THE ROLE OF POLYMER PARTICLES IN THE EMULSION POLYMERIZATION OF VINYL ACETATE

Abstract

The emulsion polymerization of vinyl acetate was carried out at 50°C using sodium lauryl sulfate as an emulsifier and potassium persulfate as an initiator, and the role of the polymer particles produced in this system was studied on the basis of a previous theory. The low value of the average number of radicals per particle obtained in this work, i.e. in the range 0.01 - 0.5, is explained by introducing a mechanism of a rapid escape of monomeric radicals produced by the chain-transfer reaction which occurs dominantly in the polymer particles. Semiempirical equations are proposed for the estimation for the average number of radicals per particle over the whole range of monomer conversion.