Patent ID: 7390866

Claim:
An elastomer comprising: (a) propylene-derived units in an amount of from 80 to 90 wt %, based on the combined weight of components (a), (b), and (c); (b) diene-derived units in an amount within the range of from 0.3 to 3 wt %, based on the combined weight of components (a), (b), and (c); and (c) ethylene-derived units in an amount of from 10 to 20 wt %, based on the combined weight of components (a), (b), and (c); wherein the elastomer has isotactic polypropylene crystallinity, a melting point by DSC of from 0 to 110° C., and a heat of fusion of from 5 J/g to 50 J/g, and wherein the elastomer is partially insoluble and the fractions soluble at 23° C. and 31° C., as measured by the extraction method described herein, have ethylene contents differing by 5 wt % or less.