Graft polymers: chain transfer and branching

Abstract

The vinyl monomers, methyl methacrylate, ethyl methacrylate, and methyl acrylate were polymerized in the presence of chlorinated rubber or poly(vinyl chloride) in homogeneous solution with benzoyl peroxide as catalyst. A graft polymer was formed by a chain-transfer reaction involving the growing polymer radicals to the backbone of chlorinated rubber or poly(vinyl chloride), in addition to homopolymer from the monomer. The homopolymer was isolated from the polymer mixture by fractional precipitation from methyl ethyl ketone solution with methanol as precipitant. The chain-transfer constants for the branching reactions were evaluated. The ratios k_p/(k_t)^½ for the grafting reactions were obtained by a correlation of chain-transfer constants with the extent of branching. The chain-transfer data were correlated on the basis of an extension of the Q-e scheme of Alfrey and Price to polymer-polymer transfer reactions. Specific effects due to the backbone are found to have considerable influence on the course of the chaintransfer reactions and k_p/(k_t)^½ of the grafting reactions.