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 OPAfilled
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.