or with mixed vulcanization systems in particular blends of a fluoroelastomer based on ch 2 u2550 cf 2 and on an elastomeric c 2 f 4 c 3 h 6 copolymer type aflas u00ae c 2 f 4 with perfluoroalkylvinylether kalrez u00ae and blends of a fluoroelastomer based on ch 2 u2550 cf 2 and an epdm terpolymer as the ingredients for obtaining vulcanizable compositions of the above said fluoroelastomers those known in the art such as those hereunder set forth are used this is an organic peroxide such as e g benzoylperoxide dicumylperoxide 2 5 dimethyl 2 5 di ter butyl peroxy hexane alpha alpha 39 bis ter butylperoxy diisopropylbenzene and aliphatic or cyclic bis peroxycarbamates this is an unsaturated di tri or polyfunctional compound such as e g triallylcyanurate triallylisocyanurate divinylbenzene m phenylene bis maleic acid imide the following examples are supplied only for the purpose of illustrating the possibilities of application of the invention according to the usual blending techniques rubber blends were prepared containing the ingredients shown in tables 1 2 3 on the so prepared compounds the tests and measurements as indicated in tables 1 2 3 were carried out a terpolymer of ch 2 u2550 cf 2 c 3 f 6 c 2 f 4 in 2 1 1 molar ratio containing as the cure site monomer a brominated olefin having mooney viscosity ml 1 4 at 100 u00b0 c 104 and a total bromine content of 3 500 ppm viton u00ae gf a copolymer of.