Sulfur cured rubber composition containing epoxidized natural rubber and carboxylated nitrile rubber

A sulfur cured rubber composition composed of, based on 100 parts by weight of rubber (phr);

• (a) 1.0 to 3.5 parts by weight of epoxidized natural rubber, wherein the level of epoxidized modification is in the range of from about 15 to 85 mole percent;
• (b) 1.0 to 15 parts by weight of a carboxylic acid group containing nitrile rubber;
• and
• (c) 98 to 70 parts by weight of a rubber selected from the group consisting of medium vinyl polybutadiene, styrene-butadiene rubber, synthetic cis-1,4-polyisoprene, synthetic 3,4-polyisoprene, natural rubber, cis-polybutadiene, styrene-isoprene rubber, styrene-isoprene-butadiene rubber, acrylonitrile-butadiene rubber and mixtures thereof, and wherein said rubber composition further comprises 5 to 85 parts by weight of a silica filler, and 0.5 to 8.5 parts by weight of a silica coupling agent.