Effect of Sulfur and Peroxide Curatives on Epoxidized Natural Rubber Toughened with Ethylene-vinyl-acetate

This study explores the influence of sulfur and peroxide (DCP) curatives on epoxidized natural rubber (ENR)/ethylene vinyl acetate (EVA) blends prepared via melt mixing at 160°C. The effect of these curatives on cure, tensile strength, fatigue and thermal degradation behavior etc. were examined. Although it was observed that the amount of EVA in the blend significantly affected the overall performance of the vulcanizates, however the ENR/EVA-sulfur cured compounds generally exhibited better physico-mechanical than the DCP-cured samples. For example, the sample E (70 phr ENR/30 phr EVA-Sulfur cured) attained about 60% higher cure rate than the sample A (70 phr ENR/30 phr EVA-DCP cured). Also, the sample E exhibited an extreme fatigue life performance (~1.7 × 104 cycles at 15% strain) which was over 170 000% higher than sample A which obtained fatigue life of 10 cycles at the same strain. Again, the sample E obtained over 1200% tensile strength higher than the counterpart sample A. Even in an unfilled state, the sulfur-cured compounds (D and E) exhibited high physico-mechanical properties than the DCP-cured counterparts including related blends containing high reinforcements (30~50 phr) contained in literature. Therefore, further engineering of such materials could render them as suitable blends for developing rubber articles like O‑rings, gaskets, heat sinks and tread compounds.