Patent ID: 7714043

Claim:
A cured elastomeric composition for use in a tire innerliner, comprising: a. from 50 to 100 phr of at least one isobutylene-based elastomer; b. less than or equal to 50 phr of natural rubber; and c. from 1 to 30 phr of at least one hydrocarbon fluid additive, wherein the hydrocarbon fluid additive has a flash point of at least 200° C., a pour point of less than or equal to −15° C., and specific gravity at 15.6° C. of less than or equal to 0.880; wherein the cured elastomeric composition has a MOCON permeability coefficient of less than or equal to T, where T=−0.1147Y+0.54 where Y is the change in brittleness determined by subtracting the brittleness in 0° C. of the cured elastomeric composition containing the hydrocarbon fluid additive from the brittleness in 0° C. of a cured composition having the same components except that it contains a naphthenic oil having a flash point in the range of 160 to 170° C., a pour point of about −40° C.±5%, and a specific gravity at 15.6° C. of about 0.91±0.01 instead of the hydrocarbon fluid additive.