ETHYLENE-VINYL ACETATE SEMIBATCH EMULSION COPOLYMERIZATION - USE OF FACTORIAL-EXPERIMENTS FOR IMPROVED PROCESS UNDERSTANDING

A good working knowledge of the mechanism and an appreciation of the e ffects the process variables have on the properties of interest are re quired for optimization and control of polymerization processes. Despi te the importance of ethylene-vinyl acetate emulsion copolymers, limit ed kinetic information is available. Results from a series of factoria l experiments are presented here which examine the emulsion polymeriza tion of ethylene with vinyl acetate. Copolymers of up to 32 wt % ethyl ene have been produced at an ethylene pressure of 500 psig and a tempe rature of 20-degrees-C. The effects of the process variables on the ra te of polymerization, copolymer composition, particle size and number, molecular weight averages, and gel content are discussed. The kinetic results obtained suggest process improvements for the production of h omogeneous copolymer. Mechanistically, the locus of polymerization has been verified as the polymer particles and little water phase polymer ization was observed.