Effect of Gamma Radiation on the Mechanical and Degradation Properties of Bromobutyl Rubber Compounds

Bromobutyl rubber (BIIR) is an isobutylene/isoprene copolymer, containing 1.9% to 2.1% bromine content. Halogenated butyl rubbers have their major applications in tires without inner tubes, various types of seals, membranes, hoses for chemical products conveying and stoppers for pharmaceutical uses. Bromobutyl rubber, when exposed to high radiation energy show two chemical effects: crosslinking and chain-scission with further degradation, prevailing chain-scission. In case there is build-up of insoluble gel, crosslinking will be predominant. Doses used in degradation study via gamma ionizing radiation were: 25 kGy, 50 kGy, 100 kGy, 150 kGy and 200 kGy and there were assessed changes in principal properties. Compounds of bromobutyl rubber showed significant radio degradation above 100 kGy. Doses higher than 100 kGy imparted changes in mechanical properties, due to degradation caused by gamma irradiation.