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An effective vulcanization recipe for tetrafluoroethylene-propylene elastomer was searched for and the following results were obtained: (1) The C2F4-C3H6 copolymer is susceptible only to peroxide and is not crosslinked at all by other reagents. (2) The peroxide vulcanization is greatly accelerated by some coagents, and triallyl isocyanurate was found to be the best cure promoter. (3) The vulcanizate obtained by using a combination of α,α′-bis-(t-butyl-peroxy)-p-diisopropylbenzene with triallyl isocyanurate as curative exhibits good mechanical properties together with excellent heat and chemical resistance. (4) The mechanism of the vulcanization reactions seems to involve a chain reaction which greatly increases the efficiency of the vulcanization reaction by the peroxide.

(1) A process to produce C2F4-C3H6 copolymer of molecular weight over 150 000 was established by exploiting a new catalyst which permits low temperature polymerization. (2) A vulcanization recipe, comprised of peroxide and TAIC, was established to give the copolymer superior vulcanizate properties. (3) Polymer structure and properties were elucidated, and the high potential as a heat-resistant elastomer was shown. (4) The resultant vulcanizate has been proved to be a unique fluoroelastomer with outstanding heat and chemical resistance as well as mechanical properties which are adequate in practice.

Tetrafluoroethylene and propylene were copolymerized in emulsion at low temperatures (≈25°C) by use of a redox catalyst containing ammonium peroxodisulfate, ferrous sulfate, ethylenediaminetetraacetic acid (EDTA) and hydroxymethane sulfinate. The kinetical study suggested that the working mechanism of the catalyst conforms the following scheme: where the reduction of the ferric ion seems to be rate determining (i.e. k1 ≫ k2) and the hydroxyl ion plays an important role. The overall polymerization reaction is supposed to proceed according to the Case I of the Smith‐Ewart theory under the experimental conditions examined.