Abstract: Copolymers of vinylidene fluoride with at least one other fluorinated- ethylenically unsaturated monomer are press-cured at about 163.degree.-204.degree. C. by crosslinking with an aromatic polyhydroxy compound in the presence of an accelerator in a weakly basic system, at least a portion of the polyhydroxy compound being blocked by conversion to acetal or thioacetal groups. At the press-cure temperature some of the acetal or thioacetal groups are decomposed and the free hydroxyl groups are reformed, thus providing crosslinking capability. The remainder of acetal or thioacetal groups are decomposed during post-cure oven heating at a higher temperature, and under those conditions copolymer vulcanization is completed. Press-cured compositions of this invention have excellent hot tensile elongation, which permits easy demoldability; and very good recyclability, which eliminates or reduces fluoropolymer waste. The compositions of this invention also have excellent mold flow properties at press-cure temperature.

Abstract: A process for rapidly curing a fluoroelastomer which comprises mixing and heating a fluoroelastomer copolymer whose interpolymerized units consist essentially of vinylidene fluoride, at least one other fluorine-containing monomer copolymerizable therewith, said monomer being a compound which contains 2-7 carbon atoms, contains no bromine, and contains at least as many fluorine atoms as carbon atoms and contains up to 3 mole percent of units derived from a bromine-containing olefin; a quaternary phosphonium compound; a bisphenol or an ammonium or phosphonium salt thereof; and a dialkylaminopyridine or a diazabicyclo compound having the formula ##STR1## where n is 2-8 or 0.2-0.8 parts by weight per hundred parts fluoroelastomer of a carboxylic acid salt of (a) or (b).