A Review of the Vulcanization of Isobutylene-Based Elastomers (Paper No. F)

摘要

The vulcanization of isobutylene-co-isoprene rubber (MR), brominated isobutylene-co-isoprene rubber (BIIR), chlorinated isobutylene-co-isoprene rubber (CIIR), and brominated isobutylene-co-para-methylstyrene (BIMS) differs from that of general-purpose elastomers. Butyl rubber (MR) has approximately 2% unsaturation in the backbone. Halobutyl rubber (BIIR and CIIR) incorporates a butyl backbone with either bromine or chlorine, which increases the reactivity of the isoprene units located in the butyl backbone. Similarly, BIMS includes bromine attached to the para-methylstyrene (PMS) group affording the completely saturated backbone a site of reactivity. Utilization of the unique attributes of butyl rubber and halobutyl rubber with their minimal backbone unsaturation and BIMS elastomer with no backbone unsaturation is found in many areas of industry. These properties offer excellent impermeation to gas and vapor, resistance to heat degradation, and improved chemical resistance as compared to general-purpose elastomers. However, this low amount of reactivity will require special consideration to vulcanize the isobutylene-based polymers. The selection of a vulcanization system type is a function of the mission profile for the final product, composite structure in which it may be used, and the product performance demands. Therefore, vulcanization systems may include an accelerator package along with resins, zinc oxide, zinc oxide and sulfur, and quinoid systems. This review will discuss the types and selection of appropriate vulcanization systems for isobutylene-based elastomers.