OPA-filled NR vulcanizates showed very slight decrease in
Tg, which may contribute to the increase of amorphous
volume fraction. Another reason that could account for
good filler dispersion as reported by Castro et al. [17] was
said to be that good filler dispersion would increase the
chain mobility and cause a Tg value shift toward a lower
temperature region.
4. Conclusion
The scorch time and cure time of carbon black-filled NR
vulcanizates prove to be the lowest when compared to the
OPA and silica-filled NR vulcanizates. On the other hand,
OPA-filled NR vulcanizates possess the highest cure rate
index over silica and carbon black-filled compound. The
carbon black-filled NR vulcanizates exhibited the highest
tensile strength followed by OPA and silica-filled NR vulcanizates.
From a reinforcement point of view, the OPA-
filled NR compound shows comparable strength over carbon
black-filled vulcanizates and actually retains the
elongation at the break of gum NR vulcanizates. Further
evidence of interaction was supported by a swelling test,
morphological studies and dynamic mechanical analysis.
Acknowledgements
This work is financially supported by the Ministry of
Science, Technology and Innovation (MOSTI) science fund
(Project no. 305/PBAHAN/6013380) and MyPhD (Z.X. Ooi).