| abstract |
A thermoplastic vulcanizate composition comprises a mixture or reaction product of a branched thermoplastic polymer having a branching index of less than 1.0; a vulcanizable elastomer; and a cross-linking agent capable of vulcanizing the elastomer, wherein the cross-linking agent does not substantially degrade or cross-link the branched thermoplastic polymer. For example, a thermoplastic vulcanizate composition comprises a mixture or reaction product of a branched polypropylene having a branching index of less than 1.0; an EPDM elastomer having ethylenic unsaturation; and a phenolic resin, wherein the branched polypropylene has a molecular weight in the range from about 100,000 to 1,000,000 and has a melt strength which is at least about 50% higher than that of a linear polypropylene having the same molecular weight. |