The effects of termination by primary radicals on the kinetics of vinyl polymerisation

Abstract

Abstract The termination reactions of macroradicals, and macroradicals by primary radicals (“primary‐radical termination”) and the dimerisation of primary radicals, which have escaped from the initial cage, are treated as diffusion‐controlled rections. Typical values for diffusion‐controlled rate constants are assigned to the reactions of the primary radicals, and the extent of the deviations from the simple rate equations and the M AYO equations, arising from primary‐radical termination, is estimated. The predictions, in the cases of methyl methacrylate and styrene polymerisations, are consistent with the deviations from the simple laws observed experimentally. The treatment does not predict the behaviour of vinyl acetate polymerisations as, surprisingly, this monomer shows no kinetic evidence of primary‐radical termination.