Studies on the Influence of Cure System on the Shrinkability of Polyolefin-Bromobutyl Blends

Influence of cure systems on the extent of shrinkage of polyolefm bromobutyl blends have been studied as a function of cure time and the polyolefin/elastomer ratio. During measurement of shrinkage, one of the parameters is kept constant while the other is varied. With the increase in cure time the shrinkability of the blends increases when elastomer content is fixed. Similarly, at constant cure time the shrinkability of the blend increases with high elastomer content. Blends elongated under high temperature (H-T) have higher shrinkage than those elongated under room temperature (R-T). DCP is more effective than sulfur for a particular set of blends so far as the shrinkability of the blend system is concerned. The morphological pattern of DCP cured relaxed samples and sulfur cured relaxed samples is corroborated by the SEM studies where the pattern appears to be more globular in nature for the former. The crystallinity of the blend depends on the curing agent, and the dose and type of polyolefin used.