Butyl-Type Polymers Containing Bromine

Abstract

Abstract Butyl rubber has been modified by attaching bromine to the polymer chain. The reaction has been considered as mainly one of addition to the double bonds, thereby lowering the unsaturation. Both sulfur and metal oxide can serve as vulcanizing agents for brominated Butyl, and both may function in the same compound, thus producing a faster rate of cure compared to Butyl. Brominated Butyl can also be covulcanized with natural rubber and GR-S, and therefore it is now possible to impart to these rubbers the excellent properties of Butyl, such as low air diffusion and resistance to ozone and flex-cracking. Still other advantages compared to Butyl rubber are higher modulus and good adhesion to other elastomers and metals. Data have been presented to show that the properties of these new Butyl-type polymers can be varied by the amount of bromine which they contain. It has also been shown that there is an optimum range of the halogen concentration required for obtaining the best properties both in mixtures with natural rubber and in brominated Butyl polymers used as adhesives. This optimum range of bromine also depends on the original unsaturation of the polymer.