Patent ID: 8013054

Claim:
A cured elastomeric composition, comprising: a) at least one C 4 -C 7 monoolefin elastomer; b) from 2 to 40 phr of at least one polyalphaolefin, wherein the polyalphaolefin comprises a oligomers of one or more C 2 to C 20 alpha-olefins having a kinematic viscosity at 100° C. of 3 to 3000 cSt and a Mw/Mn of less than 4; and c) at least one non-polar hydrocarbon polymer additive, wherein the hydrocarbon polymer additive comprises greater than 75 wt % of cyclic components and has a glass transition temperature in the of 0° C. to 80° C. and a softening point in the range of about 115° C. to about 130° C.; wherein the composition has permeation coefficient at 40° C. of 160 cc*mm/(m 2 -day) or less.