Abstract: Random propylene thermoplastic copolymers can be used to increase the elongation to break and toughness of thermoplastic vulcanizates. Semi-crystalline polypropylene is a preferred thermoplastic phase. The rubber can be olefinic rubbers. Random thermoplastic polypropylene copolymers are different from conventional Ziegler-Natta propylene copolymers as the compositional heterogeneity of the copolymer is greater with Ziegler-Natta copolymers. This difference results in substantial differences in properties (elongation to break and toughness) between thermoplastic vulcanizates modified with random thermoplastic propylene copolymers and those modified with conventional Ziegler-Natta propylene copolymers. An increase in elongation to break results in greater extensibility in the articles made from a thermoplastic vulcanizate.

Abstract: Soft, resilient thermoplastic compositions with good physical strength useful as molded parts including hoses, seals and gaskets which exhibit good flow and good surface characteristics in injection molded parts. The compositions comprise ethylene copolymer resin (e.g., ethylene vinyl acetate), halogenated butyl rubber and polychloroprene wherein the rubbers have been dynamically vulcanized to a fully cured state in the presence of the ethylene copolymer resin.