Effect of curing system on mechanical properties of Poly-propylene/polybutadiene rubber blends

In this study, polymeric blends based on polypropylene/ polybutadiene rubber (PP/BR) were prepared via melt mixing process. To increase the uniformity of the blend morphol-ogy, improve its stability and increase the compatibility between PP and BR dynamic vulcanization was applied to the blend and the influence of various curing systems, in-cluding peroxide curing and sulfur curing, on the mechanical properties and impact strength of the blend, was investigated. It was found that peroxide curing has a shorter scorch time than sulfur curing, while the cure time of peroxide curing is longer than that of compound with sulfur curing. Furthermore, the torque variations seen in peroxide cur-ing were greater than those in sulfur curing, suggesting a higher degree of cross-linking in peroxide curing. The results indicate that peroxide curing leads to a notable reduction in the elongation at break of the blend. Less reduction of elongation at break in sulfur curing compound compared to peroxide curing one was observed. The yield point of the sulfur cured composite was less than that of the peroxide cured composite. However, the im-pact resistance trend was the opposite.

Keywords:

Polypropylene , polybutadiene , dynamic vulcanization , mechanical properties