ª. BÜLBÜL et al.: THE EFFECT OF WOOD ASH ON THE MECHANICAL PROPERTIES OF RUBBER COMPOUNDS
333–339
THE EFFECT OF WOOD ASH ON THE MECHANICAL
PROPERTIES OF RUBBER COMPOUNDS
VPLIV LESNEGA PEPELA NA MEHANSKE LASTNOSTI
GUMIJASTIH ZMESI
ªaban Bülbül
1*
, Nurettin Akçakale
2
, Mustafa Yaºar
3
, Hakan Gökmeºe
4
1,4
Necmettin Erbakan University, Faculty of Seydiºehir Ahmet Cengiz Engineering, Konya 42370, Turkey
2
Abant Ýzzet Baysal University, Gerede Vocational School of Higher Education, Bolu 14900, Turkey
3
Karabük University, Faculty of Technology, Karabük 78050, Turkey
Prejem rokopisa – received: 2018-06-23; sprejem za objavo – accepted for publication: 2018-12-13
doi:10.17222/mit.2018.126
In this study, the effect of adding wood ash (oak tree) on the mechanical properties (tensile, abrasion, tearing, elongation %,
etc.) of NR/SBR-type elastomer materials was investigated. Five different compounds were prepared by adding 16 %, 32 %,
48 % and 64 % wood ash to the filler and additive materials in the general composition (G). The mechanical test results and
production costs of the new compounds composed were compared between themselves and with the G compound. The fracture
surfaces of the compounds as well as the shape and morphological distribution of the fillers in the rubber matrix were examined
using a Scanning Electron Microscope (SEM). As a result of the experimental studies, it was found that the new compounds
composed had an increased tensile and tearing strength, abrasion amounts, bending capability, unit elongation amounts and
densities in comparison to the G compound. A decrease was observed in the hardness values and material costs (production
cost) of the compounds.
Keywords: compounds, mechanical properties, wood ash
Avtorji opisujejo raziskavo vpliva dodatka lesnega pepela (hrasta) na mehanske lastnosti (natezne lastnosti, abrazija, trganje,
raztezek v %, itd.) elastomerov tipa NR/SBR. Pripravili so pet razli~nih vrst zmesi z dodatkom (16, 32, 48 in 64) w/% lesnega
pepela, ki so ga uporabili kot polnilni in dodajni material k osnovni sestavi (G; angl.: General). Rezultate mehanskih preizkusov
in stro{ke izdelave novih zmesi so primerjali med seboj in z zmesjo osnovne sestave G. Prelomne povr{ine zmesi, kakor tudi
morfolo{ko porazdelitev polnila v matrici iz gume so opazovali in analizirali s pomo~jo vrsti~nega elektronskega mikroskopa
(SEM). Na osnovi analize eksperimentalnih rezultatov avtorji ugotavljajo, da imajo izdelane nove zmesi povi{ano natezno in
stri`no trdnost, ve~jo odpornost proti abraziji in sposobnost upogibanja ter enovit raztezek v primerjavi z gumo osnovne sestave
G. Ugotavljajo tudi, da se je zmanj{ala trdota zmesi ter da so se zni`ali stro{ki njihove izdelave.
Klju~ne besede: gumijaste zmesi, mehanske lastnosti, lesni pepel
1 INTRODUCTION
Natural rubber (NR) has superior mechanical proper-
ties and excellent physical properties. Styrene Butadiene
Rubber (SBR) is a synthetic rubber that resembles natu-
ral rubber in terms of its physical properties. When
combined with natural rubber, they enhance the physical
and chemical properties as well as mechanical proper-
ties.
NR and SBR are used in many fields, especially in
shoe soles. Blending natural and synthetic rubber is not a
new idea. Studies in recent years have shown that binary
compounds have come to the forefront in providing the
desired results with the compounded rubber using the
appropriate material and methodology.
1
Natural and
synthetic rubber are not used alone, except in special
circumstances. In practice, these rubbers may not meet
the expected specifications when used alone. Rubber
compounds are frequently used in the rubber industry to
obtain compounds with lower costs as well as to improve
processability and the desired physical properties.
2
The
use of two different rubber materials in the compounds
could present features that are not possible with respect
to uniform rubber used compounds.
3
In recent years, the
increase in the demand to improve environmental aware-
ness and material properties has led to many studies.
4
Factors such as global warming, raw-material problems
and environmental pollution have been influential in the
use of renewable resources as backfilling materials for
investigated and recyclable materials. The addition of
particle-reinforced fillers to rubber materials is generally
intended to produce the desired commercial compounds.
5
According to literature studies, glass sphere, rice husk,
wollastonite, mica powder, gum, carbon black, phos-
phate, nanoclay, silica, calcite and nano calcium carbo-
nate, etc. were used by adding different fillers to rubber
compounds.
6–17
Carbon black is the most common filler
material used to impart both plastic properties to com-
pounds and to improve their physico-chemical proper-
ties.
18,19
However, due to unstable oil prices, it was
recently used both as a filler in mineral-based elastomer
materials and as a filler in non-recyclable materials.
20–22
Materiali in tehnologije / Materials and technology 53 (2019) 3, 333–339 333
UDK 620.1:67.017:631.831:621.921.8 ISSN 1580-2949
Original scientific article/Izvirni znanstveni ~lanek MTAEC9, 53(3)333(2019)
*Corresponding author e-mail:
sabanbulbul42@hotmail.com

Thus, oak wood ash, one of the most important ma-
terials among the materials that have not been recycled
contains 31.35 % calcium (Ca), 10.25 % potassium
(K
2
O), 7.57 % magnesium (Mg), 1.21 % sulfur (S) and a
small ratio of zinc (Zn). It is also a known fact that these
materials are used as fillers and additives in the polymer
sector.
23,24
According to a study of ªaban et al. carried
out in 2014, they proved that wood ash could be used as
an effective filler material in polymer materials.
25
It should be noted that our natural resources are not
infinite, that every source of production is reduced and
that our natural resources are completely lost if they are
carelessly used. The aim of this study is to show that
wood ash in the form of garbage that leads to environ-
mental pollution is a recyclable material that goes to
waste and to shed light on similar studies.
2 EXPERIMENTAL PART
2.1 Materials
NR RRS3 natural rubber and SBR 1502 styrene-buta-
diene rubber were obtained from Defne Kauçuk Import
and Export Co. Ltd., Turkey. Silica (SiO
2
), Kalsit
(CaCO
3
) and wood ash were purchased from Petkim
Inc., Miner Madencilik Co. Ltd. and Kafkas Etliekmek
Co. Ltd. Turkey, respectively. The other rubber com-
pounding ingredients used in the study were obtained
from Defne Kauçuk Import and Export Co. Ltd., Turkey.
Basic technical properties of the fillers are presented in
Table 1.
Table 1: General technical properties for the rubbers and fillers used
in the study.
Materials
Commercial
Names
Density
(g/cm
3
)
Particle Size
(μm)
Natural Rubber RSS 3 0.93 –
Styrene Butadien
Rubber
SBR 1502 0.94 –
Silica (SiO
2
)
Egesil BS 20
A
22 0
Kalsit (CaCO
3
)
Mikronize
Kalsit 0-40
2.6 25–40
Wood Ash – 2.3
20 (in
diameter)
2.2 Methods
2.2.1 Rubber compounding
The NR-SBR rubbers and fillers were compunded in
a laboratory-type banbury (Farrell brand) at 80 °C and
60 min
–1
for 10 min. After blending, the blend was left to
rest for 24 h. The dough was then blended in a two-roll
open mixer at 80 °C and at a speed of 40 min
–1
for 5 min,
followed by the addition of additives such as softeners,
activators, vulcanization accelerators and sulfur. This
stirring was continued for 3 min. Compound formula-
tions are given in Table 2.
Table 2: Composition of rubber compounds.
Compounds Sample Codes
G WA1 WA2 WA3 WA4
phr
Natural Rubber
(NR-RSS3)
50 50 50 50 50
Styrene Butadiene
Rubber (SBR 1502)
50 50 50 50 50
Silica 33.4 33.4 33.4 33.4 33.4
Calcite 26.6 26.6 26.6 26.6 26.6
Wood Ash - 16 32 48 64
Zinc Oxide 33333
Sulfur 1.5 1.5 1.5 1.5 1.5
Stearic Acid 1.5 1.5 1.5 1.5 1.5
PEG 4000
a
22222
DM
b
11111
CZ
c
11111
DPG
d
11111
a
Polyethylene glycol,
b
Dibenzothiazole disulphide,
c
N-Cyclohexyl-
2-benzothiazole sulphonamide,
d
Diphenyl guanidine
2.2.2 Vulcanization of rubber compounds
The rubber compounds were cut into small pieces
and placed into a compressible mold, specially designed
in accordance with test standards, and vulcanized in a
Hidrosan brand hot press, under a pressure of 160 MPa
at 160 °C. The vulcanization process continued for
5 min, which is a pre-determined optimum time for all
compounds. All these compounds used in the experimen-
tal studies were prepared under the same conditions.
2.2.3 Physico-mechanical characterization
All tests were performed after the compounds were
cut into the standard dimensions according to the related
test standards and were kept in an environment having 50
% relative humidity at 25±2 °C for 24 h. The tensile test
was performed (by using a Tinius H25KS tensile device)
with 10 mm/s according to ISO 37. During the tensile
test, the tensile strengths and elongation at the breaking
values of the samples were measured. Tear tests were
made according to ISO 34-1 by using the same equip-
ment as in the tensile testing. The hardness measurement
of the vulcanizates was conducted by using a Shore A
durometer (Commerciale, AFFRI 3001 model) according
to ISO 868. The densities of the compounds were
measured in line with Archimedes’principle (ISO 2781).
An abrasion test (with a Pegasil, CTC model device) was
applied in line with the ISO 4649 standard. In the abra-
sion tests, the standard test sample placed on the drum
completed 84 rotations in a 40-meter shifting distance
under 10 N perpendicular forces. A dimension stability
test was performed in accordance with the EN 12770
standard norm. Additionally, a stretching (fatigue) test
was applied to the compounds in line with the Ross-Flex
method (with a SATRA, STM 141/F model device) and
the ISO 5423 standard.
ª. BÜLBÜL et al.: THE EFFECT OF WOOD ASH ON THE MECHANICAL PROPERTIES OF RUBBER COMPOUNDS
334 Materiali in tehnologije / Materials and technology 53 (2019) 3, 333–339

2.2.4 Scanning electron microscopy (SEM) analysis
SEM images (with a Zeiss brand, Ultra/Plus model)
of the samples’ fracture surfaces after the tensile test
were observed. The fracture surfaces of the samples were
coated with 5-nm thick 100 % gold in order to prevent
electrostatic loading and increase the conductivity.
17,25,26
A Quorum, Q 150R ES model device was used for coat-
ing. During the examination of the microstructure the
preferred working voltage of the microscope was 20 kV.
The energy-dispersive x-ray spectroscopy (EDS) analysis
method was used to distinguish the components in the
sample.
3 RESULTS AND DISCUSSION
In this study, wood-ash-added NR/SBR rubber com-
pounds were examined in terms of their physical, mecha-
nical and morphological properties.
3.1 Physical and mechanical properties
The chemical and physical properties of rubber com-
pounds are directly affected by factors such as chemical
composition, particle sizes, physical properties, produc-
tion processes, ambient temperatures and the fillers used
in the rubber compounds. However, the rubber filler ra-
tios of the compounds are also one of the most important
factors affecting the rubber compounds.
3.1.1 Dimension stability and hardness
The wood ash added to the G compound firstly de-
creased the hardness of the compound and then the
hardness of the compounds increased with an increasing
ratio of wood ash in the compounds (Figure 1). The
hardness of the G compound was measured as 65 Shore
A. This value is the same as the hardness value of the
WA4 compound added with 64 % wood ash. The
hardness of the WA1 compound added with 16 % wood
ash is 60 Shore A. When compared to the G compound;
WA1, WA2 and WA3 compounds, except the WA4 com-
pound, were found to have a decreased hardness. First of
all, the decrease of the hardness of the rubber com-
pounds and an increase of the hardness again with the
increasing fill amount result from the rubber filler ratio.
It was suggested by Savran that that the rubber fill ratio
should be maximum 100 %.
27,28
In this study, except for
the WA1 compound, there is no other compound provid-
ing this condition. Therefore, the effect on the hardness
of wood ash in rubber compounds is not exactly reflected
(Figure 1).
The change in dimension of the G compound against
the temperature is 0.94 mm
3
. The maximum dimension
change in the new compounds composed was found in
the 16 % wood ash added WA1 compound (1.59 mm
3
). It
was seen that as the wood ash ratio in the compounds
increased, the dimensional changes decreased. The best
results in the new compounds were obtained in the WA4
compound. Compared with the G compound, the dimen-
sion change of the WA4 compound was increased by
29.8 %. In the searchable literature review, no data were
found about a comparison with regard to the dimensional
stability of elastomer materials. Therefore, in the com-
parison process of this study, the change in dimension
stability of rubber compounds in plants that are manu-
facturing polymer shoe soles was taken as a measure.
According to these evaluations, it is indicated that com-
pounds with 70 Shore A and a higher hardness should
have a dimension change of 1 %, and those with a hard-
ness lower than 70 Shore A should have a maximum
dimension change of 3 %. When looking at Figure 1,it
can be seen that the hardness of the composed com-
pounds is softer than 70 Shore A and at the same time
the test results obtained meet this standard.
3.1.2 Density and material cost analysis
The desired maximum density value of soles, accord-
ing to the ISO 4649 standard, is 1.5 g/cm
3
. Figure 2
shows that the samples’ densities are below the upper
limit value specified in the standard. As the supplement
ratio of wood ash filler increased, the densities of com-
posites expectedly increased as well. The density of the
compound G is 1.2 g/cm
3
. For the new compounds, the
highest density belongs to the WA4 compound. This
result is 15.83 % higher than the density of the G com-
pound and 7.91 % lower than the ISO 2781 standard.
The densities of the WA1, WA2 and WA3 compounds
ª. BÜLBÜL et al.: THE EFFECT OF WOOD ASH ON THE MECHANICAL PROPERTIES OF RUBBER COMPOUNDS
Materiali in tehnologije / Materials and technology 53 (2019) 3, 333–339 335
Figure 2: Density and material cost of wood ash filling compounds
Figure 1: Dimension stability and hardness of wood ash filling com-
pounds

are below the value specified in the ISO 2781 standard.
The density of wood ash (2.3 g/cm
3
) used in the new
compounds is higher than silica, SBR and NR. In the
new compounds, the ratio of rubber in the compounds
and silica reduced as the wood ash ratio increased.
It was observed that the cost of the compounds de-
creased as the ratio of wood ash added to compound G
increased (Figure 2). The WA4 compound with 64 %
wood ash reduced the production cost by about 40 %
compared to the G compound. The WA1 compound re-
duced the production costs by 10 %. WA2 and WA3
decreased by 20 % and 30 %, respectively. It has been
determined that the absence of any commercial value of
the wood ash will have the effect of reducing the
production of such compounds and the resulting costs of
production.
3.1.3 Abrasion and elongation
The abrasion resistance depends on factors such as
the surface roughness, size of the material, temperature,
humidity, atmosphere and pressure.
29
These factors must
be taken into account when preparing the compounds.
When the relative volume losses given in Figure 3 are
examined, it is seen that the calculated relative volume
losses increase with an increase of the wood ash added to
the compounds. According to the ISO 4649 standard, the
maximum volume loss of rubber shoe soles should be
250 mm
3
. The least relative volume loss in newly com-
posed compounds was seen in WA1. When the rubber
amount was compared with the filler amounts of the new
compounds used in the experimental studies, it was
found to be more than 100 %, except for WA1. It was
found that the total amount of filler in the WA3
compound was 111.3 %, compared to the used rubber,
and 128.4 % in the WA4 compound, thereby increasing
the relative volume loss. Micro roughening occurs on the
surfaces of the samples when prepared by adding 48 %,
64 % of the filler (due to the decrease of the rubber con-
tent in the composition). As a result, the relative volume
losses of the test specimens increased. In a study of
Tangudom et al., it is emphasized that the decrease of the
rubber ratios in the compound increases the relative
volume loss.
30
The results obtained after the abrasion test
show similarities with those obtained by Tangudom.
The percent elongation of the compounds after the
tensile test exhibited the behavior shown in Figure 3.
According to the ISO 5676 standard, the minimum elon-
gation percent for shoe soles should be 200 %. When the
test results of the percentage unit elongation values of
compound G and wood-ash supplemented compounds
were reviewed, it was seen that while the breaking
elongation of compound G was 420 %, that of wood ash
supplemented compounds varied between 856 % and
743 %. Among the new compounds added with wood
ash, the highest unit elongation value was obtained for
the WA1 compound. This increase is associated with the
1 % sulfur in the wood ash. In the study carried out by
Manshaie and Sengloyluan, it was also emphasized that
the amount of sulphuric cross-links was increased,
thereby increasing the amount of unit elongation.
31,32
The
unit-elongation values obtained from the tensile tests are
supported by these previous studies. It is known that
when the filler materials added to the compound are
decreasing, the interaction with the rubber (intercala-
tion), the tensile strength and the unit-elongation value
will decrease.
22,33
When the new compounds were com-
pared among themselves, it was seen that the amount of
filler increased, as the rubber filler interaction decreased.
For this reason, it is considered that the decrease in the
amount of elongation of the new compounds is due to
the rubber fill interaction.
3.1.4 Tensile and tearing strength
Factors affecting the tensile strength are the ratio of
filler materials in the compound, particle size, interaction
of filler materials with the compound, cross-links and
production techniques.
9,27,28
According to ISO 37 stan-
dard, a tensile strength of min. 5.88 MPa is required in
rubber-based compounds. The cross-link formation in
the NR/SBR matrix materials is seen in the form of C-C,
C-S and S-S. The tensile strength and chain lengths of
these three crosslinks are different from each other. The
cross-link with the shortest chain length (0.154 nm) is
the C-C bond. The energy used to break the C-C bond is
85 kcal/mol, and the energy required to break the other
bonds is much larger. The C-S chain length is 0.181 nm.
The minimum energy required to break this bond is 64
kcal/mol. S-S crosslinks are bonds with the longest chain
length. The bond size is 0.188 nm, and the energy re-
quired to break them is 57 kcal/mol.
34
The lengths of the
bonds composed in the compounds directly affect the
tensile strength. The tensile strength of the compounds
after the tensile test showed a behavior as seen in the
Figure 4. It was seen that the tensile strenghts of the
compounds used as wood ash filling material containing
Zn and S in their chemical composition increased to
16 % and 32 %, when added to the G compound, was
increased, compared to G compound. It decreased when
to the G compound was added 48 % and 64 % wood ash.
It is thought that the C-C bonds in the NR/SBR con-
figuration create C-S bonds with longer chain lengths
when reacting with sulfur. In a similar study about the
ª. BÜLBÜL et al.: THE EFFECT OF WOOD ASH ON THE MECHANICAL PROPERTIES OF RUBBER COMPOUNDS
336 Materiali in tehnologije / Materials and technology 53 (2019) 3, 333–339
Figure 3: Abrasion and % elongation of wood-ash filling compounds

NR/SBR compound, it was seen that the tensile test
results were similar to the tensile strengths obtained from
the C-S cross-links as a result of the reaction from C-C
bonds with sulfur. This situation is similar to a study
conducted by Shen.
35
Studies on SBR and NR type
elastomer materials indicate that with the increase of the
SiO
2
amount in the compounds, the cross-link density
also increases.
30,32
The ratio of SiO
2
in the compounds
decreases with the increase of the wood ash in the
compounds (amount in total mass). For this reason, the
tensile strength of the compounds decreases as the ratio
of the wood ash used increases.
The results of the tearing strength test in this study
show that the decrease in the tearing strength in 48 %
and 64 % wood ash entrained compounds is due to the
increase of the S content in the fillers used and the
decrease of the SiO
2
filling material. It was seen that the
tearing strength of the compounds in all combinations of
wood ash added to the test results were higher than the
tearing strength of the G compound and that with an
increase of the filler ratios, the tearing strength was
reduced (Figure 4).
The tearing strength of the WA1 compound is 12.19
kN/m and the tearing strength of the WA4 compound is
11.33 kN/m. It is seen that the tearing strength difference
between these two compounds is 0.86 kN/m. The tearing
strengths of the wood ash added compounds are very
close to each other. According to the ISO 5676 standard,
a tearing strength of at least 6 kN/m is required. Accord-
ingly, the tearing strength of the new produced com-
pounds increased by 100 % as to the standard ISO 5676.
The WA1 compound increased by 7.87 % with respect to
the tearing strength of the G compound. The tearing
strength compared to the G compound increased 6.63 %
in the WA2 compound, 1.76 % in the WA3 compound
and 0.2 % in the WA4 compound. It is known that the
tearing strength of the compounds will vary according to
the filler amount and the filler type used.
1
It was seen
that the wood ash added to the compound has the
property of increasing the tearing strength.
3.1.5 Morphological properties
SEM images of the rupture surfaces of the G, WA1,
WA2, WA3 and WA4 compounds obtained by adding
16 %, 32 %, 48 % and 64 % wood ash to the compound
G after tensile tests, are shown in Figure 5.
When SEM images of the fracture surfaces of the
compounds added with wood ash are examined, it was
seen that as the wood ash fill ratio in the compounds in-
ª. BÜLBÜL et al.: THE EFFECT OF WOOD ASH ON THE MECHANICAL PROPERTIES OF RUBBER COMPOUNDS
Materiali in tehnologije / Materials and technology 53 (2019) 3, 333–339 337
Figure 5: SEM images of tensile fracture surface of a) G, b) WA1, c) WA2, d) WA3 and e) WA4
Figure 4: Tensile and tearing strength of wood ash filling compounds

creased, the distance between the fillers decreased. On
the other hand, it was seen that the filler materials come
together (aggregate) to form interfaces. These interfaces
appear to be regions where the tearing of the wood-ash-
added compounds begins. The formation of interfaces
increases the plastic deformation. It is also confirmed by
the tensile test results that the interaction between the
added fillers and the rubber decreases as the fillers used
in the rubber matrix form interfaces. Ismail et al., stated
that, in the case of the formation of interfaces between
the matrix material and the filler material, the tensile and
tearing strengths will decrease.
4
3.1.6 Bending capability
One of the properties required for elastomer materials
is bending capability. The bending capabilities of
elastomeric materials are important in understanding the
effect of the possible cracks in the structure on the bend-
ing behavior of the material. During the bending test, the
notch growth on the samples was calculated by measur-
ing at certain intervals.
According to the ISO 5423 standard, the notch
growth at 30,000 steps should be a maximum of 4 mm.
The Ross-Flex bending test is normally completed at the
finish of 30,000 cycles. However, in this study, the num-
ber of cycles was increased first to 100,000, then to
150,000. Figure 6 shows the Ross-Flex bending test re-
sults.
When Figure 6 is examined, it was seen that the
largest growth in 30,000 steps occurred in the WA3 com-
pound (1.4 mm). When the number of steps was in-
creased, the notch growth was most abundant in the WA1
compound (1.7 mm). When the bending test results of
the G compound were examined, it was seen that the
resistance decreased as the number of steps increased. At
100,000 and 150,000 steps, it was observed that the
bending capabilities of the compounds except for the G
and WA2 compounds were more stable and there was no
growth in the notch length. It can be said that the
bending capabilities of the compounds are below the
maximum growth rate determined in the ISO 5423
standard. According to these results, it is possible to say
that the wood ashes increase the bending capability of
rubber materials.
4 CONCLUSIONS
The wood ash added to the compound increased the
density of the compounds. The reason for this is that the
used wood ash density is higher than the silica, SBR and
NR materials. According to the hardness test results of
the G compound, the hardness test results of the new
filled compounds (except WA4) were lower. The reason
for this reduction is that the hardness of the composition
increases as SiO
2
is used as a filling material. Depending
on this situation, the SiO
2
ratio (total mass) decreased as
the addition ratio of the wood ash filler in the com-
pounds increased. This also reduces the hardness of the
new filled compounds. In the WA4 compound, the total
amount of filler is more than it should be (more than
100 %), causing the compound to behave in the opposite
way. The use of wood ash as a filler material in rubber
compounds resulted in a reduction of the abrasion
resistance of the compounds. When wood ash was used
in 16 % and 32 % ratios in the compounds, it was found
to be much better than both in the compound G and other
ratios. If it is used more than 32 %, it can be said that the
tensile strength is decreased. According to the unit
elongation test results of the obtained compounds, they
were found to be much higher than the G compound. The
tearing strengths of the compounds are also higher in
compound G. According to the bending test results; after
150,000 steps, while there was a progress of 1.5 mm
after the experiment in the 2 mm opened notch before
the start of the experiment in the compound G, this
growth was lower in the filling compounds. It was found
that the wood-ash filler used increased the bending
capability. The dimensional stability test results are
below the maximum change of shape determined by the
companies that produce shoes. In the SEM images of the
tensile surfaces, the grain size was found to be an
important factor for the distribution of filler materials
added to the NR/SBR matrix. It was found that the
chemical composition of the filler and the materials to be
added to the compound was an important parameter for
their mechanical properties. It was also seen that the
amount of filler used in the compounds must be equal to
the maximum amount of rubber, otherwise it will
adversely affect properties such as abrasion, rupture,
tearing, elongation and hardness.
Acknowledgements
We would like to thank Karabük University Project
no. KBÜ-BAP-13/1DR OO3 for the financial support.
5 REFERENCES
1
K. Pal, S. K. Pal, C. K. Das, J. K. Kim, Effect of fillers on mor-
phological and wear characteristics of NR/HSR blends with e-glass
fiber, Materials and Design, 35 (2012), 863–872, doi:10.1016/
j.matdes.2011.07.074
2
R. Manshaie, S. N. Khorasani, S. J. Veshare, M. R. Abadchi, Effect
of electron beam irradiation on the properties of Natural Rubber
(NR)/Styrene–Butadiene Rubber (SBR) blend, Radiation Physics and
ª. BÜLBÜL et al.: THE EFFECT OF WOOD ASH ON THE MECHANICAL PROPERTIES OF RUBBER COMPOUNDS
338 Materiali in tehnologije / Materials and technology 53 (2019) 3, 333–339
Figure 6: Bending capability of wood ash filling compounds

Chemistry, 80 (2011), 100–106, doi:10.1016/j.radphyschem.2010.
08.015
3
M. T. Ramesan, R. Alex, N. V. Khanh, Studies on the cure and me-
chanical properties of blends of natural rubber with dichlorocarbene
modified Styrene–Butadiene Rubber and Chloroprene Rubber, React.
Funct. Polym., 62 (2005), 41–46, doi:10.1016/j.reactfunctpolym.
2004.08.002
4
H. Ismail, S. M. Shaari, N. Othman, The effect of chitosan loading
on the curing characteristics, mechanical and morphological proper-
ties of chitosan-filled Natural Rubber (NR), Epoxidised Natural
Rubber (ENR) and Styrene-Butadiene Rubber (SBR) compounds.
Polymer Testing, 30 (2011), 784–790, doi:10.1016/j.polymertesting.
2011.07.003
5
S. J. Park, K. S. Cho, Filler–elastomer interactions: influence of
silane coupling agent on crosslink density and thermal stability of
silk/rubber composites, J. Colloid Interf Sci., 267 (2003), 86–91,
doi:10.1016/S0021-9797(03)00132-2
6
D. De, P. K. Panda, M. Roy, S. Bhunia, Reinforcing effect of reclaim
rubber on natural rubber/polybutadiene rubber blends, Materials and
Design, 46 (2013), 142–150, doi:10.1016/j.matdes.2012.10.014
7
A. Malas, P. Pal, C. K. Das, Effect of expanded graphite and mo-
dified graphite flakes an the physical and thermo-mechanical proper-
ties of styrene butadiene rubber/polybutadiene rubber (SBR/BR)
blends, Materials and Design, 55 (2014), 664–673, doi:10.1016/
j.matdes.2013.10.038
8
T. P. Mohan, J. Kuriakose, K. Kanny, Water up take and mechanical
properties of natural rubber–styrene butadine rubber (NR-SBR) –
nanoclay composites, J. of Industrial and Engineering Chemistry, 18
(2012), 979–985, doi:10.1016/j.jiec.2011.10.010
9
N. Akçakale, Investigation of the effect of some additives on the me-
chanical properties of NR/SBR elastomer based sole materials,
Sakarya University (Turkey), Graduate School of Natural and
Applied Sciences, 2008
10
S. S. Siti, W. Kaewsakul, K. Sahakaro, W. K. Dierkes, J. W. M.
Noordermeer, A review on reinforcement of natural rubber by silica
fillers for use in low-rolling resistance tyres. J. of Rubber Research,
18 (2015) 4, 203–233
11
P. Saramolee, K. Sahakaro, N. Lopattananon, W. K. Dierkes, J. W.
M. Noordermeer, Compatibilisation of silica-filled natural rubber
compounds by functionalised low molecular weight polymer, J. of
Rubber Research, 19 (2016) 1, 28–42
12
E. F. Alfaro, D. B. Dias, L. G. A. Silva, The study of ionizing ra-
diation effects on polypropylene and rice husk ash composite,
Radiation Physics and Chemistry 84 (2013), 163–165,
doi:10.1016/j.radphyschem.2012.06.025
13
S. M. Kim, K. J. Kim, Effects of accelerators on the vulcanization
properties of silica vs. carbon black filled natural rubber compounds,
Polymer (Korea), 37 (2013) 3, 269–275, doi:10.7317/pk.2013.37.3.
269
14
X. Ge, M. C. Le, U. R. Cho, Fabrication of EPDM rubber/organo-
bentonite composites, Influence of hydrochloric acid on the
characteristics of modified bentonite and final products, Polymer
(Korea), 38, (2014) 1, 62-68, doi:10.7317/pk.2014.38.1.62
15
S. Prasertsri, F. Lagarde, N. Rattanasom, C. Sirisinha, P. Daniel,
Raman spectroscopy and thermal analysis of gum and silica-filled
NR/SBR blends prepared from latex system, Polymer Testing, 32
(2013), 852–861, doi:10.1016/j.polymertesting.2013.04.007
16
C. R. G. Furtado, J. L. Leblanc, R. C. R. Nunes, Mica as additional
filler in sbr-silica compounds, Eur. Polym. J., 36 (2000), 1717–1723,
doi:10.1016/S0014-3057(99)00215-3
17
G. Yan, Z. Junchi, Y. Xin, H. Dongli, X. Meimei, Z. Liqun, Pre-
paration and performance of silica/SBR master batches with high
silica loading by latex compounding method, Composites Part B, 85
(2016), 130–139, doi:10.1016/j.compositesb.2015.07.001
18
N. Suzuki, N. Ito, F. Yatsuyanagi, Effects of rubber/filler interactions
on deformation behaviour of silica filled SBR systems, Polymer, 46
(2005), 193-201, doi:10.1016/j.polymer.2004.10.066
19
A. R. Ayne, The dynamic properties of carbon black loaded natural
rubber vulcanizates, Part II. J. Appl. Polym. 6 (1962), 368–372,
doi:10.1002/app.1962.070062115
20
S. G. Hedayatollah, J. A Azam, Nanocomposites based on natural
rubber, organoclay and nano-calcium carbonate: study on the struc-
ture, cure behaviour, static and dynamic-mechanical properties,
Applied Clay Science, 119 (2016), 348–357, doi:10.1016/j.clay.
2015.11.001
21
Y. Gui, J. Zheng, X. Ye, D. Han, M Xi, L. Zhang, Preparation and
performance of silica/sbr master batches with high silica loading by
latex compounding method, Composites Part B, 85 (2016), 130-139,
doi:10.1016/j.compositesb.2015.07.001
22
N. Akçakale, A. Demirer, E. Nart, Ý. Özsert, Effects of glass spheres
on the mechanical characteristics of NR-SBR type elastomers,
Scientific Research and Essays, 5 (2010) 8, 758-762
23
N. M. Ahmed, D. E. El-Nashar, The effect of zinc oxide–phosphate
Core–shell pigments on the properties of blend rubber composites,
Materials and Design, 44 (2013), 1–11, doi:10.1016/j.matdes.
2012.07.016
24
S. S. Nizami, N. Z. Raza, F. Habib, The effect of silica on the pro-
perties of marble sludge filled hybrid natural rubber composites, J. of
King Saud University Sci., 25 (2013), 331–339, doi:10.1016/j.jksus.
2013.02.004
25
ª. Bülbül, M. Yaºar, N. Akçakale, Effect of changing of filling ma-
terials in NR-SBR type elastomer based rubber materials on
mechanical properties. Polymer (Korea), 38 (2014) 5, 664-670,
doi:10.7317/pk.2014.38.5.664
26
S. L. Flegler, J. W. Heckman, K. L. Klomparens, Scanning and trans-
mission electron microscopy, Oxford University Press, Oxford 1993
27
Ö. H. Savran, Elastomer technology 1, Publications of Rubber
Society, Ýstanbul 2001
28
Ö. H. Savran, Elastomer technology 2, basic elastomers, Publications
of Rubber Society, Ýstanbul 2001
29
M. Tekin, The effect of titanium addition and aging heat treatment on
the wear and corrosion behavior of aluminium, Karabük University
(Turkey), Graduate School of Natural and Applied Sciences (Master
Thesis), 2009
30
P. Tangudom, S. Thongsang, N. Sombatsompop, Cure and mecha-
nical properties and abrasive wear behavior of Natural Rubber,
Styrene–Butadiene Rubber and their blends reinforced with silica
hybrid fillers, Materials and Design, 53 (2014), 856–864,
doi:10.1016/j.matdes.2013.07.024
31
R. Manshaie, S. N. Khorasani, S. J. Veshare, M. R. Abadchi, Effect
of electron beam irradiation on the properties of Natural Rubber
(NR)/Styrene–Butadiene Rubber (SBR) blend, Radiation Physics and
Chemistry, 80 (2011), 100–106, doi:10.1016/j.radphyschem.2010.
08.015
32
K. Sengloyluan, K. Sahakaro, W. K. Dierkes, J. W. M. Noordermeer,
Silica-reinforced tire tread compounds compatibilized by using
epoxidized natural rubber, European Polymer Journal, 51 (2014),
69–79, doi:10.1016/j.eurpolymj.2013.12.010
33
D. E. El-Nashar, N. M. Ahmed, A. A. Yehia, The role of ion-ex-
change bentonites in changing the properties of styrene–butadiene
rubber composites. Materials and Design, 34 (2012), 137–142,
doi:10.1016/j.matdes.2011.07.072
34
S. C. George, K. N. Ninan, S. Thomas, Permeation of nitrogen and
oxygen gases through styrene–butadiene rubber, natural rubber and
styrene–butadiene rubber–natural rubber blend membranes,
European Polymer J., 37 (2001), 183-191, doi:10.1016/S0014-
3057(00)00083-5
35
J. Shen, S. Wen, Y. Du, N. Li, L. Zhang, Y. Yang, L. Liu, The
network and properties of the nr/sbr vulcanizate modified by electron
beam irradiation, Radiation Physics and Chemistry, 92 (2013),
99–104, doi:10.1016/j.radphyschem.2013.07.022
ª. BÜLBÜL et al.: THE EFFECT OF WOOD ASH ON THE MECHANICAL PROPERTIES OF RUBBER COMPOUNDS
Materiali in tehnologije / Materials and technology 53 (2019) 3, 333–339 339