Patent ID: 7905263

Claim:
An elastomeric composition, the elastomeric composition being a curable, filled rubber formulation, comprising: a halogenated interpolymer of a C 4 to C 7 isoolefin and from 8 to 10 weight percent alkylstyrene and comprising from 0.2 to 2 mole percent haloalkylstyrene, a Mooney viscosity between 28 and 32, a number average molecular weight of between 200,000and 240,000, a weight average ‘molecular weight of between 320,000 and 440,000, a z average molecular weight of between 450,000 and 650,000, and a branching index (g′) from 0.4 to 1.1, and 20 to 100 phr of a carbon black filler, wherein the elastomeric composition has a characteristic time for stress relaxation at 100° C. from an initially applied strain of 100% to 1 kPa of less than 300 seconds.