Compositions of butyl elastomers and block copolymers of polyisobutylene

摘要

An elastomeric polymer composition that exhibits improved processability and green strength comprises: from about 95 to about 70 parts by weight of one rubbery polymer selected from the group consisting of butyl rubber, chlorinated butyl rubber and brominated butyl rubber and from about 5 to about 30 parts by weight of a block copolymer having an elastomeric polyisobutylene midblock and two plastomeric endblocks of polymerized monovinylidene aromatic monomers and star-shaped block copolymers having from three to six arms wherein the inner elastomeric blocks are polyisobutylene and the outer plastomeric blocs are polymerized monovinylidene aromatic monmers for a total of 100 parts by weight of the rubbery polymer and the block copolymer. Vulcanizates of the composition that exhibit reduced permeability to gases and improved tear strength are provided together with a process for their production.