Dynamically vulcanized alloys having improved stiffness/impact balance

A process for producing a dynamically vulcanized composition, which comprises the steps of:

• (a) dynamically vulcanizing a thermoplastic polyolefin resin and an elastomer selected from the group consisting of butyl rubber, halogenated butyl rubber, a copolymer of a C.sub.4 to C.sub.7 isomonoolefin and a para-alkylstyrene, a halogenated copolymer of a C.sub.4 to C.sub.7 isomonoolefin and a para-alkylstyrene, ethylenepropylene copolymer rubber, ethylenepropylene-diene rubber, polyisoprene, styrene-butadiene rubber, nitrile rubber, chlorosulfonated polyethylene, and mixtures thereof, in the presence of a curing agent for said elastomer, at dynamic vulcanization conditions to produce a dynamically vulcanized mixture;
• (b) adding a solid particulate filler in an amount ranging from about 5 to about 70 weight percent, based on the weight of the total dynamically vulcanized composition to said dynamically vulcanized mixture resulting from step (a), said dynamic vulcanization step (a) having been conducted at conditions to cure said elastomer sufficiently to produce a dynamically vulcanized composition comprising the major portion of said solid particulate filler in said polyolefin resin.