Abstract: Curable flurooelastomeric compositions employable for preparing fuel hoses or O-rings for injectors comprising:A) 100 phr (parts) copolymers or terpolymers based on VDF with a content in fluorine of at least 67% by weight, the VDF being comprised from 30 to 5000 by weight, from 20 to 60% by weight of HFP optionally other monomeric units deriving from a monomer having ethylene unsaturation; the sum of the comonomers being 100;B) 1 to 5 phr of an adduct between an accelerator and a curing agent in molar ratio from 1:2 to 1:5, the accelerator being an onio-organic compound having a positive charge, the curing agent being a di- or polyhydroxy or di- or polythiol compound; the adduct being obtained by melting of the reaction product between accelerator and curing agent in the indicated molar ratios, or by melting of the adduct mixture 1:1 added with the curing agent in the indicated amounts.

Abstract: Curable fluoroelastomeric compositions employable for preparing fuel hoses or O-rings for injectors comprising:A) 100 phr (parts) copolymers or terpolymers based on VDF with a content in fluorine of at least 67% by weight, the VDF being comprised from 30 to 50% by weight, from 20 to 60% by weight of HFP optionally other monomeric units deriving from a monomer having ethylene unsaturation; the sum of the comonomers being 100;B) 1 to 5 phr of an adduct between an accelerator and a curing agent in molar ratio from 1:2 to 1:5, the accelerator being an onio-organic compound having a positive charge, the curing agent being a di- or polyhydroxy or di- or polythiol compound; the adduct being obtained by melting of the reaction product between accelerator and curing agent in the indicated molar ratios, or by melting of the adduct mixture 1:1 added with the curing agent in the indicated amounts.

Abstract: Curable flurooelastomeric compositions used for O-rings comprising:A) parts (phr) of a curable fluoroelastomeric copolymer having a content in F<67% by weight and comprising from 40 to 68% by weight of VDF units, from 20 to 50% by weight of HFP units, the sum being 100, and optionally one or more comonomers having ethylene unsaturation, said copolymer having a number of ionic terminals of at least 0.5 for chain;B) from 1 to 5 phr of an adduct between an accelerator and a curing agent in molar ratio from 1:3 to 1:5, the accelerator being an onio-organic compound having a positive charge, the curing agent being a di- or polyhydroxy or di- or polythiol compound; the adduct being obtained by melting of the reaction product between accelerator and curing agent in the indicated molar ratios, or by melting of the adduct mixture 1:1 added with the curing agent in the indicated amounts.

Abstract: Fluoroelastomers comprising, by mole:(a) from 33 to 75% of tetrafluoroethylene (TFE);(b) from 15 to 45% of a perfluorovinylether (PVE);(c) from 10 to 22% of vinylidene fluoride (VDF).They are endowed with high resistance to polar solvents and to bases, excellent compression set also at high temperatures, low Tg and good processability.They result particularly suitable for the manufacture of sealing elements (O-rings) for plants intended to the production of methylterbutylether (MTBE).

Abstract: The emission of the highly toxic volatile products, such as methyl bromides or iodides, or ethyl bromides or iodides, during the cure with peroxides of fluoroelastomers containing bromine or iodine atoms is substantially reduced by adding to the cure mix small amounts of substances capable of combining with the radicals which give rise to the aforesaid toxic products, thereby preventing them from forming. This procedure does not sensibly affect the cure trend and results.

Abstract: Ionically curing of VDF-containing fluoroelastomers selected from the ones containing less than 60 moles % of VDF and from the ones containing hydrogenated olefins is improved by using, as accelerators, triazinic compounds of formula: ##STR1## (R=H, C.sub.1 -C.sub.4 alkyl; R'=R or benzyl, arylalkyl; X=Cl, Br, I, a bisphenoxy radical or O--CH.sub.2 RF--CH.sub.2 R.sub.2 ; Rf=a perfluorooxyalkylene chain; R.sub.2 =--OH, --O.sup.-). What is claimed are the fluoroelastomeric compositions containing said accelerators.

Abstract: The emission of the highly toxic volatile products, such as methyl bromides or iodides, or ethyl bromides or iodides, during the cure with peroxides of fluoroelastomers containing bromine or iodine atoms is substantially reduced by adding to the cure mix small amounts of substances capable of combining with the radicals which give rise to the aforesaid toxic products, thereby preventing them from forming. This procedure does not sensibly affect the cure trend and results.

Abstract: The invention relates to new fluoroelastomeric copolymers endowed with resistance to bases and suitable in particular for preparing O-rings, comprising:______________________________________ (I) VDF 47-80 mols % HFP and/or PAVE 16-30 mols % hydrogenated olefin containing 2-25 mols % 2-4 C or (II) VDF 42-80 mols % PAVE 16-30 mols % hydrogenated olefin containing 2-30 mols % 2-4 C ______________________________________The invention relates to new fluoroplastomeric copolymers endowed with resistance to bases, comprising: ______________________________________ (III) VDF 70-99 mols % HFP and/or PAVE 0-16 mols % hydrogenated olefin containing 1-30 mols % 2-4 C ______________________________________A further object of the invention is a process for preparing the abovesaid fluoroelastomeric and fluoroplastomeric copolymers.

Abstract: Fluoroelastic copolymers, suitable for the manufacture of O-rings, comprising by weight:48-65% of VDF units21-36% of HFP units3-9% of PAVE units0-17% of TFE units

Abstract: Fluoroelastomeric copolymers, vulcanizable by ionic methods, suitable for the manufacture of "shaft seals" and "fuel hoses", comprising by weight:______________________________________ VDF 30-47% HFP 20-40% PAVE 3-20% TFE 10-30% ______________________________________

Abstract: There are described mixes, which are curable by using radical intermediates, are based on fluoroelastomers containing bromine or iodine, exhibit, during curing, a low emission of toxic vapors of methyl bromide or iodide and are characterized in that they contain, as cross-linking agents, peroxides having the following formulas: ##STR1## wherein the substitutents from R.sub.1 to R.sub.17 have the significances defined in the specification.

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: Double bonds in saturated fluoroelastomers consisting of copolymers of vinylidene fluoride with hexafluoropropene and/or chlorotrifluoroethylene, and optionally tetrafluoroethylene, are obtained by reacting the polymer in a solution of a water-insoluble solvent in the presence of an aqueous phase, an inorganic base, and a phase-transfer catalyst.