Composite material based on rubbers of the silicone type and of the ethylene-propylene copolymer or terpolymer type

A composite material comprising at least two different elastomer layers, the first layer having a first composition of from 40 to 80 percent by weight of silicone rubber and from 20 to 60 percent by weight of ethylene-propylene copolymer and/or terpolymer rubber, the second layer having a second composition whose rubber content consists essentially of from 50 to 100 percent by weight of ethylene-propylene copolymer and/or terpolymer, and from 0 to 50 percent by weight of a rubber selected from the group consisting of nitrile rubbers, styrene-butadiene rubbers, natural rubbers, fluoroelastomers, chlorosulfonated or chlorinated polyethylenes, acrylic rubbers, epichlorohydrin rubbers, thermoplastic elastomers and nonvulcanizable thermoplastics, the first composition contains more than 10 percent by weight of silica and the second composition contains more than 10 percent by weight of silica in said compositions, and the silica has a pore volume ranging from 150 to 250 m.sup.3 /gram and an average primary particle size of less than 12 nanometers.