GLASILO SLOVENSKIH TEKSTILCEV • SLOVENE JOURNAL FOR TEXTILE AND CLOTHING TECHNOLOGY, DESIGN AND MARKETING tekstilec 4/2020 • vol. 63 • 239-320 ISSN 0351-3386 (tiskano/printed) ISSN 2350 - 3696 (elektronsko/onllne) UDK677 + 687 (05) m9mm http://www.tekstilec.si Časopisni svet/Publishing Council Barbara Simončič, 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 Rebič, Odeja, d. o. o. Tatjana Rijavec, Univerza v Ljubljani Daniela Zavec, ZITTS Helena Zidarič Kožar, Inplet pletiva d. o. o. Vera Žlabravec, Predilnica Litija, d. o. o. 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I VOLUME 63 • TEKSTILEC 3 2020 ISSN 0351-3386 (tiskano/printed) I6KSIII6C UDK 677 + 687 (05) SC'ENT'F'C 242 Bestoon Othman, He Weijun, Zhengwei Huang, JingXi, Thomas Ramsey ARTICLES/ Znanstveni članki Effect of Service Quality on Service Value and Customer Retention for Clothing Store Brands in China Vpliv kakovosti storitev na njihovo vrednost in na to, koliko so kupci zvesti trgovskim blagovnim znamkam oblačil na Kitajskem 256 Beti Rogina-Car, Stana Kovačevic, Irena Šabaric Characteristics, Protection and Functional Design of Three-Layer Laminate for Medical Footwear Značilnosti, zaščita in funkcionalna zasnova trislojnega laminata za medicinsko obutev 263 Yetanawork Teyeme, Benny Malengier, Tamrat Tesfaye, Simona Vasile, Lieva Van Langenhove Comfort Evaluation of Cyclists Jerseys Using Wear Trial Test Vrednotenje udobnosti kolesarskih dresov s testom poskusnega nošenja 276 Kateryna Smykalo, Oksana Zakora Effect of Hairiness on Fabric Colour Characteristics Vpliv kosmatosti tkanine na njene barvne značilnosti 287 Khorolsuren Tuvshinbayar, Andrea Ehrmann Acoustic Investigation of Textile Fabrics Akustična raziskava tekstilnih tkanin 294 Ekrem Gulsevincler, Mustafa Resit Usal, Demet Yilmaz The Effect of Humidified Air on Yarn Properties in a Jet-Ring Spinning System Vpliv navlaženega zraka na lastnosti preje, izdelane v curkovnem prstanskem predilnem sistemu 305 Omender Kr, J N Chakraborty Eco-Friendly Vat Dyeing of Cotton Using Alkaline Iron (II) Salt as Reducing Agent Okolju prijazno barvanje bombaža z redukcijskimi barvili z uporabo alkalne železove (II) soli kot redukcijskega sredstva 242 Tekstilec, 2020, Vol. 63(4), 242-255 | DOI: 10.14502/Tekstilec2020.64.242-255 Bestoon Othman1,2, He Weijun1, Zhengwei Huang1, Jing Xi3, Thomas Ramsey1 1 China Three Gorges University, College of Economics and Management, 443000 Yichang, P. R. China 2 Erbil Polytechnic University, Koya Technical Institute, Department of Business Administration, 44001 Erbil, Kurdistan, Iraq 3 China Three Gorges University, College of International Communications, 443000 Yichang, P. R. China Effect of Service Quality on Service Value and Customer Retention for Clothing Store Brands in China Vpliv kakovosti storitev na njihovo vrednost in na to, koliko so kupci zvesti trgovskim blagovnim znamkam oblačil na Kitajskem Original scientific article/Izvirni znanstveni članek Received/Prispelo 4-2020 • Accepted/Sprejeto 7-2020 Corresponding author/Korespondenčni avtor: Jing Xi E-mail: geanxi@ctgu.edu.cn, bestoon2011@yahoo.com ORCID: 0000-0003-0071-0988 Abstract An increasing number of new Chinese clothing store brands are selling and offering similar products and services and consequently clothing store brand providers must compete to survive in this industry. They need to focus on customers' special needs and preferences to maintain and retain a long-term relationship. The objective of this study is thus to examine the relationship between service quality and customer retention for clothing store brands in China, and the mediated effect of service value in the relationship between service quality and customer retention for clothing store brands in China. A quantitative research for data collection was implemented. As many as 385 questionnaires were collected by the professor, PhD students, MSc students and BSc students of different nationalities in China. The data was analysed using SmartPLS and SPSS software. Customer perception of the quality of a service product in all sizes has a beneficial effect on customer retention. Service value affects customer retention positively. Practical implications for the target market of the clothing sector should be focused on young individuals aged 36 to 45 years, holding a Master's degree and earn more than €1,000/month. Findings indicated significant and direct relationships between service quality, service value and customer retention. It was also found that service value has a full mediated effect. This study will be of interest to the clothing store brands in understanding how service quality is essential for maintaining a long-term relationship with customers. Keywords: service quality, service value, customer retention, clothing store brands, China Izvleček Na Kitajskem je v prodaji oblačil s trgovskimi znamkami veliko novih subjektov, ki tržijo podobne izdelke in storitve. Ponudniki oblačil uveljavljenih znamk morajo tekmovati med seboj za preživetje, saj je konkurenca zelo huda. Da bi ohranili lojalnost svojih kupcev na dolgi rok, so prisiljeni upoštevati posebne potrebe in želje svojih strank. Cilj te študije je torej proučiti razmerje med kakovostjo storitev pri ohranjanju zvestobe trgovskim znamkam oblačil na Kitajskem in posrednim učinkom vrednosti storitve na razmerje med kakovostjo storitev in zvestobo trgovcem z oblačili na Kitajskem. Izvedena je bila kvantitativna raziskava z zbiranjem podatkov. Anketiranih je bilo 385 profesorjev, doktorskih študentov, magistrov in študentov univerzitetnih študijskih programov na Kitajskem. Podatki so bili analizirani s programsko opremo SmartPLS in SPSS. Dojemanje storitev kot kakovostnih v vseh vidikih ugodno vpliva na zvestobo Effect of Service Quality on Service Value and Customer Retention for Clothing Store Brands in China 243 kupcev. Vrednost storitve pozitivno vpliva na zvestobo strank. Iz tega sledi, da bi se na ciljanih trgih oblačil morali osredotočiti na mlade, stare od 36 do 45 let, ki imajo magisterij in na mesec zaslužijo več kot tisoč evrov. Pokazalo se je, da obstajajo pomembne in neposredne povezave med kakovostjo storitve, vrednostjo storitve in zvestobo strank. Ugotovljeno je bilo tudi, da ima vrednost storitve popoln mediacijski učinek. Ta študija je zanimiva za trgovine z blagovnimi znamkami oblačil, da bi laže razumeli, kako pomembna je kakovost storitev za ohranjanje dolgoročnih odnosov s strankami. Ključne besede: kakovost storitev, vrednost storitve, zvestoba kupcev, trgovska znamka oblačil, Kitajska 1 Introduction The clothing store brands nowadays not only meet customers' primary needs, such as food and shelter, they also provide much more, for example they can cover other requirements, such as personalised services, etc. As many organisations and sectors are evolving, the Chinese clothing sector has become one of the most critical drivers of Chinese economic growth and development. China was the leading global economy in 2019 [1]. In a competitive clothing sector, clothing store brands need to discover methods to improve their services through various and comprehensive programs that are different from their competition. In order to achieve this goal, clothing store brands managers need to understand and find out the needs and anticipations of their customers. Then they need to alter their product service offerings based on the needs and expectations of their customers to properly satisfy their needs [2]. In order to enhance customer retention in the clothing sector, clothing store brands need to understand that clients may be influenced by service characteristics. Inability to provide vital attention to the quality of services (tangibles, assurance, reliability, responsiveness and empathy) can lead to a negative evaluation of the clothing brands by customers, which can ruin the brand's opportunity of having more customers. Recent research has shown that consumer retention in the clothing sector can be affected by numerous marketing factors, such as promotion, price, place, product, people, process, physical evidence and after-sales service. These factors are considered essential [2] in order to achieve consumer loyalty and satisfaction. According to one source [3], the combination and mixing of all parameters affecting the retention of customers lead to the quality of the service. Knowing the impact of service quality on service value and customer retention is therefore important for clothing store brands. Since the retention of a customer is affected by the quality of the service, the marketing mix has become a major issue for all companies [3]. This study seeks to investigate the impact of service quality on service value and customer retention for clothing store brands in China. 2 Materials and methods 2.1 Customer retention Customer retention means an undertaking's ability to continue business with a specific customer or constantly adapt to their needs. Retention can also be described as love, identification, engagement, confidence, and clients' readiness to recommend and repurchase intentions; the first four expressions are emotional-cognitive retention constructs and the last two behavioural intents [4]. According to Oliver and Varki [5] customer retention is a strong commitment to continuously repurchase or repatriate a preferred product or service in the future, despite situational factors and marketing attempts that may trigger the switching of behaviour. Later, Ranaweera and Prabhu [6] define customer retention as the customer's propensity to remain with its current service provider. Many organisations today have trouble attracting new customers so their marketing department is restructured and managers are appointed to pay attention to their current customers [7]. Customer retention is very important for the clothing industry in order to ensure long-term sustaina-bility and growth and it is therefore their duty to be able to meet all of the customers' needs. They must be aware of the current situation whenever crises occur and be prepared to react rapidly. In addition, the management of the clothing store brands must guarantee that individual customers are as satisfied as possible. If the leadership of clothing store brands is serious about contributing to the success of their clients, then retention is a key element. In reality, the minimal expectation in terms of retention should be that clients will simply return to the clothing store brands withing the first year [8]. 244 Tekstilec, 2020, Vol. 63(4), 242-2.55 2.2 Service value Creation of value derives from services [9, 10]. Prior to choosing a service, customers are smart enough to consider and determine any advantages these services may have. Such a scenario has encouraged the company to provide benefits and services from the customer's point of view with a useful service for competitive benefits, profitable growth and business development. The concept of 'value development' becomes an important measure in consumer behaviour, such as customer retention and behavioural intentions that are in line with increasing recognition of service value [11, 12]. Furthermore, building customer relationships that will lead to development and profitability [13] as a key aspect in the business strategy [9] is crucial for the organisation's continued growth and development. This implies that providing greater value to clients will allow organisations to: (1) reinforce profit and maintain a competitive advantage by incorporating significant strategic directions [11, 14]; (2) simplify resource allocation by scheduling managers linked to service design and the delivery stage [15]; and (3) improve service encounter systems that drive customers to achieve beneficial results [16]. Despite a wide-ranging attention and previous research, several problems connected with the core concern of service value remain uncertain. Wu and Ledden to studies by some authors [12, 17], unresolved problems relating to the importance of the service cover (1) the definition and idea are lacking in compromise. Consequently, the structure of service value has always been misapplied in social sciences and marketing research of goods in particular [18]; (2) The findings from the empirical measure are inconsistent and the topic has been criticised for lack of agreement between academics on definitions and ideas; and (3) the connection between service value and other constructs, such as service quality and customer retention has been controversially discussed. As value-related problem discussions are yet to come to an agreement on generalisation, ongoing research of this structure is required to narrow the knowledge gap as this research attempts to explore the value of service including links to other constructs. In the Thamrin [19] study, they believe that the value of the service is situational and context-dependent. Due to its nature, the value judgment is a function of evolving norms. These norms are likely to differ depending on the environments, location, culture and the moment the value assessment was conducted. 2.2.1 Relationship between service value and customer retention Service value and customer retention are key elements of academic and business marketing because these factors are closely connected to market share, marketing relationships and purchase intention, as well as behaviour [20]. In the literature on marketing services the connection between service value and customer retention has thus been seriously deliberated. As a background and result, there were two kinds of customer retention roles to service value. According to Oliver's model [21], the first form of customer retention may lead from results of performance, such as product efficiency, quality of service or cost-based value, such as low cost. The second retention form is called value-added retention which suggests retention is derived from the value of customer service. If the client is unhappy, this will have an adverse effect on the quality of customer service. In Bolton et al. [22], the research verified that value-based retention is the outcome of a cognitive comparison method where cognitive assessment occurs before the affective reaction occurs. The first form of customer retention has been referred to for this research, which focuses on customer retention as a result of service quality where offering value to clients is extremely satisfying to clients on an ongoing basis [23]. Generally, in previous research in multiple service industries, the immediate connection of service value was recognised as a reliable predictor of customer retention and compatible with previous and present research [17, 18, 24, 25]. Recognised from previous results about important relationships for these two constructs, the current research is restricted to continuing research in this regard. The results of this research in the context of clothing store brands may lead to current information about this relationship. The first hypothesis was proposed as follows on the basis of the discussion above: H1: Service value has a positive effect on customer retention. 2.3 Service quality Service quality is frequently described as a discrepancy between service expectations and perceived service provided by the organisation and employee service performance [26]. In the early establishment of the notion of service quality, the [20] service quality model, also known as the Nordic view, recognised two dimensions of service quality, namely, technical Effect of Service Quality on Service Value and Customer Retention for Clothing Store Brands in China 245 quality linked to "what customers get" and functional quality linked to "how they get it." The research by Behera defines technical quality as "what the customer receives as a consequence of relationships with a service company" and functional quality, defining it as "the transfer of technical quality." Behera also found that the company's corporate image was constructed by the technical and functional quality of service. In his research on the mid-end model, Parasuraman et al [27] described service quality as a worldwide judgement or attitude pertaining to the general excellence or superiority of the service and Parasuraman et al [27] again quoted this concept. Edward [20] claim that Yee et al. [28] define service quality as being the most commonly accepted for studying service quality by other academics. This research uses the definition of Parasuraman et al [27]. 2.3.1 Relationship between service quality and customer retention The link between service quality and customer retention has become a focal point in literature about services [6, 29]. Service quality plays a vital role in achieving a competitive advantage by providing high-quality service capable of achieving customer retention and shaping the enterprise's beneficial result, such as customer loyalty and reducing company rivals [30]. Some of the recent research has provided coherent evidence on the immediate and beneficial relationship between service quality and retention of customers, such as studies carried out by Ranaweera, Venetis and Han [6, 29, 31]. These findings were in line with the following past studies Ennew and Hennig [32, 33]. Several scientists studied the immediate impact of customer retention on the connection between each dimension of service quality. For instance, Islam et al. [34] provided quantitative results on service quality delivery and its impact of customer retention in Malaysia's banking sector, which disclosed that the dimension of certainty, empathy, reliability, and responsiveness has a connection to but it does not have an important impact on customer retention. Only tangible dimensions have a favourable connection and an important effect on the retention of customers. The results of the assessment are not in line with [35] results obtained by the Malaysia Islamic banks using PAKSERV, taken from the SERVQUAL scale where tangible, assurance, honesty, customisation and formality dimensions have an important connection with customer retention but not reliability. Another Hume and Sullivan [30] research of the public health service discovered that the dimension of certainty, compassion and responsiveness has important customer retention relationships, they are, however, not tangible and reliable. While the research by Islam et al. [34] discovered that all SERVQUAL sizes were important for customer retention, the outcome showed that the tools used to evaluate the quality of service were extremely accurate and valid. Inconsistent results from the impact of SERVQUAL sizes on customer retention in previous research may, however, be due to cultural differences [34]. Studies applying a higher order construct of service quality are growing due to the complexity of abstract service quality. For example, studies of Rajaratnam et al. [36] in rural tourism destinations in Malaysia used seven dimensions of service quality, i.e. availability and logistics, key tourism experience, hygiene, data, safety, value-for-money and hospitality through formative strategy using the structural equation model methodology. Their research results indicate that the quality of service was important for the retention of tourists, and suggests that the quality of service was a direct precedent for customer retention. They also verified that the quality of service is a multidimensional structure. While the research of mobile communications providers in China by Daniel et al. [37] adjusted the hierarchical model of service quality as suggested by Brady [38]. Although there have been several approaches to evaluating service quality in the aforementioned literature, such as multi-dimensional service quality, one-dimensional service quality, and hierarchical service quality model, service quality remains an important building block for customer retention. This is due to the nature of the quality of service and the connection between client retention being seen as linear, which shows that high quality of service results may result in elevated customer retention. The current research proposes the following hypothesis in order to meet the current gap in clothing store brands in China: H2: Service quality has a positive effect on customer retention. 2.3.2 Relationship between service quality and service value There is no doubt that marketing scientists have long been interested in service quality and service value. 246 Tekstilec, 2020, Vol. 63(4), 242-2.55 The notion of service quality was described as the evaluation of the general excellence or superiority of the service by the customer [27]. While Cronin et al. [16] conceptualised the quality of service that reflected the performance-based assessment of the perception of service quality during a service meeting. They described perceived service quality in an article by Zeithaml et al. [39] that consisted of elements through performance, expectation and disconfirmation. Functional quality, such as response, reliability, empathy, certainty and technical quality (in tangible terms) becomes a major driver for customers in evaluating the value of purchasing a product or service in terms of cost, effort, emotion, connection and social aspects. The client will perceive the high-quality output, speed of service delivery, comfort and friendly services through the superiority of service provided by the supplier as a significant effect on the client compared to what they are giving. Service quality therefore plays a significant role in determining the value of service. Results from the research conducted by Cronin et al. [16] demonstrate that perception of quality mainly has a defined service value where it highlights quality rather than price associated with its exchange transaction. Other scholars, including De Ona and Mazzulla [40], reference past studies, such as Lai and Petrick [41], Muala and Ngo and Nguyen [42, 43] and later research, in which comparable findings consistently showed that the customer's perceived service value assessment was directly dependent on the customer's perceived service quality assessment. Ledden et al. [17] acknowledged that several scholars like Ganguli and Roy [44], Wang, Shieh, and Hsiao, [45] and Erdil and Yildiz [46] regarded quality as a value component dimension. Sweeney and Soutar [47] also stressed that the function of service value was a crucial component of decision-making, and perceived service quality was a major antecedent of service value. In distinct contexts, such as clothing store brands, further research of this connection enriches current understanding. The third hypothesis for this connection was thus proposed as follows: H3: Service quality has a positive effect on service value. 2.3.3 Service value as mediator between service quality and customer retention The function of service value is essential in the relationship between the service provider and the client. In addition, the function of service significance is substantial and unique where this variable can serve as a mediator [16] and moderator [48]. Having a better knowledge of the role of service value is therefore essential. In the connection between service quality and customer retention, service value was empirically recognised as a mediating variable [15, 49]. A study conducted by Cronin and Brady [16, 38] suggests that the customer retention evaluation was preceded by a cognitively focused service quality and service value evaluation. According toChen and Yang [49], service value serves as a more important predictor in service evaluation than service quality. Empirical research findings by Kuo et al. [50] state that the overall impacts of post-purchase intention contributed to the value of service, followed by the quality of service and customer retention. It has been found that providing a greater service value will boost customer's favourable behavioural intent and word of mouth. Research using a structural equation model conducted by Hume and Mort [30] in performing arts settings in Australia illustrates the importance of the quality of service to customer retention, while intention to repurchase was fully dependent on service value, but not the peripheral quality of service and evaluation of emotions. They suggest that executives should concentrate on core quality of service as a main factor, such as showing or acting in performing arts, to determine intention to purchase again. Their research also discovered that the quality of service, peripheral quality of service and evaluation of emotions was directly connected to the value of service, but were not important for customer retention and service value. The complicated mediation function of service value should therefore warrant further studies. Research by Kwun [51] is another proof of the mediation role of service quality. His research of a campus food service discovered that the role of service value mediation varied from gender to gender. The connection between service quality and customer retention was fully mediated by service value for female customers, while the quality of food and menu was partly mediated by the importance of service. On the contrary, only food quality was mediated by male consumers' service value. The outcome shows that evaluations produced by male and female customers on the characteristics of campus food service gave mixed trade-off advantages on the quality of service and had distinct impacts on satisfaction and customer behaviour. Effect of Service Quality on Service Value and Customer Retention for Clothing Store Brands in China 247 The results of the research by Kwun [51], Kuo et al. [50] and Cronin et al. [16] indicate that quality of service, value of service and retention of customers can jointly contribute to a significant impact on customer service intention and perception after purchase. They also suggest analysing the integration of these factors through a multivariate analytical strategy. The aforementioned literature review endorsed the function of service value as a mediating variable between the service quality relationship and the retention of customers. Continuous inquiry into this relationship will lead to current understanding due to the sort of service and place variables that may be uncertain in the relationship finding. Since the analysis of this connection has been ignored specifically in the context of the Chinese clothing store brands, the issue remains. To fill the current gap, it would therefore be useful to present the research to find a response on this relationship. Based on the empirical evidence, this research suggested the fourth hypothesis as follows: H4: Service value mediates has a positive effect on the service quality and customer retention. outcome. The research population measured who is buying at clothing store brands in China. About 385 questionnaires had valid answers and were used in this research paper for data analysis; the information was analysed using partial least square regression. According toSekaran (2003), a total of 385 answers were used and subsequently analysed, resulting in a response rate of 80% using the 5-point Likert scale for all answers with (1 = strongly disagree, 2 = disagree, 3 = undecided, 4 = agree, 5 = strongly agree). The questionnaire is split into four components: section (1) population variables (8) items; section (2) quality of service measurements (22) items from Zeithaml et al. [39]; section (3) service value (5) items from Ledden et al. [17]. Finally, section (4) adjusted (4) items from Han [31] for customer retention. In conclusion, the researcher used convenience sampling processes in social science studies as a prevalent type of sampling design (thorough sampling). Mohr and Spekman [52] provide an appropriate database for scientists to use the methods of statistical inference. This sampling design strategy is also relevant in the marketing of 2.4 Research framework Building on past empirical research, the article presents a model for finding out the relationship between service quality and customer retention in clothing store brands: Mediating effect of service value (Figure 1). Furthermore, the model indicates a number of hypotheses that support these suggested backgrounds. 2.5 Research methodology This chapter addressed the following problems pertaining to research design, such as population, sample size, sampling technique, study hypothesis, questionnaire design, method of assessment, and reliability 3 Results and discussion 3.1 Profile of respondents The aim of the profile of respondents is to study their characteristics according to the study samples that were established. In terms of gender, men accounted for 38.7% clothing consumers, while women accounted for the remainder of 61.3%. It was determined that men are less inclined to buy clothing store brands than women. Analysis by age provided information about the purchasing behaviour of people. It was shown that older people have a higher propensity to purchase clothing store brands. Figure 1: Research framework 248 Tekstilec, 2020, Vol. 63(4), 242-2.55 This study explains demographic characteristics of the respondents. It shows that respondents aged 36 to 45 years account for 30.6% of the total. The customer of a clothing store brand is represented by consumers who earn a monthly salary of between €1,001 and €1,500, or 24.7% of the total. The selection of clothing brands is highly dependent on the information available to the buyer. Clients with higher qualifications will be choos-ier in their consumption decisions. The data for the qualification level show that the highest level achieved by the largest group of respondents is master degree, which accounts for 55.1%. At 51.2% of the respondents are married, 32.7% are single, while 16.1 are other. The occupation of consumers also has an effect on their consumption behaviours. Features of respondents by occupation subjugated by government equal 12.9%. The number of respondents bought clothing brands non- government equal 15.7%, while the majority of respondents bought clothing brands 39.9% own employee, 18.8% have bought clothing brands by student and 12.7% have bought clothing brands by others. Table 1: Demographic characteristics of participants Demographic Characteristic Frequency Percentage Gender Male 236 61.3 Female 149 38.7 Age Below 25 72 18.7 25-35 89 23.1 36-45 118 30.6 46-55 42 10.9 56 and older 64 16.6 Monthly salary (EUR) Below 500 79 20.5 500-1000 85 22.1 1001-1500 95 24.7 1501-2000 83 21.6 Above 2001 43 11.1 Qualification Diploma 15 3.9 Degree 54 14 Master 212 55.1 Doctoral 104 27 Marital status Single 126 32.7 Married 197 51.2 Other 62 16.1 Occupation Government 51 13.2 Non- government 59 15.4 Own employee 154 39.9 Student 72 18.8 Others 49 12.7 Source of information Online 272 70.6 Friends 42 10.9 Relatives 14 3.6 Advertisement 24 6.2 Others 33 8.6 Effect of Service Quality on Service Value and Customer Retention for Clothing Store Brands in China 249 Table 2: Correlations among variables and discriminant validity ASS CR EMP REL RES SV TAN ASS 0.901 CR 0.799 0.832 EMP 0.891 0.832 0.899 REL 0.863 0.799 0.887 0.888 RES 0.885 0.786 0.895 0.885 0.902 SV 0.842 0.843 0.867 0.821 0.835 0.886 TAN 0.876 0.780 0.876 0.758 0.871 0.812 0.906 Note: ASS = assurance; CR = customer retention; EMP = empathy; REL = reliability; RES = responsiveness; SV = service value; TAN = tangible The results show how the respondents obtained their source of information about clothing store brands. Several response options were made available and the respondents were allowed to choose more than one option. A large portion of the respondents (272 respondents) obtained source information about clothing store brands using online services and a total of 42 respondents received source information about clothing store brands from friends. Meanwhile, 14 respondents obtained their source information about clothing store brands via their relative(s). Lastly, 24 of the respondents got their source information by advertisement and 33 of the respondents received their source information about clothing store brands from others. 3.2 Discriminant validity The degree to which items distinguish between constructs or measure separate ideas is the discriminating validity of the measures. Hair et al. [54] explained in this regard that the discriminating validity stipulates that the average variance extracted from each latent construct (AVE) should be higher than the highest square correlation of the other latent construct as recommended by Fornell and Cha [55] criterion, and that the loading of the item should be greater than all its cross loading. 3.3 Testing of hypotheses First of all, for direct hypothesis, H1 postulates an important connection between service value and customer retention where previous studies frequently support this relationship. The connection between these relationships also discovered an important aspect in the context of clothing store brands service (P = 0.467, S.E. = 0.090, t = 5.174, p < 0.000) in the same manner. In addition, R2 was found to be 0.754 in customer retention and was substantially explained by the value of the service. All service value products played key roles in shaping service value construction and thus revealed the significant role of quality service value results in building customer retention relationship. Confirmed and approved the second assumption predicting an important connection between SQ and CR. The regression outcome produced by SmartPLS showed that the link between SQ and CR was important (P = 0.430, S.E. = 0.094, t = 4.593, p < 0.000). The P value was comparatively large with the t > 2.58. Another statistical finding is that the R2 for CR was 0.704, which was near to the significant variance rate accounted for by SQ. All variables under SQ were discovered to portray SQ build considerably on the basis of Table 3. Compared to other factors in SQ, the outer weights of 0.105 and t = 4.664 for EMP had reached the largest value. This shows that EMP was the most important element in the development of service quality in the context of clothing store brands. In previous studies, the connection between SQ and SV was not always linked with a fresh idea in marketing research. SQ was discovered to be considerably combined with SV (P = 0.876, S.E. = 0.025, t = 35.084, p < 0.000) and R2 value of 0.768 as shown in Figure 1. Therefore, this study's third hypothesis was verified and adopted. SQ variables coded as TAN, REL, RES, ASS and EMP had important features in molding SQ build that caused important connection between SQ and SV which were found to be more fruitful. Finally, the hypothesis of indirect impact predicts that SV will mediate the connection between SQ and CR. In previous research, there has been numerous evidence of the role of SV as mediator between these two factors. SQ has a substantial direct impact on CR with a route coefficient of P = 0.430 250 Tekstilec, 2020, Vol. 63(4), 242-2.55 in the current research. The indirect impact of SV was 0.409 and statistically substantial with t = 5.120 (p < 0.000) after the mediating variable was inserted for regression. The path coefficient P was decreased to 0.021 for direct impact between SQ and CR but still has an important impact as shown in Tablel. Determining the amount of mediation and the outcome shows that SV has a complete mediation impact on the connection between SQ and CR in the next assessment. Therefore, it was verified and approved in the H4 hypothesis. According to Hair [40], the primary assessment criterion of the structural model by PLS-SEM is the R2 measures and to determine the significance level of the path coefficients. The reason is because the objective of the prediction-oriented PLSSEM approach is to explain the variance of endogenous latent variable and reasonably high R2 value should be obtained. A rule of thumb in marketing research studies, R2 values of 0.75, 0.50, or 0.25 for endogenous latent variables in the structural model can be represented as substantial, moderate, or weak, respectively. Accordingly, the obtained R2 value can be used to interpret the quality of the structural model which indicates the explanatory variance by the exogenous variables contained in the endogenous variable. Assessment results it can be explained the R2 was found to be 0.754 for CR, indicating that SQ can account for 75.4% of the variance in the CR, which was substantial level. 3.4 Discussion The finding of all hypotheses validated and verified the complete mediation of service quality and client retention. With the presence of service value as a mediator between service quality and client retention, the value of R2 improved from 70.4% to 75.4% for variance strength explained in client retention. Recognised service value has a complete mediation impact between service quality and customer retention, the size of the indirect impact for service value consequence. In the past, studies on the role of service Table 3: Summary of hypotheses testing results for direct and indirect effect Hypotheses Path P S.E. t-value p-value H1 SV ^ CR 0.467 0.090 5.174 0.000 H2 SQ ^ CR 0.430 0.094 4.593 0.000 H2a ASS ^ CR 0.081 0.018 4.548 0.000 H2b EMP ^ CR 0.105 0.023 4.664 0.000 H2c REL ^ CR 0.099 0.022 4.568 0.000 H2d RES ^ CR 0.082 0.018 4.518 0.000 H2e TAN ^ CR 0.082 0.018 4.578 0.000 H3 SQ ^ SV 0.876 0.025 35.084 0.000 H3a ASS ^ SV 0.166 0.007 23.915 0.000 H3b EMP ^ SV 0.215 0.006 35.250 0.000 H3c REL ^ SV 0.202 0.007 29.801 0.000 H3d RES ^ SV 0.167 0.005 33.285 0.000 H3e TAN ^ SV 0.167 0.005 32.270 0.000 H4 SQ ^ SV ^ CR 0.409 0.080 5.120 0.000 H4a ASS ^ SV ^ CR 0.078 0.015 5.053 0.000 H4b EMP ^ SV ^ CR 0.100 0.020 5.020 0.000 H4c REL ^ SV ^ CR 0.094 0.018 5.123 0.000 H4d RES ^ SV ^ CR 0.078 0.015 5.208 0.000 H4e TAN ^ SV ^ CR 0.078 0.015 5.125 0.000 Note: CR = customer retention; SV = service value; SQ = Service quality; EMP = empathy; REL = reliability; RES = responsiveness; ASS = assurance; TAN = tangible Effect of Service Quality on Service Value and Customer Retention for Clothing Store Brands in China 251 value as a mediator are not a new topic. Numerous studies provided the same results on the impact of service quality mediation such as Kwun [51] in Food Services, Chen et al. [49] in Taiwan Financial Services, [56] in clothing Services, Hume and Mort [30] in Australian Art Performance, Cronin et al. [16] in Service Environments and Brady et al. [38] in Fast Food Services in America and Ecuador. A complete mediation impact between service quality and customer retention in the environment of clothing store brands in China is the most compelling reason for service value because service quality has a powerful direct impact on service value and customer retention. Customers are constantly seeking quality in the services they have engaged in and are always a key component in the delivery of marketing and business services. High service quality establishment will result in high service value [57] and customer retention [31, 58, 59] and attracting another opportunity to increase the picture of an organisation [12, 60], encourages beneficial behaviours such as reuse intention, positive word of mouth referral and allegiance [18]. By comparison, poor quality service leads to the damage of a company's strength owing to adverse reaction, bad word of mouth and low client buyback [9]. In brief, there will be trash in the trash [54]. This research demonstrates that all dimensions of service quality worked intensively together to serve value and retention in the clothing store brands environment. Equally relevant to this research, it was observed that the measurement of quality of service in clothing store brands is better by combining functional and technical factors rather than functional aspects alone as proposed by [20]. As a quality output reaches an acceptable level, after engaging in the service, clothing store brands clients will evaluate the benefit versus disadvantages. Because clients prefer high quality in clothing store brands, perception of value becomes beneficial and minor defects that clients encounter during service consumption are ignored. This is obvious in the current research where quality performance variables in service value continued to achieve the highest effect rating, followed by value and social variables, although several elements of service quality were discovered to be poor. This finding coincided with the research by Cronin et al. [16]. Therefore, it was suggested that clothing store brands operators should concentrate on and promote any initiative to enhance quality in clothing store brands services from the moment to the time to deliver high value to their clients, leading to retention of customers. Possible initiatives such as cashless clothing payments, mini retail outlets or valet services can be regarded for value-added services to increase an excellent experience among clothing store brands customers and should guarantee precious characteristics known to the client. High customer worthiness, after service usage, will make a specific service unique that could enhance company competitiveness through elevated level of retention. This declaration was backed by the current research results where customer-represented service comparison had attained the highest loading in the retention structure compared to other parts. In addition, the results of this research consistent with the research by [16] where they discovered that retention was mainly explained by quality of service and value of service and further conclude that cognitive evaluations precede emotional reactions. Their research also shows that joint attempts are being made to enhance quality, value and retention as a means of refining perceptions of client service. In addition to suggestions, the current research also highlights manager's requirements to decide the correct approaches, embed clear direction among employee and frequent tracking to guarantee excellence in delivering value to their clients [49]. 4 Conclusion The aim of the research is to explore the service quality and service value effect on customer retention to clothing store brands in China. The study's descriptive outcome indicates that there is still a mild level of customer retention on service in clothing store brands. This implies the perception on medium level of service quality and service price of clothing store brands clients. The research framework structural assessment shows that the model has appropriate predictive significance in PLS-SEM technique for the constructs through the blindfolding procedure. Briefly, the findings of the study show the difference in the effect of service quality. The connections between service quality, service value and retention with fairly elevated statistical results were discovered to be important for an immediate impact. This demonstrates that the quality of service and the value of service are efficient variables in the retention of customers. 252 Tekstilec, 2020, Vol. 63(4), 242-2.55 Service value had shown complete mediation impacts in subsequent assessment studies. In short, it has discovered acceptance of four hypotheses developed from the study framework. Thus, the study's research goals were achieved. The research results were discussed and suggested that executives integrate workable approaches in clothing store brands in terms of mixing quality and value of service in order to provide favourable retention reactions among clothing store brands clients. Periodically evaluating customer feedback on services can help service providers improve their clothing store brands service and monitor any changes in behavioural trends that serve as inputs to further improve clothing store brands services. There have been acknowledged several constraints in the study that offer possibilities in future studies. Future studies were proposed to include intentional conduct, real behaviour, other antecedent factors and research model moderator variables. Application of the low and high order construct notion in future research is also proposed. Further validation of the results of the study was promoted through the expansion of sample size, building type, geographic region and other service industries. References 1. CVETKOVSKI, Tatjana, LANGOVIC MILICEVIC, Ana. Intercultural communication and understanding-why and how to attract tourists from China? In TISC-Tourism International Scientific Conference Vrnjacka Banja, 2018, 3(2), 238-256. 2. 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Asia Pacific Business Review, 2009, 5(4), 98-107, doi: 10.1177/097324700900500408. 256 Tekstilec, 2020, Vol. 63(4), 256-262 | DOI: 10.14502/Tekstilec2020.64.256-262 Beti Rogina-Car, Stana Kovačevič, Irena Šabarič University of Zagreb Faculty of Textile Technology, Prilaz baruna Filipoviča 28a, 10000 Zagreb, Croatia Characteristics, Protection and Functional Design of Three-Layer Laminate for Medical Footwear Značilnosti, zaščita in funkcionalna zasnova trislojnega laminata za medicinsko obutev Original scientific article/Izvirniznanstveni članek Received/Prispelo 7-2020 • Accepted/Sprejeto 9-2020 Corresponding author/Korespondenčna avtorica: doc. dr. sc. Irena Šabarič E-mail: irena.sabaric@ttf.hr Phone: +385 1 3712 554 ORCID: 0000-0002-5816-269X Abstract The aim of this paper is to determine the influence of the washing and sterilization process in real hospital conditions on the microbial barrier properties of textile laminate used in medicine for protective clothing. The paper focuses on the functional design of three-layer laminate for medical footwear in surgery and in rooms where aseptic working conditions are required. The permeability and durability of the microbial barrier were determined after 0, 10 and 20 washing and sterilization procedures according to previously developed methods. Bacterial endospores of apathogenic species of the genera Geobacillus stearothermophilus and Bacillus atrophaeus were used. A functional design of the protective shoe cover was proposed. The results showed an extremely effective microbial barrier and the durability of the sample after 0, 10 and 20 washing and sterilization procedures, and over a period of one, two and three months. Keywords: microbial barrier, three-layer laminate, medical footwear, functional design Izvleček Namen članka je bil ugotoviti vpliv pranja in sterilizacije v realnih bolnišničnih razmerah na mikrobiološke barierne lastnosti tekstilnega laminata, ki se uporablja za medicinska zaščitna oblačila. Predstavljena je funkcionalna zasnova trislojnega laminata za medicinsko obutev v operacijskih dvoranah in drugih prostorih z aseptičnimi delovnimi razmerami. Prepustnost in obstojnost mikrobne bariere sta bili določeni po nič, desetih in dvajsetih pranjih in postopkih sterilizacije po predhodno razvitih metodah. Uporabljene so bile nepatogene bakterijske endospore iz rodu Bacillus, Geobacillus stearothermophilus in Bacillus atrophaeus. Predlagana je bila funkcionalna zasnova zaščitnega pokrivala za čevlje. Rezultati po nič, desetih in dvajsetih postopkih pranja in sterilizacije ter v obdobju enega, dveh in treh mesecev odležanja vzorcev so pokazali izjemno učinkovito in obstojno mikrobno bariero. Ključne besede: mikrobna bariera, trislojni laminat, medicinska obutev, funkcionalna zasnova 1 Introduction Textile laminate is a two- or multi-layer textile material that is connected with a polymer layer to form a whole. The substrate on which the polymer layer is applied can be woven, knitted or non-woven fabric. Polyurethane (PU) is a multi-purpose coating polymer used to coat protective clothing [1, 2]. The Characteristics, Protection and Functional Design of Three-Layer Laminate for Medical Footwear 257 laminate properties are a combination of the properties of the base fabric and the polymer layer. The result of such a combination provides many properties that the individual components cannot provide. The substrate or base fabric gives the composite material mechanical strength and carries the coating layer applied to it. High-quality coated fabrics require high-quality base woven and knitted fabrics [1-5]. The polyurethane (PU) polymer layer gives the laminate the property of liquid impermeability and the possibility of water vapour transfer from the body into the environment [6-8]. Due to the comfort of the microporous structure, which allows breathing, and the possibility of passing through the sterilization medium, polyurethane (PU) is an acceptable material for a wide range of medical applications [9, 10]. Medical textiles belong to the group of technical textiles and include all textile products used in medicine, gowns, caps, medical footwear, etc. Conditions of application, i.e. multiple washing and sterilization damage the textile material, which limits its use [11]. In order to meet medical standards, reusable medical textiles must, with regard to the purpose, meet some of the basic conditions, such as being impermeable to microorganisms, being biocompatible, having the possibility of chemical and thermal sterilization, ensuring the stability of shape and dimensions; having the possibility of rational and economical production, etc. [12]. Washing or dry cleaning and sterilization allow their reuse. Reusable medical textiles are more cost-effective on account of cost reduction. How long they are used depends solely on the efficiency of the microbial barrier and mechanical properties where they are needed [13]. The function of medical textiles is often to protect against bacteria and viruses originating from staff and patients. They must be free of toxic ingredients, maintain integrity and durability, and withstand the physical conditions of standard stress during use [2, 12]. Manufacturers do not recommend woven fabrics and knits as an adequate barrier for use in medicine if they are single-layered and without surface treatment because their pores are far larger than microorganisms. However, woven and knitted fabrics are still the most commonly used textile materials for medical purposes [14, 15]. Polyurethane (PU) is one of the specific polymeric materials widely used in various fields and even in medicine for medical synthetic materials and dressings due to its exceptional properties, such as softness, comfort to touch and long-lasting pressure, and balance of mechanical properties, especially when sandwiched between textile fabrics [16]. By selecting the appropriate properties of the components in the layers of the laminate, exceptional properties can be achieved that can satisfy a variety of medical applications. The aim of this research was to determine the influence of washing and sterilization on the permeability and durability of the microbial barrier of a three-layer laminate PES (woven fabric)/PU/PES (knitted fabric) for strong and durable medical footwear. Changes were identified after 0, 10 and 20 washing and sterilization processes under real hospital conditions. The durability or retention time of the microbial barrier of sterilized, diagonally packed laminate packages (EN ISO 11607-1 2009) was determined after storage over a period of one, two and three months under real hospital conditions [17]. The aim of this work was also to create a functional design of a three-layer laminate for medical footwear. 2 Experimental part 2.1 Materials and methods A three-layer textile laminate made of PES/PU/PES and produced at the company Cateks in Cakovec, Croatia (Table 1) was used. The front side of the fabric sample is woven in plain weave, while the back side consists of knitted fabric. There is a polyurethane layer between the woven and the knitted fabric. The samples shall be used for medical purposes. Table 1: Basic parameters of the three-layer PES/PU/PES laminate Sample Composition Structure Mass per unit area (g/m2) Thickness (mm) PES/PU/PES 1st layer 100% PES woven fabric, plain 213.84 0.42 2nd layer 100% PU 3th layer 100% PES knitted fabric, tricot 258 Tekstilec, 2020, Vol. 63(4), 256-262 Figure 1: Surface view of the PES/PU/PES laminate Figure 1 shows the surface of the three-layer PES/PU/ PES laminate from the front and back side. The washing and sterilization procedures were carried out in the specialized laundry unit of the Clinical Hospital Centre Zagreb - Rebro. The sample was washed in a continuous washing machine (JENSEN brand) according to a specially defined procedure (see Table 2) [18]. The sample was sterilized in a Selectomat PL MMM hospital steam sterilizer (Munchener Medizin Mechanik) at 134 °C and at a pressure of 2.5 bar for five minutes. The samples were sterilized after each washing cycle. Table 2: Washing parameters Washing solution 0.7 g/kg Ce; 2.5 g/kg Ca Disinfecting agent 4 g/kg Cc Temperature (°C) 60 Bath ratio 1:5 Commercial names of all products are not given due to the confidentiality of the participating laundry and the impartiality of the research. Ca - polycarboxylate (< 5%), sodium hydroxide (10-20%). Cc - ethoxylated fat alcohol < C15 & < 5 EO (25-30%), solvent, 2-propanol, methanol (0.1-0.25%), amphoteric surfactants (1-2%), additives (0.1-0.25%). Ce -formic acid (50-100%). 2.2 Microbial barrier properties Samples are packed in sterilization packages and sterilized at 134 °C for five minutes (number of the samples: 18). Microorganisms are then applied to the samples under aseptic conditions by rubbing on the sample surface. The application of microorganisms is followed by incubation for 24 hours. After incubation, prints are taken with a CT3P agar plate. First from the back side, then from the front side. A 72hour incubation at 35 °C is then performed, followed by the counting of bacterial colonies (CFU) [19]. Figure 2 shows a schematic representation of the testing of microbial barrier properties. The bacterial spores of the genus Geobacillus stea-rothermophilus and Bacillus atrophaeus were used as the only dry-type microorganisms. The use of a suspension moistens the fabric and the permeability is altered [18]. 2.3 Microbial barrier durability testing The tested samples (22 cm x 22 cm) were packed in packages after 10 and 20 washing cycles (Package number: 60). Gauze was packed into each package, under which absorbent paper "Whatmann No. 1" of 1 cm2 was placed. The packed packages were sterilized (134 °C for five minutes) and placed in a protected Figure 2: Microbial barrier properties testing Characteristics, Protection and Functional Design of Three-Layer Laminate for Medical Footwear 259 warehouse with a temperature of 15-30 °C and a relative humidity of 30-60%. The storage time of the packages was one, two and three months. After the specified time, the packages were removed from the warehouse and unwrapped under sterile conditions. Using sing tweezers, the absorbent paper was removed from the package and placed in a test tube with a Brain-Heart broth. After incubation for 48 hours at a temperature of 35 °C, a change in the visually clarity of the broth was observed, i.e. whether turbidity has occurred. The sterility was additionally checked by fitting on a solid nutrient basis, while 5 ml of Brain-Heart broth was planted on an agar containing 5% sheep blood. After 48 hours of incubation at 35 °C, the number of bacterial colonies was observed [19]. 3 Results and discussion Due to the washing and sterilization procedures, a three-layer textile PES/PU/PES laminate shrinks. This, in turn, results in an increase in fabric thickness. A change in mass per unit area and thickness was determined according to the relevant standard and is shown in Table 3 [20, 21]. Table 4 shows the number of microorganisms on the front and the number of microorganisms passed through to the back. The number of microorganisms on the surface represents the number of microorganisms remaining on the surface of the sample after bacterial endospores of pathogenic species of the ge- nus Geobacillus stearothermophilus 105 and Bacillus atrophaeus 106 were rubbed with a stick. In the PES/PU/PES sample, there was a 3.8-fold increase in the number of microorganisms absorbed on the surface (283 CFU) compared to the initial values (74 CFU). However, despite the growth of microorganisms on the front of the sample, there was no leaking of microorganisms on to the back. It can be concluded that the increase in retained microorganisms on the surface layer is due to the rough surface after 20 washing and sterilization cycles. One of the reasons for the impermeability of the microbial barrier is the polyurethane layer present in the sample. The rougher surface has the ability to retain a larger number of microorganisms, which is evident from the results obtained (see Table 4). The durability of the microbial barrier was determined using the method of sterilized diagonally packed packages (one layer; EN ISO 11607-1: 2009) after storage for one, two and three months. The results of the testing of the durability and efficiency of the microbial barrier over one, two and three months after a series of 10 and 20 washing and sterilization procedures are presented in Table 5. The testing results of the durability of the microbial barrier over a period of one, two and three months show a satisfactory durability of the microbial barrier of the textile laminate. There was no contamination of the contents of the package. The impermeable microbial barrier is very important for use in medicine and other sterile areas. Table 3: Results of the design parameters of the three-layer laminate Sample Washing and sterilization cycles Mass per unit area Thickness Mean (g/m2) SDa) (g/m2) CVb) (%) Mean (mm) SDa) (mm) CVb) (%) PES/PU/PES 0 213.84 2.43 1.14 0.42 0.01 1.76 10 217.44 1.56 0.72 0.45 0.01 3.17 20 214.12 2.47 1.16 0.44 0.01 1.29 a) standard deviation;b) coefficient variation Table 4: Microbial barrier test results Sample Number of isolates Washing and sterilization cycles The average number of bacterial colonies on the front side (CFU) The average number of bacterial colonies on the back side (CFU) 6 0 74 0 PES/PU/PES 6 10 240 0 6 20 283 0 260 Tekstilec, 2020, Vol. 63(4), 242-2.55 Table 5: Results of microbial barrier durability testing after one, two and three months, and after 10 and 20 washing and sterilization procedures Sample Washing and sterilization cycles Testing after (months) 1 2 3 PES/PU/PES 10 NMRa) NMR NMR 20 NMR NMR NMR a) no growth in microorganisms in the package Figure 3: Functional design of three-layer laminate for medical footwear Figure 3 shows the functional design of a three-layer laminate for medical footwear. The design was created so that it is easy to put it on and take off, and the aesthetic component as added value was not neglected. The models shown in Figure 3 are more demanding to produce than ordinary disposable covers. They have a tread to which the upper part of the cover is sewn, which is larger than the foot or shoe. To adhere better to the foot, they are fitted with Velcro strap so that they can be worn over shoes or on bare foot, as can be seen in the examples. Three design solutions of a three-layer laminate cover to be used for microbial protection are proposed in Figure 3. Proposal a) can be easily pulled on and adjusted with the Velcro strap on the heel, while the excess material is folded forward, then covered with an accessory and secured with the Velcro strap. In example b), the heel is adjusted in the same way as in the previous model and the Velcro strap is fastened at the front to stand firmly around the foot. Similar to slippers, the model in example c) is only fixed on the side in the middle where the front and back are joined. In this way, it is more flexible and, as shown, can be easily adjusted and tightened with the Velcro strap. The proposed design is somewhat more expensive and demanding to produce, but since it is not a disposable product, it would be worthwhile to invest a little more at first. The models presented can be adapted according to needs and requirements, and it is proposed to produce them in two sizes to improve fit and therefore protection. This is also a good example of sustainabil-ity and environmental protection, as reusable covers also reduce waste, which is another added value. 4 Conclusion This paper investigates the efficiency of the microbial barrier of textile PES/PU/PES laminate with respect to washing stability and the sterilization process. Bacterial spores of the genus Geobacillus stearothermophilus and Bacillus atrophaeus were used. The durability of the microbial barrier over a period of one, two and three months after 10 and 20 washing and sterilization procedures was determined for a three-layer textile laminate. The results showed that the sample had an effective microbial barrier through 20 washing and sterilization procedures. The durability of the microbial barrier tested over three months also showed that there was no penetration of microorganisms to the inside of the sterilized packaging. From this it can be concluded that the sample has an extremely effective microbial barrier and its durability is guaranteed after 10 and 20 Characteristics, Protection and Functional Design of Three-Layer Laminate for Medical Footwear 261 washing and sterilization procedures, and after storage under strictly controlled conditions for a period of one, two and three months. The PU membrane between two polyester layers in the laminate has a major influence on this impermeable barrier. The value of retained microorganisms on the surface of the three-layer PES/PU/PES laminate was 3.8 times higher than the initial value. The process of washing and sterilizing samples often leads to their permanent shrinkage, and these changes cause a linear increase in mass and thickness. A functional design of a three-layer laminate for medical footwear with emphasis on flexibility, practicality and wearing comfort was proposed. All three proposals meet both the functional and aesthetic value. References 1. FUNG, Walter. Coated and laminated textiles. Boca Raton : CRC Press, 2002, p. 1. 2. SCOTT, Richard A. Textiles for protection. Cambridge : Woodhead Publishing, 2005, p. 117. 3. SHISHOO, Roshan. Textiles for sports. Cambridge : Woodhead Publishing, 2005, p. 17. 4. DEMBICKY, J., JAIN, S., CHARAYA, V. Characteristics of coating process. Vlakna a Textil (Fibres and Textiles), 2008, 15(1), 19-27. 5. SEN, Ashish Kumar. Coated textiles: principles and applications. 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Tekstilec, 2020, Vol. 63(4), 263-275 | DOI: 10.14502/Tekstilec2020.64.263-275 2 63 Yetanawork Teyeme'-2, Benny Malengier', Tamrat Tesfaye2, Simona Vasile3, Lieva Van Langenhove' ' Ghent University, Faculty of Engineering and Architecture, Department of Materials, Textiles and Chemical Engineering, Technologiepark 907, 9052 Zwijnaarde (UGent), Belgium 2 Bahir Dar University, Ethiopian Institute of Textile and Fashion Technology, Haile Silase Rode, 6000 Bahir Dar, Ethiopia 3 Fashion and Textiles Innovation Lab+, HOGENT University of Applied Sciences and Arts, Buchtenstraat'', 905' Ghent Belgium Comfort Evaluation of Cyclists Jerseys Using Wear Trial Test Vrednotenje udobnosti kolesarskih dresov s testom poskusnega nošenja Short scientific article/Kratki znanstveni prispevek Received/Prispelo 5-2020 • Accepted/Sprejeto '0-2020 Corresponding author/Korespondenčna avtorica: Yetanawork Teyeme E-mail: YetanaworkWubneh.Teyeme@UGent.be ORCID: 0000-0003-1530-3613 Abstract The aim of this study was to evaluate the wear comfort of four commercially available cycling outfits and understand various subjective parameters of garments through consumer perception, which will enable the design and development of an optimized outfit. A questionnaire was developed specifically to address various key aspects such as tactile sensation, garment fit with reference to size, garment assembly, garment aesthetics (style and shape), comfort (before, during and after wearing) and overall satisfaction (relating to design of the garment and style). Three outfits were fabricated from polyester fabric and one from polyamide/elastane (80%/20%) fabric. They were assessed by four male professional cyclists (age 22-25) at various stages of a test protocol of 45 minutes total duration, of which 20 minutes was flat cycling. The four tested garments showed greater differences between the sensorial comfort perceptions than thermophysiological comfort. The sensorial comfort sensation was found to be mainly correlated with fabric properties, fit, construction techniques and moisture sensation, whereas the thermophysiological comfort was found to be affected by the fabric characteristics, the test environment conditions and level of activity. Additionally, manual measurements showed great brand-based differences between garments of the same specified size M (medium). Overall, the polyamide/elastane jersey was perceived as a better cycling outfit than the polyester outfit. The results of this study provide guidance for the optimal design and development of professional cyclist outfits. Keywords: cycling garment, sensorial comfort, thermophysiological comfort, subjective wear trial Izvleček Cilj raziskave je oceniti udobnost nošenja štirih tržno dostopnih kolesarskih oblačil in razumevanje različnih subjektivnih parametrov zaznavanja oblačil potrošnikov pri uporabi, kar bo omogočilo oblikovanje in razvoj optimiziranega oblačila. Izdelan je bil poseben vprašalnik za obravnavo različnih ključnih vidikov, kot so občutek otipa, prileganje oblačila glede na velikost, sestavljanje oblačila, estetika oblačila (slog, oblika), udobje pred, med in po nošenju ter splošno zadovoljstvo, povezano z dizajnom oblačila in slogom. Tri obleke so bile izdelane iz poliestrske tkanine, ena pa iz mešanice poliamida in elastana (80 %/20 %). Ocenili so jih štirje moški poklicni kolesarji (stari od 22 do 25 let) v različnih fazah testnega proto- 264 Tekstilec, 2020, Vol. 63(4), 242-2.55 kola, kije skupaj trajal 45 minut, od tega je bilo 20 minut kolesarjenja po ravnem. Štiri preizkušena oblačila so pokazala večje razlike v otipu kot v toplotnofiziološkem udobju. Ugotovljenoje bilo, daje čutno udobje v glavnem odvisno od lastnosti tkanine, prileganja oblačila, konstrukcijskih rešitev in občutenja vlage, medtem ko na toplotnofiziološko udobje poleg značilnosti tkanine vplivajo razmere v preskusnem okolju in stopnja aktivnosti. Poleg tega so meritve pokazale velike razlike v dimenzijah med oblačili različnih blagovnih znamk, a enake velikosti M (srednje). Na splošno je bil za kolesarje bolje ocenjen dres iz mešanice poliamid/elastana kot dres iz poliestra. Rezultati te študije dajejo smernice za optimalno zasnovo in razvoj dresa za poklicne kolesarje. Ključne besede: kolesarsko oblačilo, senzorično udobje, toplotnofiziološko udobje, subjektivno poskusno nošenje 1 Introduction Clothing comfort is an essential aspect of users' performance and is taken into consideration as a quality characteristic while choosing a particular garment [1]. Clothing comfort is, however, an extremely complex subject and is the result of many interactions between physical, psychological, and physiological factors [2-4]. Sports apparel not only requires comfort, but also functionality. At the same time, these garments must have excellent thermophysiological properties adapted to a particular sport discipline [5]. Thermophysiological comfort, also referred to as thermal comfort, is crucially important for sportswear worn next to skin, where rapid heat transfer, moisture vapor and liquid moisture transfer from skin to the outer fabric surface is required [2]. These factors are influenced by the thermophysiological conditions of the human body [6-8]. Cycling is one of the most popular sports and can be performed in many different weather conditions. Therefore, the expectations that cyclists have in terms of the comfort of athletic apparel have increased. Clothing comfort includes all the comfort sensations produced by a garment [1, 9, 10]. Many studies have been conducted in relation to cycling clothing, in particular taking into consideration ergonomic issues and the effect of compression on performance and recovery [11-13]. Other fields of research cover injury reduction [14, 15], the design of cycling clothing [16, 17], and aerodynamic behaviour and various other aspects of comfort [18-23]. However, previous studies showed that cycling apparel requires further investigation. Comfort can be a psychological state, a physical sensation or both simultaneously [24]. Most importantly, the development of clothing should consider the anatomical features of individuals (anthropometric data), and biomechanical and functional features (skills and physical limitations while performing occupational or sport activities) [25]and hence tend to be complex and iterative. These factors can overlap and correlate significantly with the subjective evaluation performed and provided by users, especially regarding usability, wearability and safety. Clothing designed specifically for certain functionalities (i.e. a cycling garment worn next to the skin) has been shown to cause heat stress, and reduce the task efficiency as well as the range-of-motion of the wearer [26]. The process of design therefore begins by first establishing the many requirements of the user. An extra concern for cyclists is low back pain, the most prevalent injury and a problem for their health [26-29], and several garments have been developed to assist with fatigue and improve motor function. However, athlete compliance is likely to be affected due to the discomfort and inconvenience of these garments. A wear trial deploying various evaluation techniques was set up to investigate the functional and comfort requirements of users. The findings of comfort need and the effects of various garment attributes from different wear trials will provide insight into the design and development of proper garment criteria that are required to satisfy an athlete's critical ergonomic needs, and acting upon these insights will eventually improve their performance. The purpose of this study was to quantify the wearers' perceived comfort responses to existing cycling garments in order to identify the influential garment attributes. 2 Materials and methods 2.1 Materials 2.1.1 Test garments In this study, four commercially available cyclist outfit garments were obtained from A.S. Adventure Ghent, Belgium. All samples were short-sleeved, medium size T-shirts/jerseys. The selected garments were differentiated by fabric composition and structure as shown in Table 1. Comfort Evaluation of Cyclists Jerseys Using Wear Trial Test 265 Table 1: Fabric composition and structural parameters of selected garments A-D Garment code Fibre composition Garment size Fabric structure Courses (cm) Wales (cm) Thickness (mm) Air permeability (mm/s) A 100% PESa) Md) 1x1 rib 20 19 0.40 929.5 B 100% PES M Interlock with 1x1 rib 25 18 0.44 1,515.0 C 80% PAb)/20%ELc) M 1x1 rib 24 16 0.53 1,150.0 D 100% PES M 1x1 rib with 3D knitted 20 16 0.69 1,262.5 a>polyester; b>polyamide; c> elastane; d> medium 2.1.2 Test subjects Four male professional cyclists aged between 22 and 25 years from Bahir Dar, Ethiopia were selected to participate as human subjects in the wear trial test of the study. All subjects were healthy volunteers who exercised regularly. Each subject was given one experimental garment over a given time span. The participants were informed beforehand about the scope of the test, procedure and risks [31, 32]. Informed consent was signed by all subjects, but they were not informed about the details of the clothing materials in order to avoid any influence on their subjective ratings. However, subjects were invited to have a pre-trial before formal trials to determine their individual cycling intensity and understanding of the questions and the procedures involved. 2.2 Methods 2.2.1 Fabric characterization Fabric analysis was performed on the four different styles of purchased jerseys, including fibre compositions, knit structure, stitch density, thickness and air permeability. The thickness of the fabrics was measured according to ASTM D1777 using a MESDANLAB Digital thickness tester. The air permeability properties of the fabrics were measured using an FX 3300 air permeability tester according to the ISO 9237 standard with a 100 Pa air pressure difference and a 20 mm2 test area. 2.2.2 Garment design and size measurement comparison Garment design: To determine the recommended fit, the sizing charts provided by each retailer were taken from the relevant websites [33-37]. These charts stated the recommended size of the wearer at the chest for a small, medium and large size sample. These were observed further to assess the significance of the measurements recorded and garment assembling for the selected samples. Garment size measurements: Each sample was measured to highlight differences in garment size and shape, according to the four brands A, B, C and D. 2.3 Wear trials 2.3.1 Subjective assessment of comfort A variety of methods is typically applied to assess comfort in trials. Some studies use a combination of methods, including one or more questionnaire items. Likert-type rating scales and numeric rating scales have been used [38, 39]. Of these scales, some were oriented to assess "comfort" and "discomfort", while some were bipolar [13, 14, 19, 37]. In this study, Likert rating scales with different scales were used to assess the subjective perception of the subject. Likert scaling is a unidimensional scaling method useful when measuring latent constructs, i.e. the characteristics of people, such as attitudes, feelings and opinions. 2.3.2 Environmental conditions and test protocol To gather data about parameters affecting the thermal comfort status of the test persons, temperature, wind speed and relative humidity measurements were recorded objectively (Table 2). The measurements were carried out using the mobile app Live weather forecast widget, which provides daily weather forecasting. All tests in the scope of wear trials were conducted in actual working field environments from 6 am to 9 am, when the sun is still very low, in order to limit the effect of solar radiation. The experimental protocol was approved by Bahir Dar University, Ethiopian Institute of Textile and Fashion Technology Institutional Review Board (IRB) (10th November 2018). Test subjects followed an exercise protocol consisting of four activities for 45 minutes: the subjects first wore the T-shirt and then they rested with it for 5 minutes in the test environment prior to the conducting of the next test. The subjects then warmed up by doing stretching for 10 minutes according to their normal 266 Tekstilec, 2020, Vol. 63(4), 242-2.55 Table 2: Environmental conditions during the field trial Test day Outside temperature (°C) Relative air humidity (%) Wind speed (km/h) Avg. cycling speed (km/h) 1st 17 74 1.1 27.8 2nd 16 96 0 25.4 3rd 10 48 1.8 29 4th 10 48 0 29.5 stretching routine. Next, the subjects started cycling trials consisting of a 20 minutes flat ride, followed by cooling down (recovery) for 10 minutes (see Figure 1). 2.3.3 Response and validation We used the rating system described by Wong et al. [41, 42] and a specially designed questionnaire, as well as an assessment scale defined by ISO 10551:2004 [43] and ISO 7730:2005 [44]. At the end of each trial phase, each participant was asked about their psychological state and thermophysiological comfort, and this was recorded by rating thermal comfort and sensations, such as moisture perception, thermal sensation, and overall physiological and psychological comfort during the cycling period. The first evaluation was made during the initial touch of the fabric, during the first minute when the subjects handled and wore the garment. During exercise, subjective ratings of comfort and discomfort of the T-shirts, broadly relating to thermal and tactile experience, were recorded. The subjects were instructed at each questioning to concentrate on the area of their upper bodies. The explanation of and judgment between the various sensations and the rating scale were discussed with subjects in advance of the experiments. After each trial, the subjects were asked to compare the overall comfort of the four tested T-shirts they had worn for the trial and restate their preference. The rating scales are shown in Table 3. Subjects wear the test garments prior to testing for 5 minutes Warms up for 10 minutes Cycling trials/test doing for 20 minutes Cool down (recovery) 10 minutes Figure 1: Flow diagram of exercise protocol Table 3: Rating scales Comfort Evaluation criteria Scale Remark Psychological Clothing size fit 5-point scale 1 (too loose) ... 5 (tight fit) Stretchiness 9-point scale 1 (very stretchable) ... 9 (non-stretchy) Overall garment look 9-point scale 1 (like very much) ... 9 (dislike) Thermal Skin sweat sensation 5-point scale 1 (neutral) ... 5 (extremely wet) Skin temperature sensation 7-point scale 1 (cold) ... 7 (hot) Sensorial Stiffness and sticky sensation against the skin 9-point scale 1 (not at all) ... 9 (extremely strong) Ergonomic Easy of body movements while cycling with ensemble 5-point scale 1 (very stiff) ... 5 (very flexible) Level of ease in performing duties 7-point scale 1 (very easy) ... 7 (very difficult) Degree of comfort 9-point scale 1 (extremely uncomfortable) ... 9 (extremely comfortable) Overall fit of ensemble for the purpose 7-point scale 1 (very poorly) ... 7 (very well) Comfort Evaluation of Cyclists Jerseys Using Wear Trial Test 267 2.3.4 Statistical analysis IBM SPSS 21 statistics and Microsoft Excel software were used to analyse the results. Coefficient of variation and mean were used to quantify the variation of various subjective, physiological and objective comfort parameters. 3 Results and discussion 3.1 Fabric characterization All fibre compositions were taken directly from the care label. Samples, A, B and D were made of polyester and sample C was made of a combination of polyamide and elastane. Polyamide is a strong fibre that has excellent elastic recovery behaviour after stretching [45]. These properties are very important and crucial for (compression) sportswear garments due to the frequent strain on the fabric during use (wearing and washing). Polyester, on the other hand, is characterized by maintaining the stability of its structure, and offering excellent heat resistance and good moisture transport properties. It does not easily extend and has a low cost [46]. However, in the case of garments that require stretching, nylon is better than polyester, while polyester is favoured over nylon for maintaining stability. Fabric thickness, air permeability, structure and stich density of fabrics A-D are presented in Table 1. Fabric (A) has the lowest air permeability value (929.5 mm/s) but is the thinnest fabric. Air permeability varied significantly between fabric A and fabric B (1,515 mm/s), with thicknesses of 0.44 mm and 0.40 mm and different structures, respectively. Fabrics A and C contained different compositions of 100% PES (fabric A) and 80% PA/20% EL (fabric C), with a 1x1 rib structure. The 1x1 rib with 3D knitted sample D was the thickest (0.69 mm) and demonstrated lower air permeability than fabric B and a lower fabric density than samples A, B and C. 3.2 Garment design and size measurement comparison Design detail and size measurements were compared for the four brands of test garment purchased. There were variations in the design in each type. Detailed features of each garment sample are shown in the Figure 2. 268 Tekstilec, 2020, Vol. 63(4), 242-2.55 3.2.1 Garment size measurements samples were measured and Table 4 details the manu-Each sample was measured to highlight differences in al measurements (cm) taken for the four samples. The garment size and shape, according to the four brands measurements listed show variations between ready A, B, C and D. Figure 3 shows the points at which the to wear samples of the same size (medium). Figure 3: Measurement points of sample garments: a) A, D; b) B, C Table 4: Measurements variation of garment samples A, B, C, D Serial number Measurement point A (cm) B (cm) C (cm) D (cm) Mean ± SDa) (cm) CVb) (%) 1 Full length front 63.5 63.5 59.5 63 62.4 ± 1.9 3.10 2 Centre front length 54 54 52 53 53.3 ± 1 1.80 3 Back full length 76.5 71 70 77.5 73.8 ± 3.8 5.15 4 Centre back length 72.5 68 66 73.5 70.0 ± 3.6 5.12 5 Side seam length 45 46 43 46 45.0 ± 1.4 3.14 6 Across chest (seam to seam) front 46 49 45 48 47.0 ± 1.8 3.88 7 Collar stand length 41 42 40 47 42.5 ± 3.1 7.32 8 Collar stand width (neck circumference) 4 3 4 4 3.8 ± 0.5 13.33 9 Sleeve length 24 23.5 35 35 29.4 ± 6.5 22.12 10 Shoulder length 12.5 13.5 14 9 12.3 ± 2.3 18.41 11 Across back 42 42 40.5 47 42.9 ± 2.8 6.62 12 Cuff length straight (1/2) 14.5 13.5 11 14 13.3 ± 1.6 11.73 13 Waist length front 46 44 40 44 43.5 ± 2.5 5.79 a) standard deviation;b) coefficient of variation Comfort Evaluation of Cyclists Jerseys Using Wear Trial Test 269 This variations in the measures of the different brands for what should nominally be the same medium size are remarkable. The size seems to be derived from the same recommended chest size and waist size (centre front length has a CV of 1.8%, full front a CV of 3.1% and across chest a CV of 3.88%). The large CV for other measures (for example CV of 11.73% for cuff length) is thought to affect the fit of the garment. In particular, the chest size measure affects the pressure distributed by the garments when worn, especially if the wearer of the garment is towards the upper limit of the suggested size measurement. These variations in measurement between the sample garments illustrate the need for more detailed sizing recommendations for users to ensure correct fit and consequently sufficient compression. It is also believed that these variations in grading could affect the pressure distributed across sizes. It must be taken into consideration that only one medium size sample was measured per brand. This helps to highlight the differences between garments when consumers purchase them. Generally, it should be noted that while significant differences in grading were highlighted by these measurements, only one sample of one size was examined. Therefore, some of the measurements taken may be unrepresentative as a whole and the result of mistakes in production. The relationship between the size of the garments and the fibre content will again be of interest when looking at the pressure distribution of the samples. Where the samples have the same recommended torso size but show varying chest measurements, the effect of this on the compression will also be highly interesting. Therefore, further research to investigate these differences in grading on a much larger number of samples may be helpful. 3.3 Subjective assessment of comfort perception during cycling 3.3.1 Psychological responses Subjects were required to assess the overall look, stretchiness and clothing fit by handling and putting the garments on respectively.This was their initial preference of the sample before starting the exercise. Out of the four samples tested (Figure 4), assessments of the perceived stretchability/non-stretchability property of the garments generally fell in the "neutral" category (4-5) for sample C, B and D. In fact, these three samples are not similar by fabric type (such as fabric structure, fibre composition and thickness), as shown in Table 1. Therefore, the assessment of stretchy/non-stretchy did not differ significantly by structure, fibre composition or thickness, and provides evidence that the perception of garment stretchability is not affected solely by fabric type. 8 A B C D Test garments Figure 4: Average value of stretchiness, 9-point scale: 1 (very stretchable) ... 9 (non-stretchy) In addition, for sample A, the fabric stretchability was rated "moderately non-stretchy", while it was rated as "loose" in terms of tightness/looseness of the garment fit to the body. This agrees with garment size measurements (Table 4), which are above the average for almost all measurement points considered. Similarly, the same "loose" fit assessment was given to garment D, while garments B and C were rated as "normal/moderate" (Figure 5). The fabrics of these garments were different in terms of composition and 5 IE V N 4 .2 I 3 llll A B C D Test garments Figure 5: Average value of clothing size fit, 5-point scale: 1 (too loose) ... 5 (tightfit) 270 Tekstilec, 2020, Vol. 63(4), 242-2.55 other properties (Table 1), and it is therefore unlikely that this minor difference in fit could have contributed to greater discomfort during wear. The results further indicated that garment C constructed from polyamide and elastane material (Table 1) is liked more than the other samples (Figure 6). We concluded from the pre-test ratings of the psychological responses "clothing size fit", "stretchiness" and "overall look" that the polyamide-elastane garment C was more accepted than the polyester garments A and D, and slightly more accepted than garment B, which coincides with the slightly better fit of garment C than garment B, while garments A and D were on the loose side. Garment B was, however, considered more stretchy than garment C, so a good fit and adequate stretching contribute to better acceptance. Thus, the difference between the garments observed on these subjective dimensions under pre-test conditions may be due to the characteristics of the fabrics from which the garments were constructed, as well as the design, assembly and overall appearance/look of the ensemble. 8 A B C D Test garments Figure 6: Overall look: how well the garment is liked/ disliked, 9-point scale: 1 (well liked) ... 9 (disliked) Thermal transmission is thought to be one of the most important factors affecting clothing comfort [47, 48]. The thermal insulation of clothing is affected by many physical factors, such as fabric thickness, the amount of body surface area covered by the garment, garment design (looseness and tightness) and number of fabric layers [46]. The subjective measurements were collected during field trials during the warmup and cycling immediately after recovery stages. The test data was split and grouped over the first two days 1 and 2 and last two cold/dry days (Table 2) in order to show whether the environment influences the results or not. All clothing trials were performed in the actual working field environment (cold and warm) at an average temperature of between 10 °C and 16.5 °C, a relative humidity of between 48% and 85%, and a wind speed of 0.9 and 0.6 km/h, respectively. The average age, height and weight of the subjects were 22.8 ± 1.0 years, 173.8 ± 10.7 cm and 61.6 ± 4.5 kg, respectively as described in Table 1. Each subject tested all four of the garments on separate occasions. Thermal-sweat sensation: Professional cyclists train much more intensively, and the wetness level and expectations are therefore completely different for recreational cyclists. Physiological effects during different activity levels (such as seated, exercising and recovery condition) of the test were mostly related to moisture properties (Figures 7-9). The different garment fabrics did have effects on thermal perception and comfort, as well as on the moisture related perceptions of the wearer. The various subjective thermal-wet sensations changed in different ways during exercise under different climatic condition. Figures 7 and 8 illustrate the results. Most of the garment-related moisture sensation increased significantly with activity (Figure 7), but the warm skin temperature sensation (Figure 8) showed a decreasing trend over time in the start/recovery stage. In general, we see from the mean skin temperature of the test subjects while wearing the test 5 o 4 re u « c 3 Î 2 w 0 A B C D Test garments ■ 5' (pre test) ■ 15' (warm up for 10') ■ 25' (after 10' cycling) «35' (after 20' cycling) 45' (after 10' recovery) Figure 7: Average skin sweat sensation of test subjects while wearing analysed test garments under different activity level, 5-pointscale: 1 (neutral)... 5 (extremely wet) Comfort Evaluation of Cyclists Jerseys Using Wear Trial Test 271 a) b) Figure 8: Mean skin temperature sensation of test subjects while wearing analysed sample test garments under different activity level: a) in cold and b) in warm climatic conditions; 7-point scale: 1 (cold) ... 7 (hot) ïs 4 3 .E 1 0 A B C D Test garments ■ 5' (pre test) ■ 15' (warm up for 10') 25' (after 10' cycling) 35' (after 20' cycling) 45' (after 10' recovery) 7 6 5 2 garments in the warm and cold climatic conditions (Figure 8 a-b) that garment B resulted in greater perception of heat in both conditions, and garment A resulted in greater perception of skin wetness than garment B, but less in heat sensation in cold conditions after 20 minutes of cycling. The subjects had similar neutral skin temperature sensation while wearing garments C and D in cold conditions (Figure 8 a) and they indicated less skin wetness after 20 minutes of cycling while wearing garment D than while wearing garment A (Figure 7). From these results, we can also deduce that the loose garments A and D result in lower skin temperature sensation in hot conditions during recovery, with the loosest garment D resulting in the lowest skin temperature perception overall in warm conditions. However, for aerodynamic reasons, cyclists want to avoid loose garments. Among the good fitting garments B and C, garment C demonstrated the best temperature properties (i.e. lowest skin temperature sensation in warm conditions), but a higher sweat sensation rating after 20 minutes of cycling than garment B. This showed that the polyester garment B had a lower moisture uptake from the skin than the pol-yamide/elastane fabric C. It is important to note that even during the warmup, garment A was perceived as cold in cold conditions, while this was the case for garment D in warm conditions, demonstrating that a looser fit results in more training activity required to warm up. Considering the deviation from the neutral 4 scale in skin temperature sensation during the warmup and cycling phases, garment C performs best in cold conditions (Figure 8a), followed by garment D. Sensorial comfort: With regard to skin contact attributes in terms of the perceived sticky sensation of the skin, garment A and B were assessed as moderately sticky, one score higher than C, and two scores above the loosest garment D (i.e. where less fabric comes into contact with the skin) as shown in Figure 10. Not much variation was identified between the garments in terms of stiffness, with all recording a score close to the value of 4, meaning all give a moderately stiff touch sensation. Ergonomic comfort: Considering the degree of comfort, garment B rated as neutral (score of 5) whereas garment C was rated as very comfortable (score of 8) and was also perceived as normal (score of 3) for ease of body movements while cycling (Figure 9) and making it easier (score of 2) to perform duties. To a lesser extent, the less stiff garment B (Figure 10) was also perceived as somewhat easy for performing duties (score of 3). When we compared overall fit for the purpose of the garment, garment D was assessed as fitting poorly for the desired purpose (score of 2) and difficult to perform the task (score of 4). These differences in the skin feel sensations of the garments, combined with the perceived pre-test differences among the garments for "feel" and "comfort" 272 Tekstilec, 2020, Vol. 63(4), 242-2.55 Figure 9: Average value of ease of body movements while cycling with ensemble, 5-point scale: 1 (very stiff) ... 5 (very flexible) was made during a pre-test questionnaire in which the subjects generally expressed the most favourable opinion regarding the 80/20 polyamide/elastane fabric (C) and the least favourable opinion regarding the 100% polyester fabric (D) with respect to fabric-skin contact sensation. This pre-test also ensured that all garments, regardless of the fabric from which they were constructed, fit the participants equally well in various body areas. Adapting the polyester garment construction in such a way that it has a good stretch-ability and can thus be made to fit tighter (garment B) is highly preferred by the cyclists over the other polyester fabrics (A and D), but nevertheless remains less preferred than the polyamide garment, with a higher stickiness, lower fit and higher skin temperature sensation. Though the sweat perception of fabric B was better (lower) than fabric C after 20 minutes of cycling, this brings less weight for cyclists who expect a certain level of sweat during sport [30]. A B C D Test garments ■ Average stickness value Average stiffness value Figure 10: Average stickiness and stiffness sensation against the skin for the duration of whole activity phase, 9-point scale: 1 (not at all) ... 9 (extremely strong) suggest that the tactile characteristics of the fabrics contributed, along with the moisture and thermal sensations, to the overall assessment of the comfort of the garments during the study. The overall findings for the comparative comfort of the garments were consistent with the expected response that the considered polyamide/elastane fabric (C) tends to be more comfortable, with excellent elasticity and recovery behaviour, while polyester fabrics A-B-D are more likely to produce discomfort. This assumption 4 Conclusion Significant brand-based differences between garments of the same specified size M were observed and overall, the polyamide/elastane jersey was perceived as the best. The results suggest that thermal and moisture sensations of different T-shirts primarily relate to the different physiological state of subjects (i.e. perception of skin temperature and wetness). On the other hand, tactile sensations were found to differ between the subjects wearing different jersey, whilst differences in these sensations did not change over time (exercise), nor show any significant difference between warm and cold conditions. It therefore seems that the tactile and fit sensations were mainly determined by fabric-skin-contact, not by the environmental conditions or exercise. This suggests that the overall preferences of the subjects for clothing worn next to the skin, in both thermal conditions of these trials, were mainly determined by the tactile and fit sensations and not by the thermal-wet sensations. The result shows that sensations of comfort-discomfort in clothing worn next to the skin can be influenced by several factors, including the environment and the physiological state of the wearers, as well as the type of fibre used in manufacturing the fabrics and garment fit. The interaction between the factors is also important, and overall acceptability of a garment is not easily predicted by simple handling tests. The cyclists do seem to prefer Comfort Evaluation of Cyclists Jerseys Using Wear Trial Test 273 tight fitting garments with enough stretch. 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E-mail: smykalo.kateryna@kntu.net.ua Phone: +38 050 3962372 ORCID: 0000-0002-9670-6563 Abstract Designing the colour appearance of textiles requires taking into account their surface properties, hairiness among others. The villi protruding on the surface not only affect the quality of textile dyeing, but also largely determine its optical properties and the colour phenomenon. The analysis of studies of optical properties shows that the influence of hairiness on the phenomenon of colour is not well understood and that the amount of hairiness at which colour changes become significant for human perception remains indefinable. In this work, we studied the change in colour characteristics depending on the change in the hairiness of woollen fabrics, comparing "yarn - raw fabric", "yarn - raised fabric", "raw fabric - raised fabric". Hairiness was estimated by the hairiness index, which was obtained from the analysis of sample microphotographs of yarn and fabric using software. The value of colour characteristics (lightness, chroma and colour difference) was measured in the CIELAB colour space (1976) using a spectrophotometer. The obtained experimental results showed that the changes in lightness and saturation of textile materials from the index of its hairiness are directly proportional. However, the value of changes is different for raw and napped fabrics, undyed and dyed samples, the initial colour hue and raw material composition also making certain adjustments. This study analysed the colour difference and established the level of variation in hairiness at which the colour mismatch between woollen fabrics becomes visually noticeable. The results of the study can be used to predict the colour and design the optical properties of fabrics for weaving and finishing. Keywords: woollen fabrics, colour, hairiness index, colour characteristics Izvleček Oblikovanje barvnega videza tekstilijzahteva upoštevanje njihovih površinskih lastnosti, med katerimi je tudi kosmatost. Resice, ki štrlijo s površine, ne vplivajo samo na kakovost barvanja tekstilije, temveč v veliki meri določajo tudi njene optične lastnosti in značilnosti barve. Analiza študij optičnih lastnosti kaže, da mehanizem vpliva kosmatosti na značilnosti barve ni dobro razumljen, obseg kosmatosti, pri katerem postanejo spremembe barve pomembne za človekovo zaznavanje, pa ni nedoločljiv. V tej raziskavi so bile proučevane spremembe barvnih lastnosti zaradi spremembe kosmatosti volnenih tkanin, in sicer s primerjavo „preja - surova tkanina", „preja - kosmatena tkanina" in „surova tkanina - kosmatena tkanina". Kosmatost je bila ocenjena z indeksom kosmatosti, ki smo ga dobili z računalniško analizo mikrofotografij vzorcev preje in tkanin. Vrednost barvnih lastnosti (svetlost, kroma in barvna razlika) smo izmerili v barvnem prostoru CIELAB (1976) s pomočjo spektrofotometra. Dobljeni eksperimentalni rezultati so pokazali, da so spremembe svetlosti in nasičenosti tekstilnega materiala neposredno sorazmerne z indeksom kosmatosti tekstilije. Vrednost sprememb je različna za surove in kosmatene tkanine, nebarvane in barvane vzorce, prav tako pa dodatno vplivata začetni barvni ton in surovinska sestava. V raziskavi je bila analizirana barvna razlika in določena stopnja Effect of Hairiness on Fabric Colour Characteristics 277 variacije kosmatosti, pri kateri postane barvna neskladnost med volnenimi tkaninami vizualno opazna. Rezultate te študije lahko uporabimo za napovedovanje barve in oblikovanje optičnih lastnosti tkanin pri tkanju in plemenitenju. Ključne besede: volnene tkanine, barva, indeks kosmatosti, značilnosti barve 1 Introduction The regular change of popular colours and their shades is relatively typical of the modern fashion industry; therefore, compliance with the trend colour is one of the key properties of products that ensure the commercial success of the textile production. Nevertheless, reproducing the desired colour in a textile product is a complex challenge, which includes not only choosing the optimal ratio of the dye formulation, but also predicting the appearance of colour in the texture of the finished material [1]. Texture features need to be taken into account since the nature of reflection or absorption of light rays depends on the material roughness, which affects perception and consequently distorts the colour phenomenon. Based on the requirements for the colour design and appearance of the fabric, attention needs to be paid to the structure when dyeing, hairiness being of particular importance. On the one hand, the layer of villi affects the adhesion of the dye, increasing the hydrophobicity of the textile [2-6]. Since this leads to an increase in the contact angle, to ensure the quality of dyeing, hairiness is undesirable [7]. On the other hand, the hairiness layer significantly affects the appearance of the finished product, as it is the main surface property [8]. Studies [9-13] show that reflection, gloss, lustre, dichroic, birefringence, as well as the lightness of the fabric surface largely depend on the density of villi and their orientation, i.e. hairiness affects the phenomenon of colour [13]. The influence of hairiness on dyeing textiles is much more studied than on the phenomenon of colour. Although studies [14-17] show that hairiness increases the lightness of the surface, these results are not sufficient to determine the colour of fabrics, since the amount of hairiness at which the changes in lightness become significant for human perception remains uncertain. Therefore, predicting the colour of textiles, especially for fuzzy fabrics such as fleece or flannel, continues to be difficult. It is worth noting another difficulty in designing colours for textiles that are made from dyed yarn and are nap. The difficulty lies in choosing the appropriate colour of yarn, which should correspond to the established standard for the colour of fabric after all stages of its production and processing. The aim of this research was to study the effect of hairiness on colour indices in fabrics made from undyed and dyed yarn with a different amount of hairiness. 2 Experimental 2.1 Materials Samples of yarn and fabric from the assortment of the Vladi textile enterprise (Kharkov, Ukraine) [18], made from woollen fibres, or from a mixture of woollen and chemical fibres (cf. Table 1), were selected as the subject of the study, since hairiness is especially Table 1: Structural characteristics of textile samples Textile set Fabric composition Weave pattern Fabric weight (g/m2) Fabric density (threads/dm) S1 100% acrylic plain 280 160 S2 90% wool, 10% acrylic plain 250 120 S3 100% wool 3/2 twill 270 160 S4 80% merino wool, 20% polyester 2/4 matting 250 170 S5 60% wool, 40% polyester 2/2 twill 270 110 S6 40% wool, 5% merino wool, 35% acrylic, 20% polyester 2/2 twill 275 120 S7 50% wool, 30% polyester, 20% acrylic 2/3 twill 245 180 S8 70% wool, 30% polyester 2/2 twill 250 160 278 Tekstilec, 2020, Vol. 63(4), 242-2.55 a woollen characteristic and can easily be increased by the raising process. All samples were divided into 8 sets, each of which included yarn, a raw fabric made from this yarn and the same fabric after the raising process (cf. Table 1). Each set was prepared in two versions, i.e. undyed and dyed. Undyed samples had a natural white shade of wool. Colour samples of sets S1, S2, S4 and S8 were dyed in light colours (lightness L* > 60), the rest in dark (L* < 50). All studies were conducted in standard climatic conditions [19]. All fabrics were made of yarn of the same linear density, i.e. 100 tex. The sets differed among each other by the fibrous composition of yarn, type of weaving and fabric density. Each set was prepared in two versions, i.e. undyed and dyed. The undyed samples had a natural wool shade. The dyed samples of sets S1, S2, S4 and S8 were made in light shades (lightness L* = 60), and the rest in dark shades (L* = 50). Figure 1 shows an example of a set of textile materials selected for the study. The dyeing of the fibrous mixture to obtain dyed yarn was carried out according to the technological regime developed by and operating at the Vladi enterprise [18]. At each stage of the processing of textile materials (spinning, weaving and finishing), samples were taken according to the method described in the standard GOST 20566-75. The undyed and dyed samples of yarn and fabric were made on the same equipment, which made it possible to obtain the same experimental conditions. All experiments were performed under standard climatic conditions [19]. During the study, the structure of samples was not subjected to mechanical deformation and the villi were in the same orientation they acquired during the stabilisation. 2.2 Hairiness measurement To measure the hairiness of yarn and fabrics, the optical method was used, the essence of which is to determine the amount of hair from sample micrographs [20]. However, the use of this method in the textile industry to assess the indicators of material hairiness has some peculiarities due to the difference in the structure of yarn and fabric. The index of yarn hairiness is thus determined by the total length of fibres protruding on both sides of the body of the yarn [21], and for the fabric, hairiness is determined by the total length of fibres protruding above the fold of one side of the fabric [16]. The indicators obtained in this way do not allow for a comparative analysis of the hairiness of textile materials, which is planned in this work. Therefore, in this study, changes were made to the experimental procedure in the stage of sample preparation. The yarn for the research was previously reeled up on plates of 5 cm x 5 cm in increments equal to the diameter of yarn to obtain a solid covering that simulates the surface of the fabric. The hairiness of both yarns and fabrics was determined at the fold, the contour of which was analysed using a software application [21]. When measuring hairiness, a layer of surface (tangled) pile was taken into account (cf. Figure 2), the boundaries of which were set by the operator based on the definition of a) b) Figure 1: Example of set of samples for research (yarn, raw fabric and raised fabric) in two versions: a) undyed and b) dyed Effect of Hairiness on Fabric Colour Characteristics 279 a) b) Figure 2: Image of fabric fold with processing zones: a) actual image of fold, b) image in binary format for analysis the pile layer [8, 22]. The hairiness of the fabric was determined at the fold, which was formed along the warp and weft threads, and along the diagonal. This allowed us to level the influence of the weaving pattern and increase the objectivity of the research results. The amount of pile in the experiment was estimated by the hairiness index H of the textile material, which shows the total length of fibres of the yarn (fabric) at the fold of a 1-cm long textile sample. When determining the hairiness of a fabric, the total number of experiments was calculated in a preliminary experiment with a 95% probability used for the textile industry [23]. Ten samples were made from one fabric. For each sample, three experiments were repeated. Taking into account that eight sets of textile materials were examined in two versions (undyed and dyed), the total number of experiments (separately for raw and raised fabrics) was 10 x 3 x 8 x 2 = 480. As a result, the reliability of the obtained results was ensured. 2.3 Colour measurement The spectral characteristics of yarn and fabric samples were obtained using a system for measuring, evaluating and reproducing colour, consisting of a Spectra Scan 5100 spectrophotometer (Premier Colerscan) and applied programs, which allow solving problems in industrial coloristic applications [24]. The general principles for measuring fabric colour are in accordance with ISO 105-J01: 1997 - Textiles - Tests for colour fastness - Part J01: General prin- ciples for measurement of surface colour. This is a current standard version, which was last revised and confirmed in 2018. The measurement of the colour characteristics of samples and their entry into the software database were conducted under the conditions that ensure the measurement reproducibility of chromaticity parameters. The colour parameters of samples were repeatedly measured using the maximum available viewing area of the spectrophotometer used, i.e. a large aperture (30 mm LAV aperture). The parameters of samples were measured on a backing material similar to a white standard calibration plate (titanium dioxide) used to calibrate the device. The backing material was the same for all samples during the measurement. To obtain the required accuracy of colour characteristic measurements, each elementary spot sample was positioned on the measuring device, followed by rotation by 10° before carrying out the next measurement. After determining the required number of measurements (measurements with removing the sample from the device with an error not exceeding 0.15 units of chromaticity error AE), four control cycles of colour parameter measurements were performed in order to confirm that the averaged result for each of the four cycles was included in the permissible error AE = 0.15 units. In this work, the spectral characteristics of samples were evaluated under standard illumination D65/10, the values of the colour coordinates for which are shown in Table 2. Table 2: Values of colour coordinates under illumination D65/10 Light source A B C D65 Xo 109.83 99.07 98.07 95.02 Yo loo.oo 100.00 100.00 100.00 Zo 35.55 85.22 118.22 108.81 280 Tekstilec, 2020, Vol. 63(4), 276-286 Colour differences were calculated using the CIE L* a* b* (1976) system. Since the essence of the study of colour characteristics was to determine their change depending on the change in the hairiness of textile samples in the process of technological processing, the colour indices of the textile material with the least hairiness were taken as a standard. The following indicators were used to analyse colour characteristics: lightness L*, saturation C* and colour difference dE*. The change in the colour characteristics of samples relative to the reference sample from the corresponding set was analysed by the difference in lightness DL*, difference in saturation DC*, differences in the coordinates Da*, Db*, and the colour difference dE*. 3 Results and discussion 3.1 Changes in colour characteristics of undyed textiles The results of colour characteristics are demonstrated on the example of the set S2. Figure 3 shows micro- graphs of textile samples from this set, which were used to determine the hairiness index. According to the results of the analysis of micropho-tographs, the hairiness of the yarn had the lowest values; therefore, yarn was chosen as a reference when comparing the colour characteristics of textile samples. The change in hairiness was reflected primarily in the lightness indicators of textile materials. Thus, the lightness of the raised fabric increased in comparison with the yarn, and the colour itself became more yellow. Figure 4 shows the average yarn-to-raised-fabric colour match results from the spectrophotom-eter analysis using standard test geometry. Changes in hairiness AHtm and colour characteristics of fabrics, presented as a percentage increase relative to yarn (yarn - raw fabric, yarn - raised fabric), and the differences between the corresponding characteristics of raw and raised fabrics are shown in Table 3. Based on the results shown in Table 3, the graphical dependencies of the difference in lightness and colour saturation of undyed textile samples on the changes in their hairiness index are presented in Figure 5. a) b) Figure 3: Layer of surface pile on: a) fold of yarn, b) raw fabric, and c) raised fabric c) 81.32 65.05 0s 48.79 UL -J cc 32.53 16.26 0.00 400 500 600 700 Wavelength (nm) a) b) Figure 4: Colour matching of: a) undyed yarn and b) raised fabric from set S2 Effect of Hairiness on Fabric Colour Characteristics 281 Table 3: Results of comparison of colour characteristics of undyed textile samples Yarn - raw fabric Textile set S1 S2 S3 S4 S5 S6 S7 S8 AHtm (%) 15.53 102.06 87.82 111.22 4.47 0.91 8.82 3.85 DL* 0.42 1.18 0.79 1.23 0.03 0.02 0.14 0.00 Da* -0.02 0.55 0.67 0.12 0.03 0.00 0.1 0.06 Db* 1.14 3.01 1.5 5.54 0.35 0.03 0.47 0.56 DC* 1.15 3.10 1.51 5.54 0.33 0.03 0.49 0.57 dE* 1.21 3.28 1.82 5.68 0.35 0.04 0.5 0.57 Yarn - raised fabric Textile set S1 S2 S3 S4 S5 S6 S7 S8 AHtm (%) 91.3 168.72 153.78 177.21 84.15 71.69 69.49 91.45 DL* 0.63 1.50 1.41 1.67 1.22 1.11 0.75 1.56 Da* -0.22 -0.15 0.32 0.34 0.40 -0.25 -0.38 -0.13 Db* 2.62 5.14 3.41 5.3 1.64 1.43 1.99 1.53 DC* 2.66 5.15 3.59 5.31 1.68 1.61 1.74 1.02 dE* 2.71 5.36 3.71 5.57 2.08 1.83 2.16 2.19 Raw fabric - raised fabric Textile set S1 S2 S3 S4 S5 S6 S7 S8 AH (%) tm v ' 65.59 89.01 84.87 83.04 70.7 71.09 65.74 75.56 DL* 0.42 1.18 1.67 1.52 1.21 1.36 1.00 0.84 Da* -0.22 -0.13 -0.03 -0.12 -0.20 -0.08 -0.19 -0.13 Db* 1.17 3.12 2.99 2.85 1.66 1.35 1.22 1.91 DC* 1.15 3.10 2.95 2.75 1.44 1.14 1.46 1.91 dE* 1.26 3.34 3.42 3.23 2.06 1.91 1.59 2.09 ■S S 1,5 0,5 -0,5 □ -rf C □ 5 ° ♦ □ ♦ 0 25 50 75 100 125 150 175 200 Difference in hairiness index, AHtm (%) ♦ Yarn - raw fabric nYarn - raised fabric K 2 ♦ □ / □ / / 7 □ 4 □ 0 25 50 75 100 125 150 175 200 Difference of hairiness index, AHtm (%) ♦ Yarn - raw fabric nYarn - raised fabric 6 2 4 1 0 0 a) b) Figure 5: Change of colour characteristics for undyed samples 282 Tekstilec, 2020, Vol. 63(4), 276-286 Figure 6: Surfaces of fabric samples from set S2: raw fabric and raised fabric The analysis of graphic data showed that with an increase in the hairiness of textile materials, their colour characteristics (lightness and colour saturation) increased in direct proportion. The degree of this increase was manifested to a greater extent for the hairiness of the fabrics, since a thick layer of the surface pile covered uneven relief and pores formed by threads (cf. Figure 6). With a further increase in hairiness, the changes in the lightness of fuzzy fabrics reduced, which was confirmed by a decrease in the slope of the graph "yarn - raised fabric". Obviously, this moment came after the villi filled the space between the threads in the weave pattern and completely covered the body of the fabric (cf. Figure 6), forming a layer of solid thick pile, which is typical of fabrics after the raising [16]. The results presented in Table 3 show that hairiness increased the most for the fabric sample sets S2-S4 made from wool with a low proportion of chemi-27.72 22.17 16.63 OC 11.09 5.54 0.00 cal fibres. For these samples, the lightness of the L* colour also increased significantly. For the textiles made with the addition of acrylic fibres, the change in hairiness was less pronounced, and for these samples, the lightness DL* was correspondingly lower. The analysis of the colour of undyed samples by the change in coordinates a* and b* (deviations towards green-purple or blue-yellow) showed that the colour of some raw fabrics and all raised fabrics with greater hairiness became less red (or greener) (negative Da*). As for the increase in Db*, according to the data obtained, with an increase in the hairiness index, their colour changed towards an increase in yellowness, i.e. the natural shade of woollen fibres from which the yarn was made. This suggests that with an increase in the hairiness of textiles, its natural subtone becomes more noticeable on the surface, which may be the subject of further scientific research. 400 500 600 700 Wavelength (nm) a) Figure 7: Colour matching of: a) dyed yarn and b) raised fabric from set S3 b) Effect of Hairiness on Fabric Colour Characteristics 283 3.2 Changes in colour characteristics of dyed textiles Figure 7 shows the average yarn - raised fabric colour match results from the dyed sample set S3, as measured by a spectrophotometer with standard test geometry. The changes in hairiness AHtm and colour characteristics for dyed textile samples are shown in Table 4. According to the results presented in Table 4, the graphical dependencies of the changes in lightness and colour saturation of dyed fabrics on the changes in their hairiness index were also plotted (cf. Figure 8). The analysis of graphic data showed that the changes in the colour characteristics of undyed and dyed textile samples from their hairiness index had similar regularity: with an increase in the hairiness index, the values of colour characteristics increased proportionally. However, a certain correction in colour matching was made by the initial value of the lightness of samples, which differed significantly in initial conditions for dyed and undyed textile materials. Therefore, with almost the same increase in the hairiness index for undyed fabrics (cf. Figure 5), the level of change in colour characteristics increased with an increase in hairiness, and for dyed fabrics (cf. Figure 8), the level of lightness and saturation changes with an increase in hairiness did not practically change ("yarn - raised fabric" graphics). It should be assumed that the presence of dark tones in sets of fabrics, which are known to absorb light more than reflect, plays a significant role in the value of lightness of dyed fabrics. The increase in hairiness was reflected to a lesser extent in the level of their colour characteristics. Hence, a study of colour characteristics of dyed fabrics should be performed within groups assembled by colour tone. Table 4: Results of comparison of colour characteristics of dyed textile samples Yarn - raw fabric Textile set S1 S2 S3 S4 S5 S6 S7 S8 A Hm (%) 12.54 118.8 71.49 77.81 6.69 4.59 8.8 4.27 DL* 0.31 1.18 0.39 1.62 0.04 -0.04 0.04 0.01 Da* -0.12 0.23 -0.25 0.21 0.39 0.34 0.73 0.60 Db* 1.30 3.1 0.35 3.10 0.3 0.22 0.65 0.35 DC* 1.30 3.10 1.25 3.11 0.3 0.22 0.65 0.36 dE* 1.34 3.32 0.58 3.51 0.49 0.40 0.98 0.7 Yarn - raised fabric Textile set S1 S2 S3 S4 S5 S6 S7 S8 A Hm (%) 101.35 159.83 131.82 163.58 62.47 73.39 107.39 88.89 DL* 1.59 1.90 0.47 1.92 0.45 -0.07 1.00 0.03 Da* -0.1 -0.18 -0.03 -0.34 0.61 0.49 1.2 0.74 Db* 1.17 3.31 1.78 4.45 0.46 0.42 0.57 0.47 DC* 2.41 3.22 1.79 4.56 0.48 0.51 0.85 0.67 dE* 1.97 3.82 1.84 4.86 0.89 0.65 1.66 0.88 Raw fabric - raised fabric Textile set S1 S2 S3 S4 S5 S6 S7 S8 A Hm (%) 61.14 82.15 83.37 78.76 50.39 62.46 80.91 65.79 DL* 0.75 1.55 0.43 1.69 0.67 -0.05 0.1 1.34 Da* 0.08 -0.20 -0.14 0.02 0.83 -0.34 2.11 0.1 Db* 1.73 2.32 1.18 2.64 0.44 0.65 0.57 1.63 DC* 1.11 2.64 1.2 2.59 0.33 0.52 2.04 2.00 dE* 1.41 2.74 1.33 2.74 0.88 1.54 2.82 1.72 284 Tekstilec, 2020, Vol. 63(4), 276-286 2,5 1,5 0,5 0 -1 -0,5 ► I ] [ffl ; u« n □ w L 1 0 25 50 75 100 125 150 175 200 Difference in hairiness index, AHtm (%) ♦ Yarn - raw fabric nYarn - raised fabric 1 can be determined by an experienced colourist. To an ordinary observer, the differences between colours become noticeable at dE* > 2. If dE* > 5, the observer sees two different colours [25]. With a hairiness increase of 70% or more, the colour difference between textile materials exceeds 1 and becomes visually noticeable. A particularly significant (more than 2) colour difference was manifested for undyed samples of sets S2, S4 and could be seen with the naked eye (cf. Figure 9). As it can be seen from Figure 9, a visual comparison of two samples of undyed raw and raised fabrics of set S2, for which dE* = 3.34, showed a significant differ- Figure 9: Fabric from set S2 before rising (top) and after rising (bottom) ence in colour indicators, i.e. lightness and saturation of the raised fabric were greater. The same level of colour difference was observed for the dyed sets of textiles S1, S2, S4 (light colour). For the textile samples the lightness L* of which was below 40 (dark tones), an increase in AH did not cause a colour difference tm between them. The colour difference of the dyed textile samples with an increase in hairiness was not so noticeable for an average observer, and the deviation from a given shade occurred more often under the influence of a subtone of villi. For example, for the sets of samples S3, S5 and S6, a significant increase in hairiness did not cause significant changes in colour characteristics, while for the undyed samples of the same sets, the colour difference reached 2 or more. For the textiles of dark shades, when the reflection of light rays from a dark fuzzy surface creates the effect of gloss rather than lightness, it is advisable to supplement the study with an analysis of gloss parameters [15]. Effect of Hairiness on Fabric Colour Characteristics 285 4 Conclusion 1. Numerous investigations show that hairiness is an important formative factor in the optical properties of textile materials, since it affects not only the technological processes of dyeing textiles, but also the visual perception of the surface of the material and the textile product as a whole. 2. As a result of our experiment, it was found that with an increase in the hairiness of woollen fabrics, their colour characteristics (lightness and colour saturation) increase in direct proportion. However, the degree of increase in lightness and chroma for undyed and dyed samples is different, and depends on the initial colour tone of the fabrics. With almost the same increase in the hairiness index for undyed fabrics, the level of change in colour characteristics increases, while for dyed fabrics, it does not practically change. The study of the colour characteristics of dyed fabrics must be conducted within groups assembled by colour tone. 3. The degree of increase in lightness and saturation is higher for raised fabrics, since a thick layer of surface pile closes relief irregularities and pores formed by threads. However, with a certain amount of hairiness, the increase in lightness decreases and subsequently remains unchanged. 4. The analysis of the colour of tissue samples by changing the coordinate Da* indicates a certain redistribution of constituent colours in the structure of the colour tone, which is not visually determined. Positive values of the Db* coordinate show that with an increase in the layer of hairiness, the colour of fabrics changes in the direction of increasing yellowness (natural shade of wool fibres the yarn is made of), i.e. the natural subtone of fibres becomes more noticeable on the surface of fabrics. 5. Moreover, it was established that the colour mismatch between woollen fabrics with different degrees of hairiness becomes visually noticeable with a total colour difference of dE* > 1, which corresponds to an increase in hairiness of 70% or more. 6. The factor of the influence of hairiness on colour effects in textile materials should be taken into account when designing fabrics from dyed yarn, when developing the colour design of fabrics and when calculating technological dyeing modes to ensure the most accurate colour matching to a given sample. References 1. BECERIR, B. Color concept in textile : a review. Journal of Textile Engineering & Fashion Technology, 2017, 1(6), 240-244, doi: 10.15406/ jteft.2017.01.00039. 2. Handbook of textile and industrial dyeing : principles, processes and types of dyes. Edited by Matthew Clark.Cambridge : Woodhead Publishing, 2011. 3. MHETRE, Shamal Kamalakar. Effect of fabric structure on liquid transport, ink jet drop spreading and printing quality : PhD Thesis. Georgia Institute of Technology, 2009. 4. BACHUROVA, Marcela, WIENER, Jakub. Theoretical model of the influence of textile structure on wetting hysteresis. Fibres & Textiles in Eastern Europe, 2013, 21(2), 80-83. 5. VARESANO, Alessio, ROMBALDONI, Fabio, TONETTI, Cinzia, DI MAURO, Sandra, MAZZUCHETTI, Giorgio. Chemical treatments for improving adhesion between electro-spun nanofibers and fabrics. Journal of Applied Polymer Science, 2014, 131(2), 1-7, doi: 10.1002/ app.39766. 6. MELKI, Safi, BIGUENET, Florence, DUPUIS, Dominique. Hydrophobic properties of textile materials : robustness of hydrophobicity. The Journal of The Textile Institute, 2019, 110(8), 1221-1228, doi: 10.1080/00405000.2018.1553346. 7. SADIKOGLU, Samir. Effect of fabric hairiness and pretreatment on quality of digital DTG (Direct to Garment) printing. In NIP & Digital Fabrication Conference. San Francisco : Society for Imaging Science and Technology, 2019, 6-14, doi: 10.2352/ISSN.2169-4451.2019.35.6. 8. SMYKALO, K., ZAKORA, O., ZASHCHEPKINA, N., YARYHA, O. Hairiness as a surface property of textile. Bulletin of the Kyiv National University of Technologies and Design. Technical Science Series, 2019, 138(5), 62-70, doi: 10.30857/1813-6796.2019.5.7. 9. LEE, Wonjoung, SATO, Masako. Visual perception of texture of textiles. Color Research & Application, 2001, 26(6), 469-477, doi: 10.1002/ col.1067. 10. BICKLEY, Anthea, MCHUGH, Raymond. Lustre fabrics. Costume, 1989, 23(1), 98-109, doi: 10.1179/ cos.1989.23.1.98. 11. HAMZA, A.A., ABD EL-KADER, H.I. Optical properties and birefringence phenomena in fibers. 286 Tekstilec, 2020, Vol. 63(4), 242-2.55 Textile Research Journal, 1983, 53(4), 205-209, doi: 10.1177/004051758305300401. 12. GABRIJELCIC, Helena. Colour and optical phenomena on fabric. Tekstilec, 2007, 50(4-6), 93-132. 13. AKHTAR, Khurram Shehzad, AFZAL, Ali, IQBAL, Kashif, SARWAR, Zahid, AHMAD, Sheraz. Investigation of manufacturing and processing techniques on shade variation and performance characteristics of woven fabrics. Journal of Engineered Fibers and Fabrics, 2018, 13(3), 71-77, doi: 10.1177/155892501801300308. 14. DAVAAJAV, N., SUKIGARA, S. Surface characterization of cashmere fabrics using optical and transient thermal properties. Journal of Fashion Technology & Textile Engineering, 2018, 6(1), doi:10.4172/2329-9568.1000165. 15. ENDO, Manami, KITAGUCHI, Saori, MORITA, Hiroyuki, SATO, Tetsuya, SUKIGARA, Sachiko. Characterization of fabrics using the light reflec-tanceand the surface geometry measurements. Journal of Textile Engineering, 2013, 59(4), 75-81, doi: 10.4188/jte.59.75. 16. BUENO, Marie-Ange, DURAND, Bernard, RENNER, Marc. Optical characterization of the state of fabric surfaces. Optical Engineering, 2000, 39(6), 1697-1703, doi: 10.1117/1.602547. 17. DAS, A., CHAKROBORTY, P., KUMAR, P. Study of fabric hairiness using image processing technique. Research Journal of Textile & Apparel, 2009, 13(3), doi: 10.1108/RJTA-13-03-2009-B003. 18. Comfortable life with VLADI [accessible from a distance]. VLADI [accessed 26.05.2020]. Available on World Wide Web: . 19. ISO 139:2005 (EN) - Textiles - Standard atmospheres for conditioning and testing. Geneva : ISO Copyright Office, 2005. 20. GUHA, Anirban, AMARNATH, C., PATERIA, S., MITTAL, R. Measurement of yarn hairiness by digital image processing. The Journal of the Textile Institute, 2010, 101(3), 214-222, doi: 10.1080/00405000802346412. 21. ZAKORA, Oksana Vasilievna, LIPKOVA, Galina Ivanovna. Development of algorithm and computer program for measuring of yarn hairiness. Eastern-European Journal of Enterprise Technologies, 2012, 2(56), 28-30, http://journals. uran.ua/eejet/article/view/3887. 22. KOROBOVA, T.N., GUSEV, B.N. Modeling the yarn surface taking into account its regulated characteristics. Izvestiya Vysshikh Uchebnykh Zavedenii, Seriya Teknologiya Tekstil'noi Promyshlennosti, 2008, 309(4), 15-18, https://ttp. ivgpu.com/ wp-content/uploads/2015/11/309_5. pdf. 23. ZAKHARKEVICH, Oksana. Fundamentals of scientific research : a textbook for students of higher educational institutions. Khmelnytskyi : KhNU, 2013. 24. Color matching softwares [accessible from a distance]. Premier Colorscan Instruments [accessed 27. 6. 2020]. Available on World Wide Web: . 25. MOKRZYCKI, W.S., TATOL, M. Colour difference AE - a survey. Machine Graphics and Vision, 2011, 20(4), 383-411, doi: 10.5555/3166160.3166161. Tekstilec, 2020, Vol. 63(4), 287-293 | DOI: 10.14502/TekstHec2020.64.287-293 2 87 Khorolsuren Tuvshinbayar, Andrea Ehrmann Bielefeld University of Applied Sciences, Faculty of Engineering and Mathematics, 33619 Bielefeld, Germany Acoustic Investigation of Textile Fabrics Akustična raziskava tekstilnih tkanin Original scientific article/Izvirni znanstveni članek Received/Prispelo 10-2020 • Accepted/Sprejeto 10-2020 Corresponding author/Korespondenčna avtorica: Prof. Dr. Dr. Andrea Ehrmann E-mail: andrea.ehrmann@fh-bielefeld ORCID: 0000-0003-0695-3905 Abstract Why is it possible to distinguish between different textile fabrics by just touching them and moving your hand over them and listening to the sound? Particularly for high-quality woven fabrics, e.g. used for tailor-made suits, it is quite common that the dressmaker listens to the sound as their hand rubs the fabric. Can this approach be translated into a technical measurement? What could a sound analysis tell us about the fabric properties? As a first simple approach, we used a record player to rotate different cotton fabrics, and tested fine tips from diverse materials, such as plastic pipettes, pens, glass tips, etc. Our results show clear differences between the textile fabrics, which can be attributed to different yarn, knitted or woven structures. While the rotational mode of investigation impedes fully automated fast Fourier transform (FFT) evaluations, our first results suggest developing this promising method further. Keywords: sound analysis, woven fabrics, knitted fabrics, hairiness, surface structure, roughness. Izvleček Zakaj je mogoče razlikovati med različnimi tekstilnimi tkaninami tako, da samo premikate roko po njej in poslušate zvok? Predvsem za visokokakovostne tkanine, npr. take, ki se uporabljajo za obleke po meri, je zelo pogosto, da kroja-čica posluša zvok svoje roke, ki se premika po površini blaga. Ali je mogoče ta pristop tehnično izmeriti in kaj bi nam takšna zvočna analiza lahko povedala o lastnostih tkanine? Kot prvi preprost pristop smo s pomočjo predvajalnika gramofonskih plošč vrteli različne bombažne tkanine in preizkušali fine konice iz različnih materialov, kot so plastične pipete, pisala, steklene konice itd. Naši rezultati kažejo jasne razlike med tkaninami, ki jih lahko pripišemo različnim prejam, pletenim ali tkanim strukturam. Medtem ko rotacijski način preiskave ne omogoča popolnoma samodejne ocene hitre Fourierjeve transformacije (FFT), so naši prvi rezultati spodbudni za nadaljnji razvoj te obetavne metode. Ključne besede: analiza zvoka, tkanine, pletiva, kosmatost, površinska struktura, hrapavost 1 Introduction Textile fabrics are often used for sound absorption or acoustic insulation and investigated for this purpose by many research groups [1-5]. Some groups also work on developing acoustic sensors embedded in yarns or fabrics [6]. Only recently has the issue been addressed whether acoustic investigations of textile fabrics, i.e. per- forming an analysis of the sound created by fric-tional movement along their surfaces [7, 8], could reveal information about the fabrics. Wang et al. studied the friction sounds created by woven fabrics from natural fibres rubbing on each other and found frequency-dependent loudness, averaging over time [9]. Loudness was also the parameter investigated in some other studies, e.g. by Yi and Cho, examining different woven fabrics [10, 11]. Afterwards, 288 Tekstilec, 2020, Vol. 63(4), 242-2.55 Yi et al. as well as Kim et al. added subjective pitch, clearness and sharpness to the loudness, and found correlations with different mechanical properties, as measured with a Kawabata KES-FB [12, 13]. The same sound generator, rubbing two fabrics under a defined load against each other, was also used to investigate warp-knitted and weft-knitted fabrics in terms of loudness and loudness range [14, 15]. A comprehensive study on knitted and woven fabrics with a focus on water repellent, vapor permeable fabrics was carried out by Park and Cho, comparing acoustic and mechanical parameters [16]. A slightly different approach was chosen by Yosouf et al. [17]. They developed an instrument which follows the trajectory of a moving arm along the side of the body, in this way for the first time not following a linear trajectory, i.e. moving two fabrics against each other not exactly along warp or weft direction, but along a bent line. Evaluation of the acoustic measurements concentrated on the amplitude, as in most previous studies. Here, another approach is chosen. Instead of averaging over large areas by investigating textile-textile friction, we perform an acoustic analysis using fine tips from different materials, enabling time- and spatially resolved sound examination. In this way, it is generally possible to acoustically count warp and weft densities in woven fabrics and similar numbers in warp and weft knitted fabrics. 2 Materials and methods All textile fabrics under examination in this study consisted of 100% cotton. Table 1 gives an overview of the fabric parameters. An L3865 record player (Lenco, Nuth, Netherlands) was used to rotate the samples cut to fit the dimension of the turntable. A 130D20 microphone (PCB Piezotronics) attached to an SN 23697 AD-converter grey - white a) b) c) Figure 1: a) Cut samples under examination; b) Measurement setup with the tip holder and inserted microphone (attached to the blue connector) mounted on a lever, which allows it to carefully touch the rotating textile fabric; c) Ballpoint pen refill placed in the tip holder Table 1: Fabric parameters of the samples under investigation Name Structure Thickness (mm) Areal weight (g/m2) Courses/cm Ends/cm Wales/cm Picks/cm Green weft knitted 0.80 181 18 13 Red weft knitted 0.59 155 19 15 Violet weft knitted 1.23 255 8 7 Grey-white weft knitted 0.81 204 19 12 Jeans woven 0.79 162 13 15 Acoustic Investigation of Textile Fabrics 289 (National Instruments) was mounted on the record player instead of the common arm in a 3D printed holder for different tips, as depicted in Figure 1, in a distance of 105 mm from the middle of the turntable. The lever with the counterweight (Figure 1b) lets the tip softly touch the fabric (distance of 0 mm) so that the friction does not move the fabric, but a constant connection is ensured. The output voltage signals of the microphone were digitalised by the AD converter (sample frequency of 51.2 kHz, 24 bits) and saved and evaluated by a self-written Matlab code. Generally, the sound is produced by friction between the textile fabric and tip. Different pipettes and tubes from glass and plastics and a ballpoint pen refill (Figure 1c) were tested as tips. The plastic pipettes were found not to be stiff enough; their own bending caused undesired noise, which is why they were excluded after the first tests. The glass tubes, on the other hand, were not fine enough and impacted the textile fabrics too strongly. Finally, a stainless-steel ballpoint pen refill without dye (no-name, refill diameter of 2.51 mm, ball diameter of 1.5 mm) was chosen for the main tests. 3 Results and discussion Firstly, Figure 2 depicts exemplary time-domain results of measurements on the "red" sample (Figure 1a) on different time scales. Generally, the record player was set to 33/min, i.e. 0.55 Hz, meaning that one rotation takes 1.82 s (denoted by vertical black lines). Each measurement was performed during 6 full rotations, so that the values in the middle of the measurement duration are free from any possible bias due to starting and ending the rotational movement. Starting with the complete measurement along 6 rotation cycles (Figure 2a), there are no regularities clearly visible. Examining exactly one rotation cycle (Figure 2b) results in approx. 5-7 minima Figure 2: Measurements of time-dependent sound pressure of the red sample for different time scales: a) full measurement over 6 cycles, b) measurement during the 3rd cycle, c) measurement during the first 45° of the 3rd cycle, and d) measurement during the first 3° of the 3rd cycle 290 Tekstilec, 2020, Vol. 63(4), 242-2.55 and maxima, depending on how exactly these are counted, with varying amplitudes and wavelengths. Generally, a fourfold anisotropy may be expected due to the symmetry of a knitted fabric, which is, however, not visible here. Next, Figure 2c further decreases the time section under investigation, this time to an angle of 45° between the first and last depicted results. Now, the short-time variations inside the longer ones, seen in Figure 2b, also become visible. Finally, the time is reduced to ~ 0.015 s, corresponding to an angle of 3° which is depicted in Figure 2d. Here, the short-term variations become well visible, together with even shorter variations that can be attributed to noise. These oscillations are still not harmonic, which obviously results from the steady rotation of the system, as opposed to a linear movement, in which threads should be passed in continuous durations. Next, Figure 3 depicts sections of 3° (corresponding to Figure 2d) of the other four fabrics. Here, we see clear differences, especially between the knitted and the woven fabric ("jeans"), while the coarsest knitted fabric ("violet") does not show such strong deviations from the others. To understand these differences, it is supportive to compare the average numbers of yarns per centimetre with the measured frequencies. This is done here for the jeans woven fabric. According to Table 1, this fabric has an average number of 14 yarns/cm, assuming that counting occurs along the orientation of the warp or weft yarns, which is not the case here. For a rough estimate, however, we can assume that the well-visible maxima and minima belong to crossing one yarn at a time, while some lateral sliding correlated with shifting a yarn may occur in the more noisy regions, e.g. in the left part of Figure 3d. From the radius of the circle, on which the ballpoint pen refill is moved (105 mm), a circumference of 660 mm can be calculated, which is measured within 1.82 s. For the areas, in which measurement takes place more or less parallel to the warp or weft yarns, we can calculate a frequency of approximately 508 yarns/s, i.e. an expected time distances between subsequent maxima of approximately 2 ms. Figure 3: Measurements of time-dependent sound pressure of the other samples for identical durations: a) green, b) violet, c) grey-white, and d) jeans fabrics Acoustic Investigation of Textile Fabrics 291 Frequency (Hz) Frequency (Hz) Figure 4: FFT spectrum of the full measurement on the jeans fabric (a) and the red knitted fabric (b) For the right part of Figure 3d, a much smaller value of approximately 0.59 ms is calculated (i.e. ~ 1690 Hz), while in the left part as well as in other parts of the whole graph (not shown here), another time distance can be detected, i.e. approximately 2.1 ms (470 Hz). These values indicate that in general, the clear oscillations are correlated with the ballpoint pen refill crossing the yarns since both occur on the same time scale. However, a more sophisticated calculation is necessary to evaluate the warp and weft densities acoustically. It must also be mentioned that the highly irregular oscillations of the knitted fabrics suggest finding better methods than manual estimations of the average wavelength, which would be a necessary prerequisite of correlating frequencies to structures. For this, typically a fast Fourier transform (FFT) is applied. Figure 4 clearly shows the FFT spectrum of the measurements on the jeans fabric and on the red knitted fabric, as originally calculated for the whole measurement duration of 10.9 s (6 rotation cycles) and smoothed over 50 points to suppress the noise. Two main frequencies are visible for the jeans fabric (Figure 4a): approximately 450 Hz and approximately 1650 Hz, both quite near to the manually calculated frequencies for the jeans fabric. The smaller frequency, where a thinner and higher peak is visible, is apparently correlated to the ballpoint pen refill crossing a yarn, as calculated above, while the other peak is much broader and must thus be correlated with the ballpoint pen refill crossing yarns under other angles than 90°, resulting in crossing warp and weft yarns alternatingly and thus leading to higher frequencies. However, as mentioned above, a more sophisticated geometric model is necessary to fully understand all information available from such acoustic measurements. The FFT of the measurement on the red knitted fabric (Figure 4b), however, shows only one clear peak around 150 Hz and some smaller peaks around 520 Hz, 720 Hz and 1010 Hz. According to the above explained calculation, we would expect for this knitted fabric frequencies of approximately 690 Hz and 1090 Hz (if both yarns in a stitch are crossed) or 540 Hz (if a stitch is crossed near the head where only one yarn is detected), respectively. These expected frequencies fit to the small peaks in Figure 4b. Nevertheless, these peaks are not highly reliable due to the large background. Besides, the larger peak near 150 Hz remains unexplained. An important factor to evaluate the value of such measurements is the reproducibility. It was addressed with measurements during 6 full rotation cycles. Figure 5 depicts results of subsequent measurements on the woven jeans fabric and on one of the knitted fabrics. A time was chosen where the woven fabric showed a change in the oscillation amplitude to enable comparison between subsequent rotation cycles. For the woven fabric (Figure 5a), the first curve is clearly lower and varying stronger due to the starting process of the measurement. The others all show a reduced amplitude in a similar range, spaced by one rotation (marked by the black arrow), and also other similarities. It should, however, be mentioned that textile fabrics are soft and not completely inelastic (even a woven fabric) and it is thus obvious that - opposite to a metal plate or similar - the positions measured will always vary slightly due to the interaction between the measurement tip and fabric. The measured frequencies, however, should be similar. FFT values for the short durations depicted here allow for only a rough estimation; nevertheless, the values depicted in Figure 5a are mostly similar, except the first rotation. 292 Tekstilec, 2020, Vol. 63(4), 242-2.55 c =3 JD i— TO 3 (/) CD "O £= =! o 05 1 T ~ 1 /UU HZ * _f ~ 1600 Hz « -ipan«; fnhrir f ~ 2100 Hz X jeans fabric 0.200 0.205 0.210 0.215 t(s) Figure 5: Time-dependent sound pressure measurements at identical positions for (black) first, (red) second, (green) third, (blue) fourth, (cyan) fifth and (magenta) sixth rotation. The lines are vertically offset for clarity by a constant value. Insets depict approximate frequencies, as calculated by FFT for the visible durations. Values are shown for jeans fabric (a) and for red knitted fabric (b). The results for knitted fabrics are different. On the one hand, frequency measurements by FFT are even less exact here, while the measured frequencies are again similar. It is not possible, however, to find corresponding features in the measurements at the same position during different rotation cycles. Apparently, even a small pressure of the ballpoint pen refill is sufficient to move single threads in the stitches or elongate the knitted fabric so that in each rotation cycle a slightly different position of the knitted fabric is examined. We assume that these problems, which were already recognised in Figure 4b, can be reduced if in the next version the tip is made flexible, e.g. in the form of an elastic metal strip with a fine, rounded tip fixed in the tip holder. Probably, similar to atomic force microscopy (AFM) where the cantilevers have to be chosen according to the samples under investigation and according to the exact questions to be answered, it is necessary to define different tips for samples of different surface roughness, yarn stiffness, hairiness, etc. 4 Conclusion Acoustic measurements of different knitted and woven fabrics were performed rotating the textile fabrics on the turntable of a record player and measuring the sound of a ballpoint pen refill by a microphone. Time-domain and frequency-domain evaluations allow detecting frequencies for woven fabrics, which can be correlated with the yarn density. On the other hand, more information is contained in the FFT spectra that has to be evaluated carefully. For knitted fabrics, the soft yarns seem to be moved strongly by the ballpoint pen refill, resulting in highly irregular signals due to shifted yarns, which are crossed at random positions within a certain interval, which necessitate a more sophisticated experimental and/ or theoretical approach. Acknowledgment The authors would like to thank Nils Grimmelsmann and Joachim Wafimuth for their support in performing and evaluating the measurements, and Sonke Luck for lending them the microphone and AD-converter. References 1. CAI, Zenong, LI, Xianhui, GAI, Xiaoling, ZHANG, Bin, XING, Tuo. An empirical model to predict sound absorption ability of woven fabrics. Applied Acoustics, 2020, 170, 1-8, doi: 10.1016/j. apacoust.2020.107483. 2. ATIENZAR-NAVARRO, R., BONET-ARACIL, M., GISBERT-PAYA, J., DEL REY, R., PICO, R. Sound absorption of textile fabrics doped with microcapsules. Applied Acoustics, 2020, 164, 1-9, doi: 10.1016/j.apacoust.2020.107285. 3. SEGURA ALCARAZ, Pilar, SEGURA ALCARAZ, Jorge Gabriel, MONTAVA SEGUI, Ignacio, BONET ARACILL, Mariles. Optimisation of the sound absorption of a textile material. Dyna, 2020, 95(3), 313-316, doi: 10.6036/9570. Acoustic Investigation of Textile Fabrics 293 4. PAKDEL, Esfandiar, NAEBE, Maryam, KASHI, Sima, CAI, Zengxiao, XIE, Wanjie, YUEN, Anthony Chun Yin, MONTAZER, Majid, SUN, Lu, WANG, Xungai. Functional cotton fabric using hollow glass microspheres: focus on thermal insulation, flame retardancy, UV-protection and acoustic performance. Progress in Organic Coatings 2020, 142, 1-10, doi: 10.1016/j. porgcoat.2020.105553. 5. LI, Huiqin, ZHANG, Nan, FAN, Xiaodan, GONG, Jixian, ZHANG, Jianfei, ZHAO, Xiaoming. Investigation of effective factors of woven structure fabrics for acoustic absorption. Applied Acoustics, 2020, 161, 1-8, doi: 10.1016/j. apacoust.2019.107081. 6. HUGHES-RILEY, Theodore, DIAS, Tilak. Developing an acoustic sensing yarn for health surveillance in a military setting. Sensors, 2018, 18(5), 1-12, doi: 10.3390/s18051590. 7. YOKOI, M., NAKAI, M. The influence of random surface roughness on frictional noise. Bulletin of Japan Society of Mechanical Engineers, 1982, 25(203), 827-833, doi: 10.1299/jsme1958.25.827. 8. OTHMAN, M. O., ELKHOLY, A. H., SEIREG, A. A. Experimental investigation of frictional noise and surface-roughness characteristics. Experimental Mechanics, 1990, 30(4), 328-331, doi: 10.1007/BF02321499. 9. WANG, Pin-Ning, HO, Mig-Hsiung, CHENG, Kou-Bing, MURRAY, Richard, LIN, Chun-Hao. Study on the friction sound properties of natural-fiber woven fabrics. Fibres & Textiles in Eastern Europe, 2017, 25(2), 34-42, doi: 10.5604/12303666.1228183. 10. YI, E., CHO, G. Fabric-sound classification by autoregressive parameters. The Journal of The Textile Institute, 2000, 91(4), 530-545, doi: 10.1080/00405000008659126. 11. YI, Eunjou, CHO, Gilsoo. Fabric sound parameters and their relationship with mechanical properties. Textile Research Journal, 2000, 70(9), 828-836, doi: 10.1177/004051750007000911. 12. YI, Eunjou, CHO, Gilsoo, NA, Youngjoo, CASALI, John G. A fabric sound evaluation system for totally auditory-sensible textiles. Textile Research Journal, 2002, 72(7), 638-644, doi: 10.1177/004051750207200712. 13. KIM, Chunjeong, CHO, Gilsoo, NA, Youngjoo. Effects of basic weave differences in silk fabric and yarn type variations in satin weave on sound parameters. Textile Research Journal, 2002, 72(6), 555-560, doi: 10.1177/004051750207200616. 14. KIM, Chunjeong, CHO, Gilsoo, YOON, Hyesin, PARK, Shinwoong. Characteristics of rustling sounds created by the structure of polyester warp knitted fabrics. Textile Research Journal, 2003, 73(8), 685-691, doi: 10.1177/004051750307300805. 15. CHO, Soomin, CHO, Gilsoo, KIM, Chunjeong. Fabric sound depends on fiber and stitch types in weft knitted fabrics. Textile Research Journal, 2009, 79(8), 761-767, doi: 10.1177/0040517508099915. 16. PARK, Changsoon, CHO, Gilsoo. Analysis of acoustic characteristics of fabrics in terms of mechanical properties. Fibers and Polymers, 2012, 13(3), 403-410, doi: 10.1007/s12221-012-0403-6. 17. YOSOUF, Khaldon, LATROCH, Hadj, SCHACHER, Laurence, ADOLPHE, Dominique C., DREAN, Emilie, ZIMPFER, Véronique. Frictional sound analysis by simulating the human arm movement. AUTEX Research Journal, 2017, 17(1), 12-19, doi: 10.1515/aut-2015-0033. 294 Tekstilec, 2020, Vol. 63(4), 294-304 | DOI:'0.'4502/Tekstilec2020.64.294-304 Ekrem Gulsevincler', Mustafa Resit Usal2, Demet Yilmaz3 ' Kastamonu University, Electric and Energy Department, Abana Sabahat Mesut Yilmaz Vocational School, 37970 Kastamonu, Turkey 2 Suleyman Demirel University, Department of Mechanical Engineering, Faculty of Engineering, 32260 Isparta, Turkey 3 Suleyman Demirel University, Department of Textile Engineering, Faculty of Engineering, 32260 Isparta, Turkey The Effect of Humidified Air on Yarn Properties in a Jet-Ring Spinning System Vpliv navlaženega zraka na lastnosti preje, izdelane v curkovnem prstanskem predilnem sistemu Original scientific article/Izvirni znanstveni članek Received/Prispelo 5-2020 • Accepted/Sprejeto '0-2020 Corresponding author/Korespondenčna avtorica: Dr. Ekrem Gulsevincler E-mail: egulsevincler@kastamonu.edu.tr ORCID: 0000-0002-4787-6275 Abstract In this study, the effect of 100% atmospheric relative humidity on yarn properties was investigated using jetring nozzles and compared with the yarn properties of yarns produced with air operated jet-ring nozzles under normal conditions. As a humidification system, a pneumatic conditioner, also known as a lubricant, was used in pneumatic systems. This conditioner was connected just before the pneumatic distributor that supplies air to the nozzles. The tube in stage 2 of the conditioner was filled with pure water at room temperature (25 °C ± 2 °C). The air conditioner dose was adjusted to 100% atmospheric relative humidity. The use of humidified air to jet-ring nozzles had a slight positive effect on all yarn properties (yarn hairiness, yarn irregularity, yarn elongation and yarn tenacity). According to the results, it resulted in a 1% to 3% improvement in yarn quality. This study is the first example and an original study in this field, as there is no study using humidified air in existing jet-ring air nozzle studies. It was proven in this study that humidified air results in a slight improvement in yarn properties. Keywords: yarn quality, yarn hairiness, jet-ring, nozzle-ring, air nozzle, yarn properties Izvleček V tej študiji je bil proučevan vpliv 100-odstotne relativne zračne vlažnosti na lastnosti preje, izdelane z uporabo curkovnih šob, in njena primerjava z lastnostmi preje, izdelane z uporabo curkovnih šob v normalnih okoliščinah. Kot sistem za vlaženje se v pnevmatskih sistemih uporablja pnevmatski vlažilec, ki se uporablja tudi kot mastilna naprava. Ta naprava je nameščena tik pred pnevmatski razdelilnik, ki v šobe dovaja zrak. Cevka mastilne naprave je bila v drugi fazi napolnjena s čisto vodo sobne temperature (25 °C ± 2 °C). Delovanje klimatske naprave je bilo naravnano na 100-odstotno relativno vlažnost zraka. Uporaba navlaženega zraka na curkovni šobi je nekoliko izboljšala vse lastnosti preje (kosmatost, neenakomernost, raztezek in trdnost preje). Rezultati zagotavljajo 1-3-odstotno izboljšanje kakovosti preje. Ta študija je prva na tem področju, saj v obstoječih študijah prstanskih curkovnih šob uporaba navlaženega zraka ni znana. Ključne besede: kakovost preje, kosmatost preje, curek-prstan, obroč šobe, zračna šoba, lastnosti preje The Effect of Humidified Air on Yarn Properties in a Jet-Ring Spinning System 295 1 Introduction Within the textile sector, the measurement and evaluation of yarn hairiness and hairiness variation on the yarn gradient line is an important part of the total quality control of a yarn. Particularly as the result of various technological developments, an increase in machine speeds and an increase in quality expectations, yarn hairiness has become an important yarn parameter that should be controlled through measurement. Spinning systems used in yarn production function according to the principle of real or false twist. The most typical example of a spinning machine functioning according to the actual bending principle is the conventional ring spinning system. The conventional ring spinning system, one of the first developed spinning systems, has been one of the most widely used spinning methods from the past to the present. One end of a fibre bundle or group of filaments is held constant while the twist type based on the principle of turning the other end along its axis is called a true twist. In contrast, a false twist imparts a temporary twist to the fibre bundle. However, after separation from the twist element, the fibres are parallel and untwisted. As a result, there is no twist on the fibre bundle and therefore no real strength is imparted to the yarn. This principle is contrary to normal yarn with the specific requirement to gain strength. Nevertheless, if the system is modified, it is possible to spin a yarn with a suitable strength value with the false twist principle in the same system. The most important developments in the field of spinning have been in the field of false twist or winding spinning. The original idea of the false twist principle is based on the addition of fibres to the false twist structure following the removal of the torque at the output of the false twist element and the rotation of the inserted fibres in the opposite direction. This is very similar to the idea that the fibres emerging from the yarn surface are wound around the centre of the yarn. Such fibres trapped in the structure ensure the high cohesion of the yarn even after twisting. Various researchers have used devices and processes that have similar effects on their patents. One of the most important patents is Murata's air-jet spinning system. The first design for the concept of obtaining fibres by collecting and twisting fibres using a rotating fluid was developed by Gotzfried [1]. Gotzfried [1] and then Pacholski et al. [2] showed that air jets entering tangentially into the nozzle hole caused a vortex in the nozzle, and could be twisted to the yarn passing through the centre of the rotating air stream at high speeds [3]. The development of modified spinning systems with the addition of air nozzles to various spinning systems and research on the effect of these systems on yarn properties have been studied in recent years. 1.1 Jet-ring (nozzle-ring) spinning system This system is based on the placement of air nozzles used in the air-jet spinning system between the output system of the conventional ring spinning system and the yarn guide system, referred to as a jet-ring or nozzle-ring (Figure 1). Air is fed into the air nozzle used in the jet-ring system at a certain pressure value. Compressed air creates a rotating air vortex in the nozzle. The air vortex ensures that the fibre ends that protrude outward from the yarn body are wound up in the yarn body, thereby reducing yarn hairiness [5]. In addition to low yarn hairiness, fabrics made from the aforementioned yarns are smoother and more resistant to pilling than fabrics made from conventional ring-spun yarns. Air nozzles thus provide improved yarn properties and long-term advantages due to improvements in fabric performance. Figure 1: Use of an air nozzle on a jet-ring spinning system 296 Tekstilec, 2020, Vol. 63(4), 294-304 The first experiments with jet -ring or nozzle-ring spinning system were carried out towards the end of the 1990s by Wang et al. [6]. Recently, however, many researchers have been working on yarn properties, in particular on the improvement of yarn hairiness over the use of air nozzles in a conventional ring spinning system [5-9]. Yilmaz [7] evaluated the effect of a pseudo-twist on the yarn properties of compressed air fed into the air ring in the conventional ring spinning system. In order to determine the performance of the core, the yarns produced as Ne 30/1 yarn represent the linear density. In this study, the air nozzle in the conventional ring spinning systems were assembled and produced using yarns, referred in literature as "jet-ring yarn". Yilmaz determined that there was not a single type of flat hair with the lowest hairiness values. It has been determined that the rate of improvement in hairiness values changes depending on the structural parameters and air pressure value. However, it was found that different yarn types were effective on other yarn properties that determine the yarn quality, as well as yarn hairiness. It was determined that a jet-ring modified yarn spinning system consisting of an air nozzle results in a reduction in the number of short fibres of measuring 1 mm and 2 mm, as well as the long hair count. 2 Material and methods 2.1 Air nozzle A jet-ring (nozzle-ring) spinning system comprises three basic components: compressed air, nozzle and yarn. Compressed air with a certain value from the compressor is transported to the level and passed through the thread. The nozzle assembly (Figure 2c) has a very simple structure and consists of a nozzle housing (Figure 2a) and nozzle body (Figure 2b). The nozzle body part has a circular cross-section consisting of the twisting chamber (main hole) (1), a) b) Figure 2: Nozzle (a) housing, (b) body and (c) assembly injectors (2), connecting screw for the nozzle housing (3) and the nozzle outlet (4) (Figure 2b). The main hole extends from the nozzle inlet to the nozzle outlet. The injectors are positioned tangentially to the twisting chamber. The nozzle housing conveys the compressed air from the compressor to the twisting chamber section of the device via the injectors [8, 9]. Flow volume is illustrated in Figure 3. As shown in Figure 3, the design parameters of the air nozzles are composed of twist chamber diameter (Dtc), injector diameter (Di) and injector angle (0). A nozzle length is 27mm and twisting chamber diameter of § = 2 mm was maintained in all samples. 2.2 Experimental setup The structural parameters of the jet-ring nozzle used to determine the effect on air humidified nozzles are given in Table 1. Ten nozzle types were defined for this experiment. Generally, air nozzles do not work on a bending chamber diameter of more than § = 3 mm and an injector diameter of more than § = 0.9 mm [5, 7, 9]. In this study, samples with large twist chamber and injector diameters were preferred in order to minimize the effect of humidified and increased air density on the pressure loss problem. Yarn production was performed using a Merlin SP43 conventional ring spinning machine made by the Pinter Group, with a capacity of 16 spindles. Jet-ring air nozzles mounted on a conventional ring spinning machine are shown in Figure 4. 2.3 Air humidifier system A pneumatic conditioner, also known as a lubricant, was used as the air humidification system, which is generally connected to the compressor outlet in pneumatic systems (Figure 5). This conditioner was connected just before the pneumatic distributor that supplies air to the nozzles. A typical pneumatic lubricant consists of two stages. In the first stage, the The Effect of Humidified Air on Yarn Properties in a Jet-Ring Spinning System 297 moisture in the air is maintained, i.e. atmospheric humidity is established. Water is an undesirable feature in pistons, cylinders, pneumatic actuators or similar systems that generally operate within a pneumatic system. For this reason, special pneumatic dryers are also used in large industrial plants. In the second stage of the conditioner, the dried air was lubricated using oil contained in the conditioner tube at the desired dose. The aim of this approach is to ensure that pneumatic systems function with oil, silently and over a long useful life. In this study, it was used outside the purpose of the conditioner. The tube in the second stage of the conditioner was filled with pure water at room temperature (25 °C ± 2 °C) instead of oil. The air leaving the conditioner in this way can be air containing moisture or even water instead of oily air. The aim of this study was not to contain water, but to obtain air with 100% relative humidity. Therefore, before starting the experiment, the conditioner dose was adjusted to 100% relative humidity. Humidity measurements were confirmed using an E+E brand model EE160 temperature and relative humidity transmitter (Figure 6). The EE160 temperature and relative humidity transmitter can Figure 3: 3D model drawing of a conventional nozzle flow volume with four injectors Table 1: The structural parameters of the jet-ring nozzle Nozzle no. (mm) Injector diameter (mm) Injector qty Injector angle (°) 1 3 0.8 4 20 2 3 0.8 4 25 3 3 0.8 4 30 4 3 0.8 4 35 5 3 0.8 4 40 6 3 0.9 4 20 7 3 0.9 4 25 8 3 0.9 4 30 9 3 0.9 4 35 10 3 0.9 4 40 298 Tekstilec, 2020, Vol. 63(4), 242-2.55 Figure 4: Jet-ring air nozzles mounted on a conventional ring spinning machine Figure 5: Pneumatic lubricator for use with an air-nozzle humidifier 1 - jetring air nozzle hoses, 2 - pneumatic air distributor, 3 - pneumatic lubricator - air outlet, 4 - ball valve, 5 - pneumatic lubricator, 6 - pneumatic lubricator - air inlet, 7 - air flow direction, 8 - stage 2, 9 - stage 1 be used to measure ambient temperature with an accuracy of ± 0.3 °C and relative humidity with an accuracy of ± 2.5%. With its analog/modbus output, the EE160 can transfer digital data to PLC (programmable logic controller) or HMI (human machine interface, touch screen) systems. In this study, EE160 temperature and humidity transmitter was connected to an electrical panel containing an HMI, and data analysis was performed (Figure 7). 2.4 Yarn production One-hundred percent cotton yarns were produced in this experiment. We produced cotton jet-ring yarns of 19.6 tex (Table 2). In all yarn productions, importance was given to working with the same spinning parameters, e.g., the same twist multiplier, draft, spindle speed and traveller type (Table 3). The number of injectors was kept constant as four pieces. In all jet-ring yarn productions, the air pressure was kept at 125 kPa (gauge). The Effect of Humidified Air on Yarn Properties in a Jet-Ring Spinning System 299 Figure 6: E+E EE160 temperature and humidity Figure 7: Electrical panel containing HMI transmitter Table 2: Fibre properties Fibre properties 19.6 tex Staple length (mm) 30.53 Micronaire 4.52 U.I. (uniformity index) 85.7 Strength (cN/tex) 34.5 Breaking elongation (%) 6.4 SFI (short fibre index) 6.9 +b (yellowness) 7.9 Rd (reflectance degree) 72.1 CG (colour grade) 41-2 SCI (spinning count index) 160 Table 3: Spinning particulars Parameters 19.6 tex Roving count (tex) 472 Twist (1/m) 830 3.7 Mean spindle speed (rpm) 13000 Take up speed (m/min) 15.7 Traveller type SFB 2.8 PM udr Traveller ISO No. 31.5-50 Ring diameter (mm) 38 Draft/Break draft 1.181 Total draft 50.4 2.5 Yarn tests Yarn hairiness, irregularity and imperfection tests were carried out using an Uster Tester 3. Tensile property (percentage of elongation and tenacity measured as cN/tex) tests were carried out using an Uster Tensorapid. The cops and bobbins of each system were fed in the same order to the testers. Yarn test details are given in Table 4. The tests were 300 Tekstilec, 2020, Vol. 63(4), 294-304 Table 4: Test particulars for each yarn sample Yarn properties Test device Test length (m) Test number Total length (m) Yarn irregularity and imperfections Uster Tester 3 400 1 400 Yarn hairiness Uster Tester 3 400 1 400 Tensile properties Uster Tensorapid 0.5 10 5 carried out under the same atmospheric conditions (75% ± 5% relative humidity and 25 °C ± 2 °C), and we conditioned samples for a minimum of 72 hours before the tests. All the tests were carried out on the same testers and test results were analysed statistically to determine any significant differences. 3 Results and discussion 3.1 Yarn hairiness results The effect of conditioned and normal air on yarn hairiness (H) is illustrated in Figure 8 for an injector diameter of Q = 0.8 mm and in Figure 9 for an injector diameter of Q = 0.9 mm. In both injector diameter values, normal air and conditioned air resulted in similar hairiness values in the first measurement. In the second measurement one week later, an increase in hairiness was expected, as the yarn was completely dry. On the contrary, however, a surprising slight reduction in hairiness occurred. For yarn produced using a humidified air nozzle, hairiness values in the second measurement (after one week) decreased by approximately 0.1-0.2 compared to the hairiness values in other measurements. Conditioning (humidified) air improves the yarn hairiness value. Expressed in percentages, it means an improvement in hairiness of about 1.5% to 3.5%. 3.2 Yarn irregularity results The effect of conditioned and normal air on yarn irregularity (% Cv m) is illustrated in Figure 10 for an injector diameter of § = 0.8 mm and in Figure 11 for an injector diameter of § = 0.9 mm. A slight decrease in yarn unevenness was observed according to the condensed air measurements of an injector diameter of § = 0.9 mm. The situation is slightly different for condensed air measurements of yarns produced in configurations with an injector diameter of § = 0.8 mm. A reduction in yarn irregularity was observed when using humidified air in 20° and 25° nozzle configurations. However, the yarn irregularity value increased in both in a 30° nozzle configuration, and in a 35° nozzle configuration (second condition) and in a 40° nozzle configuration (first condition). Nevertheless, in general, it can be said that the yarn irregularity value is reduced by 0.1% to 0.4% in yarns produced with humidified air. Humidified air was observed to improve both yarn irregularity and yarn hairiness. Injector diameter 0 = 0.8 mm Normal/humidified air yarn hairiness measurement 6,9 6,8 6,7 £ 6,6 I 6,5 « | 6,4 ^ 6,3 6,2 6,1 6,0 Injector angle -■ Normal air □ Humidified air first measurement □ Humidified air second measurement Figure 13: Effect of conditioned and normal air on yarn elongation (injector diameter: < = 0.9 mm) The Effect of Humidified Air on Yarn Properties in a Jet-Ring Spinning System 301 Injector diameter 0 = 0.9 mm Normal/humidified air yarn hairiness measurement 6,9 6,8 6,7 6,6 6,5 6,4 6,3 6,2 6,1 Injector angle - ■ Normal air ■ Humidified air first measurement □ Humidified air second measurement 6,29 6,35 6,85 6,84 6,39 6,17 6,14 6,13 6,35 6,58 Figure 9: Effect of conditioned and normal air on yarn hairiness (injector diameter: < = 0.9 mm) Injector diameter 0 = 0.8 mm 13,8 13,6 13,4 IT > 13,2 F' was less than 0.05. The ANOVA table also shows a term of residual error, which measures the amount of variation in the response data left unexplained by the model. The lack of fit term in the residual indicates the variation due to model inadequacy. All p-values for the lack of fit (larger than 0.05 for all responses) indicate that the model adequately fits the data. In other words, the form of the model chosen to explain the relationship between the factors and the response is correct and all the prerequisites associated with the use of ANOVA are met as well. The concentrations of FeSO4, NaOH, temperature and time were significant model factors, the model equation in coded form being shown in equation 3. K/S = -1248 + 9.32 x A + 73.89 x B + 1.19 x C + 1.82 x D - 0.32 x A x B + 0.01 x A x C -1.16 x A x D - 0.04 x B x C - 0.05 x B x (3), D - 3.88E-004 x C x D -0.02 x A2 - 1.04 x B2 - 1.85E-004 x C2 - 1.24E-003 x D2 where different values of A, B, C, D are presented in Table 4. A is the dimensionless number taken from Table 4 neglecting the unit, i.e. considering the absolute minimum values, A = 25, B = 26, C = 60 and D = 60. The same is true for the intermediate and maximum dimensionless values of A, B, C and D as shown in Table 4. This equation can predict the theoretical K/S of dyed specimens for given dyeing parameters. Subtracting non-significant factors from equation 3 having p-val-ue beyond 0.5, i.e. AD, CD and C2, the final equation stands to: K/S = -1248 + 9.32 x A + 73.89 x B + 1.19 x C + 1.82 x D - 0.32 x A x B + 0.01 x A x (4). C - 0.04 x B x C - 0.05 x B x D - 0.02 x A2 - 1.04 x B2 - 1.24E-003 x D2 Table 6: ANOVA table for K/S Source Sum of squares df Mean square F value p-value Prob > F Significance Model 213.42 14 15.24 14.69 < 0.0001 Yes A - Iron(II)salt 5.33 1 5.33 5.14 0.0427 B - NaOH 6.02 1 6.02 5.80 0.0330 C - Temp. 155.52 1 155.52 149.83 < 0.0001 D - Time 8.84 1 8.84 8.52 0.0129 AB 10.24 1 10.24 9.87 0.0085 AC 2.40 1 2.40 2.31 0.1541 AD 0.12 1 0.12 0.12 0.7371 BC 1.96 1 1.96 1.89 0.1945 BD 11.22 1 11.22 10.81 0.0065 CD 0.12 1 0.12 0.12 0.7371 AA2 1.38 1 1.38 1.33 0.2717 BA2 5.83 1 5.83 5.62 0.0354 CA2 9.259E-003 1 9.259E-003 8.920E-003 0.9263 DA2 6.70 1 6.70 6.45 0.0259 Residual 12.46 12 1.04 Lack of fit 10.94 10 1.09 1.44 0.4783 No Pure error 1.52 2 0.76 Cor total 225.88 26 Eco-Friendly Vat Dyeing of Cotton Using Alkaline iron (II) Salt as Reducing Agent 313 3.3.1 Influence of FeSO4 and NaOH concentrations on K/S The combined effect of FeSO, and NaOH concentrations on K/S at moderate time and temperature is shown in Figure 3a. A lower concentration of NaOH (26 g/l) and high concentration of FeSO4 (35 g/l) resulted in maximum K/S, i.e. 21.8. At a lower concentration of NaOH, decreasing the concentration of FeSO, resulted in a decrease in the colour strength (K/S) of cotton. At a higher concentration of NaOH, there was an increase in the K/S value up to a certain limit after which it decreased with a further increase in the FeSO concentration. An 4 increased concentration of FeSO4 might decrease the concentration of NaOH in the dyebath due to the formation of insoluble Fe(OH)2 affecting the solubility of the reduced vat. A lower concentration of NaOH had a positive effect on K/S. Additional NaOH might resist the diffusion of particles through fibre pores. 3.3.2 Influence of FeSO4 and temperature on K/S The combined effect of FeSO4 and temperature on K/S at moderate NaOH and time is shown in Figure 3b. A higher FeSO4 concentration and temperature resulted in maximum K/S, i.e. 21.8. At lower temperature, decreasing the FeSO4 concentration, the K/S value increased, whereas at high temperature, decreasing the FeSO, concentration resulted in decreased K/S. At lower temperature, the activation energy of dyeing was too low to solubilise ferrous hydroxide, resulting in decreased K/S. Figure 3a: Effect of interaction of iron (II) salt and NaOH on K/S FeS04i Figure 3b: Effect of interaction of iron (II) salt and NaOH on K/S 314 Tekstilec, 2020, Vol. 63(4), 305-320 3.3.3 Influence of FeSO4 and time on K/S The combined effect of FeSO4 and time on K/S at moderate NaOH and temperature is shown in Figure 3 c. A higher concentration of FeSO4 and moderate time resulted in maximum K/S, i.e. 21.8. At a higher as well as at a lower concentration of FeSO,, the K/S value showed an increasing trend for moderate time and went further on decreasing. At shorter and longer times, the K/S value showed an increasing trend with an increase in the concentration of FeSO4. At a higher concentration of FeSO4, the vat dye completely diffused into fibre pores at moderate time; additional time may further reduce this effect. Longer dyeing time may possibly reduce the activation energy required for the absorption and fixation of the dye on fibre surfaces. 3.3.4 Influence of NaOH and time on K/S The combined effect of NaOH and time on K/S at moderate concentration of FeSO4 and temperature is shown in Figure 3d. A low concentration of NaOH and longer time resulted in maximum K/S, i.e. 21.8. At shorter time with increased NaOH concentration, there was an increase in the K/S value up to a certain limit succeeded by a decrease regardless of a further increase in the NaOH concentration. At longer time, there was a decrease in the K/S value with an increase in the NaOH concentration. At a lower concentration of NaOH, there was an increase in K/S with time and at a higher concentration of NaOH, there was a decrease in K/S with time. A longer time of the dyebath by decreasing the alkali concentration may achieve the desired reduction potential that increases colour strength. Figure 3c: Effect of interaction of iron (II) salt and time on K/S Figure 3d: Effect of interaction of NaOH and time on K/S Eco-Friendly Vat Dyeing of Cotton Using Alkaline iron (II) Salt as Reducing Agent 315 D: Time Figure 3e: Effect of interaction of time and temperature on K/S 3.3.5 Influence of temperature and time on K/S The combined effect of temperature and time on K/S at a moderate concentration of FeSO, and NaOH is shown in Figure 3e. Higher temperature and moderate time resulted in maximum K/S, i.e. 21.8. At higher as well as at lower temperature, there was an increase in the K/S value up to a certain point of time after which it decreased despite a further increase in time. A longer time period at higher temperature may take additional water due to the exhaustion of the dyebath, which changes ferrous iron to ferric iron, resulting in reduced reduction potential. For a shorter as well as a longer amount of time, there was an increase in the K/S value with an increase in temperature. 3.4 Influence of NaOH on reduction potential and pH In the alkaline iron (II) salt system, 0.84 g of NaOH was taken for the stoichiometry requirement. At that time, pH was neutral as well. A further addition of extra NaOH was responsible for an increase in the solubility of ferrous hydroxide, which increased the reduction potential. Fe(OH)2 solubility increased with an increase in the alkalinity at a certain limit. It was calculated that 3 g Iron (II) salt required 0.84 g of NaOH for the stoichiometric requirement. Additional NaOH was used to maintain the alkaline medium. In this study, 1.8 g NaOH was used for sol-ubilisation. The amount of sodium hydroxide varied in the reaction medium from 0.15 g to 5.65 g. The effect of this variation on the evolution of the redox potential of the medium and pH was investigated. The experimental results are shown in Figure 4. It can be observed that at sodium hydroxide amounting to 0.15 g to 0.75 g, there was a slow increase in the redox potential and pH, respectively. The increase in the amount of sodium hydroxide led to a rapid jump of the redox potential and pH. At a further addition of 2.25 g of NaOH, the reduction potential and pH remained quasi stable. Therefore, it appears that the alkali addition increased the rate of the vat reduction with iron (II) salt. Figure 4: Effect of alkali concentration on pH and reduction potential of dyebath 3.5 Stability of reduction baths 3.5.1 In absence of dye The stability of reduction baths was studied in the absence of the dye for up to 24 hours with hy-drosulphite and the alkaline iron (II) salt system. Reduction baths were prepared and covered; the reduction potential and pH of the baths were checked after being stored for a specific period of time. Vat Table 7: Stability of reduction baths in absence of dye Time (h) Reduction potential, U (mV) and pH at various stages Before reduction of dye After reduction of dye After completion of dyeing Hydro Iron II Hydro Iron II Hydro Iron II pH U (mV) pH U (mV) pH U (mV) pH U (mV) pH U (mV) pH U (mV) 0 12.84 -872 13.95 -708 12.70 -760 13.83 -705 12.40 -748 13.71 -665 1 12.84 -865 13.94 -718 12.58 -755 13.85 -705 12.28 -750 13.69 -633 2 12.83 -870 13.96 -711 12.39 -767 13.84 -648 12.19 -720 13.70 -639 4 12.82 -782 13.93 -705 12.60 -740 13.83 -646 12.20 -730 13.65 -634 8 12.80 -706 13.94 -713 12.40 -685 13.84 -660 12.34 -640 13.67 -620 12 12.82 -680 13.94 -704 12.54 -660 13.82 -655 12.32 -610 13.68 -620 24 12.86 -655 13.92 -696 12.40 -620 13.81 -641 12.27 -580 13.65 -616 316 Tekstilec, 2020, Vol. 63(4), 242-2.55 Green XBN (1%) was then added to the baths. The dyeing was carried out, with the results presented in Table 7. There was a progressive drop in U (mV) and pH in both reduction baths with the passage of time. K/S gradually decreased with an increase in storage time in both reduction systems. Hydrosulphite-based reduction baths retained the required reduction potential for up to four hours compared to the alkaline iron (II) salt-based reduction baths in 24 hours. 3.5.2 In presence of dye Reduction baths with hydrosulphite and alkaline iron (II) salt were prepared, followed by the addition of Vat Green XBN (1%). The baths were covered and stored for up to 24 hours. The results were noted in terms of pH and reduction potential, and are presented in Table 8. The rate of the fall in the reduction potential was higher in the hydrosulphite system. In contrast, alkaline iron (II) salt-based systems showed a very slow fall in the reduction potential. However, pH remained in both systems at a higher level. Reduced dyebaths showed the maximum colour strength for dyeing at 0-2 hours (cf. Table 9). The hydrosulphite bath showed stability for up to four hours compared to that in the alkaline iron (II) system for 24 hours with a progressive fall in colour strength with time. 3.6 Fastness performance The colourfastness of cotton dyed in the hydrosul-phite and alkaline iron (II) salt systems was evaluated. The results are shown in Table 10. The lightfast-ness of dyed cotton remained very good to excellent and almost the same in both systems for the ten dyes Table 8: Stability of reduction baths in presence of dye Time (h) Reduction potential, U (mV) and pH at various stages Before dye reduction After dye reduction After completion of dyeing Hydro Iron II Hydro Iron II Hydro Iron II pH U (mV) pH U (mV) pH U (mV) pH U (mV) pH U (mV) pH U (mV) 0 12.74 -850 13.64 -780 12.60 -865 13.53 -790 12.30 -810 13.34 -770 1 12.74 -810 13.58 -765 12.38 -825 13.46 -775 12.18 -770 13.26 -760 2 12.73 -770 13.47 -760 12.29 -775 13.40 -760 12.09 -760 13.35 -720 4 12.72 -740 13.55 -740 12.5 -735 13.45 -745 12.10 -640 13.29 -730 8 12.70 -690 13.51 -730 12.30 -670 13.36 -740 12.19 -520 13.32 -697 12 12.72 -500 13.55 -725 12.34 -450 13.48 -735 12.12 -400 13.42 -695 24 12.66 -450 13.50 -710 12.2 -400 13.35 -720 12.05 -350 13.24 -685 Eco-Friendly Vat Dyeing of Cotton Using Alkaline iron (II) Salt as Reducing Agent 317 under study, except for the Yellow 5G dye. Wash fastness, and dry and wet crock-fastness results showed identical, excellent fastness properties for both the hydrosulphite and alkaline iron (II) salt systems, except for the Brown R dye. Overall, the colourfast-ness of cotton dyed using the alkaline iron (II) salt systems showed comparable performance with the cotton dyed with the hydrosulphite system. Table 9: Effect of storage time on K/S in presence and absence of dye Time (h) Colour strength (K/S) Sodium hydrosulphite Alkaline iron (II) salt Presence of dye Absence of dye Presence of dye Absence of dye 0 22.7 22.6 21.4 21.2 1 20.2 22.7 21.4 18.9 2 18.9 20.8 22.12 18.4 4 15.9 16.4 20.68 16.43 8 0 0 19.46 16.2 12 0 0 17.8 15.9 24 0 0 14.5 13.4 Vat dye Reducing system Wash fastness Crock fastness Light fastness Colour change Stain on cotton Stain on wool Dry Wet Brown BR Hydrosulphite 5 5 5 5 4-5 7 Alk. iron (II) 5 5 5 5 4-5 7 Yellow 5G Hydrosulphite 5 5 5 5 5 5 Alk. iron (II) 5 5 5 5 5 5 Gold Orange Hydrosulphite 5 5 5 5 5 7 Alk. iron (II) 5 5 5 5 5 7 Red 6B Hydrosulphite 5 5 5 5 5 7 Alk. iron (II) 5 5 5 5 4-5 7 Grey M Hydrosulphite 5 5 5 5 5 7 Alk. iron (II) 5 5 5 5 4-5 7 Brown R Hydrosulphite 5 5 5 5 5 8 Alk. iron (II) 5 5 5 5 4-5 7 Indigo Hydrosulphite 5 5 5 5 4-5 7 Alk. iron (II) 5 5 5 5 4-5 7 Blue BC Hydrosulphite 5 5 5 5 4-5 8 Alk. iron (II) 5 5 5 5 4-5 8 Olive Green B Hydrosulphite 5 5 5 5 5 7 Alk. iron (II) 5 5 5 5 5 7 Green XBN Hydrosulphite 5 5 5 5 4-5 8 Alk. iron (II) 5 5 5 5 4-5 8 Table 10: Colourfastness of cotton dyed in hydrosulphite and alkaline iron (II) salt systems 318 Tekstilec, 2020, Vol. 63(4), 242-2.55 3.7 Comparison of colour strength of treated samples A comparison was made of the colour strength of the samples dyed with different vat dyes with hydrosulphite, alkaline iron (II) salt system and HCl-treated after the soaping in the alkaline iron (II) salt system. Figure 5 shows that all these dyes showed comparable colour strength in the hydrosulphite and alkaline iron (II) salt system though the HCl-treated samples showed slightly lower colour strength. Table 11: Effect of pH on solubility pH Solubility of Fe(OH)2 (g/l) 7 0.0143 8 0.27 9 0.55 10 0.83 11 1.11 12 1.39 13 1.67 14 1.95 d> ° Vat dyes ■ Hydrosulphite □ Alkaline Iron (II) salt □ HCl treated Figure 5: Comparison of K/S obtained as control, reference and HCl-treated In addition to the result without an HCl treatment, there was a slight difference in colour strength between the control and reference sample. The alkaline iron (II) salt system might be used as an alternative reducing agent; however, it gives a non-uniform deeper shade, indicating the deposition of the insoluble dye and insoluble iron on samples. For a brighter and uniform shade, an HCl treatment is required. 3.8 Solubility of Fe(OH)2 3.8.1 Effect of pH The effect of alkali on the solubility of Fe(OH)2 is determined by titrating the standard dyebath solution with K2Cr2O7. Fe(OH)2 is insoluble at pH 7; a gradual addition of NaOH increases pH, resulting in the solubility of Fe(OH)2. The optimised concentration of alkaline iron (II) salt was taken and pH varied from 7 to 14 by adding NaOH and increasing the solubility of Fe(OH)2 by up to 1.95 g/l as shown in Table 11. 3.8.2 Effect of temperature in alkaline medium The solubility of Fe(OH)2 only by adding NaOH was not adequate for the reduction of the vat dye. At low temperature, the heat or chemical energy is not sufficient for the diffusion or penetration of the dye into fibre pores. The increase in temperature is essential to synergise the reduction potential. The effect of temperature on solubility in an alkaline medium was hence studied. In Figure 6, it is shown that with an increase in temperature in an alkaline medium, the solubility of Fe(OH)2 increased, showing a better result in colour strength. An incomplete vat dye reduction was found at lower temperature and a complete dye reduction at higher temperature. At 30 °C, the solubility of Fe(OH)2 was 1.95 g/l compared to that at 90 °C, which was 3.07 g/l. The amount of total Fe(OH)2 at iron (II) salt 30 g/l and NaOH 27 g/l was 23.4 g/l, where the amount of soluble Fe(OH)2 in the dyebath was 3.07 g/l, the rest remaining insoluble. 3,5 3 ^ 2,5 ii 2 !5 f 1,5 1 0,5 0 Ä 5—-1- 20 40 60 80 100 Temperature (5°C) Figure 6: Effect of temperature in alkaline medium on solubility of Fe(OH)2 Eco-Friendly Vat Dyeing of Cotton Using Alkaline iron (II) Salt as Reducing Agent 319 4 Conclusion In this study, alkaline iron (II) salt was used to replace sodium hydrosulphite in the vat dyeing of cotton. Iron (II) salt forms Fe(OH)2 in a reaction with NaOH; the former may act as a strong reducing agent. However, due to a very poor solubility of Fe(OH)2 in lower alkaline pH, its performance as a reducing agent cannot be realised. An increase in the concentration of NaOH increases the solubility of Fe(OH)2, thus approaching to a concentration of both chemicals, i.e. FeSO, and NaOH, to attain * 4 * the reduction potential as high as -780 mV, showing the capability to reduce all vat dyes. An increase in temperature enhances the reduction potential of the bath as well. The surface colour strength of cotton remained almost comparable along with colourfast-ness. 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