Studies on the use of nano zinc oxide and modified silica in NR, CR ...

Use of nano zinc oxide in styrene butadiene rubber
Figure 6.4(a) shows the variation in tensile strength of the vulcanizates
with time of ageing at 100°C. The vulcanizates with 2phr ZnO(p) and ZnO(s)
show fairly good resistance to ageing at 100°C compared to those containing
5phr conventional ZnO.
Figure 6.4(b) shows the modulus of the vulcanizates with time of
ageing. The increase in modulus after ageing may be due to increase in
crosslink density. During thermal ageing crosslink formation or crosslink
breakage can take place or an existing crosslink may break and a stable
linkage can be formed. All these changes greatly influence the performance of
the vulcanizates. Tensile modulus of vulcanizates with 2phr ZnO(p) and 2phr
ZnO(s) are superior compared to vulcanizate with 5phr ZnO(c).
Figure 6.4(c) shows the change in elongation at break of the
vulcanizates with time of ageing. Vulcanizates with 2phr ZnO(p) and ZnO(s)
showed better retention in elongation at break after ageing. This again shows
that vulcanizates with ZnO(p) and ZnO(s) can improve the ageing resistance
of SBR vulcanizates.
Figure 6.4(d) shows the tear strength of the vulcanizates with time of
ageing at 100°C. Retention in tear strength of the vulcanizates with 2phr
ZnO(p) and ZnO(s) after ageing is superior than to vulcanizate with 5phr
conventional ZnO.
The above results indicate that low dosage of ZnO(p), ZnO(s) can
improve the tensile properties of vulcanizates compared to higher dosage of
ZnO(c) vulcanizate.
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