi, izdelcnimi ali organizacijskimi inovacijami). Dinamika zmanjševanja vplivov izbranih podjetij na okolje je dodatno prikazana v tabeli 3, v kateri so navedeni ukrepi za vsako posamezno fazo okoljskega življenjskega cikla posebej, in sicer za primer tistih podjetij, ki so v svojih porocilih dejansko prikazala napredek z navajanjem konkretnih številskih podat­kov in niso dolocenega kriterija le tekstovno omenja­la. Prikazana je razlika med prvim in zadnjim prou­cevanim letom porocanja, vendar le za tista podjetja, ki so navajala konkretne številske podatke (torej niso dolocenega pojma oziroma okoljskega ukrepa samo omenjala v besedilu). Videti je, da se najvec ukrepov nanaša na fazo proizvodnje in na fazo pridobivanja surovin. Bistveno manj pogosto podjetja porocajo o ukrepih glede faze uporabe, ravnanja s tekstilnimi odpadki po uporabi in o transportu, ceprav so ti trije prav tako pomembni. Faza uporabe se nanaša na vzdrževanje tekstilnih izdelkov (pranje, sušenje in likanje). Veckrat se je potrdilo, da je ta faza življenjskega cikla lahko celo med okoljsko najbolj obremenjujocimi [66]. Res je, da je v tem primeru vpliv na okolje (raba energije, vode in detergentov) v najvecji meri odvisen od po­trošnikov in aparatov, ki jih uporabljajo [1], vendar bi jih izdelovalci lahko pogosteje opozarjali, saj ima­jo za to na voljo razlicne možnosti (spletne strani, družbena omrežja, etikete). Potrošniki imajo izjemno pomembno vlogo pri spremembah v smeri trajno­stnega razvoja, saj s svojo izbiro o nakupu oblacil in pritiski na velika podjetja tekstilne industrije silijo le-ta v bolj odgovorne odlocitve. Le Gap Inc. in H&M sta poudarila, da kupce izobražujejo o nacinu pranja in sušenja oblacil, da bi cim bolj zmanjšali vpliv na okolje v omenjeni fazi. V porocilih je tudi relativno malo podatkov o fazi ravnanja s tekstilnimi odpadki, kar lahko pripišemo dejstvu, da so metode recikliranja oblacil še vedno v fazi razvoja. Vsa izbrana podjetja so porocala o tem, da so (vsaj za dolocen cas) že organizirala progra­me zbiranja rabljenih oblacil v trgovinah, le dve od izbranih podjetij, H&M in C&A, pa sta navedli, da sodelujeta s podjetjem I:CO, ki se ukvarja s sortira­njem zbranih oblacil in njihovo ponovno uporabo ali recikliranjem [67]. Najpomembnejša intervencija za izboljšanje položaja tekstilne industrije bi zagoto­vo bila zmanjšana poraba oblacil oziroma izdelova­nje kakovostnih oblacil z dolgo življenjsko dobo ob hkratnem upoštevanju okoljskih in socialnih proble­mov [68], kar pa bi resno poseglo v poslovni model hitre mode. Vprašanje je, ali si izbrana podjetja želijo posegati vanj, ceprav je prav hitra moda danes eden glavnih vzrokov obremenjevanja okolja v tekstilni panogi [14, 69]. Ceprav so vsa proucevana podjetja v porocanje zajela svojo dobavno verigo, pa so pri uvajanju izboljšav za rabo energije oz. porocanju o tem še vedno v veliki meri osredotocena na svoje lastne poslovne procese, kamor štejemo prodajalne, dis­tribucijske centre in upravo, ceprav le-ti po njiho­vih ocenah pomenijo v povprecju zgolj okrog deset odstotkov vseh vplivov podjetja na okolje. Prav vsa proucevana podjetja so zavezana k ciljem preneha­nja izpušcanja zdravju nevarnih kemikalij v okolje do leta 2020 (angl. Zero Discharge of Hazardous Chemicals), kar zahteva sistemske spremembe v celotni dobavni verigi podjetij [3]. To pomeni, da bi velika tekstilna podjetja morala prevzeti odgo­vornost in pritisniti na svoje dobavitelje, da izve­dejo spremembe v smeri trajnostnega razvoja. Skrb zbujajoce je, da je hkrati s porocili o trajnostnem razvoju, ki smo jih proucevali, izšlo veliko porocil neodvisnih institucij, ki še vedno opozarjajo na šte­vilne nepravilnosti v povezavi s tekstilno panogo (glej na primer [21, 70–73]), v vsakem od tovrstnih porocil pa je omenjeno vsaj eno od podjetij, ki smo jih zajeli v vzorec raziskave. O tovrstnih porocilih pa je nujno tudi kriticno raz­misliti. Vsa proucevana podjetja v svojih porocilih o trajnostnem razvoju sicer omenjajo najbolj perece probleme tekstilne panoge in dolocene ukrepe, ven­dar redkeje porocajo o konkretnem napredku v do­locenem obdobju. Prav tako vsa proucevana podjetja v svojih porocilih v veliki meri navajajo zgolj pozi­tivne informacije. Cetudi so bila trajnostna porocila v vseh primerih pripravljena na podlagi smernic, ki jih je razvila organizacija Global Reporting Initiative [29], še vedno nimamo mednarodnega standarda za trajnostno porocanje, zato se podatki in nacini po­rocanja v porocilih precej razlikujejo, saj so odlocit­ve prepušcene podjetjem. Roca in Searcy [62] sta na primeru 94 kanadskih podjetij iz razlicnih panog ugotovila, da le-ta v svojih porocilih uporabljajo kar 585 razlicnih okoljskih indikatorjev, kar zagotovo ne pripomore k transparentnosti porocanja. O širokem naboru uporabljenih okoljskih kazalnikov za primer trajnostnih porocil v tekstilni panogi porocajo tudi Kozlowski in soavtorji [37] ter Saygili in soavtorji [34]. Zaradi te težave so Garcia-Torres in soavtorji [39] predlagali lasten nacin vrednotenja okoljskih oz. trajnostnih kriterijev za podjetja, ki so povezana s problemom hitre mode. Zavedamo se, da so poleg okoljskih vidikov traj­nostnega razvoja izjemno pomembni tudi socialni, med katere uvršcamo pošteno placilo, otroško delo, pravico do združevanja delavcev, izobraževanje za­poslenih, diskriminacijo žensk, diskriminacijo ras, prisilno delo in druge [16, 29, 74]. Ceprav smo v pri­spevku podrobneje osredotoceni na okoljske krite­rije trajnostnega porocanja, smo v loceni razširjeni študiji proucevali tudi socialne [74]. Ugotovili smo, da vecina proucevanih podjetij v svojih porocilih o trajnostnem razvoju po obsegu vsaj polovico poro­cila namenja tudi socialnim vidikom, med katerimi izstopa vidik ‚‘delovne razmere‘‘, ki ga proucevana podjetja navajajo v okviru celotne dobavne verige, kar prav tako lahko pripišemo cedalje hujšemu pri­tisku javnosti [8, 72]. Podrobnejši pregled socialnih kriterijev v trajnostnih porocilih presega namen in cilje tega clanka in je podrobneje proucen in opisan v [74]. Tovrstna porocila sicer kažejo, da se podjetje ukvar­ja s trajnostnim razvojem, vendar pa je tovrstne in­formacije treba sprejemati tudi z doloceno mero pazljivosti, saj je porocanje o trajnostnem razvoju v glavnem usmerjeno k poudarjanju pozitivnih infor­macij in prikrivanju negativnih [29]. Tako so poro­cila o trajnostnem razvoju še vedno vse prepogosto namenjena zgolj dobri javni podobi [62, 64, 75–76]. Tudi raziskava Flash Eurobarometer [77] je poka­zala, da vecina prebivalcev Evropske unije ne zaupa povsem porocilom podjetij, v katerih le-ta objavljajo svoje dejavnosti na podrocju varovanja okolja. Za pripravo trajnostnih porocil so namrec potrebni verodostojni podatki, pri cemer so za tekstilno panogo (sploh za segment oblacil in hitre mode) dodaten problem dobavne verige in potrošniške na­vade oziroma razvade. Panoga je razdrobljena na vec razlicnih maloprodajnih segmentov (športna oblacila, luksuzna oblacila, hitra moda ipd.), zato je tudi pojem ‚trajnosti‘ v tej panogi težko enoznacno opredeliti. Tako je implementacija pojma ‚trajnosti‘ še vedno predmet razprav, saj obstajajo specificne zahteve med posameznimi segmenti. S porocili o trajnostnem razvoju velika podjetja vplivajo na razvoj celotne panoge. Razumevanje celovitih vplivov tekstilne panoge na okolje, ki jih povzrocajo velika podjetja na eni strani in razu­mevanje pravilnega informiranja oz. porocanja na drugi, je pomembno tudi za vzpostavitev trajno­stnih politik malih in srednje velikih podjetij (ki so pogosto dobavitelji velikim podjetjem), saj jim velika podjetja postavljajo dolocene zahteve. Mala in srednje velika podjetja pa s tovrstnimi poroci­li pridobijo veliko koristnih informacij o trendih v tekstilni panogi, ki jim bodo morala slediti [14]. Tudi prodajalci tekstilnih izdelkov z njimi pridobi­jo informacije o oblacilih, ki jih prodajajo, kar jim omogoca lažjo komunikacijo z njihovimi kupci in možnost diverzifikacije izdelkov, dobijo pa lahko tudi nove ideje za promocijo. Zato so izsledki razi­skave koristni tudi za slovenske modne oblikovalce. Kot navajajo avtorji porocila Fashion at the Cross Roads [68], manjša podjetja v zadnjem casu mar­sikje že vodijo v pozitivnih spremembah tekstilne panoge v smeri trajnostnih zahtev. 4 Sklep Ker postajajo izzivi trajnostnega razvoja izjemno po­membni za podjetja tekstilne panoge, je pomembno pridobiti cim vec verodostojnih informacij za poro­canje oz. komuniciranje z javnostjo in deležniki. To ni le znacilnost tekstilne panoge, temvec tudi drugih, saj postaja porocanje o trajnostnem razvoju v gospo­darstvu cedalje pomembnejše. Z raziskavo smo želeli ugotoviti, kako izbrana podjetja tekstilne industrije v svojih porocilih o trajnostnem razvoju porocajo o iz­branih okoljskih kriterijih. Rezultati nakazujejo, da je v proucevanih primerih viden napredek v smeri upo­števanja okoljskih vidikov v obravnavanih obdobjih, saj v svoja porocila o trajnostnem razvoju vsako leto vkljucujejo vec konkretnih podatkov. Ugotovili smo, da cedalje vecji pomen pridobivata ogljicni in vodni odtis. V okviru življenjskega cikla oblacil se v prouce­vanih podjetjih najpogosteje osredotocajo na ukrepe v fazi proizvodnje in pridobivanja surovin, najmanj pa v fazi uporabe. Vsa proucevana podjetja so v svojih porocilih navajala zgolj pozitivne informacije, le v majhni meri so bili izpostavljeni tudi neuspehi pri doseganju dolocenih ciljev trajnostnega razvoja. V pricujocem clanku smo se omejili na okoljske vi­dike trajnostnega razvoja. Zavedamo se, da so poleg okoljskih vidikov trajnostnega razvoja izjemno po­membni tudi socialni, o katerih podjetja tudi poro­cajo. Obe skupini vidikov sta v marsicem povezani in medsebojno odvisni, verodostojno trajnostno poro­canje pa mora seveda zajeti tako ene kot druge vidike. Eden glavnih izzivov v prihodnje bo zagotovo tudi, kako spremeniti potrošniško kulturo v tem tržnem segmentu. Verjetno bi k vecji dinamiki in intenziteti ukrepov trajnostnega razvoja pripomogle aktivnosti, poveza­ne s pridobitvijo certifikatov ISO 14001 ali EMAS, ki od podjetij zahtevajo vzpostavitev aktivne okoljske politike. Razen podjetja Adidas namrec prouceva­na podjetja na dostopnih porocilih in na spletnih straneh ne porocajo, da so si katerega od omenjenih certifikatov pridobila. Pricakujemo lahko, da se bodo raziskave o trajno­stnem porocanju v prihodnje še okrepile. Naša raz­iskava je prispevek k boljšemu razumevanju teh so­dobnih trendov. Rezultati prinašajo nova spoznanja in vpogled v strategije trajnostnega porocanja podje­tij v tekstilni panogi s poudarkom na proizvodnji in prodaji oblacil. Dodatno prinašajo v slovenski prostor informacije za bolj jasno razumevanje pomembnih trendov v panogi. Pricujoca raziskava ima tudi dolocene omejitve. Treba je poudariti, da je bil naš vzorec raziskovanja relativno majhen, zato rezultatov ne moremo posploševati na celotno tekstilno panogo. Prav tako smo se v raziskavi omejili zgolj na velika in tuja podjetja s specificnim poslovnim modelom s poudarkom na oblacilnih iz­delkih. Ceprav so v dobavnih verigah tovrstnih izdel­kov zajete vse faze tekstilne panoge (vkljucno s proi­zvodnjo), pa ima oblacilni sektor svoje specifike, zato rezultatov raziskave ni mogoce neposredno prenašati tudi na preostale sektorje tekstilne panoge. Za celovitejšo sliko bi bilo treba prouciti tudi razvoj in implementacijo ekoinovacij v tekstilni panogi (produktnih, proizvodnih, organizacijskih) in poi­skati korelacije s pristopi pri trajnostnem komunici­ranju. Ker sta namen naše raziskave izkljucno pregled in analiza trajnostnih porocil, se z opisom, trendi in vrstami ekoinovacij v pricujocem prispevku ne ukvarjamo. Vsekakor pa iskanje korelacij med ekoi­noviranjem in trajnostnim porocanjem prispeva do­datna pomembna spoznanja pri razumevanju odziva podjetij na zahteve trajnostnega razvoja. Zanimivo podrocje raziskav v tem kontekstu bi bilo tudi iskanje odgovorov, kako se na okoljsko problematiko odzi­vajo potrošniki, saj so eden kljucnih elementov pri spreminjanju sedanjih tržnih praks. Viri 1. Environmental improvement potential of tex­tiles (IMPRO-textiles): scientific and policy re­ports [online]. European Commission [accessed 23.03.2019]. Available on World Wide Web: . 2. RESTA, Barbara, GAIARDELLI, Paolo, PINTO, Roberto, DOTTI, Stefano. Enhancing envi­ronmental management in the textile sector: an Organisational-Life Cycle Assessment ap­proach. Journal of Cleaner Production, 2016, 135, 620-632, doi: 10.1016/j.jclepro.2016.06.135. 3. Destination zero: seven years of detoxing the clothing industry [online]. Greenpeace [accessed 23.03.2019]. Available on World Wide Web: . 4. The state of fashion 2019 [online]. McKinsey & Company [accessed 15.04.2019]. Available on World Wide Web: . 5. GARDETTI, Miguel Angel,TORRES, Ana Laura. Sustainability in fashion and textiles: values, de­sign, production and consumption. Greenleaf Publishing, 2013. 6. ISAKSSON, Raine, STEIMLE, Ulrich. What does GRI-reporting tell us about corporate sustainabil­ity? The TQM Journal, 2009, 21(2), 168-181, doi: 10.1108/17542730910938155. 7. Toxic threads: the big fashion stitch-up [on­line]. Greenpeace [accessed 26.04.2019]. Available on World Wide Web: . 8. Follow the thread [online]. Human Rights Watch [accessed 03.05.2019]. Available on World Wide Web: . 9. TUKKER, Arnold, HUPPES, Gjalt, GUINÉE, Jeroen, HEIJUNGS, Reinout, DE KONING, Arjan, VAN OERS, Lauran, SUH, Sangwon, GEERKEN, Theo, VAN HOLDERBEKE, Mirja, JANSEN, Bart, NIELSEN, Per. Environmental Impacts of Products (EIPRO): analysis of the life cycle environmental impacts related to the final consumption of the EU-25. Seville: European Commission Joint Research Centre, 2006. 10. DRAPER, Stephanie, MURRAY, Vicky, WEISSBROD, Ilka. Fashioning sustainability: a review of sustainability impacts of the clothing industry. London: Forum for the Future/Marks and Spencer, 2007. 11. TURKER, Duygu, ALTUNTAS, Ceren. Sustainable supply chain management in the fast fashion industry: an analysis of corporate reports. European Management Journal, 2014, 32(5), 837-849, doi: 10.1016/j.emj.2014.02.001. 12. BOMGARDNER, Melody. Cleaning the clothing industry. Chemical & Engineering News, 2016, 94(26), 30-32. 13. ŽURGA, Zala, FORTE TAVCER, Petra. Zeleno potrošništvo in upoštevanje ekoloških oznak pri nakupu tekstilij. Tekstilec, 2013, 56(2), 100-110. 14. Timeout for fast fashion [online]. Greenpeace [accessed 04.03.2019]. Available on World Wide Web: . 15. BOUCHER, Julien, FRIOT, Damien. Primary microplastics in the oceans: a global evalua­tion of sources[online]. International Union for Conservation of Nature [accessed 10.05.2019]. Available on World Wide Web: . 16. RAWORTH, Kate. Trading away our rights. Oxford : Oxfam Publishing, 2004. 17. OVEREEM, Pauline, THEUWS, Martje. Flawed fabrics: the abuse of girls and women workers in the South Indian textile industry[online]. Centre for Research on Multinational Corporations (SOMO) [accessed 29.05.2019]. Available on World Wide Web: . 18. BAYDAR, Gülden, CILIZ, Nilgun, MAMMADOV, Aydin. Life cycle assessment of cotton textile products in Turkey. Resources, Conservation and Recycling, 2015, 104, 213–223, doi: 10.1016/j.resconrec.2015.08.007. 19. MORGAN, Andrew. The true cost [movie]. Untold Creative, 2015. 20. Pesticide concerns in cotton [online]. Pesticide Action Network UK (PAN UK) [accessed 10.01.2019]. Available on World Wide Web: < http://www.pan-uk.org/cotton/>. 21. Dirty laundry: unravelling the corporate connec­tions to toxic water pollution in China [online]. Greenpeace [accessed 23.03.2019]. Available on World Wide Web: . 22. LUONGO, Giovanna. Chemicals in textiles: a potential source for human exposure and envi­ronmental pollution: doctoral thesis. Stockholm: Stockholm University, 2015. 23. ARSHAD, Khubaib, SKRIFVARS, Mikael, VIVOD, Vera, VOLMAJER VALH, Julija,VONCINA, Bojana. Biodegradation of nat­ural textile materials in soil. Tekstilec, 2014, 57(2), 118-132, doi: 10.14502/Tekstilec2014.57.118-132. 24. PERIC, Nenad, MAMULA NIKOLIC, Tatjana, SLIJEPCEVIC, Milica. Clothes consumption in Republic of Serbia: customer behaviour overview. Tekstilec, 2019, 62(2), 137-147, doi: 10.14502/Tekstilec2019.62.137-147. 25. CANIATO, Federico, CARIDI, Maria, CRIPPA, Lucca, MORETTO, Antonella. Environmental sustainability in fashion supply chains: an explan­atory case based research. International Journal of Production Economics, 2012, 135(2), 659-670, doi: 10.1016/j.ijpe.2011.06.001. 26. FENG, Penglan, NGAI, Cindy Sing-bik. Doing more on corporate sustainability front: a longitu­dinal analysis of CSR reporting on global fashion companies. Sustainability, 2020, 12(6), 1-18, doi: 10.3390/su12062477. 27. HIGGINS, Colin, COFFEY, Brian. Improving how sustainability reports drive change: a critical discourse analysis. Journal of Cleaner Production, 2016, 136, 18-29, doi: 10.1016/j.jclepro.2016.01.101. 28. The road ahead: the KPMG survey of corporate responsibility reporting 2017 [online]. Klynveld Peat Marwick Goerdeler (KPMG) [accessed 02.06.2019]. Available on World Wide Web: . 29. Information about Global Reporting Initiative [online]. Global Resource Institute [accessed 23.01.2019]. Available on World Wide Web: . 30. GUZIANA, Bozena, DOBERS, Peter. How sus­tainability leaders communicate corporate activ­ities of sustainable development. Corporate Social Responsibility and Environmental Management, 2013, 20(4), 193-204, doi: 10.1002/csr.1292. 31. SDG reporting challenge 2018: from promise to reality: does business really care about the SDGs? [online]. PricewaterhouseCoopers (PwC) [ac­cessed 20.10.2019]. Available on World Wide Web: . 32. HAHN, Rüdiger, KÜHNEN, Michael. Determinants of sustainability reporting: a re­view of results, trends, theory, and opportuni­ties in an expanding field of research. Journal of Cleaner Production, 2013, 59, 5-21, doi: 10.1016/j.jclepro.2013.07.005. 33. GALLEGO-ÁLVAREZ, Isabel, BELÉN LOZANO, Maria, RODRIGUEZ-ROSA, Miguel. An analysis of the environmental information in internation­al companies according to the new GRI stand­ards. Journal of Cleaner Production, 2018, 182, 57-66, doi: 10.1016/j.jclepro.2018.01.240. 34. SAYGILI, Ebru, SAYGILI, Arikan Tarik, GÖREN YARGI, Seher. An analysis of the sustainability disclosures of textile and apparel companies in Turkey. Tekstil ve Konfeksiyon, 2019, 29(3), 189-196, doi: 10.32710/tekstilvekonfeksiyon.471049. 35. DA GIAU, Alessandro, MACCHION, Laura, CANIATO, Federico, CARIDI, Maria, DANESE, Pamela, RINALDI, Rinaldo, VINELLI, Andrea. Sustainability practices and web-based com­munication analysis of the Italian fashion industry. Journal of Fashion Marketing and Managament, 2016, 20(1), 72-88, doi: 10.1108/JFMM-07-2015-0061. 36. BUBICZ, Marta Elisa, FERREIRA DIAS BARBOSA-PÓVOA, Ana Paula, CARVALHO, Ana. Social sustainability management in the apparel supply chains. Journal of Cleaner Production, 2021, 280, 1-18, doi: 10.1016/j.jclepro.2020.124214. 37. KOZLOWSKI, Anika, SEARCY, Cory, BARDECKI, Michal. Corporate sustainability reporting in the apparel industry: an analysis of indicators disclosed. International Journal of Productivity and Performance Management, 2015, 64(3), 377-397, doi: 10.1108/IJPPM-10-2014-0152. 38. DICKSON, Marsha A., LOCKER, Suzanne, ECKMAN, Molly. Social responsibility in the global apparel industry. New York : Fairchild Books, 2009. 39. GARCIA-TORRES, Sofia, REY-GARCIA, Marta, ALBAREDA-VIVO, Laura. Effective disclosure in the fast-fashion industry: from sustainability reporting to action. Sustainability, 2017, 9(12), 1-27, doi: 10.3390/su9122256. 40. DIENES, Dominik, SASSEN, Remmer, FISCHER, Jasmin. What are the drivers of sustainability reporting? A systematic review. Sustainability Accounting, Management and Policy Journal, 2016, 7(2), 154-189, doi: 10.1108/SAMPJ-08-2014-0050. 41. LOZANO, Rodrigo, NUMMERT, Benjamin, CEULEMANS, Kim. Elucidating the relation­ship between sustainability reporting and or­ganisational change management for sustaina­bility. Journal of Cleaner Production, 2016, 125, 168-188, doi: 10.1016/j.jclepro.2016.03.021. 42. VIEIRA, Antonio Pedro, RADONJIC, Gregor. Disclosure od eco-innovation activities in European large companies‘ sustainability re­porting. Corporate Social Responsibility and Environmental Management, 2020, 27(5), 2240-2253, doi: 10.1002/csr.1961. 43. LYON, Thomas P., MAXWELL, John W. Greenwash: corporate environmental disclosure under threat of audit. Journal of Economics and Management Strategy, 2011, 20(1), 3-41, doi: 10.1111/j.1530-9134.2010.00282.x. 44. MION, Giorgio, LOZA ADAUI, Cristian R. Mandatory nonfinancial disclosure and its con­sequences on the sustainability reporting quality of Italian and German companies. Sustainability, 2019, 11(17), 1-28, doi: 10.3390/su11174612. 45. Make a difference: sustainability progress re­port 2014 [online]. Adidas Group [accessed 26.05.2019]. Available on World Wide Web: . 46. How we create responsibility: sustainability progress report 2015 [online]. Adidas Group [accessed 26.05.2019]. Available on World Wide Web: < https://www.adidas-group.com/media/filer_public/9c/f3/9cf3db44-b703-4cd0-98c5-28413f272aac/2015_sustainability_progress_re­port.pdf>. 47. Calling all creators: sustainability progress re­port 2016 [online]. Adidas Group [accessed 26.05.2019]. Available on World Wide Web: . 48. Everyday, everywhere, everyone: corporate responsibility report 2014 [online]. C&A [ac­cessed 26.05.2019]. Available on World Wide Web: . 49. Global sustainability report 2015 [online]. C&A [accessed 26.05.2019]. Available on World Wide Web: . 50. Global sustainability report 2017 [online]. C&A Sustainability [accessed 26.05.2019]. Available on World Wide Web: < http://sustainability.c-and-a.com/home/>. 51. Our futures are woven together: Gap Inc. global sustainability report 2013 – 2014 [online]. Gap Inc. [accessed 26.05.2019]. Available on World Wide Web: . 52. Global sustainability report 2015–2016 [online]. Gap Inc. [accessed 26.05.2019]. Available on World Wide Web: . 53. Global sustainability report 2017 [online]. Gap Inc. [accessed 26.05.2019]. Available on World Wide Web: . 54. Conscious actions sustainability report 2015 [on­line]. H&M [accessed 26.05.2019]. Available on World Wide Web: . 55. The H&M Group sustainability report 2016 [online]. H&M [accessed 26.05.2019]. Available on World Wide Web: < https://s3-us-west-2.amazonaws.com/ungc-production/attach­ments/cop_2017/375021/original/HM_group_SustainabilityReport_2016_FullReport_en.pdf?1491989012>. 56. H&M Group sustainability report 2017 [online]. H&M [accessed 26.05.2019]. Available on World Wide Web: . 57. Nike, Inc. FY12/13 sustainable business perfor­mance summary [online]. Nike Inc. [accessed 26.05.2019]. Available on World Wide Web: . 58. Sustainable innovation is a powerful engine for growth: FY14/15 sustainable business report [on­line]. Nike Inc. [accessed 26.05.2019]. Available on World Wide Web: . 59. Maximum performance minimum impact: FY16/17 sustainable business report [online]. Nike Inc. [accessed 26.05.2019]. Available on World Wide Web: . 60. KRIPPENDORF, Klaus. Content analysis: an in­troduction to its methodology. 2nd ed. Thousands Oaks : SAGE, 2004. 61. BENGTSSON, Mariette. How to plan and per­form a qualitative study using content analysis. NursingPlus Open, 2016, 2, 8-14, doi: 10.1016/j.npls.2016.01.001. 62. ROCA, Laurence Clément, SEARCY, Cory. An analysis of indicators disclosed in corpo­rate sustainability reports. Journal of Cleaner Production, 2012, 20(1), 103-118, doi: 10.1016/j.jclepro.2011.08.002. 63. ASIF, M., SEARCY, C., DOS SANTOS, P., KENSAH, D. K. A review of Dutch corporate sus­tainable development reports. Corporate Social Responsibility and Environmental Management, 2013, 20(6), 321-339, doi: 10.1002/csr.1284. 64. LANDRUM, Nancy E., OHSOWSKI, Brian. Identifying worldviews on corporate sustaina­bility: content analysis of corporate sustainability reports. Business Strategy and the Environment, 2018, 27(1), 128-151, doi: 10.1002/bse.1989. 65. TORELLI, Riccardo, BALLUCHI, Federica, FURLOTTI, Katia. The materiality assessment and stakeholder engagement: a content anal­ysis of sustainability reports. Corporate Social Responsibility and Environmental Management, 2020, 27(2), 470-484, doi: 10.1002/csr.1813. 66. A product lifecycle approach to sustaina­bility [online]. Levi Strauss & Co. [accessed 19.4.2019]. Available on World Wide Web: . 67. Building textile circularity [online]. I:Collect (I:CO) [accessed 01.06.2019]. Available on World Wide Web: . 68. Fashion at the cross roads: a review of initiatives to slow and close the loop in the fashion indus­try [online]. Greenpeace [accessed 02.06.2019]. Available on World Wide Web: . 69. BREWER, Mark K. Slow fashion in a fast fash­ion world: promoting sustainability and respon­sibility. Laws, 2019, 8(24), 1-9, doi: 10.3390/laws8040024. 70. Toxic threads: polluting paradise [online]. Greenpeace [accessed 02.06.2019]. Available on World Wide Web: . 71. THEUWS, Martje, OVEREEM, Pauline. The Myanmar dilemma: can the garment industry deliver decent jobs for workers in Myanmar? [online]. Centre for Research on Multinational Corporations (SOMO) [accessed 02.06.2019]. Available on World Wide Web: . 72. THEUWS, Martje, SANDJOJO, Virginia, VOGT, Emma. Branded childhood: how garment brands contribute to low wages, long working hours, school dropout and child labour in Bangladesh [online]. Centre for Research on Multinational Corporations (SOMO) [accessed 26.06.2019]. Available on World Wide Web: . 73. THEUWS, Martje, OVEREEM, Pauline. Quick scan of the linkages between the Ethiopian garment industry and the Dutch market [on­line]. Centre for Research on Multinational Corporations (SOMO) [accessed 05.11.2019]. Available on World Wide Web: . 74. KUMER, Špela. Primerjalna analiza porocil o tra­jnostnem razvoju za podjetja tekstilne industrije: magistrsko delo. Maribor : Ekonomsko-poslovna fakulteta, 2019. 75. WILSON, Martha. A critical review of environ­mental sustainability reporting in the consumer goods industry: greenwashing or good business? Journal of Management and Sustainability, 2013, 3(4), 1-12, doi: 10.5539/jms.v3n4p1. 76. GARCIA-TOREA, Nicolas, FERNANDEZ-FEIJOO, Belen in DE LA CUESTA, Marta. CSR reporting communication: defective reporting models or misapplication? Corporate Social Responsibility and Environmental Management, 2020, 27(2), 952- 968, doi: 10.1002/csr.1858. 77. Attitudes of Europeans towards building the single market for green products: Flash Eurobarometer 367 [online]. European Commission [ac­cessed 13.11.2019]. Available on World Wide Web: . Preglednica 1: Seznam upoštevanih porocil o trajnostnem razvoju tekstilnih podjetij Table 1: List of considered sustainability reports of selected companies Podjetje/ Company Leto izdaje prvega pregledanega porocila/Year of publication of first examined report Leto izdaje drugega pregledanega porocila/ Year of publication of second examined report Leto izdaje tretjega pregledanega porocila/ Year of publication of third examined report Viri/ References Adidas Group 2014 2015 2016 45-47 C&A 2014 2015 2017 48-50 Gap Inc. 2013-2014 2015-2016 2017 51-53 H&M 2015 2016 2017 54-56 Nike Inc. 2012-2013 2014-2015 2016-2017 57-59 Okoljski vplivi/ Environmental impacts Ukrepi proucevanih podjetij, za katere so v porocilih na voljo konkretni številski podatki/Measures taken, reported by quantitative data Število podjetij, ki so porocala/ Number of reporting companies Napredek v obravnavanem obdobju/ Improvements achieved in examined period of time Izvor tekstilnih materialov/Source of textile materials Uporaba trajnostno pridobljenega bombaža/ Use of sustainable cotton 5 Od 2014. do 2016. povecanje za 38 % [45-47]./ From 2014 to 2016, increase by 38% [45-47] Leta 2017 10–krat vec trajnostnega bombaža kot leto prej [52-53]./ In 2017, 10 times more sustainable cotton than the year before [52-53] Leta 2015 40 %, leta 2017 67 % [48-50]./ In 2015, 40%; in 2017, 67% [48-50] Leta 2015 34 %, leta 2017 59 % [54-56]./ In 2015, 34%; in 2017, 59% [54-56] Leta 2015 24,1 %, leta 2017 54,1% [58-59]./ In 2015 24.1%; in 2017, 54.1% [58-59] Uporaba recikliranega poliestra/Use of recycled polyester 2 Leta 2017 1,7 % (v prejšnjih porocilih ne omenjajo številskih podatkov) [53]./ In 2017, 1.7% (they do not mention numerical data in previous reports) [53] Leta 2015 uporabili 31.220 t, leta 2017 33.265 t [58-59]./ In 2015, 31,220 t were used; in 2017, 33,265 t [58-59] Uporaba trajnostno pridobljenih materialov/Use of sustainable-sourced materials 2 Leta 2015 20 %, leta 2017 35 % [54-56]./ In 2015, 20%; in 2017, 35% [54-56] Leta 2015 19 %, leta 2017 29,6 % [58-59]./ In 2015 19%; in 2017, 29.6% [58-59] Uporaba kemikalij/Use of chemicals Oblacila brez perfluoriranih spojin/Perfluorocarbon-free finished products 1 Leta 2014 90 % oblacil, 2016 96 % [45-47]./ In 2014, 90% of clothing, in 2016, 96% [45-47] Raba energije/ Energy consumption Raba energije iz obnovljivih virov v lastnih procesih/Consumption of renewable and sustainable energy in own processes 2 Leta 2015 78 %, v letu 2017 96 % [54-56]./ In 2015, 78%; in 2017, 96% [54-56] Leta 2015 14 %, leta 2017 22 % [57-59]./ In 2015, 14%; in 2017, 22% [57-59] Okoljski vplivi/ Environmental impacts Ukrepi proucevanih podjetij, za katere so v porocilih na voljo konkretni številski podatki/Measures taken, reported by quantitative data Število podjetij, ki so porocala/ Number of reporting companies Napredek v obravnavanem obdobju/ Improvements achieved in examined period of time Zmanjšanje rabe energije v lastnih procesih/Energy consumption reduction in own processes 1 Od leta 2007 do 2017. zmanjšanje za 9 % [54-56]./ 9% reduction from 2007 to 2017 [54-56] Zmanjšanje rabe energije v proizvodnji pri dobaviteljih/Energy consumption reduction in own processes 2 Od leta 2015 do 2017. zmanjšali porabo za pribl. 1 kW za kg oblacil v fazi barvanja in konfekcioniranja [58-59]./From 2015 to 2017, energy consumption reduction by approx. 1 kW per kg of clothing in the dyeing and finishing processes [58-59] Leta 2015 zmanjšali porabo za 30 milijonov kWh, leta 2017 za 98 milijonov kWh [54-56]./In 2015, they reduced consumption by 30 million kWh, in 2017 by 98 million kWh [54-56] Vodni odtis/ Water footprint Zmanjšanje porabe vode/Water consumption reduction 5 Poraba 121 l/kg oblacil leta 2014 in 95 l/kg oblacil leta 2016 [45-47]./ Consumption of 121 l/kg of clothing in 2014 and 95 l/kg of clothing in 2016 [45-47] Od leta 2016 do 2017. zmanjšanje za 14 % [50]./ From 2016 to 2017, a decrease of 14% [50] Od leta 2014 do 2016. prihranili 3,3 mrd l; leta 2017 prihranili 2,4 mrd l [51-53]./ From 2014 to 2016, they saved 3.3 billion l; in 2017, they saved 2.4 billion l [51-53] V letu 2016 prihranili 2,3 milijona m3, v letu 2017 pa 7,82 milijona m3 [55-56]. Leta 2017 za 55 % kavbojk med proizvodnjo ni bilo porabljeno vec kot 35 l vode na kos, leta 2015 takšnih 50 % kavbojk [54-56]./ Saved 2.3 million m3 in 2016 and 7.82 million m3 in 2017 [55-56]. In 2017, 55% of jeans did not consume more than 35 l of water per piece during production, in 2015 50% of such jeans [54-56] Od leta 2015 do 2017. zmanjšali porabo za skoraj 10 l na kg oblacil v fazi barvanja in konfekcioniranja [58-59]./ From 2015 to 2017, reduction of nearly 10 l per kg of clothing in the dyeing and finishing processes [58-59] Okoljski vplivi/ Environmental impacts Ukrepi proucevanih podjetij, za katere so v porocilih na voljo konkretni številski podatki/Measures taken, reported by quantitative data Število podjetij, ki so porocala/ Number of reporting companies Napredek v obravnavanem obdobju/ Improvements achieved in examined period of time Ogljicni odtis/ Carbon footprint Zmanjšanje izpustov toplogrednih plinov v lastnih procesih/Greenhouse gases emissions reduction in own processes 3 Od 2015. do 2016 zmanjšanje za 11 % [46-47]./ From 2015 to 2016, a decrease of 11% [46-47] Od 2008. do 2014. zmanjšanje za 33 % [51]./ From 2008 to 2014, a decrease of 33% [51] Od leta 2016 do 2017. zmanjšanje za 21 % [55-56]./ From 2016 to 2017, a decrease of 21% [55-56] Zmanjšanje izpustov toplogrednih plinov pri proizvodnji/ Greenhouse gases emissions reduction in suppliers' manufacturing processes 3 Od leta 2016 do 2017. zmanjšanje za 16 % [50]./ From 2016 to 2017, a decrease of 16% [50] Od leta 2015 do 2016. zmanjšanje za 47 % [54-55]./ From 2015 to 2016, a decrease of 47% [54-55] Od 2015 do 2017. zmanjšanje s 4,78 na 4,55 kg CO2e/kg oblacil pri barvanju in konfekcioniranju [58-59]./ From 2015 to 2017, reduction from 4.78 to 4.55 kg CO2e/kg of clothing in dyeing and finishing processes [58-59] Trdni odpadki/ Solid wastes Zmanjšanje kolicine odpadkov v lastnih procesih/Waste reduction in own operations 1 Od 2015. do 2016. zmanjšanje za 28 % [46-47]./ From 2015 to 2016, a decrease of 28% [46-47] Možnost vracanja rabljenih oblacil/Garment collecting initiative for reuse and recycling 1 Od 2013. do 2017. so zbrali 57.000 t oblacil [54-56]./ From 2013 to 2017, 57,000 tons of clothing were collected [54-56] Preglednica 2: Porocanje o okoljskih kriterijih in ukrepih v trajnostnih porocilih Table 2: Reporting on environmental criteria and measures in sustainability reports Preglednica 3: Porocanje o okoljskih kriterijih in ukrepih za posamezno fazo življenjskega cikla izdelka v trajnostnih porocilih Table 3: Reporting on environmental criteria and measures in sustainability reports for different life cycle phases Faza življenjskega cikla/ Life cycle phase Ukrepi podjetij/ Measures taken by companies Število podjetij, ki so porocala v prvem proucevanem porocilu/ Number of companies that reported in the first examined report Število podjetij, ki so porocala v zadnjem proucevanem porocilu/Number of companies that reported in the last examined report Pridobivanje surovin/ Raw materials extraction Uporaba trajnostno pridobljenega bombaža/Use of sustainable cotton 3 5 Uporaba recikliranega poliestra/Use of recycled polyester 1 2 Uporaba trajnostno pridobljenih materialov/Use of sustainable-sourced materials 1 2 Proizvodnja/ Production Oblacila brez perfluoriranih spojin/Perfluorocarbon-free finished products 1 1 Zmanjšanje porabe energije v proizvodnji/Energy consumption reduction in suppliers' manufacturing processes 0 2 Zmanjšanje porabe vode v proizvodnji/Water consumption reduction in suppliers' manufacturing processes 4 5 Zmanjšanje izpustov toplogrednih plinov v proizvodnji/Greenhouse gases emissions reduction within the supply chain 0 3 Transport/ Transport Vsi prevozniki, s katerimi sodelujejo, so vpisani v bazo Clean Shipping Index, s cimer pripomorejo k zmanjšanju izpustov/Transport service providers must follow the Clean Shipping Project requirements for emissions reduction 1 1 Uporaba/ Use Ozavešcanje kupcev o nacinu pranja in sušenja oblacil z namenom prihraniti vodo v fazi uporabe/Actions that encourage conscious garment care by customers 0 1 Ravnanje z odpadki/ Solid wastes treatment Možnost vracanja rabljenih oblacil/Garment collecting initiative for reuse and recycling 1 1 221 Tekstilec, 2021, Vol. 64(3), 221–229 | DOI: 10.14502/Tekstilec2021.64.221-229 Gregor Lavric1, Igor Karlovits1, Deja Muck2, Eva Petra Forte Tavcer2, Urška Kavcic1 1 Pulp and Paper Institute, Bogišiceva 8, 1000 Ljubljana, Slovenia 2 University of Ljubljana, Faculty of Natural Sciences and Engineering, Department of Textiles, graphic arts and design, Snežniška 5, 1000 Ljubljana, Slovenia Influence of Ink Curing in UV LED Inkjet Printing on Colour Differences, Ink Bleeding and Abrasion Resistance of Prints on Textile Vpliv sušenja tiskarske barve v UV LED kapljicnem tisku na barvne razlike, razlivanje tiskarske barve in odpornost proti drgnjenju potiskanih tkanin Original scientific article/Izvirni znanstveni clanek Received/Prispelo 10-2020 • Accepted/Sprejeto 3-2021 Corresponding author/Korespondencni avtor: Gregor Lavric mag. graph. ing. E-mail: gregor.lavric@icp-lj.si ORCID: 0000-0001-8094-9395 Abstract Digital printing techniques are increasingly present in the field of textile printing. Particularly prominent is the inkjet printing technique using water-based inks, while UV LED inkjet printing also increasingly being in use. UV LED inkjet is primarily not intended for direct clothing printing; however, it can be used especially as a hybrid solution in the soft signage market. It is a great option for the printers that are not engaged only in textile print­ing, and want a more versatile print portfolio, extending it to non-clothing textile products, e.g. soft signage and non-wearable products. As these types of products often require colour reproduction of logos, accurate colour reproduction, good ink adhesion and sharpness are important just like in other printing technologies. In order to evaluate the impact of UV LED radiation amount on colour differences, ink bleeding and abrasion resistance, six different fabric samples (five woven and one nonwoven) were printed using a UV LED inkjet printer. Based on the results of colour difference, it was established that a reduction of UV radiation (by half the manufacturer’s recommended amount) had no effect on this parameter. However, perceptible colour differences were observed with the use of different M measurement conditions defined by the international standard ISO 13655-2017. Reducing the amount of UV radiation had no effect on the adhesion and durability of the printed ink. Small differences detected in these two parameters were mainly a consequence of the properties of textile materials and not of decreased UV radiation. Keywords: UV LED inkjet printing on textile, ink curing, ink bleeding, colour differences, abrasion resistance Izvlecek Digitalne tiskarske tehnike so cedalje bolj prisotne na podrocju tekstilnega tiska. Pri tem ima vodilno vlogo predvsem kapljicni tisk s tiskarskimi barvami na vodni osnovi, cedalje bolj pa je prisoten tudi UV LED kapljicni tisk. Ceprav njegov prvotni namen ni tiskanje oblacil, je hibridna rešitev za tiskarje, ki poleg tekstilnih potiskujejo tudi druge vrste materialov. Med nabor tekstilnih izdelkov, ki se lahko tiskajo z uporabo tehnologije UV LED kapljicnega tiska, spadajo predvsem neoblacilni izdelki in t. i. mehke oznake. Tudi pri teh so natancna barvna reprodukcija, obstojnost in kakovost odtisov kljucnega pomena. Da bi ovrednotili vpliv sušenja tiskarske barve, ki je eden kljucnih procesov v UV LED kapljicnem tisku, smo med raziskavo z razlicnima kolicinama UV-sevanja zamreževali oz. sušili tiskarsko barvo, odtisnjeno na šestih (petih tkanih in enem netkanem) tekstilnih vzorcih. Na podlagi rezultatov meritev barvnih razlik smo ugotovili, da zmanjšanje kolicine UV-sevanja (za polovico glede na tisto, ki jo priporoca izdelovalec tiskalnika) ni vplivalo na ta parameter. Sorazmerno velik vpliv na barvne razlike odtisov pa smo zaznali ob uporabi razlicnih M merilnih pogojev, ki jih definira mednarodni standard ISO 13655-2017. Zmanjšanje kolicine UV-sevanja ni vplivalo na adhezijo in obstoj­nost odtisnjene tiskarske barve. Majhne razlike, zaznane pri teh dveh parametrih, so bile predvsem posledica lastnosti tekstilnih materialov in ne posledica zmanjšanja kolicine UV-sevanja. Kljucne besede: UV LED kapljicni tisk na tekstil, sušenje tiskarske barve, razlivanje tiskarske barve, barvne razlike, ­odpornost proti drgnjenju 1 Introduction The presence of digitisation has been on an increase in virtually every industrial sector in recent years, which is also reflected in the field of textile print­ing. Digital printing techniques are becoming each year more prevalent in this segment, as evidenced by the Smithers Pira data, which predict more than 10% annual growth by 2023 [1]. Digital printing techniques are replacing analogue printing with the predominance of inkjet printing. Inkjet printing is based on spraying tiny droplets (with a volume of few picolitres) of liquid ink onto the printing sub­strate. The droplets are placed with great precision, enabling reproduction of high-quality images. The inkjet printing market share is growing mainly be­cause it offers an economic alternative to other print techniques, having the advantage of full variability and low set-up costs. It allows economic printing of single copies on virtually any flat or flexible printing substrate (stone, polymers, glass, ceramics, compos­ites, textiles etc.) [1, 2]. The dominant water-based technologies (with reac­tive, acid or pigmented inks) have the largest market share, while UV inkjet is a subtype of inkjet printing which is not intended for direct clothing printing but can be used especially as a hybrid solution in the textile soft signage market. It is a great option for printers that are not engaged only in textile printing and want their versatile print portfolio to extend to non-clothing textile products, e.g. soft signage and non-wearable products. As soft signage often includes colour reproduction of logos, an accurate colour re­production is important just like in other printing technologies [3]. The main disadvantage of UV LED inkjet is the possibility of ink components migra­tion and reaction with the human skin when used for wearable textile printing. Its greatest advantage, however, is that the printing ink dries as soon as it is applied onto the printing substrate and cured with a UV LED lamp. This enables printing with a great­er amount of printing ink (better surface coverage and a more accurate colour reproduction with less influence of the printing material) and, above all, printing on (all) non-absorbent printing materials [2, 3]. Immediate drying is enabled by the photoini­tiator, a component of printing ink that encourages the crosslinking of the printed layer of ink under the influence of UV radiation from lamps, which are a part of printers. Currently, the following photoini­tiators are mainly in use: benzyl dimethyl ketal, 2-hydroxy-methyl-1 ­phenyl propane and hydroxy­cyclohexyl phenyl ­ketone. As a source of UV radia­tion, LED lamps are primarily used on modern print­ing devices. They use significantly less energy than conventional mercury lamps while producing less harmful ozone. Their advantage is also the narrow­er radiation range, with usually only one dominant peak located in the UV A region (320–395 nm) [2]. Two books by Ujiie [4] and Cie [5], along with an article by Malik, Kadian and Kumar [6] defined digital printing technologies and especially inkjet printing in detail, providing an overview of techni­cal specifications of different parameters involved in the printing of textiles. When printed, UV inks are very low in viscosity and penetrate deeply into the fabric to adhere to the surface. The ink must be exposed directly to UV light to obtain a cure from a UV bulb. UV curable inks and their applications in industrial inkjet printing are described also in the book by Zapka [7] where the author mentions that the UV exposure time can influence image quality. An overview of influencing factors is presented in Figure 1. Regarding published research, the UV inkjet printing on textiles (esp. UV LED inkjet) has not been widely researched yet. The article by Hankock and Lin [8] covered the production of UV inkjet inks, while in the paper by Edison [9], the optimisation of UV cur­able inks was defined in terms of optimal jet output. Yi et al. [10] investigated the importance of mono­mers and comonomers in UV LED inks. Their work indicates that the monomer has not only a substan­tial influence on the dispersion and cure rate of UV LED ink but also a major effect on the film-forming properties of the ink. The mechanisms of attachment to textile fibres primarily include the interaction of chemical binding, mechanical interaction and fibre structure diffusion. The influence of industrial fabrication parameters on the crosslinking density of UV resin was studied by Seipel et al. in 2018 [11]. A UV responsive smart textile was produced with inkjet printing and UV LED curing of a specifically designed photochromic ink on a PET fabric. The authors found out that in­creased ink deposition, or curing with higher intensi­ty, i.e. higher lamp intensity and/or lower belt speed, increased the crosslinking density of ink. Hence, it formed a thicker or more distinct layer on the PET fabric surface. The effect of the deposited ink amount and curing settings on print durability is also de­scribed in this paper. A higher polymer crosslinking density is achieved as the print creates a strong insu­lation layer on the PET surface. The prints cured with the lowest curing intensity exhibited a lower polymer crosslinking density; however, they were slightly less durable and flexible. Mikuž et al. [12] compared the properties of inkjet printed, ultraviolet cured pigment prints with screen-printed, thermo-cured ­pigment prints. The colorimetric parameters of printed fab­rics showed minimal and acceptable differences. A comparison of colour fastness properties proved that good colour fastness is achieved on pigment-printed fabrics produced with both printing techniques. The flat-screen-printed fabrics had better colour fastness to washing, perspiration and rubbing, while ink-jet-printed fabrics showed better colour fastness to dry-cleaning and light. Tse et al. [13] studied the us­ability of image-based instruments for print quality evaluation. Regarding colour quality, the test results indicate that the fabric structure, yarn size and the hydrophilic/hydrophobic aspect of the fabric are the most important variables. Moreover, it was estab­lished that the colour gamut for larger size yarn is greater than for smaller size yarn and that there was an apparent downshift in the a*–b* plane for the knit­ted sample, indicating a colour shift between the two types of fabric structures. Bae, Hong and Lamar [14] found out that the texture of woven textiles caused a measurable effect on colour in inkjet printing, both using instrumental and perceptual measures. Colour reproduction is not only characterised by the interaction between light, dyes, pigments and textile structure, but also by the measurement conditions and geometry, and by the multi-layering of inks and process parameters. The multi-layering of inks and process parameters, e.g. washing fastness of printed inks, were studied by Kašikovic et al. [15] in 2018. Two commercial spectrophotometers with different measuring geometries were used in a paper written by Milic et al. [16] to determine the measuring uncer­tainty of spectrophotometric ­measurements of print­ed textile materials. Study findings suggest that, de­spite different measuring geometry, instruments had similar measurement repeatability behaviour (repeat­ability of readings from different parts of the same sample) in the case of used digitally printed polyester materials. The material preparation process (material was folded three times and placed on a black or white backing) had an important influence on measure­ment variability. In the recent study by Karlovits, Lavric and Kavcic [17], four differently structured textile materials were printed with a UV LED inkjet printer. The spectrophotometric measurements of prints were conducted according to ISO 13655:2017 [18]. The obtained results revealed that the texture and aperture size had influence on colour differenc­es, while the measurement mode differences were more prominent in the areas with higher than lower ink coverages, especially when using the polarisation filter for ink coverages over 150%. Even though UV curing is one of the key processes in UV LED inkjet printing, its influence on print prop­erties has not been widely researched in the literature. The aim of the research, therefore, was to describe the influence of the UV LED radiation amount on colour differences, ink bleeding and abrasion resistance of prints printed with a UV LED inkjet printer on six different fabric samples. The study also evaluated the influence of M mode measurement conditions on colour differences in the UV LED inkjet printing. The M mode measuring conditions are defined by the international standard ISO 13655:2017 [18] and are widely used especially for paper and cardboard printing applications. They are a response to the in­creasing presence of optical brighteners in papers and cardboards, which creates challenges for successful colour management and accurate colour reproduc­tion. Optical brighteners are chemical substances added to different materials (e.g. paper, board, fab­rics) to enhance their brightness. They absorb invis­ible ultraviolet radiation at wavelengths below 400 nm and emit it in the blue end of the visible spectrum at approximately 400 to 450 nm through an electro­physiological alteration (fluorescence process). This process is activated only when the M1 measuring condition is used for spectrophotometric measure­ments. By choosing this measurement condition, the measurement is performed using the D50 illumi­nation condition with the UV component of light included. At the M2 measuring condition, this part of the light is excluded (UV cut), while the measurement condition M0 is based on the measurements with the Standard Illuminant A. As by scope, ISO 13655:2017 is not applicable just for paper and board types of substrates, and there is no other specific standard regarding the measurement conditions for digitally printed textiles. It is more common that the print­er will use a spectrophotometer, which covers more types of printing materials, and these differences are important for evaluation. 2 Materials and methods 2.1 Materials The influence of UV curing in the UV LED inkjet printing on colour differences, print sharpness and abrasion resistance was evaluated on six different fabric samples (5 woven and 1 nonwoven). Their properties are presented in Table 1. Printing forme preparation A digital printing forme (cf. Figure 2) was designed using the computer program Adobe Illustrator CC (Adobe, USA) and saved as PDF without the colour profile attached. It consisted of 18 colour patches with the area of 4 cm2 (CMY patches with 50% and 100% tone value; RGB patches with 50% and 100% tone value, where e.g. 50% R is defined as 50% M + 50% Y and 100% R is defined as 100% M + 100% Y etc.) The total ink coverage scale consists of patches in which the tone values gradually increase (from 50% C + 50% M + 50% Y + 50% + 100% B to 100% C + 100% M + 100% Y + 100% B), lines and a control element for print sharpness evaluation. The file was then pro­cessed using a SAi PhotoPRINT DX Plus (SAi, USA) raster image processor. Linearization without colour corrections was performed. Printing process The samples were printed with an Apex UV 1610 UV LED flatbed inkjet printer (Apex, China) equipped with Toshiba CE4 on-demand piezo electric inkjet print heads and two UV LED lamps (one on the left and one on the right side of print heads). Sakata soft LED UV inks (Sakata, Japan) were used. They were formulated to cure when exposed to UV light with the wavelength of 395 nm. The printing parame­ters were set to 8 passes, with the printing speed of 0.84 m/s (one-directional printing – from right to left). The print head height was set 0.8 mm above the material top and the jetting frequency to 10.28 kHz. The printing ink drop size was 6 picolitres. The ink was cured using one or both UV lamps. Five prints were made on each fabric sample. Spectrophotometric measurements and colour differences calculation Spectrophotometric data were obtained using a spec­trophotometer X-Rite i1 Pro 2 Basic (X-Rite, USA) and BabelColor PatchTool (BabelColor, Canada) software. The measurements were performed with the M0, M1 and M2 measurements modes (cf. Table 2) on stand­ardised white backing. The measuring conditions were set to 45°/0° ring illumination optics, D50 standard illuminant and 2° standard observer. Colour differenc­es (.E00) were calculated using BabelColor PatchTool software in accordance with ISO 13655:2017 [18]. Five measurements were made on each colour patch. Ink bleeding evaluation The ink bleeding evaluation was done following the method described by Hladnik and Muck in 2011 [19]. It is based on the measurements of the area (mm2) and perimeter (mm) of a selected printed element that are compared with the measurements of its un­distorted digital form from the printing form. The measurements were conducted using an ImageJ 1.48v (ImageJ, USA) computer program on TIFF images with the resolutions of 600 ppi obtained with CanoScan 5600F (Canon, Japan) without any colour distortions and corrections. Crockfastness evaluation Crockfastness was measured according to ISO 105-X12:1993 on a CM-5 Crockmeter (AATCC Atlas, USA). Ten measurements were performed for dry and wet crockfastness tests. Colour fastness to washing Colour fastness to washing at 40 °C was tested in accordance with ISO 105-C06:2010. FTIR ATR analysis The FTIR ATR printing ink analysis was performed using a Perkin Elmer Spectrum Two FTIR spec­trometer (Perkin Elmer, USA). For the purpose of the analysis, printing ink was printed on an inert glass surface with one and two UV lights used for curing, and then peeled from it and analysed. In this way, a potential impact of the textile on the analysis was nullified. 3 Results and discussion Table 3 shows the average values of colour differences among the prints printed using one or two UV lamps on each textile sample. Colour differences were cal­culated based on the spectrophotometric values of all colour patches on the printing form. All patches were measured under the M0, M1 and M2 measuring conditions. Based on the results shown in Table 3, it can be con­cluded that between two different amounts of UV radiation, there was a minimal effect on the colour reproduction of textile samples. The average calculat­ed colour difference was 0.55 .E00. Such a colour dif­ference is almost unnoticeable to the human eye and is most likely a consequence of short-term repeata­bility of the measuring instrument and the printer. Despite the 50% reduction in UV radiation from the radiation recommended by the printer manufacturer, it still polymerised the ink and thus prevented fur­ther penetration, which could lead to greater colour variations. However, this was not fully confirmed by the FTIR analysis, the result of which is shown in Figure 3. As it can be seen from Figure 3, the sample of print­ing ink that was less crosslinked (red curve) achieved slightly higher absorbance values across the entire spectrum (from 450 to 4000 cm–1) than the sample that was crosslinked to a greater extent. The verti­cal shift of curves can be attributed to the difference in the amount of twisting and stretching vibrations between molecules and atoms, which was more no­ticeable at the less crosslinked sample of printing ink. The difference is clearly noticeable also at approx. 807 cm–1, which indicates a greater presence of C=C bonds in the less crosslinked sample. The amount of unreacted C=C double bonds between acrylic mole­cules is a direct indicator of UV ink polymerisation (several unreacted C=C double bonds indicate a low­er degree of ink polymerisation). A much greater influence on colour differences, espe­cially for samples V1 and V4, which contained optical brighteners, can be observed due to the selection of measuring conditions. The results shown in Table 4 were obtained by measuring the prints dried using two UV LED lamps, the only variable factor being the choice of the measurement condition. Optical brighteners present in textile samples (V1 and V4) affected the colour reproduction significantly (cf. Table 4). This is the main reason for relatively big colour differences (on average between V1 and V4; M0 : M1 1.10, M0 : M2 2.98 and M1 : M2 4.07 .E00). The majority of colour differences (more than 60%) were detected in the least covered fields (50% CMY). Mainly due to the properties of tested materials (structure and weaving), spectrophotometric meas­urements were also influenced by optical brighteners in more covered fields or patches (the influence of optical brighteners present not only on the surface of the fibres but also on their circumference). Such colour differences are perceptible through close ob­servation (M0 : M1) and at a glance in the case of comparing M2 measuring conditions with M1 and M0. The colour differences of samples without opti­cal brighteners were negligible. Negligible were also the differences in the area and perimeter of selected printed elements which were measured for print­ing sharpness determination and are presented in Table 5. The differences in areas and perimeters caused by lower UV radiation are minimal and can be attrib­uted to the deviation of the method. Despite the one lamp being turned off, a sufficiently strong crosslink­ing occurred quickly enough for the printing ink not to spill or bleed. The differences among the samples, however, can be attributed to their different structure. Table 6 represents the colour fastness properties of samples to washing at 40 °C. Reduced ink curing did not influence this parameter on woven samples, while it improved colour fastness to washing of the nonwoven sample V6. The absence of empty spaces between the threads in this sample retained a greater amount of printing ink on the fabric surface. The ink layer was slightly more flexible with reduced curing. This affected the result of colour fastness to washing; however, it did not affect the results of the Crock test shown in Table 6. The results of the crock test (cf. Table 7) were not affected by the reduction in curing. Small differ­ences can be attributed to the standard deviation of the method, which is based on the visual assess­ment. Among the samples, the worst result was achieved with the nonwoven sample (V6). The printing ink layer, which remained on the surface of the sample, was more exposed when rubbed than in other samples. 4 Conclusion Reducing the amount of UV radiation used for print­ing inks curing (by half the manufacturer’s recom­mended amount) had no significant effect on the colour differences and print sharpness of printed textiles. A selection of different measuring condi­tions, however, caused perceptible colour differences in two samples which had optical brighteners, the other four had no significant changes. The difference between the applied two levels of radiation did not influence the ink properties, and thus the differences due to additional ink fluorescence and other optical effects. The FTIR analysis showed a difference in the degree of polymerisation of the printing ink, which was cured with one or two lamps, however, from the applicative point of view, the difference proved to be practically irrelevant. It is very important that the presence of optical brighteners is taken into ac­count and that modern and calibrated measuring instruments are used for colour measurements. The adhesion and fastness tests resulted in small, insig­nificant differences, indicating that the drying can be done equally efficiently with just one lamp on textile materials. The differences in the crockmeter were mainly due to the material properties and not a result of drying exposure variation. References 1. The future of digital textile printing to 2023 [online]. Smithers [accessed 16. 10. 2020]. Available on World Wide Web: . 2. MAJNARIC, Igor. Osnove digitalnog tiska. Zagreb : Graficki fakultet Sveucilišta u Zagrebu, 2015. 3. KARLOVITS, Igor, LAVRIC, Gregor. Standardizacija tiska na tekstilu - izzivi na poti k njej. Graficar, 2020, 5, 9–13. 4. Digital printing of textiles. Edited by Hitoshi Ujiie. Boca Raton : CRC Press; Cambridge : Woodhead Publishing, 2006. 5. CIE, Christina. Ink jet textile printing. Cambridge : Woodhead Publishing, 2015. 6. MALIK, S K, KADIAN, Savita, KUMAR, Sushil. Advances in ink-jet printing technology of tex­tiles. Indian Journal of Fibre & Textile Research, 2005, 30(1), 99–113. 7. Handbook of industrial inkjet printing: a full system approach. Edited by Werner Zapka. Weinheim : John Wiley & Sons, 2017. 8. HANCOCK, Andrew, LIN, Long. Challenges of UV curable ink-jet printing inks – a formulator’s perspective. Pigment & Resin Technology, 2004, 33(5), 280–286, doi: 10.1108/03699420410560470. 9. EDISON, Sara. Optimization of UV curable inkjet ink properties for jet stability. In 2006 UV & EB technical conference proceedings [online]. RadTech [accessed 16. 10. 2020]. Available on World Wide Web: . 10. YI, Qing, WEI, Fu Wei, HUANG, Bei Qing, WANG, Qi. Effect of monomer on performance of UV-LED inkjet ink. Applied Mechanics and Materials, 2013, 469, 68–73, doi: 10.4028/www.scientific.net/AMM.469.68. 11. SEIPEL, S., YU, J., PERIYASAMY, A.P., VIKOVÁ, M., VIK, M., NIERSTRASZ, V.A. Characterization and optimization of an ink­jet-printed smart textile UV-sensor cured with UV-LED light. IOP Conference Series Materials Science and Engineering, 2017, 254(7), 1–4, doi: 10.1088/1757-899X/254/7/072023. 12. MIKUŽ, Mašenka, ŠOŠTAR-TURK, Sonja, FORTE-TAVCER, Petra. Properties of ink-jet printed, ultraviolet-cured pigment prints in com­parison with screen-printed, thermo-cured pig­ment prints. Coloration Technology, 2010, 126(5), 249–255, doi: 10.1111/j.1478-4408.2010.00254.x. 13. TSE, Ming-Kai, BRIGGS, John C., YONG, Kim, LEWIS, Armand. Measuring print quality of dig­itally printed textiles. In Recent progress in ink jet technologies II. Edited by Eric Hanson and Reiner Eschbach. Springfield : Society for Imaging Science and Technology, 1999, p. 548-612. 14. BAE, Ji Hyun, HONG, Kyung Hwa, LAMAR, Traci May. Effect of texture on color variation in inkjet-printed woven textiles. Color Research and Application, 2015, 40(3), 297–303, doi: 10.1002/col.21865. 15. KAŠIKOVIC, Nemanja, VLADIC, Gojko, MILIC, Neda, NOVAKOVIC, Dragoljub, MILOŠEVIC, Rastko, DEDIJER, Sandra. Colour fastness to washing of multi-layered digital prints on tex­tile materials. Journal of the National Science Foundation of Sri Lanka, 2018, 46(3), 381-391, doi: 10.4038/jnsfsr.v46i3.8489. 16. MILIC, Neda, NOVAKOVIC, Dragoljub, KAŠIKOVIC, Nemanja. Measurement uncer­tainty in colour characterization of printed tex­tile materials. Journal of graphic engineering and design, 2011, 2(2), 16–25. 17. KARLOVITS, Igor, LAVRIC, Gregor, KAVCIC, Urška. Colourimetric changes due to measure­ment conditions on inkjet UV-LED printed tex­tiles. In 3rd International Printing Technologies Symposium. Edited by Mehmet Oktav et al. Istanbul : Printing Industry Education Foundation, 2019, 132-138. 18. ISO 13655:2017. Graphic technology – spectral measurement and colorimetric computation for graphic arts images. Geneva : International Organization for Standardization, 2017, 1–49. 19. MUCK, Deja, HLADNIK, Aleš. Nazobcanost robov predmetov in razlivanje crnila [online]. Obdelava digitalnih slik [accessed 16. 10. 2020]. Available on World Wide Web: . Figure 1: Factors in UV LED inkjet printing influenced by exposure time [7] Table 1: Sample properties Sample Weave type (ISO 3572:1976) Thread count warp/weft (ISO 7211-2:1984) Thickness (mm) (ISO 5084:1996) Composition (ISO/TR 11827:2012) Optical brighteners (ISO 3664:2009) Mass per unit area (g/m2) (ISO 3801:1977) V1 plain weave 25/21 0.354 100% CO YES 134 V2 plain weave 51/30 0.228 100% CO NO 121 V3 plain weave 35/21 0.316 50% PES/50% CO NO 171 V4 plain weave 24/21 0.460 100% PES YES 204 V5 crepe weave 30/21 0.573 100% PES NO 199 V6 fleece / 1.170 100% PES (nonwoven) NO 151 Figure 2: Digital printing forme Table 2: Description of measuring conditions Measuring condition Light source Filter M0 undefined/tungsten none M1 D50 + controlled UV none M2 tungsten UV cut Table 3: Average colour differences (.E00) among prints printed using one and two UV lamps Sample Measuring condition M0 M1 M2 V1 0.51 0.51 0.53 V2 0.30 0.29 0.30 V3 0.69 0.69 0.69 V4 0.56 0.55 0.58 V5 0.52 0.52 0.52 Figure 3: FTIR spectra of black process printing ink cured with one (red curve) and/or two UV LED lamps (black curve) Table 4: Colour differences (.E00) caused by selection of measuring condition Sample Measuring condition M0 : M1 M0 : M2 M1 : M2 V1 1.13 3.03 4.15 V2 0.01 0.03 0.04 V3 0.02 0.05 0.06 V4 1.07 2.92 3.99 V5 0.02 0.05 0.07 Table 5: Areas and perimeters of selected printed element Sample Curing – number of active lamps while printing Area (mm2) Perimeter (mm) Ideal, digital element / 190 115 V1 1 187.8 114.9 2 188.2 114.3 V2 1 191.0 115.2 2 190.6 114.2 V3 1 193.7 117.4 2 194.7 118.5 V4 1 189.8 113.9 2 189.2 114.9 V5 1 187.6 115.7 2 189.4 117.5 V6 1 190.6 121.4 2 190.4 122.4 Table 6: Colour fastness to washing at 40 °C Sample Colour fastness to washing 2 UV lamps Colour fastness to washing 1 UV lamp V1 4/5 4/5 V2 4 4/5 V3 4/5 4/5 V4 3 3 V5 5 5 V6 4 5 Table 7: Crock test evaluation Sample Grade Dry 1 UV lamp Dry 2 UV lamps Wet 1 UV lamp Wet 2 UV lamps V1 3 3 3 2/3 V2 2/3 2/3 3 3 V3 2/3 2/3 2 2 V4 2/3 2/3 1/2 1/2 V5 2 2 1/2 1/2 V6 2 2 1 1 230 Tekstilec, 2021, Vol. 64(3), 230–246 | DOI: 10.14502/Tekstilec2021.64.230-246 A. N. M. Masudur Rahman1,2, Shah Alimuzzaman1, and Ruhul A. Khan2 1 Bangladesh University of Textiles (BUTEX), Department of Fabric Engineering, Faculty of Textile Engineering, 92, Shaheed Tajuddin Ahmed Avenue, Tejgaon I/A, Dhaka-1208, Bangladesh 2 Institute of Radiation and Polymer Technology (IRPT), Polymer Composite Laboratory, Bangladesh Atomic Energy Commission, Dhaka-1349, Bangladesh Performance Evaluation of PLA Based Biocomposites Reinforced with Photografted PALF Ocena ucinkovitosti biokompozitov na osnovi polimlecne kisline, ojacenih s fotoinducirano cepljenimi ananasovimi listnimi vlakni Original scientific article/Izvirni znanstveni clanek Received/Prispelo 11-2020 • Accepted/Sprejeto 3-2021 Corresponding author/Korespondencni avtor: Assist Prof A. N. M. Masudur Rahman E-mail: masudfabric@yahoo.com Mobile: +8801553342607 ORCID ID: 0000-0002-4483-6606 Abstract In this study, biocomposites were fabricated through a compression moulding technique that used untreated and grafted pineapple leaf fibre separately with polylactic acid (PLA) as a matrix. For grafting, pineapple leaf fibre (PALF) was chemically modified using two different monomers, i.e. 2-hydroxyethyl methacrylate (HEMA) and methyl methacrylate (MMA) solutions, in the presence of methanol (MeOH) and photoinitiator (Darocur-1664) under ultraviolet (UV) radiation with the aim of improving thermo-mechanical characteristics. Based on grafting efficiency and mechanical attributes, the intensity of UV radiation and monomer concentration were maxi­mized. A series of solutions, created by varying the concentrations (10–60%) of monomers in MeOH along with 2% photoinitiator, were prepared. Experimental results revealed that composites made of PALF grafted with 30% HEMA at the 15th pass and 40% MMA at the 20th pass of UV radiation achieved the optimum mechanical properties compared with an untreated PALF/PLA composite. The optimized solutions were further enhanced by adding various concentrations (0.5–1.5%) of urea, with the best mechanical features achieved using a 1% concentration of urea. The chemical bonds formed due to photografting were viewed using Fourier transform infrared spectroscopy (FTIR). Degradation behaviour under heat was determined through thermogravimetric analysis, which found that photografted PALF/PLA showed significantly better thermal stability than the un­treated composite sample. A water uptake test showed that grafting reduced the water retention capacity of the treated composite significantly. Crystallization characteristics were inspected using a differential scanning calorimeter, which showed that grafted PALF had a substantial effect on the degree of crystallization of PLA. In addition, scanning electron microscopy was used to monitor the interfacial bond, and revealed that interfacial adhesion was enhanced by the incorporation of photografted PALF into the matrix. Keywords: photografting, PALF, thermo-mechanical properties, PLA, UV radiation Izvlecek V tej raziskavi so bili iz neobdelanih oziroma površinsko aktiviranih listnih ananasovih vlaken in polimlecne kisline (PLA) kot matrice po postopku oblikovanja z vlecenjem izdelani biokompoziti. Za izboljšanje termomehanskih lastnosti so bila ananasova listna vlakna (PALF) kemicno modificirana s pomocjo dveh razlicnih monomerov, in sicer raztopine 2-hidroksietil metakrilata (HEMA) in raztopine metil metakrilata (MMA) v prisotnosti metanola (MeOH) in fotoiniciatorja (Darocur-1664) ter uporabe ultravijolicnega sevanja (UV). Intenziteta sevanja UV-žarkov in koncentracija monomera sta bila optimizirana glede na ucinkovitost cepljenja in mehanske lastnosti kompozitov. Pripravljena je bila serija 10–60-od­stotnih raztopin monomera v metanolu z dodatkom 2-odstotnega fotoiniciatorja. Eksperimentalni rezultati so pokazali, da so optimalne mehanske lastnosti dosegli kompoziti, ojaceni s predhodno cepljenimi vlakni PALF s 30-odstotnimi HEMA in 15 cikli osvetljevanja z UV-žarki, medtem ko so kompoziti iz predhodno cepljenih vlaken s 40-odstotno raztopino MMA dosegli optimalne lastnosti po 20 ciklih osvetljevanja z UV-žarki. Optimiziranim raztopinam je bila dodana secnina v 0,5–1,5-odstotnih koncentracijah, pri cemer so bile najboljše mehanske lastnosti kompozitov dosežene z uporabo enoodstotne koncentracije secnine. Kemicne vezi, ki so nastale zaradi cepljenja vlaken, so bile dokazane s pomocjo infrardece spektroskopije s Fourierjevo transformacijo (FTIR). Termogravimetricna analiza je pokazala, da je kompozit PALF/PLA s cepljenimi vlakni imel bistveno boljšo toplotno stabilnost kot kompozit PALF/PLA z neobdelanimi vlakni. Prav tako je cepljenje vlaken znatno zmanjšalo sposobnost zadrževanja vode v kompozitu. Z diferencialno termicno kalorimetrijo je bilo ugotovljeno znatno zvišanje stopnje kristalinicnosti PLA v kompozitu PALF/PLA, ki je vseboval cep­ljena vlakna. Poleg tega je bila za spremljanje medfazne adhezije v kompozitu uporabljena tudi rastrska elektronska mikroskopija, ki je pokazala povecanje adhezije z vkljucitvijo fotoinduciranih cepljenih vlaken PALF v matrico. Kljucne besede: fotoinducirano cepljenje, PALF, termomehanske lastnosti, PLA, UV-sevanje 1 Introduction Interest in plant extracted lignocellulosic fibres as a reinforcing filler in composites has risen significantly during the last few decades for environmental rea­sons. However, research carried out in this area has determined that the integration of lignocellulosic fibres enhances the qualities of plastics. Plant-based fibres showed some notable benefits when compared to artificial fibres. For instance, they have compara­ble physico-mechanical properties, are inexpensive, cause no skin irritation, consume a small amount of energy during production and supply more O2 to the environment, and emit lower amounts of CO2 and toxic fumes during heat treatment, while the most prominent property is that they are renewable and decomposable. Due to their eco-friendly nature, these natural fibres are used in engineering applica­tions in numerous sectors, such as the textile, auto­motive, aeronautic and construction industries, and in biomedical sectors [1-9], and thus encourage scien­tists to search for more and new classes of green and sustainable materials. In this regard, polylactic acid (PLA) is preferred for accelerating biodegradation in composites as a matrix because it is a biopolymer sourced from renewable products, it facilitates pro­cessing and has high thermo-mechanical properties compared to other thermoplastics, in combination with reduced manufacturing costs. PLA-based com­posites reinforced with plant-sourced bast fibres have already been studied, although much variation has been found in their properties. To establish suitable applications of composites made with PLA, further enhancement is required through reinforcement, where natural fibres are preferred for that purpose [10, 11]. This study focuses on lingo-cellulosic pineapple fibre, which can serve as a favourable reinforcement, as it is abundantly available in tropical countries. Pineapple fibre is collected from the leaves of the pineapple plant, which are often discarded after the collecting of fruits. Currently, pineapple leaf fibre (PALF) holds no commercial value except for the nutritional purpose of its fruit, and is considered agro-waste. It is thus necessary to develop the standard of PALF by en­hancing the physico-chemical and thermo-mechan­ical properties that might exaggerate the demand for consumption of the fibre. A study of PALF showed that it possesses outstanding thermal and mechan­ical characteristics that are equivalent to common lignocellulose fibres, such as jute, ramie and hemp, which are already established and extensively used as reinforcements in composite materials [12]. The fibre contains 67-82% cellulose, 18.8% hemicellulose, 4-15% lignin, 1-3% pectin, 4% waxing material, and a small amount of ash (3%). The density and diameter range is 1.07-1.52 g/cm3 and 20-80 µm respective­ly, together with a tensile strength (TS) of 413-1627 MPa, a Young’s modulus (YM) of 34.5-82.51 GPa and elongation at break (Eb) of 1.6-3% [13, 14]. Thus, cellulose is the main component of PALF constituting anhydro-glucose units (1, 4-ß conformation). These units comprise –OH groups that are mainly respon­sible for the higher moisture take up of PALF as the main drawback relative to other plant-extracted nat­ural fibres. Consequently, chemical treatment is cru­cial for enhancing the characteristic properties of the fibre, so that physical, mechanical and thermal prop­erties, as well as sustainability, will be superior while at the same time preserving its environment-friendly property [15, 16]. For overcoming the problems associated with nat­ural fibres, many researchers have attempted to de­velop existing properties using different chemical treatments, such as change of functionality, graft copolymerization and acetylation, with the aim of improving its quality and genetically enhancing end products for diversified applications in numerous fields [17]. One of the most successful methods for developing the physico-mechanical behaviour of nat­ural fibres is grafting with vinyl monomers under a radiation-induced method [18]. Radiation process­ing technology is a convenient way for grafting and modifications due to the introduction of stronger cross-linking through the rapid free radical propaga­tion reaction of the multifunctional vinyl monomer, along with the reduction of the hydrophilic nature of cellulose fibre [19]. Over the decades, the impact of radiation on polymeric substrates, predominantly UV and . (gamma), has been examined comprehen­sively. These radiations create ionization through the production of electrons, ions and free radicals [20]. Photo cross-linkable polymers contain functional groups that can directly form a cross-linked poly­mer through light-induced reactions. Photoinitiators have numerous applications in photo-induced po­lymerization. The benefits of photocuring treatment in polymers include improved monomer stability, a significant reduction in reaction time, low energy consumption, etc. [21, 22]. Numerous studies have already been performed on monomer-based grafting with cellulosic fibres [23-25] to enhance potentialities under certain environmental conditions, particularly on jute, which has already gained considerable inter­est from many researchers. However, fewer reports can be found on radiation and photocured grafting. Nevertheless, sounder study, noticeably skilful efforts and cautious experimental techniques are required to achieve the full commercial benefits in this area. The present study involves the modification of PALF to optimize the fibre’s attributes with the aim of broadening its future use in industrial applications. For this purpose, PALFs were treated with two types of acrylic monomers under various intensities of UV radiation, and the resulting treated fibres were fur­ther set to produce PALF/PLA composites. A brief examination was carried out on thermo-mechani­cal properties of the treated composites and further proved that the composites can be used for diversified applications with better serviceability. 2 Experimental 2.1 Materials PLA pellets and PALF were supplied from DS fibres, Belgium and Madhupur, Bangladesh respectively. The molecular weight and density of PLA was 209 kDa and 1.273 g/cm3 respectively. Two types of monomer 2-hydroxyethyl methacrylate (HEMA), methyl methacrylate (MMA) and the swelling agent methanol (MeOH) were acquired from the German Company E. Merck. Darocur-1664, whose function was as photoinitiator, was purchased from Ciba-Geigy. The structures of the used monomers are shown in Figure 1. Urea, which was used as an addi­tive and acetone (CH3COCH3), was purchased from British Drug House, UK. 2.2 Evaluation of fibre properties Fibre density was measured using the simplest meth­od established by Archimedes where no equipment is required. At first, an open air-dried sample is weighed and weighed again after being dipped in a degassed fluid whose density was predetermined. The change in mass is referred to as buoyant force, which is then converted to specimen volume by dividing the fluid density. Finally, sample density was calculated by dividing the open air-dried sample weight by vol­ume. This type of calculation is covered by the ASTM D3800 standard [26]. The ISO 1973:1996 standard was used to determine the linear density of the fibres. Ten fibre tufts with a mass of several milligrams were taken from the sample and the fibres of each tuft were brought into parallel arrangement according to the relevant meth­od. The middle part of each combed tuft was 50 mm in length. Five fibres were taken from each of ten bun­dles in turn, so as to form a bundle of 50 fibres. Ten such bundles were made. These bundles were weighed individually using a scale, to an accuracy of 0.1 mg. The following equation was used to determine the mean linear density of fibre in each bundle. (1) where, L represents the mean linear density of the fibre in each bundle (dtex), m represents the mass of fibre bundle (mg), n represents the number of fibres in the bundle and l represents the length of the indi­vidual fibres in the bundle (mm). Firstly, single fibres were separated manually from the bundle of pineapple fibres. The mechanical prop­erties of individual fibres were determined according to the ASTM D3822 standard. The tests were done us­ing universal Titan SN1410 series (James Heal) test­ing equipment. During testing, a load cell of 20 N and a gauge length of 10 mm were maintained. The test speed was 2 mm/minute. Five specimens were tested for each type of test. The data presented in Table 1 are the average values of the five tests for each case. Some properties of the used fibre are presented in Table 1. 2.3 Grafting of PALF with monomers PALFs were first cut into the desired length (20-25 mm). To eliminate foreign components and dirt, the fibres were washed with acetone followed by drying at 105 °C in an oven and then weighed. The monomers (HEMA, and MMA) were used independently in various concentrations (10-60%) in the formulation. A 2% photoinitiator (Darocur-1664) and methanol (MeOH) were incorporated into the final compo­sition. For swelling the cellulose backbone with the aim of improving impregnation, the monomers were appropriately mixed individually with methanol and the formulated solutions were stirred continuously for 1 hour to eliminate bubble formation. The result­ing compositions are shown in Table 2. The dried virgin PALFs were immersed for 10 minutes in these resulting solutions. The soaked fibres were then sub­jected to irradiation with UV light. A UV radiation source (Minicure-200, IST Technik, Germany) was used for the irradiation of the fibres at the wave­lengths of 254-313 nm, together with 50A current operated at 2kW power. A conveyor belt (length of 1 m) present in the UV irradiator rotates at a speed of 4 m/minutes around a mercury lamp. One movement towards the light is considered one pass. Specimens were kept on the conveyor and allowed to pass con­tinuously through the UV source, and the number of passes was recorded. Before testing, the irradiat­ed samples were kept in a relaxed state for 24 hours. Grafting percentage was calculated from the weight gain basis principle: (2) where, A and B represent weight of the sample after and before treatment respectively. 2.4 Composite manufacturing process 2.4.1 Fabrication of PLA sheets The PLA and PALF were dried properly at 80 °C for 10 hours in vacuum conditions to remove moisture and avoid the creation of voids during the manufacturing process. First, PLA films of 1 mm thickness were pre­pared from pre-weighed pellets using a compression moulding machine (Carver Inc. model 3856, USA) at a temperature of 190 °C for 10 minutes, applying a pressure of 50 bar. Cooling was done for 5–7 min­utes at the same pressure using a different moulding machine. The PLA films were cut to the required size (18 cm × 18 cm) and weighed. 2.4.2 Fabrication of composite laminates Prior to fabricating PALF/PLA composites, PALF fibre was cut to a length of 20–25 mm. Composites hav­ing 3 mm thickness were prepared by sandwiching three layers of PALF between four pre-weighed PLA sheets. The dimension of the mould was 18 cm × 18 cm × 3 mm for the preparation of composites. The sandwiched PLA sheets were then placed between two steel moulds with randomly oriented PALF and heated at 190 °C at a pressure of 50 bar for 10 minutes in a Carver heat press (shown in Figure 2). They were then allowed to cool by passing water from an inlet pipe over both upper and lower plates for 10 minutes. The composite sheet was then removed from the mould plate to undergo natural cooling for 30 minutes at room temperature. Composites were manufactured using untreated and monomer treated fibres separately by maintaining the formulations shown in Table 3. The composite samples of the required dimensions were then cut carefully with a grinding machine from a large composite sheet for the purpose of determining different physical and mechanical properties. 2.5 Mechanical testing of composites The mechanical properties of composites were de­termined in accordance with the ISO 527-4:1997 standard using a universal testing machine (Instron 5569). The load was 10 kN with an extension rate of 2 mm/minutes using a 25 mm gauge length. The flex­ural properties were measured in accordance with the ISO 14125:1998 method with a different Instron (type 4411) machine using a load cell of 5 kN and a speed of 2 mm/minute. The Izod test method (BS EN ISO 180: 2000+A2:2013) was used to determine the impact property, followed by the use of an Avery pendulum impact tester with a specimen size of 80 mm × 15 mm × 3 mm. For tensile and bending tests, a sample size of 60 mm × 25 mm × 3 mm was main­tained. To determine the final result, the mean value of 10 specimens was calculated at an accuracy of ± 0.5%. All of the experiments were performed under standard atmospheric conditions (25 °C ± 2 °C and 65% ± 2% RH). Table 4 shows the properties of PLA and virgin PALF/PLA composite. Table 4: Mechanical behaviours of pure PLA and untreated PALF/PLA (UC) composite Properties Neat PLA PALF/PLA PALF fibre content (wt.%) 0.0 40 Tensile strength (MPa) 62.0 ± 2.5 111.7 ± 4.5 Young’s modulus (GPa) 5.8 ± 0.5 10.8 ± 1.1 Flexural strength (MPa) 87.5 ± 3.5 175.0 ± 6.0 Flexural modulus (GPa) 6.3 ± 0.4 13.6 ± 0.7 Impact strength (kJ/m2) 6.9 ± 0.7 15.3 ± 1.5 2.6 Thermogravimetric analysis (TGA) To investigate the thermal stability and decomposi­tion configuration of PALF/PLA composites, thermo­gravimetry (TG) and derivative thermogravimetry (DTG) were carried out using a TA Instrument Q500 under nitrogen atmospheric conditions. For testing, small pieces of samples were prepared (10-20 mg wt.) and positioned into crucibles. The experiment was performed at temperature ranging from 0-600 °C with 5 °C/minute scan rate, and the corresponding weight loss (%) was recorded. 2.7 Differential scanning calorimetry (DSC) Thermal behaviour and melting features of PLA and PALF/PLA composites were examined using a differ­ential scanning calorimeter (model TA instrument DSC Q100) under nitrogen atmospheric conditions. The specimens were scanned from -20 to 220 °C at a heating rate of 10 °C/minute. The cooling rate was same as the heating rate. The following calculation was used to determine the degree of crystallinity: (3) where .Hm represents the melting enthalpy of pure PLA and PALF/PLA composites and .Hf repre­sents the melting enthalpy of 100% crystalline PLA (93.7 J/g). 2.8 Water retention test To study the swelling behaviour of composites, a water retention test was performed to simulate the soaking phenomena of fibres. To determine the water retention capacity, a 5 g sample was immersed in a beaker holding 200 ml of deionized water. The sam­ples were withdrawn periodically, wiped carefully and weighed. The water retention (%) was determined by means of the following weight gain formula: Wz (%) = [(Wx - Wy/Wy)] × 100(3) where Wz represents the water absorption quantity and Wx, and Wy represent the mass of the specimens before and after immersion. 2.9 Morphological studies To observe the interfacial bonding of composites, fractured surface images were viewed using a scan­ning electron microscope (Philips XL30) with an acceleration of 5.0 kV. 3 Results and discussion In this work, two types of acrylic monomers were selected to achieve enhanced features of PALFs by means of a radiation-induced graft copolymeriza­tion technique. A brief study was made of the impact of UV radiation and monomer concentration (%) on grafting and mechanical properties, the effect of addi­tives on mechanical properties, and the water absorp­tion of grafted PALF/PLA composites. The variation in thermal properties and morphological changes due to grafting and radiation were also studied. 3.1 Grafting (Gf) PALFs were dipped for 10 minutes in solutions produced according to a predetermined formula at various concentrations (10-60%) of MMA and HEMA, followed by UV irradiation at different in­tensities (5-30 UV passes). The results are depicted in Figures 3 and 4, where grafting is shown against UV intensities with regard to monomer concentra­tions. The grafting percentage indicates the amount of cross-linkage produced between monomer and fibre. The grafting values were comparatively low at minor concentrations of monomer, and increased to a certain level of concentration before decreasing. The grafting (%) upsurge with the increase in UV dose reaches an extreme level at a definite intensity of UV and then declines as UV intensity is increased. However, the optimum grafting in most of the ex­periments was seen at the 15th UV pass for HEMA and the 20th pass for MMA treated fibre. After 20 passes, the amount of grafting decreases, possibly due to the degradation of the polymer under radiation. Nevertheless, the maximum grafting value (17.8%) was observed for 30% HEMA cured with 15 passes of UV radiation (H3 sample). The optimum grafting occurs at the 15th pass (Gf = 15.7%) of UV radiation for MMA with a 40% concentration (M4 sample), af­ter which the grafting value falls, as seen in Figures 3 and 4 respectively. Hereafter, all tests were performed under these optimized conditions. Among the three monomers, HEMA treated fibres showed more graft­ing (%) than the MMA monomer, possibly due to its bulkier functional group with a long polymer chain. At a lower level of monomer concentration, free rad­icals form very quickly through propagation reac­tions. The photoinitiator strongly supports acrylic monomers to accelerate these reactions. Therefore, branched structures are produced by using double bonds during graft copolymerization. With an in­crease in monomer concentration, the residual un­saturation amount also rises, resulting in the quicker formation of 3-D network structures, which restricts mobility [27, 28]. After the achievement of the high­est Gf (%), the amount of grafting was reduced with an increase in monomer concentration, which ex­perimental data indicated might be the result of two main factors. At the upper level of concentration, the radical-radical formation reaction can be the result of recombination methods and additional homopoly­mers may instead generate the creation of monomer, together with cellulose. An additional factor may be the inadequate soaking of MeOH with the backbone of cellulose due to a lower quantity of solvent, which inhibits the monomer molecules’ ability to penetrate the cellulose molecules, resulting in fewer sites that are actively involved in the reaction at the backbone of cellulose, and thus continuously decreases the number of reacting sites with a lower level of MeOH present in the case of upper monomer concentration. It is evident that the rate of cross-linking formation was proportional when radiation was initially ap­plied. However, the termination of radical-radical reaction was enhanced greatly by an increase in the monomer concentration and consequently reduced the degree of scission reaction and oxidation [29, 30]. 3.2 Effect of UV radiation on the mechanical performance of the composites Strength is a vital physical property of any textile material, since every change in physical or chemical composition always results in a variation in strength. That also happened in our case. The evaluation of the tensile strength (TS), Young’s modulus (YM), flexural strength (FS), flexural modulus (FM) and impact strength (IS) of virgin PALF/PLA composites were expressed by taking the mean values that were determined to be 111.7 ± 3.5 MPa, 10.8 ± 1.1 GPa, 175 ± 6 MPa, 13.6 ± 0.7 GPa, and 15.3 ± 0.8 KJ/m2 respectively (according to Table 4). It is evident from the table that the tensile and flexural properties of the biocomposite are higher than neat PLA after the incorporation of PALF, as anticipated. The graphical presentation of the TS, YM, FS, FM and IS of mono­mer (HEMA, and MMA) treated PALF composites are seen in Figures 5-7 against the intensities of UV with regard to monomer concentration. The highest TS of 156.3 ± 3 MPa, YM of 15.4 ± 0.15 GPa, FS of 243 ± 5 MPa, FM of 18.7 ± 0.8 GPa, and IS of 21.6 ± 0.9 KJ/m2 were achieved by the HC sample (30% HEMA) while the optimum TS of 149.4 ± 4 MPa, YM of 14.9 ± 0.3 GPa, FS of 237.3 ± 5.5 MPa, FM of 18.5 ± 0.7 GPa and IS of 20.9 ± 0.6 KJ/m2 were achieved by the M4 (40% MMA) sample respectively. Analysed data showed that TS, YM, FS, FM, and IS improved to 40, 42.6, 38.9, 37.5 and 41.7% respec­tively for the HC composite, while the results for the MC composite were 33.7, 38.4, 35.6, 36.2 and 37.2% respectively compared to the UC sample. The values indicate that the amount of grafting directly influenc­es mechanical properties. The higher the grafting, the better the mechanical behaviours of the composites. Experimental results also showed that TS, YM, FS, FM and IS rise with an increase in UV intensity up to a certain dose and then declined as UV intensity rose. It was reported that maximum TS, YM, FS, FM and IS were exhibited by the HC sample at the 15th UV pass, and at the 20th UV pass for the MC sample. The reason for the improvement in mechanical prop­erties with an increase in UV doses may be attribut­ed to intercross-linking formation among adjacent cellulose elements. During the application of UV light, free radicals were created by the photoinitiator (Darocur-1664) and are responsible for starting the free radical reaction. Originally, free radical reactions take place among -OH groups existing in cellulose and monomers and consequently develop properties. During the reaction process, inter reaction between -OH groups may also occur. In the case of HEMA, the reaction mechanism comprises two stages: first, the formation of poly(HEMA) and second, the acrylic groups present in HEMA react with the –OH group of PALF, as illustrated in Figure 8 (a) and 8 (b) respec­tively. Similar mechanisms also occurred between MMA and PALF during UV curing. Fundamentally, initiators assist in the initiation of the reaction of the monomer, through which free rad­ical oxygen is formed, but does not actually impart in the reaction. At this time, a homo-polymerization reaction may occur. The treatment of cellulosic fibres with monomers reduces the hydrophilic property, which also imparts developed tensile properties. The experimental data showed that under UV radiation, the mechanical properties improve to a guaranteed value, after which declines may be attributed to two contrasting and simultaneous occurrences referred to as photo-crosslinking, which is responsible for the development of fibre properties and photo-degrada­tion, for which reason fibre characteristics deteriorat­ed. In the case of lower intensities, photo-crosslink­ing takes place due to the stabilization of free radicals by combination reaction. The grafting efficiency is higher if a higher number of active sites is created on the polymer. At higher intensities of radiation, however, polymer degrade into fragments due to the breaking of the main chain, resulting poor mechan­ical properties [31, 32]. The improvement in the mechanical properties of composites due to the incorporation of photografted PALF is also evident from the stress-strain curve. Typical tensile stress-strain curves of the neat PLA matrix, and the untreated PALF/PLA and monomer treated PALF/PLA composites are shown in Figure 9. In the .gure, neat PLA shows a more linear be­haviour, while the composites behave more non­linearly as the strain increases. The linear phase corresponds to the linear deformation of the fibre and matrix, while the nonlinear deformation of the composites has been explained as a three-phase mechanism. First, a microcrack initiates at the fi­bre-end/matrix interface and propagates along the fibre lengths. Second, the matrix undergoes plastic deformation. Finally, the microcracks in the matrix open and propagate through the deformed matrix. Due to the pulling out of fibres from the matrix, catastrophic crack propagation also takes place through the matrix. 3.3 Analysis of the mechanical behaviours of composites following the integration of an additive Experimental data revealed that the H3 (30% HEMA) and M4 (40% MMA) solutions provided improved properties of the treated PALFs. During treatment, various concentrations (0.5-1.5%) of urea were incor­porated into the augmented formulations. Tables 5 and 6 show the achieved results of TS, YM, FS, FM and IS with Gf (%). The Gf and mechanical behav­iours improved due to the addition of urea into the H3, and M4 solutions at optimal radiation intensi­ty. The best enhanced mechanical properties were achieved through the addition of 1% urea. It was reported that HC sample (30% HEMA treated + 1% urea) showed an increase of 51% in TS, 49.5% in YM, 45.7% in FS, 46.3% in FM and 47.4% in IS com­pared to the UC sample. A similar increase was also observed for other monomer treated composites by adding urea. The presence of >C=O groups neigh­bouring the nitrogen atom in urea has an elongated pair of electrons; by activating them during reac­tion through an additive, a bridge is formed between cellulose and monomer. Oxygen existing in >C=O groups has a great affinity to electrons. As a result, electrons are closely populous around it, thus draw­ing additional electrons from the nitrogen atom of urea, and generating certain advantageous situations for the expansion of the monomer molecules and the backbone of cellulose through additives. Urea possesses some properties that when added would stimulate segregation by complex compound forma­tion with monomer molecules, which might lead to an increase in the concentration of monomer at the grafting position and thus accelerate the reaction mechanism at that point [33]. 3.4 Thermogravimetric analysis (TGA) One of the restrictive features in using plant-based lignocellulosic fibres in composite materials is lower thermal stability. In this study, an attempt was made to increase the thermal stability of PALF/PLA com­posites through photografting. The thermal stability of the UC, HC, and MC samples were studied using TG and DTG curves, as illustrated in Figures 10 and 11 respectively. Both untreated and treated fibre com­posites lost weight in three steps, although decom­position actually occurs in two main phases that are similar to other lignocellulosic fibre composites, as shown in TG curves. For the UC (virgin PALF/PLA) composite, initial weight loss (of 9.9%) was recorded at between 30-105 °C due to the removal of moisture from the fibres. At temperatures above 200 °C (onset temperature), however, thermal stability was reduced and fibre degradation occurred. In brief, stage I (200-285 °C) corresponds to the cleavage of glycosidic linkages of cellulose with the thermal deg­radation of hemicellulose and pectin (18.6% weight loss), while stage II (275-382 °C), where maximum weight loss (53.5%) was seen, corresponds to a-cellu­lose degradation. As lignin consists of aromatic rings that make it complex, its structure decomposed slow­ly over the entire range of temperatures [34]. Table 7 shows the weight loss (%) of untreated and monomer grafted PALF/PLA composites at different tempera­ture intervals. It can be clearly seen from the graphs that grafting increased the thermal stability of PALF/PLA com­posites. All the monomer treated grafted fibre com­posites showed improved thermal stability compared to that of untreated samples, as presented in Figure 10. In the initial stage, treated fibre composites (both HC and MC) demonstrated very low weight loss (5.3 and 5.8% for the HC and MC sample respectively), which actually depends on the amount of grafting, as well as the small amount moisture present in the grafted fibre. Grafted composite samples also exhib­ited a significantly lower amount of weight loss in stage I (8.7-9.1% between 245-343 °C) and stage II (58.8-59.6% between 332-492°C) than the untreated samples. Among the treated samples, 30% HEMA treated PALF/PLA (HC) we more resistant to heat than other samples, probably due to their stronger cross-linkage formation than the other samples. The reaction between the chemical components of monomers and –OH of PALF changes the structure by forming cross-linkage, resulting in the improved strength of the mechanical bond between PALF and the monomer. The complex structure of cross-linkage prevents further degradation, which in turn increases the degradation temperature in stages I and II, and is also responsible for the low weight loss in these two stages. Moreover, free radicals formed due to UV radiation also react with the cellulose and alter its chemical nature, thus creating more hydrophobic and stronger covalent bonds, and increased thermal stability [35]. The degradation of PALF is primarily dependent on the degradation of cellulose, which is the leading constituent of the fibre. However, the chemical structure of cellulose is altered due to pho­tografting, which influences the degradation reaction of cellulose and thus the degradation temperature. Together, this contributes to the enhanced thermal stability of photocured PALF/PLA composites. DTG curves (Figure 11) also provide evidence of the three-stage degradation of modified fibre composites, with weight loss profiles that confirm the developed ther­mal properties of the monomer treated PALF/PLA. 3.5 Differential scanning calorimetry The melting behaviour and degree of crystallinity of neat PLA and PALF/PLA composites were examined using DSC. Figure 12 shows the DSC curves of the UC, HC and MC samples, together with pure PLA, and a summary of results is presented in Table 8. It is evident from the graphs that the addition of PALF fibre into the PLA matrix changed the glass tran­sition and melting temperature of the composites. Observations reveal that the untreated fibre compos­ite exhibited improved Tg relative to neat PLA, which indicates the changing properties from flexible to hard [11]. It is evident that the melting temperature (onset) and melting enthalpy decreased marginally due to the incorporation of PALF into PLA, which may be attributed to the role of PALF as a diluent, resulting in the smaller amount of heat required to melt the UC and the resulting lower Tm. Another rea­son may be that the polymer chains in PLA might be diffused and weakened due to the presence of PALF [10]. Due to radiation induced grafting, the hydrophilic characteristic of PALF is greatly reduced, which further develops adhesion between PALF and PLA resulting in the higher melting temperature of photocured PALF composites (HC and MC) than the untreated sample (UC). It is evident from Table 8 that crystallinity (%) de­creases when PALF is added to the matrix PLA, which is due to the amorphousness of PALF. Nevertheless, (monomer + UV) treated composites demonstrated an increased degree of crystallinity because, during grafting under radiation treatment, both fibre and monomer have active points and pro­duce a complex structure by forming cross-linkage, which ultimately reduces amorphousness and in­creases crystallinity (%). 3.6 Swelling behaviour Water absorption indicates the soaking performance of fibres, which is deemed to be a barrier property. Figure 13 shows water absorption (%) with respect to swelling time (days). For this test, neat PLA, UC (composite without treatment of PALF), HC (30% HEMA treated at the 15th UV pass) and MC (40% MMA treated at the 20th UV pass) samples were se­lected. Observations reveal that the UC sample soaks water in a distinctive way, while the monomer treated samples absorb water at very high rate during the initial 10-15 days. After that time, the absorption rate declined in an almost static manner, while the untreated fibre composite demonstrated continuous water soaking with the progression of time. After 30 days, neat PLA and UC sample absorbed water up to 2.5, and 75.8% respectively, while that rate was 38 and 40.6% for the HC and MC samples respectively, which is actually determined by their grafting values. Because of grafting, void space in the fibre was filled by polymers, and several hydroxyl groups present in the cell wall polymer were replaced during the bond formation of chemical groups, thus reducing the hy­groscopicity of treated fibre. The degree of crystallini­ty of the composites is also responsible for their water retention behaviours, as pure PLA demonstrated a degree of crystallinity of 49%, which decreased to 39, 38 and 34% for the HC, MC and UC composites respectively. It was thus established that water ab­sorption primarily occurred in amorphous regions. For this reason, grafted fibre composites exhibited lower water absorption than untreated composites. Thus, from the above result, it can be stated that an increase in grafting values significantly reduced the water retention capacity of photografted fibre rein­forced composites. 3.7 SEM analysis To understand fibre matrix adhesion, SEM micro­graphs of the composites were studied. The tensile fracture surface of untreated and monomer treated PALF/PLA composites are shown in Figures 14 (a), and 14 (b) and (c) respectively. The untreated PALF partially adhered to the matrix PLA, indicating weak adhesion. More voids and debonding were found on untreated the PALF/PLA composite. A high degree of fibre agglomeration and wider gaps at interfaces result in poor mechanical and thermal properties. An improved fibre-matrix bonding in grafted PALF/PLA was seen, as PALF was entirely surrounded with PLA, while good dispersion can be seen in Figure 14 (c). Also evident is a lower number of voids with improved fibre distribution, indicating a better inter­face between fibre and matrix, which in turn led to enhanced mechanical and thermal properties, which supports the achieved experimental results. 4 Conclusion A photografting technique was used to modify PALF fibres with two types of vinyl monomers, i.e. HEMA and MMA, while the mechanical properties of produced composites were successfully assessed. Based on grafting and mechanical properties, the concentration of monomers and radiation intensity were augmented. Taking into account the relevant parameters, the achieved results illustrated that com­posites made of PALF grafted with 30% HEMA at the 15th UV pass and 40% MMA at the 20th UV pass of UV radiation resulted in optimized mechanical properties. Moreover, the addition of urea (1%) into the optimized solution significantly enhanced the mechanical properties of the composites. Optimized mechanical properties were achieved by fragmenting (glucosidic + weaker) bonds and forming a stronger cross-linkage. The water uptake behaviour of the grafted sample showed a more hydrophobic nature than the virgin sample. Thermogravimetric studies demonstrated that photografting improved the ther­mal stability of the composites, as well as their resis­tance to degradation under heat. Although various surface pretreatments can improve the mechanical properties of cellulosic fibre, it can be concluded with a high degree of certainty from this experimental study that photografting is an effective, safe and pol­lution-free process for the development of the ther­mo-mechanical behaviours of PALF/PLA compos­ites, which can lead to prospects for the commercial and industrial application of PALF fibres. References 1. SIAKENG, Ramengmawii, JAWAID, Mohammad, ARIFFIN, Hidayah, SAPUAN, S.M. Mechanical, dynamic, and thermomechanical properties of coir/pineapple leaf fiber reinforced polylactic acid hybrid biocomposites. Polymer Composites, 2019, 40(5), 2000–2011, doi: 10.1002/pc.249 2. SOOD, Mohit, DWIVEDI, Gaurav. Effect of fiber treatment on flexural properties of natural fiber reinforced composites: a review. Egyptian Journal of Petroleum, 2018, 27(4), 775–783, doi: 10.1016/j.ejpe.2017.11.005. 3. OUSHABI, A., SAIR, S., OUDRHIRI HASSANI, F., ABBOUD, Y., TANANE, O., EL BOUARI, A. The effect of alkali treatment on mechanical, morphological and thermal properties of date palm fibers (DPFs): study of the interface of DPF–polyurethane composite. South African Journal of Chemical Engineering, 2017, 23, 116–123, doi: 10.1016/j.sajce.2017.04.005. 4. PICKERING, K.L., ARUAN EFENDY, M.G., LE, T.M. A review of recent developments in natural fibre composites and their mechanical perfor­mance. Composites Part A: Applied Science and Manufacturing, 2016, 83, 98–112, doi: 10.1016/j.compositesa.2015.08.038. 5. MOHAMMED, L., ANSARI, M.N.M., PUA, G., JAWAID, M., SAIFUL ISLAM, M. A review on natural fiber reinforced polymer composite and its applications. International Journal of Polymer Science, 2015, 2015, 1–15, doi: 10.1155/2015/243947. 6. ALI, A., SHAKER, K., NAWAB, Y., JABBAR, M., HUSSAIN, T., MILITKY, J., BAHETI, V. Hydrophobic treatment of natural fibers and their composites - a review. Journal of Industrial Textiles, 2018, 47(8), 2153–2183, doi: 10.1177%2F1528083716654468. 7. FARUK, O., BLEDZKI, A.K., FINK, H.-P., SAIN, M. Biocomposites reinforced with nat­ural fibers: 2000–2010. Progress in Polymer Science, 2012, 37(11), 1552–1596, doi: 10.1016/j.progpolymsci.2012.04.003. 8. KIRUTHIKA, A.V. A review on physico-mechan­ical properties of bast fibre reinforced polymer composites. Journal of Building Engineering, 2017, 9, 91–99, doi: 10.1016/j.jobe.2016.12.003. 9. RAMESH, M., PALANIKUMAR, K., HEMACHANDRA REDDY, K. Plant fibre based bio-composites: sustainable and renewa­ble green materials. Renewable and Sustainable Energy Reviews, 2017, 79, 558–584, doi: 10.1016/j.rser.2017.05.094. 10. KAEWPIROM, S., WORRARAT, C. Preparation and properties of pineapple leaf fiber reinforced poly (lactic acid) green composites. Fibers and Polymers, 2014, 15(7), 1469–1477, doi: 10.1007/s12221-014-1469-0. 11. HUDA, Masud S., DRZAL, Lawrence T., MOHANTY, Amar K., MISRA, Manjusri. Effect of chemical modifications of the pineapple leaf fiber surfaces on the interfacial and mechan­ical properties of laminated biocomposites. Composite Interfaces, 2008, 15(2-3), 169–191, doi: 10.1163/156855408783810920. 12. RAHMAN, H., ALIMUZZAMAN, S., SAYEED, M.M.A., KHAN, R.A. Effect of gamma radia­tion on mechanical properties of pineapple leaf fiber (PALF)-reinforced low-density polyethyl­ene (LDPE) composites. International Journal of Plastics Technology, 2019, 23(2), 229–238, doi: 10.1007/s12588-019-09253-4. 13. MITTAL, M., CHAUDHARY, R. Experimental investigation on the mechanical properties and water absorption behavior of randomly orient­ed short pineapple/coir fiber-reinforced hybrid epoxy composites. Materials Research Express, 2018, 6(1), 015313, doi: 10.1088/2053-1591/aae944. 14. ASIM, M., ABDAN, K., JAWAID, M., NASIR, M., DASHTIZADEH, Z., ISHAK, M.R., & HOQUE, M.E. A review on pineapple leaves fibre and its composites. International Journal of Polymer Science, 2015, 2015, 1–16, doi: 10.1155/2015/950567. 15. HUJURI, U., CHATTOPADHAY, S.K., UPPALURI, R., GHOSHAL, A.K. Effect of maleic anhydride grafted polypropylene on the mechan­ical and morphological properties of chemically modified short-pineapple-leaf-fiber-reinforced polypropylene composites. Journal of Applied Polymer Science, 2008, 107(3), 1507–1516, doi: 10.1002/app.27156. 16. NAJEEB, M.I., SULTAN, M.T.H., ANDOU, Y., SHAH, A.U., EKSILER, K., JAWAID, M., ARIFFIN, A.H. Characterization of silane treat­ed Malaysian Yankee Pineapple AC6 leaf fiber (PALF) towards industrial applications. Journal of Materials Research and Technology, 2020, 9(3), 3128–3139, doi: 10.1016/j.jmrt.2020.01.058. 17. KESHK, S., SUWINARTI, W., SAMESHIMA, K. Physicochemical characterization of differ­ent treatment sequences on kenaf bast fiber. Carbohydrate Polymers, 2006, 65(2), 202–206, doi: 10.1016/j.carbpol.2006.01.005. 18. ZAMAN, H.U., KHAN, M.A., KHAN, R.A., SHARMIN, N. Effect of chemical modifications on the performance of biodegradable photocured coir fiber. Fibers and Polymers, 2011, 12(6), 727–733, doi: 10.1007/s12221-011-0727-7. 19. GUL-E-NOOR, F., KHAN, M.A., GHOSHAL, S., KHAN, R.A., MAZID, R.A., SARWARUDDIN CHOWDHURY, A.M. Effect of urea on the me­chanical properties of gelatin films photocured with 2-ethylhexyl acrylate. Journal of Polymers and the Environment, 2010, 18(3), 224–230, doi: 10.1007/s10924-010-0172-5. 20. ZAMAN, H.U., KHAN, M.A., KHAN, R.A. Effect of nonionizing radiation on the physicomechan­ical properties of banana fiber/pp composites with HEMA. Polymer composites, 2012, 33(8), 1424–1431, doi: 10.1002/pc.22269. 21. SULTANA, S., KHAN, R.A., KHAN, M.A., ZAMAN, H.U., SHAHRUZZAMAN, M., BANU, P., NURUZZAMAN KHAN, M., MUSTAFA, A.I. Preparation and mechanical characterization of gelatin-based films using 2-hydroxyethyl meth­acrylate cured by UV radiation. Polymer-Plastics Technology and Engineering, 2010, 49(6), 560–566, doi: 10.1080/03602551003652680. 22. ZAMAN, H.U., BEG, M.D.H., KHAN, M.A., KHAN, R.A. A comparative study of gamma and ultraviolet radiation on gelatin film with 2-ethylhexyl acrylate. Journal of Adhesion Science and Technology, 2013, 27(24), 2653–2665, doi: 10.1080/01694243.2013.799029. 23. ZAMAN, H.U., KHAN, M.A., KHAN, R.A. Improvement of physicomechanical proper­ties of grafted coir fiber with ethyleneglycol di­methacrylate: effect of UV radiation. Journal of Polymer Engineering, 2012, 32(2), 135–141, doi: 10.1515/polyeng-2011-0131. 24. KHAN, R.A., SALMIERI, S., DUSSAULT, D., TUFENKJI, N., URIBE-CALDERON, J., KAMAL, M.R., SAFRANY, A., LACROIX, M. Preparation and thermo-mechanical characteri­zation of chitosan loaded methylcellulose-based biodegradable films: Effects of gamma radiation. Journal of Polymers and the Environment, 2012, 20(1), 43–52, doi: 10.1007/s10924-011-0336-y. 25. ZAMAN, H.U., KHAN, R.A., KHAN, M.A. Effects of surface pretreatment on the me­chanical and dielectric properties of photo­curing jute fibers. International Journal of Polymeric Materials, 2012, 61(9), 723–736, doi: 10.1080/00914037.2011.610043. 26. ZAMAN, H.U., KHAN, M.A., KHAN, R.A. Effect of nonionizing radiation on the physicomechan­ical properties of banana fiber/pp composites with HEMA. Polymer composites, 2012, 33(8), 1424–1431, doi: 10.1002/pc.22269. 27. ROY, J.K., AKTER, N., ZAMAN, H.U., ASHRAF, K., SULTANA, S., SHAHRUZZAMAN, N.K., RAHMAN, M.A., ISLAM, T., KHAN, M.A., KHAN, R.A. Preparation and properties of coir fiber-reinforced ethylene glycol dimeth­acrylate-based composite. Journal of Thermoplastic Composite Materials, 2014, 27(1), 35–51, doi: 10.1177%2F0892705712439568. 28. ZAMAN, H.U., KHAN, R.A., KHAN, M.A., DALOUR HOSSEN BEG, M. Physico-mechanical and degradation properties of biodegradable photografted coir fiber with acrylic monomers. Polymer Bulletin, 2013, 70(8), 2277–2290, doi: 10.1007/s00289-013-0950-z. 29. KHAN, M.A., MASUDUL HASSAN, M., DRAZAL, L.T. Effect of 2-hydroxyethyl meth­acrylate (HEMA) on the mechanical and ther­mal properties of jute-polycarbonate compos­ite. Composites Part A: Applied Science and Manufacturing, 2005, 36(1), 71–81, doi: 10.1016/j.compositesa.2004.06.027. 30. MIZANUR RAHMAN, M., AHMED, F., CHOWDHURY, Z.Z., SARWARUDDIN CHOWDHURY, A.M., KHAN, M.A. Enhanced physico-mechanical properties of EGDMA treated locally produced jute clothes by thermal curing method. Polymer-Plastics Technology and Engineering, 2007, 46(7), 713–720, doi: 10.1080/15583720701271625. 31. ZAMAN, H.U., KHAN, R.A., KHAN, M.A. Effects of surface pretreatment on the me­chanical and dielectric properties of photo­curing jute fibers. International Journal of Polymeric Materials, 2012, 61(9), 723–736, doi: 10.1080/00914037.2011.610043. 32. ZUBER, M., ZIA, K.M., BHATTI, I.A., ALI, Z., ARSHAD, M.U., SAIF, M.J. Modification of cellulosic fibers by UV-irradiation. Part II: af­ter treatments effects. International Journal of Biological Macromolecules, 2012, 51(5), 743–748, doi: 10.1016/j.ijbiomac.2012.07.001. 33. MASUDUL HASSAN, M., RABIUL ISLAM, M., KHAN, Mubarak A. Effect of additives on the im­provement of mechanical and degradable prop­erties of photografted jute yarn with acrylamide. Journal of Polymers and the Environment, 2002, 10(4), 139–145, doi: 10.1023/A:1021191920387. 34. DE ROSA, I.M., KENNY, J.M., PUGLIA, D., SANTULLI, C., SARASINI, F. Morphological, thermal and mechanical characterization of okra (Abelmoschus esculentus) fibres as potential re­inforcement in polymer composites. Composites Science and Technology, 2010, 70(1), 116–122, doi: 10.1016/j.compscitech.2009.09.013. 35. FORTUNATI, E., PUGLIA, D., MONTI, M., SANTULLI, C., MANIRUZZAMAN, M., FORESTI, M. L., VAZQUEZ, J., KENNY, J. M. Okra (Abelmoschus esculentus) fibre based PLA composites: mechanical behaviour and biodegradation. Journal of Polymers and the Environment, 2013, 21(3), 726–737, doi: 10.1007/s10924-013-0571-5. Monomer Chemical structure 2-hydroxyethyl methacrylate (HEMA) Methyl methacrylate (MMA) Figure 1: Chemical structure of the monomers used in this study Table 1: Physico-mechanical features of used PALF in the study Properties PALF fibre Density (g/cm3) 1.523 ± 0.35 Linear density (dtex) 6.8 ± 0.78 Tensile strength (MPa) 182.7 ± 7.6 Young’s modulus (GPa) 6.347 ± 0.87 Elongation at break (%) 2.75 ± 0.45 Table 2: Composition of different formulations (w/w %) Materials H1 H2 H3 H4 H5 H6 HEMA 10 20 30 40 50 60 MeOH 88 78 68 58 48 38 Darocur-1664 2 2 2 2 2 2 Materials M1 M2 M3 M4 M5 M6 MMA 10 20 30 40 50 60 MeOH 88 78 68 58 48 38 Darocur-1664 2 2 2 2 2 2 PALF PLA Sheet PLA Pellets Heating & Pressure Heated Platen 2 Teflon Sheet PALF PALF PLA Sheet Mold Frame Heated Platen 1 PLA Compression Molding Manufactured Composite Figure 2: Fabrication model of PALF/PLA composites by compression moulding Table 3: Composite formulations Composite termed as Type of treatment on fibre Composition (PALF: PLA) UC Untreated 40:60 HC 30% HEMA treated (H3 sample) 40:60 MC 40% MMA treated (M4 sample) 40:60 Figure 4: Grafting (%) of MMA treated PALF against UV intensities as a function of various monomer concentrations Figure 3: Grafting (%) of HEMA treated PALF against UV intensities as a function of various monomer concentrations Figure 5: Tensile strength and Young’s modulus of monomer treated optimized PALF/PLA composites with regard to UV intensities Figure 6: Flexural strength and Flexural modulus of monomer treated optimized PALF/PLA composites with regard to UV intensities Figure 7: Impact strength of monomer treated optimized PALF/PLA composites with regard to UV intensities a) b) Figure 8: a) Formation of poly(HEMA) during applying UV radiation; b) Cross-linking mechanism between PALF and HEMA Figure 9: Tensile stress-strain curve of neat PLA and PALF/PLA composites Table 5: Grafting and tensile properties of photografted PALF/PLA composites treated with urea Composites Concentration of urea 0.5% 1% 1.5% Gf TS (MPa) YM (GPa) Gf TS (MPa) YM (GPa) Gf TS (MPa) YM (GPa) HC 18.6 162.4 ± 3.2 15.8 ± 0.14 19.7 168.6 ± 3 16.1 ± 0.57 18.9 163.1 ± 2.8 15.9 ± 0.16 MC 16.5 155.3 ± 2.8 15.3 ± 0.25 17.4 161.2 ± 2.4 15.7 ± 0.22 16.3 154.8 ± 2.5 15.2 ± 0.27 Table 6: Flexural and impact properties of photografted PALF/PLA composites treated with urea Composites Concentration of urea 0.5% 1% 1.5% FS (MPa) FM (GPa) IS (kJ/m2) FS (MPa) FM (GPa) IS (kJ/m2) FS (MPa) TS (MPa) IS (kJ/m2) HC 249.3 ±5 19.3 ± 3.2 21.4 ± 0.7 255.1 ±6 19.8 ± 3 22.5 ± 0.3 250.2 ±4 19.4 ± 1.8 21.6 ± 0.5 MC 243.8 ±4 18.9 ±2.8 20.6 ± 0.3 251.4 ±5 19.3 ± 2.4 21.7 ± 0.2 245.3 ±6 18.8 ± 1.7 20.7 ± 0.27 Table 7: TG data of untreated and grafted PALF/PLA composites Composites Temperature (°C) Weight loss (%) Initial stage Stage I Stage II Initial stage Stage I Stage II UC 30-105 200-285 285-398 9.9 18.6 66.7 HC 90-198 251-343 343-492 4.6 8.7 58.8 MC 82-192 245-332 332-479 4.5 9.1 59.6 Figure 10: TG curves for untreated and photografted optimized PALF/PLA composites Derivative weight (%/°C) Figure 11: DTG curves for untreated and photografted optimized PALF/PLA composites Table 8: Thermal properties of neat PLA and grafted PALF/PLA composites Material Glass transition ­temperature, Tg (°C) Melting temperature, Tm (°C) Melting enthalpy, .Hm (J/g) Degree of ­crystallinity, Xc (%) Onset melting temperature Peak melting temperature Neat PLA 61 167 175 46 49 UC 63 151 162 32 34 HC 65 161 169 37 39 MC 64 157 166 36 38 Figure 12: DSC curves for untreated and photografted optimized PALF/PLA composites Figure 13: Water uptake (%) of untreated and monomer treated optimized PALF/PLA composites with regard to soaking time a) b) c) Figure 14: SEM micrograph of: a) untreated PALF/PLA composite, b) and c) 30% HEMA treated PALF/PLA composite 247 Tekstilec, 2021, Vol. 64(3), 247–259 | DOI: 10.14502/Tekstilec2021.64.247-259 Mustafijur Rahman1, Mohammad Abbas Uddin1, Md. Moynul Hassan Shibly2, Nusrat Binta Hossain3, Mohammad Forhad Hossain1, Muriel Rigout4 1 Department of Dyes and Chemicals Engineering, Bangladesh University of Textiles, Dhaka, Bangladesh 2 Department of Textile Engineering, Primeasia University, Dhaka, Bangladesh 3 Puls Trading Far East Limited, H&M Bangladesh Liaison Office, Dhaka, Bangladesh 4 School of Design, University of Leeds, Leeds, LS2 9JT, UK Synthesis and Characterisation of Azo-Based Dichlorotriazine Reactive Dye with Halochromic Behaviour Sinteza in karakterizacija diklorotriazinskega reakcijskega barvila na azoosnovi s halokromnim odzivom Original scientific article/Izvirni znanstveni clanek Received/Prispelo 11-2020 • Accepted/Sprejeto 3-2021 Corresponding author/Korespondencni avtor: Mustafijur Rahman E-mail: musta130@gmail.com Phone: +8801913061184 ORCID: 0000-0001-8411-0933 Abstract Halochromism or pH sensitivity has tremendous potential for applications in various textile fields, such as protective clothing, wound dressings, etc. Reactive dye is mostly used to colour cotton or other regenerated cellulose fibres due to its better fastness and wide range of hue, from vivid to dull shades. In this research work, an azo-based dichlorotriazine reactive dye was synthesised from H-acid (4-amino-5-hydroxy-2,7-naphthalen­edisulfonic acid) and 4-nitroaniline, which incorporates a halochromic behaviour. The change of colour of this dye was evaluated both in the the solution stage and coloured fabric stage in various pH solutions. A visible change of colour with the alteration of pH was observed after dyeing textile fabric with the synthesised dye. However, a significant difference was observed in a few cases with regard to the change of colour with the alteration of pH in the solution stage and coloured fabric stage. The dyed fabric also displayed very good to excellent wash fastness properties. Generally, the reactive dye synthesised in this research demonstrated an obvious change of colour with the alteration of the pH level. Keywords: chromism, H-acid, 4-nitroaniline, synthesis, halochromic, dichlorotriazine, reactive dye Izvlecek Halokromizem ali obcutljivost na pH ima široke možnosti za uporabo na razlicnih tekstilnih podrocjih, kot so zašcitna oblacila, povoji za rane itd. Reaktivna barvila zaradi boljše obstojnosti in širokega razpona barvnih odtenkov, od živih do pastelnih tonov, vecinoma uporabljajo za barvanje bombaža ali regeneriranih celuloznih vlaken. V tej raziskavi je bilo iz 4-amino-5-hidroksi-2,7-naftalendisulfonske kisline (H-kislina) in 4-nitroanilina sintetizirano diklortriazinsko reaktivno barvilo na azoosnovi. Barvilo omogoca halokromni odziv, to je spremembo barve, ki je bila ocenjena v raztopini in na obarvani tekstiliji pri razlicnih vrednostih pH raztopin. Po barvanju tkanine s sintetiziranim barvilom je bila opažena vidna sprememba barve s spreminjanjem vrednosti pH. V nekaj primerih je bila ugotovljena tudi pomembna razlika v spremembi barve s spremembo vrednosti pH raztopine in na obarvani tkanini. Obarvana tkanina je imela tudi zelo dobro do odlicno obstojnost pri pranju. Na splošno je reaktivno barvilo, sintetizirano v tej raziskavi, pokazalo zaznavno spremembo barve s spreminjanjem vrednosti pH. Kljucne besede: kromizem, H-kislina, 4-nitroanilin, sinteza, halokromen, diklorotriazin, reaktivno barvilo 1 Introduction Chromic materials reversibly change colour as a re­action to a change in external stimulus. Based on the nature of the stimulus, the resulting chromism is classified as thermochromism (induced by tempera­ture), photochromism (induced by light), halochro­mism (induced by pH), etc. [1]. Chromic materials are widely used to cover products to exhibit chromic phe­nomena in the field of smart or intelligent materials [2]. For various textile uses, such as wound dressings, protective garments, etc., the concept of halochro­mism may be of tremendous significance. Because of their flexibility, comfort, and ability to cover huge surfaces, these halochromic textile pH-indicators are more beneficial than traditionally applied sensor elements. For this reason, research usually focuses on the connection between the chemical construction of dyes and their halochromic nature in liquid instead of their performance in a textile substance. The per­formance evaluation of the dyes absorbed in a textile material is also essential [3]. Azo dyes have been well-accepted on the global mar­ket because of their simple synthesis process, the ca­pability to produce a wide range of shades, and their vast applications in various fields, such as papers, textiles, additives, cosmetics and organic synthesis [4-5]. Around 60-70% of azo dye is consumed in the traditional textile wet-processing industry [6]. In the case of azo dye, an associated p-configuration is ob­served, and is linked to two aromatic subdivisions (generally benzene and naphthalene derivatives) by a nitrogen–nitrogen double bond (N=N) [7-8]. As a result of the fairly easy synthesis process and the wide range of colours, azo dyes are the most available category of colourants. Some azo dyes change colour because of their chromic characteristics related to extrinsic consequence [2]. Reactive dye has the ability to remove the unfixed dye from the fabric surface more efficiently, ensuring excellent washing fastness to dyed or printed fabric based on the colour change in shade and staining of an adjacent textile substrate [9]. Reactive dyes have the advantage over natural dyes and other synthetic dyes. They form a covalent bond between the dye and fibre after application to the fibre surface. This covalent bond is produced between a carbon atom of the dye molecule and an oxygen, sulphur, or nitrogen atom of an amino, hy­droxy, or thiol compound on the polymer matrix. Due to the formation of a strong covalent bond after the application of dyes to the textile substrate, this dye is difficult to remove and, as a result, has superior wash fastness characteristics [6]. Today, several examples of chromic phenomena have been applied in our everyday life, such as photochro­mic lenses for spectacles and thermochromic tem­perature indicators, for example, in baby spoons [10]. Another significant aspect of chromism is halochro­mism, which depends on the degree of acidity or pH level. Halochromic or pH-sensitive materials, includ­ed under the subclass of ionochromic materials, vary in colour depending on pH, and are currently subject to more frequent researches [11]. Halochromic dyes that cause a change from one colour to another due to a bathochromic or hypsochromic shift of the ab­sorption peak upon (de)protonation are categorised as positive and negative halochromic dyes, respec­tively [12]. The basic principle of the colour change of a halochromic substance is the protonation or de­protonation of the dye molecule, causing a different electron arrangement, resulting in a change in the colour of that material. The origin of apparent col­our alteration of halochromic dye is the ring-open­ing of the dye molecule upon (de)protonation, or on tautomerism, as tautomers have various colours and tinctorial strengths [13]. In addition to the more well-known thermochromism and photochromism, the comparatively less-utilised halochromism or pH sen­sitivity has tremendous potential for use in various textile applications as pH sensors [3]. Halochromic textiles have huge potential as sensors that can signal a medium’s pH through the simple visual observation of colour, and can be implemented in a wide variety of fields [14]. Hesus et al. (1892) first declared that the human skin surface is acidic, and this concept was confirmed again by Schade and Marchionini (1928) [15, 16]. This acidic medium differs in the pH range between 4-6, which is influenced by a person’s ana­tomical state and age. Due to the presence of differ­ent acids, such as amino acids, fatty acids and others formed and discharged by the keratinocyte coating and the skin protuberances, the natural lactate-bi­carbonate buffer structure of the body shifts on to an acidic medium [16]. In chronic wounds, the me­dium of pH has been found in the range of 7.15–8.9. A wound’s pH shifts alkaline to neutral and later becomes acidic as the wound advances towards the healing process [17]. A halochromic wound dressing can be implemented as an indicator to monitor the state of the wound surface’s healing just by observ­ing the alteration of colour in the bandage without removing the gauze. Thus, a pH-indicator wound dressing can be an effective observation system. Consequently, potential damage to a patient’s wound area might be reduced, as well [14]. For this reason, the successful application of halochromic dye as a textile pH indicator on wound dressing can play a crucial role in the field of medical textiles. Furthermore, in the human body, pH value plays a significant role in many other crucial processes. Thus, halochromic textile might play a vital role in determining the acidity of sweat, nasal discharge, urine, etc. [18, 19]. On the other hand, a textile pH indicator in protective clothing can identify the exist­ence of acid vapours in an operating environment [1]. However, no significant previous research attempt or literature has been found to synthesise reactive azo-based halochromic dye as a potential pH sensor for textile materials. The principal aim of this research article was to syn­thesise a new azo-based dichlorotriazine reactive dye from H-acid (4-amino-5-hydroxy-2,7-naphtha­lenedisulfonic acid) and 4-nitroaniline, which have halochromic properties. The change in colour of this dye was observed in various pH solutions. After that, 100% cotton woven fabric was dyed with the newly synthesised dye following the conventional dichlo­rotriazine reactive dyeing procedure. In addition, the halochromic behaviour of the dyed fabric was ­investigated at various buffer pH solutions. To inves­tigate and analyse the halochromic behaviour of syn­thesised dye in the solution stage, analytical methods such as UV-vis spectroscopy, were used. CIELAB val­ues of the dyed fabric in various pH solutions were ex­amined using a chroma meter. Finally, the purity and molecular arrangement of the synthesised dye were investigated using thin-layer chromatography (TLC). 2 Experimental 2.1 Fabric In this research, 100% cotton plain weave fabric, with a mass of 102.93 gm/m2, and a fabric density of 48 threads/cm in warp and 32 threads/cm in the weft direction was used. The fabric was provided by Whaley’s of Bradford (UK). 2.2 Chemicals For dye synthesis, H-acid (4-Amino-5-hydroxy-2,7-naphthalenedisulfonic acid, 88%), cyanuric chloride (= 99%), 4-nitroaniline (= 99%), nitrous acid (HNO2) (99%), sulfamic acid (H3NSO3) (99%), dihydrogen phosphate ([H2PO4]-) (= 99%) and disodium hydro­gen phosphate (Na2HPO4) (= 99%) were supplied by Sigma-Aldrich, UK and used as received. Disodium hydrogen phosphate (Na2HPO4) and citric acid (C6H8O7) were used for the preparation of buffers. 2.3 Synthesis of azo-based dichlorotriazine reactive dye The synthesis of the dye comprised three steps: mod­ification of H-acid (4-amino-5-hydroxy-2,7-naphtha­lenedisulfonic acid), diazotising of nitroaniline (4-ni­troaniline) to obtain diazonium salt, and coupling by reacting the obtained diazonium salt in the modified H-acid (4-amino-5-hydroxy-2,7-naphthalenedisul­fonic acid) solution. Modification of H-acid (Step 1) H-acid (4-Amino-5-hydroxy-2,7-naphthalenedi­sulfonic acid, 5.0 g, 0.012 mol) was dissolved in 50 cm3 water and the pH adjusted to pH 7 with an NaOH dilute. The solution was then cooled to 0-5 °C in an ice bath. Cyanuric chloride (2.8 g, 0.015 mol) was dissolved in acetone (20 cm3), cooled in an ice bath to 0-5 °C, then added to the H-acid solution over 30 minutes at 0-5 °C with no pH control. The reaction, shown in Figure 1, was stirred for a further 15 minutes, monitored at intervals for the presence of free aromatic amine with Ehrlich reagent. Small amounts of cyanuric chloride dissolved in acetone were added at 15-minute intervals, if required, to lead the reaction to completion, after which the pH was raised to pH 6 using NaOH (1M). Diazotisation (Step 2) 4-nitroaniline (1.65 g of nitroaniline; 2.24 g of dini­troaniline, 0.012 mol) was dissolved in water (50 cm3) and cooled to 0–5 °C in an ice bath. Concentrated hydrochloric acid (3 cm3) was then added with me­chanical stirring. A solution of sodium nitrite (1.0 g, 0.014 mol) in water (20 cm3) was added to the solution of nitroaniline in drop form over 15 minutes. When the addition of sodium nitrite was complete, the re­action solution was stirred for a further 30 minutes at 0–5 °C. A small quantity of sulfamic acid (99%, 97.09 g/mol) was added to destroy excess nitrous acid until starch–iodide paper no longer turned blue. Coupling (Step 3) The modified H-acid solution of step 1 was cooled to 0-5 °C, and its pH raised to pH 9-10 with the addi­tion of NaOH. The diazonium salt prepared in step 2 was poured into an ice-cold solution containing 7.4 g sodium acetate and 3.63 g acetic acid to raise its pH to a neutral level. The diazonium salt solution was immediately added to the modified H-acid from step 1 in drop form over 30 minutes at 0-5 °C. The pH of the solution was kept between 9.5 and 10, using NaOH dilute throughout the process. The solution was then left stirring for one hour, after which the temperature was no longer controlled. Precipitation and filtration procedure of the synthesised dye After completing the dye synthesis, sodium chloride (20% w/v) was added to the synthesised dye solu­tion to separate the dye. The solution was stirred continuously using a mechanical stirrer until all of sodium chloride was dissolved. The separation of the solid dye from the liquid mixture was achieved using vacuum filtration. In a Buchner funnel, the combination of precipitated dye and fluid was dis­charged over a filter paper. The liquor was drained over the funnel into a flask through a vacuum, and filter paper captured the solid dye. Finally, the filtrat­ed dye was mixed with 0.6 g potassium dihydrogen phosphate and 1.4 g disodium hydrogen phosphate. The dye was then placed in a desiccator for 12 hours to dry thoroughly. 2.4 Dyeing procedure of synthesised dichlorotriazine reactive dye The dyeing procedure, schematically presented in Figure 2, was carried out in Labomat BFA-8 (Mathis, Switzerland) infrared lab dyeing machine. Cotton fabric was dyed using the dichlorotriazine reactive dyeing technique. A higher dye concentration (5% on the mass of fabric) was applied to get a reasonably deep shade. With specific concentrations of dyestuff, 60 g/L of salt and 10 g/L of soda ash were applied for the dyeing of cotton fabric with synthesised dye. The liquor-to-goods ratio used in this dyeing process was 10:1. At first, the required amount of dyestuff was added to a dye bath at at a temperature of 30 °C. The salt was then added in three steps at intervals of 10 minutes, 10 minutes and 15 minutes. The dye bath was run for 15 minutes in this condition. After that, soda ash was added in two steps, at 15-minute intervals. The fabric was dyed for 30-40 minutes at 30 °C [20]. After completing the dyeing process, the fabric was rinsed in cold water for 2 minutes, boiled at 80 °C for 5 minutes, warm-rinsed at 60 °C for 5 minutes, and finally rinsed in cold water for 2 minutes. The fabric was then dried thoroughly [20]. 2.5 Preparation of McIlvaine buffer system Buffers of different pH values were prepared to meas­ure the change of colour of both dyes in solution and fabric. A total of 20 mL of buffer solution was pre­pared using 0.2 M disodium hydrogen phosphate and 0.1 M citric acid of the appropriate amount according to Table 1. 2.6 Analysis UV-vis spectrophotometry In this study, the change of maximum wavelength and absorbance of dye in different pH solutions was identified using a M550 (CamSpec, UK) double-beam scanning UV/Visible spectrophotometer. All sam­ple solutions were placed in quartz cuvettes with a 10 mm light path. The amount of dye concentration was calculated based on a calibration curve. The spec­tra were recorded from 400 nm to 700 nm. Colorimetric measurements A CS-200 chroma meter (Konica Minolta, Japan) was used to measure the CIELAB values of the dyed fabric to analyse the change of colour in an aque­ous solution at different pH values, maintained by hydrochloric acid (HCl) and sodium hydroxide (NaOH). Measurements of colour were performed under the following conditions: white tile: X = 271.04, Y = 281.28, Z = 285.31; viewing angle: 65°; capture angle: 1°. pH analysis The pH analysis was performed using a Metrohm 654 digital pH meter (Metrohm, UK) combined with a reference electrode and glass electrode. Thin-layer chromatography (TLC) analysis In this research, TLC was used to analyse the purity and individualise the chemical components present in the synthesised dye. Thin-layer chromatography was performed using ethyl acetate-m-butanol-n-pro­panol-water in a ratio of 1:2:3:4 as the mobile phase, while an aluminium plate coated with silica gel 60 F254 (Merck, UK) was used as the stationary phase. The developed plate was studied under both visible and ultraviolet light (360 nm wavelength), and finally, the retention factor (Rf) was determined [22, 23]. The value of Rf was calculated using the following equation (1): (1) Colour fastness to washing The colour fastness to washing test of dyed fabric was carried out according to the ISO 105-CO6:2010 (ISO, 2010) Standard in a GyroWash Tester (James Heal, UK). The washed specimen was evaluated visually using the Grey Scale according to the ISO 105-A02 (for assessing colour change) and ISO 105-A03 (for assessing staining) Standards. Determination of response time The response time was recorded after immersing the synthesised dyes into various buffer solutions until a visible change in the colour of the solution occurred. The response time was also determined after absorp­tion of the dyed fabric sample at different buffer solu­tions until the clear visible alteration of colour in the fabric surface appeared. 3 Results and discussions The chemical structure of the synthesised dye is shown in Figure 3. Figure 3: Structure of the synthesised dye Figure 3 shows that the synthesised dye molecule contains an azo (-N=N-) group as a chromophore or colour- bearing group, and two sulphonate groups (SO3-) as a water solubilising group. Due to the pres­ence of two sulphonate groups, the water solubility of this dye is high. The dye molecule possesses a bridg­ing group, such as -NH-, which increases substantivi­ty because of hydrogen bond formation. On the other hand, the dichlorotriazine group acts as the reactive functional system in this synthesised dye [24]. The UV-visible absorption spectrum of the synthe­sised dye was determined by dissolving it in distilled water (0.05 g/L solution) at a wavelength of between 400-700 nm. From Figure 4, the wavelength of maximum absorption (.max) of the synthesised dye is identified at 506 nm, which appeared in the visi­ble region of the spectrum due to the ascription on p–p* transition of the azo (N=N) chromophore group of synthesised reactive dye [25]. The spectral peak appears slightly wide, resulting in some impurities present in the dye [26]. 3.1 Visual observation of colour change in the solution stage of dye in different pH solutions The synthesised dye solution (5 g/L concentration) is applied in different Mcllvaine buffer solutions (pH range of 2.2-12) to detect the visual change of colour, as presented in Figure 5. It is evident from the visual perception of the dye solution at different pH values shown in Figure 5 that at pH 2.2, the dye’s solution appeared reddish-orange. After that, it turned red and continued until pH 7. However, the colour of the solution turned bluish-red at pH 8. The dye solution’s colour became purple at pH 9.2 and finally turned dark blue in extremely al­kaline conditions at pH 12. 3.2 UV-vis spectrophotometer results of the synthesised dye in different pH solutions The shifts of maximum wavelength (.max) and absorb­ance of the synthesised dye (0.05 g/L concentration) solution were analysed in a buffer solution of different pH values. The results are shown in Table 2. Table 2 shows that in the visible area of the spec­trum, a significant increase of absorbance is detected at 670 nm in pH 7.0. The .max differs with pH from 622 nm at extremely acidic pH to 430 nm at extremely alkaline pH, which corresponds to the visual col­our transition from reddish-orange to dark-blue. The principal reason for the colour change is the protonation or deprotonation of the dye molecules, resulting in various electron configuration changes [27]. Protonation and deprotonation of studied dye are presented in Figure 6. From pH 2.2 to 3.0, a significant bathochromic shift .max (43 nm) occurred due to the protonation of synthesised dye (Figure 6, structure Ia) [28], while in acidic conditions, the proton and hydrogen bond of the dye’s hydroxyl group might be powerful. Therefore, deprotonation becomes more difficult until it reaches acidic to alkaline conditions. The electron-donating substituents, such as hydroxyl (-OH) and amino (-NH-) groups, present in this structure are comparatively less active in acidic and neutral conditions. For this reason, from pH 3.0 to pH 7.0, a negligible bathochromic shift (5nm) was observed. However, these ­electron-donating substituents gradually became active in alkaline conditions. As a consequence, the dye converted from protonated to deprotonated form (Figure 6, structure IIa). Upon (de)protonation, the dye trans­formed into anionic form, while the dye’s mo­lecular chain became open (Figure 6, Structure IIb), which results in a visible colour change of the synthesised dye. Finally, azo/hydrazone tautomer­ism was exhibited in the synthesised dye structure (Figure 6, Structure Ib). For this reason, a signif­icant hypsochromic shift .max (240 nm) was seen with a rise in pH from neutral (pH 7) to extremely alkaline (pH 12) condition [29]. 3.3 Colour change observation of dyed fabric in different pH solution The appearance of the cotton fabric dyed with syn­thesised dye is shown in Figure 6. The colour of the cotton fabric after dyeing with syn­thesised dye appeared reddish-pink, as seen in Figure 7. This research further investigated the halochromic behaviour of the dyed fabric sample in different pH solutions, as shown in Figure 8. Figure 7: Cotton fabric’s appearance dyed with syn­thesised dye concentration of 5% on the mass of fabric (o.m.f.) It is evident from Figure 8 that an obvious change of colour was observed in the dyed fabric by changing the pH level. In an extremely acidic solution (pH 2.2), the colour of the dyed fabric appeared orange, while at pH 3, the colour became light-orange. The colour of the fabric turned reddish-orange at pH 4. At pH 5, the colour became light-pink, turned in dark-pink at pH 6, and became reddish-pink at pH 7. However, at pH 8, the fabric’s appearance became purplish-pink, turned bluish-pink at pH 9.2, and eventually turned darker-blue at pH 12. 3.4 Colorimetric measurements Figure 9 shows that at various pH solutions, CIELAB values of the fabric coloured with the synthesised dye alter as well. According to CIELAB colour space, L* constitutes lightness; coordinate a* denotes red/green hue element, and coordinate b* indicates yellow/blue hue attributes of the colour [30]. A significant change of CIELAB values has been observed in Figure 9 from pH 2.2 to pH 4.0 and from pH 8.0 to pH 12. On the other hand, a minor change of CIELAB values has been exhibited at pH values ranging from 4 to 8. In pH solution 2.2, the value of CIE L* is considerably higher, the value of CIE a* is positive, and the value of CIE b* is also positive. For this reason, the sample became lighter, reddish, and slightly yellowish, and the surface colour of the dyed fabric appeared orange in the solution. At pH 3.0, the value of CIE L* is decreased, the value of CIE a* is increased and positive, whilst the value of CIE b* is decreased and turned to negative. The sample be­came darker, more reddish, and marginally blue. The decrease of CIE b* value usually brings a bluish tone to the fabric colour [31]. At pH 4, the sample became darker, slightly reddish, and bluer as the CIE L* value decreased, a* slightly raised, and b* decreased signif­icantly. The visual appearance of the fabric turned reddish-orange in the solution at pH 4. From pH 4 to pH 8, because of the slight variation of a* and b* values, the fabric’s colour appeared in marginally dif­ferent shades. The fabric’s colour eventually became bluish-pink at pH 9.2 due to a lower CIE b* value. Finally, in a powerful alkaline solution (pH 12), the value of CIE a* and CIE b* became the lowest, while the colour of the fabric shifted from bluish-pink to dark-blue. The CIELAB values of dyed fabric immersed in dif­ferent pH solutions are presented in Figure 9. 3.5 Wash fastness test analysis of fabric dyed with synthesised dye The results of washing fastness of dyed cotton fabric are presented in Table 3. The colour fastness to washing test of fabric dyed with synthesised reactive dye is assessed visually using a grey scale. The results, depicted in Table 3, showed that dyed fabric had very good (rating of 4-5) wash fastness properties. Furthermore, the dyed fab­ric showed slight to negotiable colour staining (rat­ing of 4–5) on the adjacent cotton fabric. This result can be attributed to the elimination of unfixed dye molecules from the surface of the coloured cotton fabric during the wash fastness test, which then shifted to the adjacent white cotton fabric [32]. The synthesised reactive dyed fabric exhibited very good wash fastness because of the chemical fixation of dye molecules to the fibre surface through strong cova­lent bond formation, which ultimately resulted in the dyes’ resistance to fading after washing [33]. Based on the obtained results, it can be concluded that the synthesised dye demonstrated a wash fastness rating analogous to the commercial reactive dye. 3.6 Thin-layer chromatography (TLC) analysis The TLC analysed plate of the synthesised dye is shown in Figure 10. Figure 10: TLC plate for the synthesised dye after the solvent almost reached the top of the plate It is evident from Figure 10 that the TLC plate con­tains only one component, which appeared as a large red smear. This component is slightly spread on the TLC plate. Here, the distance travelled by the mixed solvent solution is 7.4 cm on the TLC plate. On the other hand, the distance travelled by the dye component was 4.6 cm. As a result, the Rf val­ue of this component was 0.62. It is assumed that this component was the synthesised azo-based di­chlorotirazine reactive dye. The value of Rf indicates synthesised dye is moderately polar. Based on the identification of only one component in the TLC analysis, the synthesised dye is deemed reasonably pure [23]. 3.7 Response time analysis The response time was recorded for colour changes of synthesised halochromic dye and colour changes of synthesised dyed cotton fabric in various buffer solutions. It was observed that the change in the col­our of synthesised dyes occurred immediately after immersion in various pH solutions. On the other hand, it took a comparatively longer time to visualise a noticeable colour change when the dyed fabric was immersed in various buffer solutions. The response time of the cotton fabric sample dyed with synthe­sised halochromic reactive dye was approximately 25-30 minutes to visually notice a colour change in the fabric surface in various pH solutions. From this experiment, it is evident that, apart from the differ­ence in halochromic behaviour, there is a substantial variation of retention time for synthesised dyes in solutions and fibrous textile matrices. The probable reason for this might be the gradual wetting proper­ties of textile fabric, the strength of the interaction between the dyes and fibres, and the molecular struc­ture [14, 34]. Generally, it can be assumed that this pH-sensi­tive reactive dye can be successfully applied to cot­ton fabric using a standard colouration process. However, it was observed that the diazo component used in this synthesis process produces some impu­rities. It is thus essential to recognise these impu­rities and address their effect on a dye’s solubility. On the other hand, a significant difference in col­our change in the solution stage and coloured fab­ric stage under various pH conditions was observed and may be because halochromism differs based on the constructional nature and molecular density of the fibrous substrates. Moreover, difficulties were encountered by dye molecules in accessing the fi­bre surface due to the slow wettability of fabric, and in the formation of a covalent bond between the dye and the hydroxyl group of cellulose, while after being applied to the fabric surface, dye mol­ecules were immobilised as the surrounding mi­cro-environment of the dye changed from solution to the fibrous textile matrix [14, 34]. This variation can be minimised in future work by synthesising halochromic reactive dye with a higher reactivity, more solubility, the higher affinity of dye molecules to the fabric surface, and the selection of a low­er-density and more hydrophilic fabric matrix. As a result, the dye might show a comparatively similar level of colour transition both in the solution stage and the dyed fabric stage. 4 Conclusion The fundamental aim of this research work was to synthesis an azo-based dichlorotriazine pH-sensi­tive reactive dye that will show a change in colour with the alteration of the pH solution. The colour change of this dye was observed in the solution and the dyed fabric stage. The synthesised reactive dye exhibited different halochromic properties in various pH environments. The dye synthesised from H-acid and 4-nitroaniline showed a colour transition from reddish-orange in pH 2.2 to red in pH 4.0, and even­tually turned blue in alkaline conditions. In the dyed fabric, the colour turned orange to reddish-orange in the pH range 2.2-4.0, became light-pink at pH 5.0, turned bluish-pink in alkaline conditions (pH 9.2), and finally became deep-blue at pH 12. The halochro­mic dye synthesised in this research demonstrated colour transition from acidic to the alkaline environ­ment both in the solution stage and dyed fabric state. As a result, the effectual application of halochromic reactive dye on cellulose fabric as textile pH sen­sors, such as those used to monitor wound healing through a change in colour on a wound dressing, might play a crucial role in the area of medical textile materials. However, some variation of colour change in the solution and dyed fabric stage was observed, and might be due to a change in the dye molecules’ surrounding microenvironment after incorporation into the fibrous matrix. Overall, it can be concluded that the azo-based reactive dye synthesised in this research and applied to cotton fabric using a standard reactive dyeing process, as well as the dyed textile material itself, demonstrated decent halochromic attributes and could be used as textile pH indicators. References 1. VAN DER SCHUEREN, Lien, DE CLERCK, Karen. Halochromic textile materials as in­novative pH-sensors. Advances in Science and Technology, 2012, 80, 47–52, doi: 10.4028/www.scientific.net/ast.80.47. 2. BAMFIELD, Peter, HUTCHINGS, Michael G. Chromic phenomena: technological applications of colour chemistry. Cambridge : The Royal Society of Chemistry, 2010. 3. VAN DER SCHUEREN, Lien, DE CLERCK, Karen. Coloration and application of pH-sen­sitive dyes on textile materials. Coloration Technology, 2012, 128(2), 82–90, doi: 10.1111/ j.1478-4408.2011.00361.x. 4. Industrial dyes: chemistry, properties, applica­tions. Edited by Klaus Hunger. Weinheim : John Wiley & Sons, 2007. 5. AARTSEN, Mark Gerald et al. (IceCube Collaboration). First observation of PeV-energy neutrinos with IceCube. Physical Review Letters, 2013, 111(2), 021103, doi: 10.1103/PhysRevLett.111.021103. 6. CHRISTIE, Robert M. Colour chemistry. Cambridge : The Royal Society of Chemistry, 2014. 7. The chemistry and application of dyes. Edited by David R. Waring and Geoffrey Hallas. New York, London : Plenum Press, 2013. 8. LAZAR, Thomas. Color chemistry: synthesis, properties, and applications of organic dyes and pigments, 3rd revised edition : book review. Color Research & Application, 2005, 30(4), 313–314, doi: 10.1002/col.20132. 9. MORRIS, K.F., LEWIS, D.M., BROADBENT, P.J. Design and application of a multifunctional re­active dye capable of high fixation efficiency on cellulose. Coloration Technology, 2008, 124(3), 186–194, doi:10.1111/j.1478-4408.2008.00140.x. 10. SENGUPTA, Amit, JAGADANANDA, Behera. Smart chromic colorants draw wide attention for the growth of future intelligent textile materials. Journal of Advanced Research in Manufacturing, Material Science & Metallurgical Engineering, 2014, 1(2), 89–112. 11. NTOI, Lumanyano L.A. Multiple chromisms associated with dithizone: Master thesis. Bloemfontein : University of the Free State, 2016. 12. VAN DER SCHUEREN, L., DE CLERCK, K., BRANCATELLI, G., ROSACE, G., VAN DAMME, E., DE VOS, W. Novel cellulose and polyamide halochromic textile sensors based on the encapsulation of Methyl Red into a sol-gel matrix. Sensors and Actuators B: Chemical, 2012, 162(1), 27–34, doi:10.1016/j.snb.2011.11.077. 13. VAN DER SCHUEREN, L., DE CLERCK, K. The use of pH-indicator dyes for pH-sensitive textile materials. Textile Research Journal, 2010, 80(7), 590–603, doi:10.1177/0040517509346443. 14. SCHADE, H., MARCHIONINI, A. Der Säure­mantel der Haut (nach Gaskettenmessungen). Klinische Wochenschrift, 1928, 7(1), 12–14, doi:10.1007/bf01711684. 15. SCHNEIDER, L.A., KORBER, A., GRABBE, S., DISSEMOND, J. Influence of pH on wound-heal­ing: a new perspective for wound-therapy? Archives of Dermatological Research, 2007, 298(9), 413–420, doi: 10.1007/s00403-006-0713-x. 16. GETHIN, G. The significance of surface pH in chronic wounds. Wounds, 2007, 3(3), 52–56. 17. YANG, Yiran, GAO, Wei. Wearable and flexible electronics for continuous molecular monitoring. Chemical Society Reviews, 2019, 48(6), 1465-1491, doi: 10.1039/C7CS00730B. 18. MORRIS, D., COYLE, S., WU, Y., LAU, K. T., WALLACE, G., & DIAMOND, D. Bio-sensing textile based patch with integrated optical de­tection system for sweat monitoring. Sensors and Actuators B: Chemical, 2009, 139(1), 231–236, doi:10.1016/j.snb.2009.02.032. 19. MURATHAN, Ayse, FIDANOGLU, Pelin. Synthesis of dichlorotriazine Reactive dyestuff and application to cellulosic fibre. Journal of the Faculty of Engineering and Architecture of Gazi University, 2009, 24(2), 285–291. 20. MCILVAINE, T.C. A buffer solution for col­orimetric comparison. Journal of Biological Chemistry, 1921, 49(1), 183–186, doi:10.1016/s0021-9258(18)86000-8. 21. SRIKULKIT, K., SANTIFUENGKUL, P. Salt-free dyeing of cotton cellulose with a model cat­ionic reactive dye. Coloration Technology, 2000, 116(12), 398–402, doi:10.1111/j.1478-4408.2000.tb00017.x. 22. NAMIR, H., HADŽIC, R., MALEŠEVIC, I., JURCEVIC, M., STARCEVIC, D.. Application of thin layer chromatography for qualitative anal­ysis of gunpowder in purpose of life prediction of ammunition. International Journal of Biosensors & Bioelectronics, 2019, 5(1), 4–12. 23. GILES, C.H., HASSAN, A.S.A. Adsorption at or­ganic surfaces V-A study of the adsorption of dyes and other organic solutes by cellulose and chitin. Journal of the Society of Dyers and Colourists, 1958, 74(12), 846–857, doi:10.1111/j.1478-4408.1958.tb02236.x. 24. AL-RUBAIE, L.A.-A.R., MHESSN, R.J. Synthesis and characterisation of azo dye para red and new derivatives. Journal of Chemistry, 2012, 9(1), 465–470, doi: 10.1155/2012/206076. 25. SIDDIQUA, Umme Habibah. Synthesis of nov­el reactive dyes for textile applications: Thesis. Faisalabad: University Of Agriculture, 2016. 26. TRUPP, S., ALBERTI, M., CAROFIGLIO, T., LUBIAN, E., LEHMANN, H., HEUERMANN, R., YACOUB-GEORGE, E., BOCK, K., MOHR, G.J. Development of pH-sensitive indicator dyes for the preparation of micro-patterned optical sensor layers. Sensors and Actuators B: Chemical, 2010, 150(1), 206–210, doi: 10.1016/j.snb.2010.07.015. 27. DE MEYER, T., HEMELSOET, K., VAN SPEYBROECK, V., DE CLERCK, K. Substituent effects on absorption spectra of pH indicators: an experimental and computational study of sulfon­phthaleine dyes. Dyes and Pigments, 2014, 102, 241–250, doi:10.1016/j.dyepig.2013.10.048. 28. MCGUIRE, Raymond G. Reporting of objective color measurements. HortScience, 1992, 27(12), 1254–1255. 29. GONZÁLEZ-PEŃA, M.M., HALE, M.D.C. Colour in thermally modified wood of beech, Norway spruce and Scots pine. Part 1: colour evo­lution and colour changes. Holzforschung, 2009, 63(4), 385–393, doi:10.1515/hf.2009.078. 30. BURKINSHAW, S.M., KABAMBE, O. Attempts to reduce water and chemical usage in the re­moval of bifunctional reactive dyes from cotton. Part 2 bis(vinyl sulfone), aminochlorotriazine/vinyl sulfone and bis(aminochlorotriazine/vinyl sulfone) dyes. Dyes and Pigments, 2011, 88(2), 220–229, doi:10.1016/j.dyepig.2010.07.001. 31. MORRIS, K.F., LEWIS, D.M., BROADBENT, P.J. Design and application of a multifunctional re­active dye capable of high fixation efficiency on cellulose. Coloration Technology, 2008, 124(3), 186–194, doi:10.1111/j.1478-4408.2008.00140.x. 32. STOJKOSKI, V., KERT, M. Design of pH re­sponsive textile as a sensor material for acid rain. Polymers, 2020, 12(10), 1–15, doi: 10.3390/polym12102251. Figure 1: Route for the formation of dichlorotriazine reactive dye Figure 2: Standard exhaust method for dichlorotriazine-based reactive dye [20] Table 1: McIlvaine buffer system in different pH [21] pH required 0.2 M Na2HPO4 (cm3) 0.1 M citric acid (cm3) 2.2 0.40 19.6 3.0 4.11 15.89 4.0 7.71 12.29 5.0 10.30 9.70 6.0 12.63 7.37 7.0 16.47 3.53 8.0 19.45 0.55 Figure 4: UV-vis spectrum of the synthesized dye Dye solution pH 2.2 Color: Reddish Orange Dye solution pH 3 Color: Red Dye solution pH 4 Color: Red Dye solution pH 5 Color: Red Dye solution pH 7 Color: Red Dye solution pH 8 Color: Bluish Red Dye solution pH 9.2 Color: Purple Dye solution pH 12 Color: Dark blue Figure 5: Colour change of synthesised dye in different pH solutions Table 2: UV-vis analysis of dye synthesised from H-acid and 4-nitroaniline in different pH solutions Mcllvaine’s buffer pH Dye solution pH Maximum wavelength (.max) (nm) Absorbance 2.2 2.24 622.00 1.06 3.0 3.02 665.00 1.05 4.0 4.08 667.00 0.75 5.0 4.99 670.00 0.82 7.0 7.01 670.00 1.40 8.0 8.10 630.00 0.95 9.2 9.21 489.00 0.94 12.0 12.11 430.00 0.56 Figure 6: Acid -alkali equilibrium of the synthesised dye in aqueous buffer solutions Dye solution pH 2.2 Color: Orange Dye solution pH 3 Color: Light Orange Dye solution pH 4 Color: Reddish Orange Dye solution pH 5 Color: Light Pink Dye solution pH 6 Color: Dark Pink Dye solution pH 7 Color: Reddish Pink Dye solution pH 8 Color: Purplish Pink Dye solution pH 9.2 Color: Bluish Pink Dye solution pH 12 Color: Dark Blue Figure 8: Colour change of cotton fabric dyed with synthesised dye in different pH solutions Figure 9: CIE LAB values of dyed fabric at different pH solutions Table 3: Colour fastness to washing assessment of dyed cotton fabric Change of colour Visual assessment using grey scale Colour staining of adjacent multifibre fabrics Wool Acrylic Polyester Nylon Cotton Acetate 4/5 4/5 5 4/5 4/5 4/5 5 260 Tekstilec, 2021, Vol. 64(3), 260–271 | DOI: 10.14502/Tekstilec2021.64.260-271 Marta Stjepic, Sabina Bracko University of Ljubljana, Faculty of Natural Sciences and Engineering, Aškerceva 12, 1000 Ljubljana, Slovenia Colour Memory Analysis for Selected Associative Colours Analiza barvnega spomina za izbrane asociativne barve Original scientific article/Izvirni znanstveni clanek Received/Prispelo 11-2020 • Accepted/Sprejeto 3-2021 Corresponding author/Korespondencna avtorica: Assoc Prof dr. Sabina Bracko Phone: +386 1 20 03 238 E-mail: sabina.bracko@ntf.uni-lj.si ORCID ID: 0000-0002-3140-7263 Abstract Colours are one of the most important factors in everyday life. The exact number of existing colours is not yet fully known. Nevertheless, people are known for having poor colour memory. The ability to remember colours depends both on the characteristics of an individual and the situation in which the colour needs to be recalled. The field of colour memory (perception and memory of unusual colours) has been very poorly researched. The aim of this study was to analyse long-term colour memory for selected associative colours, comparing it with short-term colour memory. The research approach was based on observation, with observers observing for a period of time a particular colour, image, or a descriptively given reference colour. Colour was treated sepa­rately from associations in the first part, and related to associations in the second and third parts. The first part contained all the reference colours shown independently of associations, the second part contained grayscale images of brands, and the third part comprised descriptively given colours. The result analysis showed that people remember colours very poorly. Observers generally performed better in testing short-term memory. Moreover, the way the template was presented had a noticeable effect on the long-term colour memory. When the image was given in grey, the results were better. The descriptive rendering of reference colours shown did not contribute to better results. The gender of observers did not significantly affect the results. Keywords: associative colours, colour memory, colour perception, colour difference Izvlecek Barve predstavljajo enega izmed najpomembnejših dejavnikov v vsakdanjem življenju. Tocno število obstojecih barv še ni povsem znano. Znano pa je, da imajo ljudje slab barvni spomin. Sposobnost pomnjenja barv je odvisna tako od znacilnosti posameznika kot tudi od situacije, v kateri nastopi potreba po priklicu barve. Podrocje barvnega spomina, zaznavanje in pomnjenje nevsakdanjih barv je zelo slabo raziskano. Namen dela je bila analiza dolgotrajnega barvnega spomina za izbrane asociativne barve in primerjava s kratkotrajnim barvnim spominom. Raziskovalni pristop je temeljil na opazovanju vzorcnih predlog. Opazovalci so dolocen cas opazovali izbrano barvo, podobo ali opisno podano referencno barvo. Barva je bila v prvem delu obravnavana loceno od asociacij, v drugem in tretjem delu pa se je navezovala na asociacije. Prvi del je vseboval vse referencne barve, prikazane neodvisno od asociacij, drugi sivinske podobe blagovnih znamk, tretji pa opisno podane barve. Rezultati so pokazali, da si ljudje zelo slabo zapomnijo barve. Opazovalci so se v splošnem bolje odrezali pri testiranju kratkorocnega spomina. Nacin podajanja predloge je opazno vplival na dolgo­rocni spomin in barvne razlike. Ko je bila predloga podana kot sivinska podoba, so bile razlike manjše, opisno podajanje referencnih barv pa ni pripomoglo k boljšim rezultatom. Spol opazovalcev ni opazno vplival na rezultate. Kljucne besede: asociativne barve, barvni spomin, zaznavanje barv, barvna razlika 1 Introduction Human senses form the foundation of a person and their existence. Our smell, taste, touch, hearing and sight play a key role in our understanding of the world. We use our senses to receive information from the environment. In this way, we also obtain information about various brands and companies. In consequence, the so-called “Sensory market­ing”, i.e. effect on customer well-being, perception and behaviour, was invented. The aspect of vision proved to be the most decisive in this field. People start explaining visual impressions of surround­ings at a very early age. Most consumers thus have complete confidence in their vision. It allows them to do almost everything, from performing every­day tasks to distinguishing between different pack­aging and brands in the store. Visual information is extremely influential and the most important visual element turned out to be colour. Colours carry meaning and communicate information. Scientists have found that colour arrangements af­fect attitude as well as feelings and mood [1]. Our age and gender significantly influence which colour patterns we prefer. Fakin et al. found that in gen­eral the most popular colours are blue and green, with blue prevailing among male observers. Brown and pink turned out to be the least popular colours. The results varied throughout different age periods. One of the more noticeable changes was the popu­larity of black, which has grown in recent years in the younger population and has become less popu­lar in elder age groups [2]. People update and build their archives of colour im­pressions on a daily basis, facing new experiences. They can name these impressions; however, they cannot avoid making mistakes when trying to recall them from their long-term memory. A comparison of a colour in the current situation with the one from the past happens completely automatically, natural­ly, yet the choice and the results vary depending on the circumstances and colour shades [3]. The ways of testing colour memory are very different. Perez-Carpinell stated [4] that colour memory is succes­sive colour matching after a certain time has elapsed from the observation. Comparing the colour from our long-term memory with the present is much more important as it may seem at first glance. People choose fresh fruits and vegetables based on their previous experience, which means freshness, ripe­ness. They usually select and buy clothes according to their colour preferences and they pick the colour that matches the rest of their outfit [5]. A simultaneous comparison of samples with the ref­erence colour is usually very accurate. The results of the research confirmed as many as 96% correct results. In the case of the remaining 4%, the colour difference was minimal [6]. A successive comparison occurs when some time elapses between the obser­vation of a given reference colour and the sample. In this case, the colour memory is used, which is more common in everyday life [4]. Research has also con­firmed that the more we increase the pause time, the greater the colour differences; however, only to a certain extent. If increased over 15 min, no major differences are observed [7–10]. Bodrogi and Tarczali [11] studied how colour mem­ory is affected by the surroundings of a colour pat­tern, when it is observed within a certain image or context. Prototype paints or associative colours, e.g. the colour of the sky, plants, and skin, were observed as a simple colour pattern shown in a photorealistic image. The results showed that the association could be influenced by the added image despite the longer time period having passed since remembering the colour stored in long-term memory. The aim of our study was hence to examine how the method of recall from memory affects our long-term memory. To examine this, we used in addition to in­dependent colour patterns two options, i.e. grayscale images of brands and a description of associative colours. A comparison of short-term and long-term memory was performed on the basis of calculated colour differences. 2 Experimental The experimental part was based on an observation experiment, which was divided into three parts. In the first part, observers were exposed to a single co­lour for 5 s, then after a 10 s pause, they used a cir­cular template to select the colour they thought was the reference. The set of colours used in the first part was then repeated in the second and third part. The first part thus contained 16 colours, and the second and third contained 8 colours each. The second part contained grey images of certain brands, and the third part included descriptions of associative well-known colours. In addition to short-term memory, we also tested long-term memory. In the first part of the study, colours were considered independently of associations, and in the second and third part, they were considered in conjunction with corresponding associations. 2.1 Preparation of reference colours and patterns Reference colours were divided into two groups, each containing 8 colours. The first group (cf. Table 1) con­tained associative colours that are tied to everyday experiences, i.e. cinnamon brown, grass green, sky blue, cyan, lemon yellow, colour of an orange, pur­ple red and magenta. The second group (cf. Table 2) consisted of associative colours related to brands and companies, i.e. Starbucks green, blue colour of the European Union, Facebook blue, Milka purple, ­yellow colour of the Post office Slovenia, Mueller or­ange, red colour from the University of Ljubljana and red-pink colour of the Mercator store. We checked the representative colours of companies online and in collections. Those related to descriptive naming were selected according to the colour values that were reported most often. Colour values were presented in the CIELAB colour space using L*a*b* coordinates [12]. All reference colours and associated patterns were prepared with Photoshop. The entire template was made in InDesign to ease the reading of the results. The method of selection and the conditions taken into account are described below. Selection of samples according to each reference colour For each reference colour, we prepared 8 different visually similar colour samples, which were selected according to three basic colour properties, i.e. hue, lightness and saturation (cf. Figure 1). Samples were obtained by changing the CIELAB hue difference, .H*ab, by 2 units, CIELAB lightness difference, .L*, by 3 units, and saturation, i.e. CIELAB chroma dif­ference, .C*ab, by 3 units. An exception was the blue colour of the European Union, where the samples did not differ enough from each other for the observer to be able to distinguish among them; therefore, we changed them by 5 units (–5, –10 and –15). 2.2 Test preparation Test group The test group consisted of 12 observers, 8 female and 4 male. The age range was 15–30 years, since people are most sensitive to perception in this period [11, 13]. The oldest observer was 24 years old and the youngest was 16 years old, for at younger observers deviations could occur [8]. In accordance with recommenda­tions [9], all participants previously performed the Farnsworth-Munsell hue colour vision test to demon­strate their ability to distinguish colours and assure their normal colour vision. Observers had different educations in different fields of study. Some also had poorer eyesight and used glasses; however, this did not affect the test results. Observation conditions The conditions of observation were the same for all observers, ensuring comparable results and ex­cluding the influence of possible external factors. A 25-inch Dell U2518D monitor with the resolution of 1920 × 1080 and brightness of 350 cd/m2 was used. Brightness was set to maximum value. The testing was performed in a dark room, the only light source being the screen. The observer was positioned 50 cm away from the screen, sitting at a 90° angle to the screen. Before each test, we checked the screen brightness and the display resolution of the screen image. Presentation of colour templates For each reference colour, four different templates were prepared (cf. Figure 2). The first colour template contained only the reference colour shown in the shape of a square measuring 6 × 6 cm. The other two templates contained a reference colour and 8 associ­ated samples. The templates differed from each other in the arrangement of colour patterns. Each sample was shown in the form of a 6 × 6 cm square as well. The squares were arranged in a circle in the middle of the template. To ease the observing and reduce eye fatigue, the background colour was neutral grey (L* = 75, a* = –3, b* = –2). The third template depended on the group the colour was from. In Group 1, i.e. tied to colour names, the template only contained a description of the colour on white background. The typography used was an 87-point Myriad Pro. In Group 2, i.e. colour tied to the brand, the image of the brand was shown in a 6 × 6 cm square in grey tones on white background. A neutral grey background was displayed for 10 s between each reference colour template and the sample template (cf. Figure 2). 2.3 Performance of testing We first explained the course of the research in detail to each observer to have time to adjust to a dark space. The first part of the study contained all 16 reference colours from both the first and the sec­ond group, the observers not being aware of this. A template with a reference colour was displayed for 5 s, which was followed by a 10-second pause with a neutral grey background to calm the eyes and pre­vent the glow of colours. Studies [14] have confirmed that memorising is best in the first 5 s, prolonging the time not having any major effect on the results. The observer then selected a sample for which they considered it is the same as the reference. The time for sample selection was not limited, since this has not been shown as necessary in previous studies [14, 15]. A new template with a reference colour followed. In the second part, the observer observed grey im­ages of well-known companies and brands. The ­attachment was displayed for 5 s, then they chose the colour sample for which they thought it belonged to the company. At this stage, we checked long-term memory bound to associative colours. In the third part of the research, associative colours were given descriptively. The same as in the previous parts, the template was shown for 5 s. Based on the experience, the observer selected a colour sample that they associated with the description. 2.4 Evaluation of colour differences The reference colours and the selected colour samples were defined by the coordinates of the CIELAB colour space and the colour differences, .E*ab, were calculat­ed using the basic CIELAB equation [12]. Moreover, the contributions of CIELAB lightness difference, .L*, saturation, i.e. CIELAB chroma difference, .C*ab, and CIELAB hue difference, .H*ab, were calculated, describing the differences between the observed ref­erence colour and memorised colour represented by the selected sample [16]. 3 Results with discussion 3.1 Overview of colour differences In the first part of the study, where short-term col­our memory was tested, male observers (.E*ab = 5.09) performed slightly better than female (.E*ab = 5.26). CIELAB lightness differences were minimal (.L* = 0.04), similarly observed in previous stud­ies [17]. The differences in saturation were also small (.C*ab = 0.29). According to the results of our study, hue was remembered the least accurately (.H*ab = 4.95), which contradicts with the findings of some other studies [6]. In this case, male ob­servers performed better (.H*ab = 4.69) than female (.H*ab = 5.21) (cf. Table 3). In the second part of the study, which was based on brand recognition, female observers (.E*ab = 4.99) performed better than male (.E*ab = 5.21), which might be due to women being more often in con­tact with brands and companies. Again, the CIELAB lightness differences were very small (.L*= 0.07), the average difference in saturation being slightly larger (.C*ab = 1.40). The largest difference was ob­served as CIELAB hue difference (.H*ab = 5.00), where larger deviations were detected by male observers (.H*ab = 5.21) compared to females (.H*ab = 4.79). In the last part, related to the conceptual representa­tion of associative colours, the average colour dif­ference was the highest (.E*ab = 5.33), which can be attributed to poor colour memory, especially unre­liable long-term memory. The CIELAB lightness dif­ference for selected samples was approximately one unit (.L*= 1.09) and no major deviations in saturation were observed (.C*ab = 0.86). The largest contribution to the CIELAB colour difference was detected as the CIELAB hue difference (.H*ab = 5.13). The latter is unusual and in contradiction to some previous re­search [6], as it would be expected that this property is remembered most accurately as basic colour infor­mation. CIELAB lightness differences are expected to be small, although most studies show that observers remember light reference patterns as even lighter and dark as darker [7, 13] (cf. Table 3). 3.2 Comparison of long-term and short-term memory Reference colours Group 1: well-known objects The first group contained associative reference col­ours that relate to familiar concepts and objects. The results (cf. Figure 3) showed that the average colour difference for Group 1 of the reference colours was greater in Part 3 of the study (.E*ab = 5.27) than in Part 1 (.E*ab = 4.40). The first part was based on short-term memory and the third part on long-term mem­ory. Observers had to recall only what they thought was most appropriate colour and then select a sample. Given that all observers successfully passed the colour vision test, the reason for errors was primarily their poor long-term memory for colours. The total value of the colour difference was mostly due to the CIELAB hue difference, which was also larger in Part 3 (.H*ab = 4.16) than in Part 1 (.H*ab = 3.70). There were no ma­jor lightness differences (Part 1: .L*= 1.04 and Part 3: .L*= 1.11) nor chroma differences (Part 1: .C*ab = 1.83 and Part 3: .C*ab = 1.47). On average, observers chose darker and less saturated samples. In general, we can say that the differences are greater when dealing with long-term colour memory. For most reference colours, a larger colour difference was found in Part 3 and a smaller one in Part 1. The results showed that the best recognised refer­ence colour was in Part 1 of the study colour 1-IV (cyan) with the smallest overall colour difference (.E*ab = 1.89). The reason can be attributed to the uniqueness and unnaturalness of the colour. A much larger colour difference was observed in Part 3 of the study (.E*ab = 6.43), when observers had to recall the same colour from memory and select the correct pat­tern. Let us mention that most of the observers were full-time students in the field of graphic arts, this colour hence being well known to them. Similarly, it is worth mentioning the reference colour 1-VIII (magenta), which was also well recognised by the ob­servers, especially in Part 3 of the study (.E*ab = 2.61). The worst recognised reference colours were 1-V (lemon yellow) and 1-VI (orange fruit). In both cas­es, the average colour differences were high, which can be attributed to the fact that both yellow and orange have a smaller number of light levels and the differences increase rapidly. We attribute the large discrepancies to our perceptions of the colour of an orange and our experience of it. A similar study was performed using a monochromatic light source that also displayed a lemon yellow colour. Otherwise, this colour is supposed to have the highest accuracy, with the wavelength peak at 570 nm (in addition to blue with the peak at 494 nm). The observers recognised it best and the results had the smallest deviations from the reference colour in a given case. Improvement followed by using the association with a lemon [14]. The biggest contribution to the total CIELAB colour dif­ference was due to the CIELAB hue difference which in some cases almost equalled the total colour differ­ence. All reference colours that achieved a larger total CIELAB colour difference in Part 3 than in Part 1 of the study also exhibited a larger CIELAB hue difference in Part 3 than in Part 1: 1-I (cinnamon brown), 1-II (grass green), 1-IV (cyan), 1-VI (orange fruit) and 1-VII (purple-red). Due to the predominant influence of the CIELAB hue difference on the total colour difference, the reverse also applies to all other reference colours. The deviations in CIELAB lightness were relatively small, with the exception of the reference colours 1-I (cinnamon brown, Part 3: .L*= –2.42), 1-III (sky blue, Part 1: .L*= 2.83 and Part 3: .L*= 2.42), 1-VI (orange fruit, Part 1: .L*= –3.58) and the reference colour 1-VII (purple red, Part 3: .L*= –4.67). Even when there was a larger deviation, observers chose darker samples than the reference. An exception was found only for the reference colour 1-III (sky blue), for which lighter samples were chosen. We also detected similarly small differences in saturation when recalling colours from memory. Observers selected less saturated samples in most cases. Major deviations were only in the case of the reference colours 1-I (cinnamon brown, Part 3: .C*ab = 3.79), 1-VII (purple red, Part 1: .C*ab = –2.84 and Part 3: .C*ab = –3.98) and the reference colour 1-VIII (magenta, Part 1: .C*ab = –2.84). The comparison of Parts 1 and 3 of the research agrees with our assumptions that the differences will be greater in Part 3, which is tied to long-term memory, and this is also in agreement with previ­ous investigations [8, 9]. Regardless of the fact that the observers had the reference colours descriptively given, this did not affect their final decision. Each one of us has a different idea of objects; therefore, we choose different colour patterns depending on our memory. The evocation of associations by means of a verbal description of colour did thus not affect the improvement of long-term memory. The only excep­tion may be the reference colour 1-VIII (magenta), which achieved noticeably better results when given descriptively. This colour is well known by its name and the descriptive rendering in this case led to mi­nor colour differences. The explanation for better recognition could also lie within the Weber’s law [18], as its initial stimulus intensity is higher due to its chromaticity, grey background and dark room. Reference colours Group 2: brand colours The second group contained associative reference colours that relate to companies and brands. The re­sults are shown in Figure 4. The average colour dif­ference in Part 1 of the study was .E*ab = 6.01 and in Part 2 .E*ab = 5.13. Contrary to our expectations, the results were better in Part 2, when observers selected samples based on long-term memory. The reason can be found in the fact that most observers are often in contact with the colours of the brands that were pre­sented as a reference. Whenever there is a connection between a colour and an object or an image from our memory, there are differences in selected patterns and thus in research results. An improvement and a smaller deviation of the overall colour difference was observed compared to the situation where there were no associations [15, 19]. The results for the reference colours 2-III (Facebook blue), 2-IV (Milka purple), 2-VI (Mueller store or­ange) and 2-VIII (red-pink colour of the Mercator store) were consistent with the findings of a small­er colour difference in Part 2. The reference colour 2-VIII achieved the largest colour difference within Part 1 (.E*ab = 9.42) and the smallest colour difference within Part 2 (.E*ab = 2.75) as it was best recognised. All observers recognised this brand very successful­ly. The reference colour 2-VI (Mueller store orange) was less recognisable (Part 1: .E*ab = 6.68 and Part 2: .E*ab = 5.62), perhaps due to less frequent encoun­ters with it, or just a human tendency to remember bright colours less well. In the case of the reference colour 2-III (Facebook blue), the differences (Part 1: .E*ab = 5.87 and Part 2: .E*ab = 5.00) occurred most likely due to different screen renderings of the appli­cation of the mentioned social network and the previ­ously changed representative colour of the application. The reference colour 2-IV (Milka purple) was very well recognised by most observers (Part 1: .E*ab = 5.35 and Part 2: .E*ab = 3.86). In fact, they had bigger problems in Part 1, when they had to imprint the colour in their memory and recognise it after 10 seconds. Interestingly, the reference colour 2-VII (red colour of the University of Ljubljana, Part 1: .E*ab = 5.53 and Part 2: .E*ab = 5.69) achieved very similar colour differences in both parts of the research. Due to the fact that all observers are in frequent contact with this colour, such results differ from expectations in the case of long-term memory and can be explained by a variety of representations, as the problems are mainly a consequence of inconsistent rendering and rendering of colours; the overall graphic image of the University of Ljubljana uses a darker colour than the website. The reason for the deviation of the reference colour 2-I (Starbucks green) is probably that its rec­ognition depends on the frequency of encountering the brand. The observers who are not very familiar with it consequently did not recognise it well in Part 2 of the study. The reference colour 2-II (blue colour of the European Union) made greater differences (Part 1: .E*ab = 4.95 and Part 2: .E*ab = 6.19), most likely due to the inconsistency in its representations (flags, screens, application, TV etc.). Each participant has thus a completely different idea of this colour. The average CIELAB lightness differences were very small in both Part 1 and 2 of the study (Part 1: .L*= 0.43 and Part 2: .L*= 0.14). Generally, observers chose lighter samples than the reference colour. The average CIELAB chroma differences were slightly larger (Part 1: .C*ab = –1.21 and Part 2: .C*ab = –1.37). Observers mostly chose less saturated samples. The colour differences were predominantly displayed as the CIELAB hue difference (Part 1: .H*ab = 5.59 and Part 2: .H*ab = 4.49), which again had the greatest impact on the total colour difference. Consistent with the total CIELAB colour difference, the CIELAB hue difference was greater in Part 1 than in Part 2 for the majority of Group 2 reference colours. The comparison of Parts 1 and 2 of the research does not match our assumptions that the differences will be greater in Part 2, which depended on long-term memory. The differences were smaller in Part 2, where observers selected samples according to the grey im­age of the brand. Evidently, the way the suggestions were made was crucial for minor colour differences and had an impact on better long-term memory re­sults. Similar results were found in a research when observers used a black and white photography of a reference coloured object [20]. According to the results, observers performed better in Part 2 of the study when observing grayscale brand suggestions, with some exceptions that were either not well known among observers or differed in the ways in which they were depicted and the applications they encoun­tered: 2-I (Starbucks green), 2-II (blue colour of the European Union), 2-V (yellow colour of the Post of­fice Slovenia) and 2-VII (red colour of the University of Ljubljana). According to the Weber-Fechner law, the perceived magnitude of a stimulus, in this case colour, is proportional to the logarithm of the physi­cal stimulus intensity [21]. Consequently, such results could reflect the inability of the human visual system to distinguish relatively small colour differences in case of highly saturated colours. 4 Conclusion The result analysis confirmed that people have a de­ficient memory for colours. Observers performed much worse in the part of the study that was tied to long-term memory. We can therefore confirm that our long-term memory is not as accurate as short-term. Although an unreliable colour memory can lead to unpleasant surprises when selecting a certain hue, e.g. when buying clothes, this can be improved by offering suitable support or association. The re­sults showed that the way colour suggestions are made has a significant impact on colour differences when testing colour memory. When the suggestions were given only with the help of verbal descriptions of reference colours, the results were worse, conse­quently confirming our hypothesis that deviations are greater with long-term memory. In the case of grayscale brand proposals, however, observers achieved better results. Here, the association with the help of a grayscale template had a strong impact on improving long-term memory. The results showed that our memory for lightness is relatively accurate. In general, the colours in our memory are slightly more saturated than they really are. The largest share of the total colour difference was exhibited as the hue difference, which is in contradiction to some previous research. Female observers remembered the colours slightly better than male, the differences between the two genders not being substantial. References 1. AMSTEUS, Martin, AL-SHAABAN, Sarah, WALLIN, Emmy, SJÖQVIST, Sarah. Colors in marketing: A study of color associations and context (in) dependence. International Journal of Business and Social Science, 2015, 6(3), 14. 2. FAKIN, Darinka, SMOLJANOVIC, Lavra, OJSTRŠEK, Alenka. Detection and percep­tion of colour regarding gender and age. Tekstilec, 2020, 63(1), 50–59, doi: 10.14502/Tekstilec2020.63.50-59. 3. BYNUM, Carlisle, EPPS, Helen, KAYA, Naz. Color memory of university students: influence of color experience and color characteristic. College Student Journal, 2006, 40(4), 824–831. 4. PÉREZ-CARPINELL, Joaquín, BALDOVÍ, Rosa, DOLORES DE FEZ, M., CASTRO, José. Color mem­ory matching: time effect and other factors. Color Research and Application, 1998, 23(4), 234–247, doi: 10.1002/(SICI)1520-6378- (199808)23:43.0.CO;2-P. 5. FORNAZARIC, Milena, TOROŠ, Ivan. Relationship between behavioural factors and colour preferences for clothing. Tekstilec, 2018, 61(1), 4–14, doi:10.14502/Tekstilec2018.61.4-14. 6. CAR, Ajda, BRACKO, Sabina. Influence of basic colour parameters on colour memory. Tekstilec, 2019, 62(4), 232–241, doi: 10.14502/Tekstilec2019.62.232-241. 7. HAMWI, Violet, LANDIS, Carney. Memory for color. The Journal of Psychology, 1955, 39(1), 183–194, doi: 10.1080/00223980.1955.9916168. 8. PÉREZ-CARPINELL, Joaquín, J. CAMPS, Vincente, TROTTINI, Mario. Color memory in children. Color Research and Application, 2008, 33(5), 372–380, doi: 10.1002/col.20433. 9. PÉREZ-CARPINELL, Joaquín, DE FEZ, Dolores, BALDOVI, Rosa, SORIANO, Juan Carlos. Familiar objects and memory color. Color Research and Application, 1998, 23(6), 416–427, doi: 10.1002/ (SICI)1520-6378(199812)23:63.0.CO;2-N. 10. PÉREZ-CARPINELL, Joaquín, CAMPS, Vicente J., TROTTINI, Mario, PÉREZ-BAYLACH, Carmen M. Color memory in elderly adults. Color Research and Application, 2006, 31(6), 458–467, doi: 10.1002/col.20258. 11. BODROGI, Peter, TARCZALI, Tünde. Colour memory for various sky, skin, and plant colours : effect of the image context. Color Research and Application, 2001, 26(4), 278–289, doi: 10.1002/col.1034. 12. HUNT, Robert William Gainer, POINTER, Michael. Measuring color. 6th edition. Chichester : Wiley & Sons, 2011, pp. 41-72. 13. ROMERO, Javier, HITA, Enrique, JIMENEZ DEL BARCO, Luis. A comparative study of successive and simultaneous methods in colour discrimina­tion. Vision Research, 1986, 26(3), 471–476, doi: 10.1016/0042-6989(86)90169-6. 14. SELIGER, Howard H. Measurement of memory of color. Color Research and Application, 2002, 27(4), 233–242, doi: 10.1002/col.10067. 15. RATNER, Carl, MCCARTHY, John. Ecologically relevant stimuli and color memory. The Journal of General Psychology, 1990, 117(4), 369–377, doi: 10.1080/00221309.1990.9921143. 16. CIE. Colorimetry. 4th Edition. Vienna : CIE, 2018, pp. 29–30, doi: 10.25039/TR.015.2018. 17. SIPLE, Patricia, SPRINGER, Robert M. Memory and preference for the colors of objects. Perception and Psychophysics, 1983, 34(4), 363–370, doi: 10.3758/BF03203049. 18. FAIRCHILD, D. Mark. Color appearance models. 3rd edition. Chichester : John Wiley & Sons, 2013, pp. 37–39. 19. LANTZ, Delee, STEFFIRE, Volney. Language and cognition revisited. The Journal of Abnormal and Social Psychology, 1964, 69(5), 472–481. 20. TARCZALI, Tünde, PARK, Du-Sik, BODROGI, Peter, KIM, Chang Yeong. Long-term memory colors of Korean and Hungarian observers. Color Research and Application, 2006, 31(3), 176–183, doi: 10.1002/col.20192. 21. PORTUGAL, R. Doyle, SVAITER, Benar F. Weber-Fechner Law and the optimality of the log­arithmic scale. Minds and Machines, 2011, 21(1), 73–81, doi: 10.1007/s11023-010-9221-z. Table 1: Reference colours with CIE L*a*b* coordinates; Group 1: colours of well-known objects Reference colour Sample L* a* b* 1-I 56 38 56 1-II 48 -23 25 1-III 79 -18 -22 1-IV 91 -51 -15 1-V 95 -10 76 1-VI 68 45 74 1-VII 56 76 69 1-VIII 60 93 -61 Table 2: Reference colours with CIE L*a*b* coordinates; Group 2: colours of brands and logos Reference colour Sample L* a* b* 2-I 37 -36 19 2-II 15 46 -77 2-III 38 4 -39 2-IV 39 25 -43 2-V 84 9 83 2-VI 61 52 62 2-VII 48 66 53 2-VIII 48 72 26 Figure 1: Reference colours with appropriate samples in a*b* plane of CIELAB colour space Presentation of colour templates Part 1 Part 2 Part 3 Figure 2: Presentation of colour templates when testing colour memory Table 3: Average colour differences in Part 1 (short-term memory), Part 2 (long-term memory using grayscale image) and Part 3 (long-term memory using description of colour) Part Part 1 Part 2 Part 3 Gender Female Male All Female Male All Female Male All |.H*ab| 5.21 4.69 4.95 4.79 5.21 5.00 5.05 5.21 5.13 |.C*ab| 0.62 1.96 0.29 1.33 1.48 1.40 0.86 0.85 0.86 |.L*| 0.34 0.27 0.04 0.43 0.28 0.07 0.72 1.47 1.09 |.E*ab| 5.26 5.09 5.18 4.99 5.42 5.21 5.17 5.48 5.33 Figure 3: Comparison of Part 1 (short-term memory) and Part 3 (long-term memory using description of colour) for samples 1-I–1-VIII: CIELAB colour difference (.E*ab), CIELAB hue difference (.H*ab), CIELAB chroma difference (C*ab) and CIELAB lightness difference (.L*) Figure 4: Comparison of Part 1 (short-term memory) and Part 2 (long-term memory using grayscale image) for samples 2-I–2-VIII: CIELAB colour difference (.E*ab), CIELAB hue difference (.H*ab), CIELAB chroma difference (C*ab) and CIELAB lightness difference (.L*)