STUDIES ON THE INFLUENCE OF CURE SYSTEM ON THE SHRINKABILITY OF POLYOLEFIN-BROMOBUTYL BLENDS

Influence of cure systems on the extent of shrinkage of polyolefin bro mobutyl blends have been studied as a function of cure time and the po lyorefin/elastomer ratio. During measurement of shrinkage, one of the parameters is kept constant while the other is varied. With the increa se in cure time the shrinkability of the blends increases when elastom er content is fixed. Similarly, at constant cure time the shrinkabilit y of the blend increases with high elastomer content. Blends elongated under high temperature (H-T) have higher shrinkage than those elongat ed 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 s ystem is concerned. The morphological pattern of DCP cured relaxed sam ples and sulfur cured relaxed samples is corroborated by the SEM studi es where the pattern appears to be more globular in nature for the for mer. The crystallinity of the blend depends on the curing agent, and t he dose and type of polyolefin used.