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: Covulcanizable compositions comprising (A) 55-100% by weight of an elastomeric copolymer of vinylidene fluoride with perfluoropropene optionally tetrafluoroethylene and containing from 0.001 to 2% by weight of bromine; (B) 0-45% by weight of a tetrafluoroethylene and propylene copolymer; (C) 0.7-2.5 parts for 100 parts of mix (A)+(B) of a bisphenol compound; (D) 0.3-1.5 parts for 100 parts of mix (A)+(B) of an organic guaternary compound of ammonium, phosphonium or aminophosphonium; (E) 0.4-5 parts for 100 parts of mix (A)+(B) of an organic peroxide; (F) 1-5% by weight of (A)+(B) of a peroxide cross-linking coagent.

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: 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.

Abstract: Vulcanizable compositions of fluoroelastomers based on vinylidene fluoride with one or more monomers containing an ethylene unsaturation and at least one fluorine atom, having improved processability and improved chemical stability, and comprising, as a processing coadjuvant, a mono- or dihydroxypolyfluoroether having a means molecular weight higher than or equal to 400 for the monohydroxypolyfluoroethers and higher than or equal to 2500 for the dihydroxypolyfluoroethers.

Abstract: Co-vulcanizable compositions comprising a fluoroelastomer (A) composed of from 40% to 85% by mol of vinylidene fluoride, from 15% to 35% by mol of perfluoropropene and from 0 to 30% by mol of tetrafluoroethylene; a copolymer (B) containing from 40% to 60% by mol of tetrafluoroethylene and from 40% to 60% by mol of propylene; and (C) a compound belonging to the class of bis-peroxydicarbamates.

Abstract: Fluoroelastomer compositions vulcanizable with peroxides having improved processability and compatibility properties and comprising, as additives, ethylene polymers and ethylene-propylene or ethylene-butene copolymers having, along the polymer chain, ester groups of the type--COOR where R is a C.sub.1 -C.sub.8 alkyl, wherein the ester groups amount to 0.5-10% by weight as referred to the total polymer. Such polymer additives contain the ester group bound to a carbon atom of the chain either directly or through a --CH.sub.2 -- or in the form ##STR1## where R is a C.sub.1 -C.sub.8 alkyl group.

Abstract: Vulcanizable compositions of fluoroelastomers based on vinylidene fluoride with one or more monomers containing an ethylenic unsaturation and at least one fluorine atom, which utilize as a cross-linking agent a dihydroxypolyfluoroether having a molecular weight of from 360 to 2000.

Abstract: Vulcanizable fluoroelastomer compositions having as base a copolymer of vinylidene fluoride (from 40 to 84 mol %) with perfluoropropene (15 to 30 mol %) and with tetrafluoroethylene (0.30 mol %) and containing a vulcanizing agent of the polyhydroxy compound type, an accelerator of the aminophosphinic compound type, metal oxides and/or hydroxides of basic character and an alkyl, cycloalkyl or aryl compound from the group of phosphoric esters, aminophosphoric esters, sulfoxides and sulfones.

Abstract: Fluoroelastomeric compositions based on vinylidene fluoride, having a high adhesion to metals in the vulcanized state, and characterized in that they contain small amounts of chlorotrifluoroethylene which is present as a comonomer of an elastomeric copolymer of vinylidene fluoride.

Abstract: Vulcanizable fluoroelastomer compositions based on vinylidene fluoride, comprising, as a vulcanizing system, a polyhydroxyl aromatic compound, a divalent metal compound of basic nature, and an accelerator consisting of a salt of ammonium or of phosphonium or of quaternary amino-phosphonium in which the anion is a complex of a Cd or Zn or Ni or Pb halide.