Patent ID: 8389616

Claim:
A polymer composition comprising: a. about 85 wt % to about 97.5 wt %, based upon the weight of a, and b, of a nitrile-group containing elastomer selected from the group consisting of acrylonitrile-butadiene copolymer rubber, carboxylated acrylonitrile-butadiene copolymer rubber, at least partially hydrogenated acrylonitrile-butadiene copolymer rubber, at least partially hydrogenated carboxylated acrylonitrile-butadiene rubber, and mixtures thereof, wherein the elastomer has: i. a Mooney Viscosity of about 15 MU to about 115 MU; and ii. a nitrile monomer content of about 0.1 wt % to about 50 wt %, based upon the weight of the elastomer; and b. about 2.5 wt % to about 7.5 wt %, based upon the weight of a, and b, of a non-functionalized plasticizer (“NFP”), wherein the NFP is a polyalphaolefin derived from C 5 to C 18 alphaolefins and has: i. a kinematic viscosity at 100° C. of about 4 cSt to about 1000 cSt; ii. a flash point of about 200° C. or more; iii. a viscosity index of about 120 or more; and iv. a specific gravity of about 0.865 or less; and wherein the composition has: i. a 25% compression set at 70 hours and −30° C. that is at least 110% of the same composition without the NFP; and ii. a retained tensile strength, in MPa, after 168 hours at 175° C., that is at least about 88% of the retained tensile strength of the same composition that has not been aged.