Patent ID: 8609760

Claim:
A natural rubber blend, comprising: 100 phr natural rubber; from about 5 to about 25 phr of one or more propylene-ethylene copolymers consisting of propylene and ethylene, said propylene-ethylene copolymers containing from about 10 to about 16 wt % ethylene and having a melting temperature (Tm) of from 60° C. to 105° C.; a heat of fusion of from about 40 J/g to about 80 J/g, and MFR ASTM-1238D, 2.16 kg, 230° C., of about from 1 g/10 min to about 90 g/10 min; wherein (a) aging effect on tensile strength aged at 100° C., 72 h is at least one third less significant on said natural rubber blend than on a blend free of the propylene-ethylene copolymer, but is otherwise identical in terms of its constituents, and (b) aging effect on ultimate elongation aged at 70° C., 72 h is at least one half less significant on said natural rubber blend than on a blend free of the propylene-ethylene copolymer, but is otherwise identical in terms of its constituents.