Thermoplastic elastomeric blends of olefin rubber and polyolefin resin

An elastoplastic composition comprising a blend of thermoplastic crystalline polyolefin resin, in an amount sufficient to impart thermoplasticity to the composition, and cured EPDM rubber in the form of small dispersed particles essentially of a size of about 50 microns number average or below, in an amount sufficient to impart rubber-like elasticity to the composition, in which the rubber is cured with phenolic curative comprising phenolic curing resin and cure activator to the extent that no more than about five percent of curable rubber is extractable in boiling xylene.

A process for preparing elastoplastic compositions which comprises (1) masticating about 15-75 parts by weight of EPDM rubber and 85-25 parts by weight thermoplastic crystalline polyolefin resin per 100 total parts by weight of rubber and polyolefin resin, and phenolic curing resin, in an amount sufficient to cure the rubber, at a temperature sufficient to soften or melt the polyolefin resin;

• and, for a time, sufficient to obtain a homogeneous mixture in which the rubber is in the form of small dispersed particles essentially of a size of about 50 microns number average or below, (2) adding cure activator, (3) continuing masticating the mixture at curing temperature until the rubber is cured to the extent that no more than about five percent of curable rubber is extractable in boiling xylene.

An elastoplastic composition comprising a blend of thermoplastic crystalline polyolefin resin, in an amount sufficient to impart thermoplasticity to the composition, and EPDM rubber, in an amount sufficient to impart rubber-like elasticity to the composition, in which the EPDM rubber is cured with phenolic curative comprising about 5 parts to 20 parts by weight phenolic curing resin and about 0.01 to 10 parts by weight cure activator per 100 parts by weight of EPDM rubber.