Abstract: The present invention relates to compositions based on elastomeric polymers of vinylidene fluoride, hexafluoropropene and optionally tetrafluoroethylene suitable for providing microcellular foamed vulcanized articles by extrusion or compression molding. In the case of the production of extruded articles based on vinylidene fluoride and hexafluoropropene copolymers, the compositions comprise: the copolymer, bisphenol AF, a quaternary phosphonium or aminophosphonium salt, azodicarbonamide, MgO, Ca(OH)2, zinc stearate and a plasticizer, each of the components being contained in an exactly defined proportion.

Abstract: Use of additives of the classes of mono- and/or di-hydroxypolyfluoroethers comprising the fluoropolyoxyalkylenic repeating units chosen from the following ones: (C.sub.3 F.sub.6 O); (CFXO) wherein X=F, CF.sub.3 ; (CH.sub.2 CF.sub.2 CF.sub.2 O); (CF.sub.2 (CF.sub.2).sub.z CF.sub.2 O) wherein z is an integer equal to 1 or 2; (C.sub.2 F.sub.4 O), in curable compositions of fluoroelastomers to improve the coefficient of friction without lowering the adhesion with bonding agents to metal reinforcements.

Abstract: The present invention relates to compositions based on elastomeric polymers of vinylidene fluoride, hexafluoropropene and optionally tetrafluoroethylene suitable for providing microcellular foamed vulcanized articles by extrusion or compression molding. In the case of the production of extruded articles based on vinylidene fluoride and hexafluoropropene copolymers, the compositions comprise: the copolymer, bisphenol AF, a quaternary phosphonium or aminophosphonium salt, azodicarbonamide, MgO, Ca(OH).sub.2, zinc stearate and a plasticizer, each of the components being contained in an exactly defined proportion.

Abstract: Fluoroelastomeric compositions peroxy-curable, endowed with improved characteristics of processability and compatibility, and with enhanced low-temperature properties, comprising, as additives, vinylidene fluoride cotelomers having the general formula:R[(CH.sub.2 CF.sub.2).sub.n (C.sub.3 F.sub.6).sub.m (C.sub.2 F.sub.4).sub.p (C.sub.2 F.sub.3 Cl).sub.q ]X (I)wherein:X=Br, I;R is a possible halogenated alkyl radical;n, m, p, q are integers, m, p, q may also be zero.

Abstract: New perfluoropolyethers comprising repeating units chosen from among ##STR1## statistically distributed along the chain, having a controlled molecular weight and brominated end groups, prepared starting from the product of the photochemical oxidation of C.sub.2 F.sub.4, and/or C.sub.3 F.sub.6, containing peroxidic oxygen, and subsequent treatment in liquid phase with bromine, at temperatures ranging from -40.degree. to 130.degree. C. in the presence of ultraviolet radiations, said new perfluoropolyethers derivatives being useful as additives in rubber mixes vulcanizable with peroxides, in amounts of 0.01 to 5 parts by w per 100 parts by weight of elastomer, optionally in combination with non brominated perfluoropolyethers, to improve the processability in the extrusion and the detachability of the vulcanized articles from the molding.

Abstract: The use of liquid neutral perfluoropolyethers in amounts below 1 part by weight per 100 parts by weight of elastomer, and of derivatives thereof having brominated end groups, in amounts of 0.01 to 5 parts by weight per 100 parts by weight of elastomer, having a molecular weight ranging from 500 to 10,000, as additives in rubber mixes vulcanizable with peroxides, in order to improve the processability in the extrusion and the detachability of the vulcanized article from the molding dies.

Abstract: Metal-fluoroelastomer composites constituted by a metal part and by a cured fluoroelastomer part bonded to each other with high adhesion strength, wherein the fluoroelastomeric part is constituted by a copolymer containing from 35 to 80 mol % T of vinylidene fluoride, from 15 to 35 mol % of hexafluoropropene, from 0 to 30 mol % of another comonomer selected from fluoro-olefins and/or perfluorovinyl ethers, and from 0.001 to 2 wt. % of bromine.

Abstract: New perfluoropolyethers comprising repeating units chosen from among ##STR1## statistically distributed along the chain, having a controlled molecular weight and brominated end groups, prepared starting from the product of the photochemical oxidation of C.sub.2 F.sub.4, and/or C.sub.3 F.sub.6, containing peroxidic oxygen, and subsequent treatment in liquid phase with bromine, at temperatures ranging from -40 to 130.degree. C. with the presence of ultraviolet radiations, said new perfluoropolyethers derivatives being useful as additives in rubber mixes vulcanizable with peroxides, in amounts of 0.01 to 5 parts by w per 100 parts by weight of elastomer, optionally in combination with non brominated perfluoropolyethers to improve the processability in the extrusion and the detachability of the vulcanized articles from the molding.