Abstract: Use in curable fluoroelastomer compositions of additives having polyacetal structure of general formula: HOCH2—[Rf—CH2O(CH2O)cCH2]t—Rf—CH2OH  (I) wherein: c=1-10, preferably 1-3; t=0.5-20. Rf=poly-fluorooxyalkylenic chain, having number average molecular weight ({overscore (M)}n) in the range 500-2,500, preferably 1,000-2,000; the number average molecular weight of the formula (I) additive is in the range 3,000-15,000, preferably 3,000-10,000.

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: Use of perfluoropolyethers having perfluoroalkyl end groups with a molecular weight ranging from 500 to 1500, in amounts from 0.5 to 3 parts by weight per 100 parts by weight of elastomer and, optimally, in combination wit polytetrafluoroethylene having a molecular weight lower than about 200,000, as additives to the polymerization latex of rubbers vulcanizable by means of peroxides in order to improve the detachability of the vulcanizate from forming molds.