Materials Sciences and Applicatio n, 2011, 2, 802-810
doi:10.4236/msa.2011.27109 Published Online July 2011 (http://www.SciRP.org/journal/msa)
Studies on Mechanical and End-Use Properties of
Natural Rubber Filled with Snail Shell Powder
Isaac Ogbennaya Igwe, Augustina Adanna Ejim
Department of Polymer and Textile Engineering, Federal University of Technology, Owerri, Nigeria.
Received February 21th, 2011; revised March 21th, 2011; accepted April 2nd, 2011.
ABSTRACT
A series of natural rubber-snail shell powder vulcanizates were compounded on a two-roll mill, and moulded on a com-
pression moulding machine. The mechanical and end-use properties of the natural rubber vulcanizates were investi-
gated at snail shell powder contents, 0 to 20 pphr. The snail shell powder was characterized for filler properties and
sieved to 0.075, and 0.30 μm particle sizes. Carbon black was used as the reference filler. Results showed that the ten-
sile strength, modulus, elongation at break, and resilience of the rubber vulcanizates were not enhanced on addition of
snail shell powder. The hardness of the rubber vulcanizes were marginally increased at high snail shell powder content.
However, the specific gravity of the rubber vulcanizates showed increases with increase in snail shell powder content.
At a filler content above 5 pphr, snail shell powder exhibited good flame retardant property in the vulcanizates. The
swelling indices of snail shell powder (0.075 μm) filled natural rubber were generally good, and better than those of
snail shell powder (0.30 μm) filled natural rubber. Carbon black was found to show more property improvement for the
natural rubber vulcanizates when compared to snail shell powder. Although the mechanical properties of snail shell
powder filled natural rubber vulcanizates were not good, there were improvements in the end-use properties, an indica-
tion that snail shell powder could still find utilization in the rubber industry where specific end-use property of a rubber
product is required.
Keywords: Snail Shell Powder, Natural Rubber, Filler, Vulcanizates, Mechanical Properties
1. Introduction
Polymers such as polyolefins and elastomers are widely
exploited but are often not used as neat polymers. These
polymers are frequently compounded with natural min-
erals so as to improve their properties, as well as to re-
duce cost. In the vulcanization of rubber, carbon black is
the main filler in use. The properties impacted by carbon
black to the rubber compound depend on several factors
such as particle size, structure, physio-chemical nature of
the surface area, and particle porosity. However, because
of the origin of carbon black from petroleum, carbon
black causes pollution, and gives the rubber a black col-
our. The filler is also costly [1,2]. Thus, investigations
are now on, aimed at finding suitable reinforcing agents
to replace carbon black in the compounding of rubber
products. Sepiolite, Kaolin, and precipitated silica were
commonly used as reinforcing agents. However, their
reinforcing properties are lower than those of carbon
black. Because of their inorganic origin, these mineral
fillers are not compatible with polymer matrices. The
particle size, structure, and surface characteristics are
important factors that are considered in determining the
reinforcing ability of a filler to rubber compounds. The
particle size is especially important because a reduction
in particle size provides a greater surface area [3].
Thus, the use of talc, nano-ZnO, nano-CaCO3, and
nano-Al2O3 as substitutes for carbon black in rubber
compounding has been suggested [4]. These fillers have
small particle sizes and exhibit superior physical and
mechanical properties in the vulcanizates when com-
pared to the conventional micrcomposites. They also
offer new techniques, and business opportunities in the
rubber industry.
Different materials have been used to reinforce natu-
ral/synthetic rubber and are reviewed below. Arroyo et al
[1] studied the use of ctadecylamine modified mont-
morillonite as substitute for carbon black in natural rub-
ber (NR) compounds. The organo clay was reported to
improve the strength of the natural rubber without having
any reduction in the elasticity of the material. Zang et al.
[5] studied the flammability of montmorillonite (MMT)

Studies on Mechanical and End-Use Properties of Natural Rubber Filled with Snail Shell Powder803
/SBR nancomposites and reported that the maximum heat
release rate (HRR) of SBR decreased from 1987 to 1442
KW/m2 with the introduction of nanclay (20 pphr). The
reinforcing effects of coal shale-based fillers on natural
rubber were studied by Zhao and Xiang [6]. In this study,
two kinds of coal shale were micro cracked, burned, and
modified by epoxidaton with natural rubber (ENR), and
then used as reinforcing fillers for natural rubber (NR).
Result showed that the ultra micro coal-shale powder
was a good filler for NR.
The use of clay in producing butadiene rubber (BR)
nan˚Composite was reported by Kim et al. [7]. The ten-
sile and tear strengths of BR/Cloisite 2OA (clay) com-
posites were 4.4 times, and 2 times greater than that of
unfilled BR, respectively. The rebound resilience, com-
pression set, and abrasive resistance of BR/Cloisite 2OA
was approximately twice larger than that of BR.
Yang et al. [8] investigated the influence of graphite
particle size, and shape on the properties of acrylonitrile
butadiene rubber (NBR) at 20, 40, and 60 pphr filler con-
tents. It was found that the graphite having the smallest
particle size possessed the best reinforcing ability, while
the largest graphite particles imparted the lowest function
coefficient of the composites among four fillers investi-
gated. Anserifer et al. [9] studied the properties of natural
rubber reinforced with synthetic precipitated amorphous
white silica nanofiller. The hardness, tensile strength, and
compression set were improved when the filler was in-
corporated into the rubber. However, the tear strength,
elongation at break, and cyclic fatigue life were ad-
versely affected. The effect of recycled rubber powder
(RRP) on tensile properties and swelling behaviour of
natural rubber (NR) compounds was investigated in the
concentration range, 0 to 50 pphr by Ismail et al. [10]. It
was reported that increasing the RRP content produced
natural rubber compounds that have better resistance to
swelling and lower the elongation at break. However, the
tensile stress M100 (stress at 100% elongation) increased
slightly.
Osman et al. [11] studied the effect of maleic anhy-
dride- grafted polypropylene (MAPP) on the properties
of recycled newspaper (RNP) filled polypropylene
(PP)/natural rubber (NR) composites and reported that
the incorporation of MAPP reduced the water uptakes of
the composites. The effects of partial or complete re-
placement of carbon black (CB) and silica on the proper-
ties of paper sludge (PS) filled natural rubber composites
were elucidated by Ismail et al. [12]. PS/silica filled
natural rubber composites was reported to exhibit lower
maximum torque, tensile properties and fatigue life com-
pared to the PS/CB filled natural rubber composites.
Sobhy and Tamman [13] in their studies found that the
tensile strength of wheat husk fibres (WHFS)/ethylene-
propylene-diene terpolymer (EPDM) composites was
decreased as the filler content increased.
The use of agricultural by-products to reinforce natural
rubber has similarly received the attention of researchers.
Such agricultural by-products investigated included ba-
nana peel, rice husk, spent mango, bean seed skin and
groundnut shell [14], cocoa pod and rubber seed shell
[15], and short pine apple leaf fibre [16]. These agricul-
tural by-products exhibited varying performance charac-
teristics on natural rubber compounds.
In the present study, the use of snail shell powder as a
filler in compounding natural rubber is reported. The
snail shell powder was sieved to two particle sizes
namely, 0.075, and 0.30 µm. Snail shell powder content
of 0 to 20 pphr were used for the purpose of the study.
Carbon black was used as the reference filler. The use of
snail shell powder in reinforcing natural/synthetic rubber
had not been reported in the scientific literature to our
knowledge. However, the industrial potential of rein-
forcing polypropylene, a thermoplastic polymer with
snail shell powder was reported by Igwe [17]. Snail shell
is a domestic waste and presently, does not have any
known domestic/industrial applications in our locality. It
could be found littering dustbins in our big cities and
farm yards in villages.
2. Materials and Methods
Natural rubber and other vulcanizing agents such as zinc
oxide, anti-oxidant (TMQ), stearic acid, accelerator
(TBBS), soluble sulphur, and carbon black were kindly
supplied by Dunlop PLC, Lagos, Nigeria. Linseed oil
was purchased from a chemical store at Aba, Nigeria.
Snail shell, from which snail shell powder was produced,
was collected lcally within Owerri Metropolis, Nigeria.
The snail shell powder was sieved to two particle sizes,
namely, 0.075 and 0.30 μm, respectively. Snail shell
consists essentially of calcium carbonate in a matrix of
protein [18]. The snail shell powder which was used as a
filler in this study was characterized for weight loss on
ignition (ASTM D 1509, 1983), moisture content (ASTM
D 1510, 1983), and oil absorption (BS 3483, Part B7)
according to standard prcedures.
2.1. Preparation of Natural Rubber Vulcanizates
Table 1 gives the ingredients used in compounding natu-
ral rubber. The ingredients are arranged in the order in
which they were used during the compounding prcess. A
two-roll mill was used in the compounding prcess. After
compounding, samples were obtained, coded accordingly,
and prcessed further by curing.
2.2. The Curing Prcess
Each rubber vulcanizate produced was placed in a rectan-

Studies on Mechanical and End-Use Properties of Natural Rubber Filled with Snail Shell Powder 804
Table 1. Compounding recipe (pphr).
Materials Contents (pphr)
Natural rubber 100
Stearic acid 3
Zinc oxide (ZnO) 3
aTMQ 1
bTBBS 1
Soluble sulphur 1.8
Linseed oil 2
Filler (snail shell powder) Variable (2,5,7,10,15,20)
gular shaped mould and introduced into a compression
moulding machine for 40 min at 140˚C, and pressure of
1800 psi to produce a rectangular sheet measuring 7.40 ×
23.10 cm. After curing, samples were produced and set
for property testing. Natural rubber vulcanizates of snail
shell powder, particle sizes, 0.075, and 0.30 μm were
prepared in this study for subsequent investigations.
2.3. Tests on Vulcanized Natural Rubber
The cured sheets were subjected to conditioning for 24 hr
at room temperature, 32˚C. The following tests were car-
ried out on the rubber samples using standard prcedures:
tensile strength, tensile modulus, elongation at break,
hardness, resilience, flame retardancy, specific gravity,
and swelling index.
3. Results and Discussion
3.1. Analysis of Snail Shell Powder
Some characteristics of snail shell powder (SSP) have
been determined alongside those of carbon black (CB)
which served as the reference filler in this study, and are
shown in Table 2.
The higher weight loss on ignition recorded for SSP
when compared to CB is an indication that CB is more
resistant to thermal effect. The effectiveness of a filler
may be measured by the carbon content. The higher the
value, the greater is the reinforcing effect [16]. Table 2
shows that carbon black lost the least amount of moisture
on heating. The oil absorption values for the fillers (Ta-
ble 2) indicates that the aggregate structure of carbon
black is only greater than that of snail shell powder of
particle sizes, 0.30 and 0.075 μm by about 3.56 and 4.18
kg respectively. It is well known that CB consists of
modular subunits called particles by ASTM classification
[15]. The similarity in the oil absorption values for the
fillers may be an indication that SSP of particle sizes,
0.30 and 0.075 μm have structures that may be closely
related to CB in the sense considered above, and there-
fore may produce similar effects in the vulcanizates.
3.2. Properties of Natural Rubber Vulcanizates
Figure 1 shows that the tensile strength of SSP filled
natural rubber showed initial increases in tensile strength
Table 2. Some characteristics of snail shell pow de r .
Parameter SSP CB
Loss on ignition (%) 43.33 91
Moisture content (%) 18.33 2.70
Oil absorption (kg) 4.65 (0.075 μm) 8.83
5.27 (0.30 μm) -
with increases in SSP content upto 2 pphr; after which
decreases in tensile strength with increases in SSP con-
tent was observed.
The decrease in tensile strength of rubber vulcanizates
with increase in filler contents has been reported by Is-
mail et al. [2], who working with oil palm wood flour
reinforced epoxidized natural rubber found that the ten-
sile strength of rubber vulcanizates decreased with in-
creases in wood flour content. On the contrary however,
Mishra and Shimpi [19] reported general increases in
tensile strength of nano-CaCO3 filled SBR with increases
in filler content until maximum tensile strength was
reached, after which the tensile strength decreased with
any further increase in filler content. The tensile strengths
of rubber vulcanizates filled with SSP, particle size,
0.075 μm were in most cases smaller than that of unfilled
natural rubber vulcanizates. Similarly, natural rubber
filled with SSP of particle size, 0.30 μm exhibited higher
tensile strength than those filled with SSP, particle size,
0.075 μm at filler contents below 18 pphr. This result is
unexpected. Generally, the smaller the particle size of a
filler, the greater is the tensile strength of the vulcani-
zates, and rice versa [2]. The better filler dispersion, and
filler-matrix interaction are generally believed to be the
two main factors responsible for the trend observed
above.
The reference filler, CB, showed steady and significant
increases in the tensile strength of the vulcanizates, and
which were in all cases higher than the tensile strength of
SSP filled NR. As was pointed out earlier, the effective-
ness of a filler may be measured by its carbon content.
The higher the values, the greater the reinforcing ability.
From the results of weight loss on ignition test, carbon
black has more carbon content than SSP, and they might
explain in part the better reinforcing ability exhibited by
carbon black over SSP. It should be noted that tensile
strength increase is a result of additional reinforcement
of the polymer phase. The degree of reinforcement de-
pends on the extent of polymer and filler interaction. In
the present investigation, the interactive forces are en-
visaged to increase with carbon black content, and so,
does the degree of reinforcement.
The poor strength property exhibited by snail shell
powder could be attributed to the geometry of the filler.
For irregularly shaped fillers, the strength of the compos-

Studies on Mechanical and End-Use Properties of Natural Rubber Filled with Snail Shell Powder 805
Figure 1. The effect of filler content and particle size on tensile strength of filled natural rubber.
ites decrease due to the inability of the filler to support
stresses transferred from the polymer matrix [19].
The effects of filler content and particle size on the
modulus of filled natural rubber vulcanizates are shown
in Figure 2. The modulus of unfilled natural rubber vul-
canizate is 1.84 MPa. It is evident from the figure that the
modulus of snail shell powder filled natural rubber vul-
canizates are always less than that of unfilled rubber
vulcanizate, at all the filler contents and particle sizes
investigated.
Figure 2 also shows a decrease in the modulus of
filled rubber vulcanizates within the filler contents, 20 to
15 pphr. At a higher filler content, 20 pphr, the modulus
increased again.
The modulus of carbon black filled natural rubber vul-
canizate is observed to increase steadily with increasing
carbon black content, and were in all cases higher than
the ones of unfilled natural rubber vulcanizate, and snail
shell powder filled natural rubber vulcanizates. These
observations reveal that polymer matrix-filler interaction
is an important factor controlling the modulus. It is well
known that natural rubber forms a strong adsorptive bond
with carbon black [20].
The surface activity is also an important factor indi-
cating the extent of polymer filler interaction; with good
polymer filler interaction, there could be increases in
modulus. Based on this concept, carbon black has very
high surface activity, which provided greater reinforce-
ment in comparison with snail shell powder. The de-
crease in modulus of snail shell powder vulcanizates in
the loading range studied may suggest that snail shell
powder is not a good reinforcing material (filler) for
natural rubber as the carbon black.
The decrease in the modulus of snail shell powder
filled natural rubber observed in this study contrasted
sharply with some previous reports on natural rubber
vulcanizates. For example, Ismail et al. [10] who worked
on oil palm wood flour reinforced epoxidized natural
rubber reported a general increase in the modulus of the
composites with increasing oil palm wood flour content.
Similarly, Ahmad et al. [20] reported that at 100% elon-
gation, polyethylene blends filled with silica and calcium
carbonate increased with increasing filler content. How-
ever, Okieimen and Imanah [15] who studied powdered
cocoa pod, and rubber seed shell filled natural rubber
vulcanizates reported both increases, and decreases in the
modulus of the rubber blends with increasing filler con-
tent.
The poor modulus observed for snail shell powder
filled natural rubber in this study could again be attrib-
uted to poor rubber-snail shell powder interaction since
stronger rubber-snail shell powder interaction would
have increased the effectiveness of the stress transferred
from the rubber matrix to snail shell powder particles
dispersed in the rubber matrix and this would subse-
quently enhance the modulus of the vulcanizates.
In this study however, the more the incorporation of
snail shell powder into natural rubber, the poorer the en-
visaged interaction between the two and hence, the ob-
served decrease in modulus of the system with increasing
filler content.
Figure 3 shows the effect of filler content, particle
size, and type on elongation at break (EB) of vulcanized
natural rubber. The EB of unfilled natural rubber val-
conizate is 85.85%. A close examination of Figure 3
shows that the EB of carbon black, and snail shell pow-
der (particle sizes, 0.075 and 0.30 mm) filled natural
rubber vulcanizates are always less than the EB of un-

Studies on Mechanical and End-Use Properties of Natural Rubber Filled with Snail Shell Powder 806
Figure 2. The effect of filler content and particle size on modulus of filled natural rubber.
Figure 3. The effect of filler content and particle size on elongation at break of filled natural rubber.
filled rubber vulcanizate at the filler contents studied.
Generally, the addition of fillers into natural rubber leads
to decreases in EB of rubber vulcanizates, irrespective of
whether the filler is reinforcing or inert [15]. The trend,
decreases in EB with increasing filler content may be due
to the non-stiffening of the rubber chains, and hence, non
resistance to stretch when strain is applied. Figure 3 also
shows that the EB of rubber vulcanizates of snail shell
powder, particle sizes, 0.075 and 0.30 μm are quite simi-
lar.
The resilience (%) of filled and unfilled rubber vul-
canizates is shown in Figure 4. Carbon black is observed
to increase the heat build up in rubber vulcanizates
within the filler content, 2 to 7 pphr after which de-
creases in heat build up with increases in carbon black
content is observed till the figure fell below the heat
build up of unfilled rubber vulcanizate (87.7%) at 20
pphr carbon black content.
Snail shell powder filled natural rubber is however
observed to behave differently. The resilience of snail
shell powder, particle size, 0.075 μm filled natural rubber
vulcanizate is observed to be unaffected with increases in
filler content within the range, 2 to 10 pphr, and has the
same value as the unfilled rubber vulcanizate. At 15 to 20

Studies on Mechanical and End-Use Properties of Natural Rubber Filled with Snail Shell Powder 807
Figure 4. The effect of filler content and particle size on resilience of filled natural rubber.
pphr filler contents, the resilience of the rubber vulcani-
zates decreased to a content value of 83.6% in the two
filler contents. For snail shell powder (0.30 μm) filled
natural rubber, the resiliences at 2 to 5 pphr, and 15 to 20
pphr filler contents have the same value (83.6%), and
which are lower than the resiliences at 7 to 10 pphr filler
contents. The smaller sized snail shell powder exhibited
higher resilience when compared to the larger sized one
within the filler contents, 2 to 7 pphr after which both
particle sizes exhibited similar resilience values.
As should be expected, the resilience of smaller sized
snail shell powder filled natural rubber vulcanizates
would have been greater than that of larger sized snail
shell powder but this was not generally observed in this
study. Heat generation in a rubber compound is not an
intrinsic material property; it depends on the structure of
filler particles, and also, on the nature of the crosslinks in
the vulcanizate [21]. With decreasing particle size of the
filler, the specific surface area would increase. This will
lead to an increase in filler-filler, and polymer-filler in-
teractions, thereby increasing the heat build-up. At high
filler content (20 pphr), both carbon black and snail shell
powder have the same resilience value in the vulcani-
zates; an indication that the resilience of natural rubber
vulcanizates at high filler loadings is independent of the
nature of the filler or filler particle size. Generally, car-
bon black showed high resilience values when compared
to snail shell powder in the rubber vulcanizates.
Figure 5 shows the effect of filler content and particle
size on the hardness of vulcanized natural rubber. The
hardness of unfilled vulcanized natural rubber is 39. The
figure shows no appreciable increase in the hardness of
vulcanized rubber with increasing snail shell powder
content. A previous study [22] has reported a general
increase in the hardness of vulcanized natural rubber
with increases in filler content. At any snail shell powder
content considered, there was no appreciabe affect of
filler size on the hardness of vulcanized natural rubber.
This may be an indication of low impact strength of the
vulcanizates, and enhancement of abraision, and which
makes snail shell powder to act as a non-reinforcing filler.
Carbon black showed more improvement in the hardness
of vulcanized natural rubber than snail shell powder. This
can be attributed to the likely more uniform dispersion of
carbon black in the polymer matrix as well as better car-
bon black-natural rubber interactions in the system.
The effect of filler content and particle size on the spe-
cific gravity of natural rubber vulcanizates is shown in
Figure 6. Figure 6 shows a general continuous increase
in specific gravity for all the compositions with increases
in filler content in comparison to the unfilled natural
rubber vulcanizate at any given filler particle size con-
sidered. However, at any given snail shell powder con-
tent considered, the specific gravity of the vulcanizates
decreases with increase in the particle size of snail shell
powder. The findings of this study are in agreement with
the work of Mishra and Shimpi [19] who reported a gen-
eral increase in the specific gravity of rubber vulcani-
zates with increases in filler contents. The increase in the
specific gravity with a reduction in the filler particle size
can be attributed to the filler size effect where the smaller
sized filler is envisaged to be more uniformly dispersed
in the rubber matrix, and which would keep the rubber
chains intact on crosslinking. The increase in specific
gravity of the vulcanizates was more pronounced for
carbon black than for snail powder.
The greater increase in specific gravity shown by car-
bon black could be attributed to the better compatibility,
and more uniform dispersion of carbon black in the rub-
ber matrix.

Studies on Mechanical and End-Use Properties of Natural Rubber Filled with Snail Shell Powder 808
Figure 5. The effect of filler content and particle size on hardness of filled natural rubber.
Figure 6. The effect of filler content and particle size on specific gravity of filled natural rubber.
The swelling indices of the different filler composi-
tions (vulcanizates) in toluene at room temperature are
shown in Figure 7. All the vulcanizates showed de-
creases in swelling index with increase in filler contents
at the filler particle sizes considered. Also worthy to note
is that the swelling index at a given snail shell powder
content and different filler (SNS) particle sizes are very
similar; an indication that the swelling index of the vul-
caizates does not strongly depend on the snail shell
powder particle size. The reduction in swelling index
observed in this study with decreases in snail shell pow-
der particle size may be due to the greater crosslinking of
rubber since the envisaged uniform bring the chains
closer, and keep them intact. Carbon black sobbed the
least amount of toluene when compared to carbon black.
The rate of burning of different filled rubber vulcani-
zates is illustrated in Figure 8. The figure shows that at
any given particle size of snail shell powder considered,
the rate of burning of the vulcanizates was observed to
decrease with increases in filler content at snail shell
powder content above 5 pphr. In order words, the snail
shell powder is inefficient as a filler in retarding the rate
of burning of rubber vulcanizates at filler content less
than 5 pphr. Carbon black was observed to reduce the
rate of burning of rubber vulcanizates at all the filler
contents investigated. It is important to note that the de-
creases in the rate of burning of snail shell powder filled
rubber vulcanzates with increases in filler content and at
any given filler particle size is very marginal, and may
point to the fact that the flame retardant property of snail

Studies on Mechanical and End-Use Properties of Natural Rubber Filled with Snail Shell Powder 809
Figure 7. The effect of filler content and particle size on swelling Index of filled natural rubber.
Figure 8. The effect of filler content and particle size on flame retardancy of filled natural rubber.
shell powder in the vulcanizate is not particularly good.
Figure 8 also shows that the rate of burning of snail shell
powder filled rubber vulcanizates decreases with de-
creases in filler particle size. This again is attributed to
the envisaged greater dispersion of the smaller sized filler
in the vulcanzates, and which resulted in greater absorp-
tion of energy, and hence, less tendency for the vulcani-
zates to burn.
This study shows that carbon black is superior to snail
shell powder in retarding the rate of burning of rubber
vulcanizates.
4. Conclusions
The use of snail shell powder as a filler in compounding
natural rubber has been studied. The tensile strengths of
snail shell powder (SNS) filled natural rubber vulcani-
zates were found to be appreciably higher than that of
unfilled rubber vucanizate at 2 pphr filler content. Carbon
black, the reference filler, exhibited high tensile strengths
in the vulcanzates and which were, in all cases, higher
than those of snail shell powder filled rubber vulcanizates.
The modulus of SNS filled rubber vulcanizates is always
less than that of unfilled rubber vulcanizate at all the
filler contents and particle sizes investigated. Carbon
black was found to exhibit very high modulus in the
natural rubber vulcanizates.
Carbon black was found to increase the hardness of
vulcanized rubber more than snail shell powder, and this
increased with increase in carbon black content. A gen-
eral continous increase in specific gravity with increase
in filler content was observed in this study for all the
filled rubber vulcanizates. At any given snail shell pow-

Studies on Mechanical and End-Use Properties of Natural Rubber Filled with Snail Shell Powder 810
der content considered, the specific gravity of the vul-
canizate decreased with increase in the particle size of
snail shell powder. All the filled rubber vulcanizates
showed decreases in swelling index with increase in filler
content at the filler particle size considered. The rate of
burning of snail shell powder filled rubber vulcanizates
was observed to decrease with increase in the filler con-
tent at snail shell powder content above 5 pphr.
REFERENCES
[1] M. Arroyo, M. A. Lopez-Manchado and B. Herrero, “Or-
gano-montmorillonite as Substitute for Carbon Black in
Natural Rubber Compounds,” Polymer, Vol. 44, No. 8,
2003, pp. 2447-2453.
doi:10.1016/S0032-3861(03)00090-9
[2] H. Ismail, H. D. Rozman, R. M. Jaffri and Z. A. Mohd
Ishak, “Oil Palm Wood Flour Reinforced Epoxidized
Natural Rubber Composites: Effects of Filler Content and
Size”. European Polymer Journal, Vol. 33, No. 10-12,
1997, pp. 1627-1632.
doi:10.1016/S0014-3057(97)00020-7
[3] L. Zhang, Y. Wang, V. Way, Y. Sin and D. Yu, “Mor-
phology and Mechanical Properties of Clay/Styrene-Bu-
tadiene Rubber Nancomposites,” Journal of Applied
Polymer Science, Vol. 78, No. 11, 2000, pp. 1873-1878.
doi:10.1002/1097-4628(20001209)78:11<1873::AID-APP
40>3.0.CO;2-8
[4] H. Zhang, Y. Wang, L. Zhang and J. Yang, “Preparation
and Prcessing of Novel Polymer Materials,” Journal of
Applied Polymer Science, Vol. 97, No. 3, 2004, pp.
844-849. doi:10.1002/app.21797
[5] H. Zhang, Y. Wang, Y. Wu, L. Zhang and J. Yang, “Study
on Flammability of Montmorillo Nite/Styrene-But-Adiene
Rubber Nancomposites,” Vol. 97, 2005, pp. 844-849.
[6] M. Zhao and Y. Xiang, “Natural Rubber Vulcanizate
Reinforced by Modified Coalshale-Based Fillers,” Jour-
nal of Applied Polymer Science, Vol. 93, No. 3, 2004, pp.
1397-1400. doi:10.1002/app.20506
[7] M. Kim, D. Kim, S. R. Chowdhury and G. Kim,
“Melt-Compounded Butadiene Rubber Nancomposites
with Improved Mechanical Properties and Abraision Re-
sistance,” Journal of Applied Polymer Science, Vol. 102,
No. 3, 2006, pp. 2062-2066. doi:10.1002/app.23738
[8] J. Yang, M. Tian, Q. Jia, L. Zhang and X. Li, “Influence
of Graphite Particle Size and Shape on the Properties of
NBR,” Journal of Applied Polymer Science, Vol. 102, No.
4, 2006, pp. 4007-4015. doi:10.1002/app.24844
[9] A. Ansarifar, S. F. Shiah and M. Bennett, “Optimizing the
Chemical Bonding between Silanised Silica Nanofiller
and Natural Rubber and Assessing Its Effects on the
Properties of the Rubber,” International Journal of Adhe-
sion and Adhesives, Vol. 26, No. 6, pp. 454-463.
doi:10.1016/j.ijadhadh.2005.06.008.
[10] H. Ismail, R. Nordin and A. M. Noor, “Cure Characteris-
tics, Tensile Properties and Swelling Behaviour of Recy-
cled Rubber Powder-Filled Natural Rubber Compounds,”
Polymer Testing, Vol. 21, No. 4, 2002, pp. 565-569.
doi:10.1002/app.24844
[11] H. Osman, H. Ismail and M. Mustapha, “Effects of Maleic
Anhydride Polypropylene on Tensile, Water Absorption,
and Morphological Properties of Recycled Newspaper
Filled Polypropylene/Natural Rubber Composites,” Jour-
nal of Composite Materials, Vol. 44, No. 12, pp. 1477-1491.
doi:10. 1177/0021998309359212, January, 2010.
[12] H. Ismail, A. Rusli, A. R. Azura and Z. Ahmad, “The
Effects of Partial Replacement of Paper Sludge by Com-
mercial Fillers on Natural Rubber Composites,” Journal
of Reinforced Plastics and Composites, Vol. 27. No.
16-17, November 2008, pp. 1877-1891.
doi:10.1177/0731684408088888
[13] M. S. Sobhy and M. T. Tamman, “The Influence of Fibre
Length and Concentration on the Physical Properties of
Wheat Husk Fibre-Rubber Composites,” Vol. 2010, No.
2010. doi:10. 1155/2010/528173.
[14] B. F. Adeosun, “Mechanical and Rheological Properties
of Natural Rubber Composites Reinforced with Agricul-
tural Waste,” Nigerian Journal of Polymer Science and
Technology, Vol. 1, No. 1, 2002, pp. 58-62.
[15] F. E. Okieimen and J. E. Imanah, “The Characterization
of Agricultural Waste Products as Fillers in Natural Rub-
ber Formulations,” Nigerian Journal of Polymer Science
and Technology, Vol. 3, No. 1, 2003, pp. 210-216.
[16] N. Lopattananon, K. Panawarangkul, K. Sahakaro and B.
Ellis, “Performance of Pineapple Leaf Fibre-Natural
Rubber Composites: The Effect of Fibre Surface Treat-
ments,” Journal of Applied Polymer Science, Vol. 102,
2006, pp. 1974-1984.
[17] I. O. Igwe, “Studies on the Properties of Polypropylene
Filled with Agricultural and Domestic Wastes,” Journal
of Research in Engineering, Vol. 4, No. 2, 2007, pp. 9-13.
[18] A. S. M. Salenddin and K. M. J. Wilbur, “Chemical
Composition of Snail Shell,” Journal of Zoology, Vol. 47,
1969, pp. 51-55.
[19] S. Mishra and N. G. Shimpi, “Mechanical and Flame –
Retardant Properties of Styrene-Butadiene Rubber Filled
with CaCO3 as a Filler and Linseed Oil as an Extender,”
Journal of Applied Polymer Science, Vol. 98, No. 6, 2005,
pp. 2563-2571. doi:10.1002/app.22458
[20] A. Ahmad, D. H. Mohd and I. Abdullah, “Mechanical
Properties of Filled NR/LLDPE Blends,” Iranian Polymer
Journal, Vol. 13, No. 3, 2004, pp. 173-178.
[21] V. Sridhar, R. N. P. Choudhary and D. K. Tripathy, “Ef-
fect of Carbon Black on Relaxation Phenomenon of
Chlorobutyl Vulcanizates,” Journal of Applied Polymer
Science, Vol. 102, No. 2, 2006, pp. 1809-1820.
doi:10.1002/app.23640
[22] R. A. Kruger, M. Hovy and D. Wardle, “The Use of Fly
Ash Fillers in Rubber,” International Ash Utilization
Symposium, Centre for Applied Energy Research, Uni-
versity of Kentucky, 1999, p. 72.