KINETICS OF SEEDED EMULSION POLYMERIZATION OF VINYL-ACETATE WITH NO ADDED EMULSIFIER

Kinetics of emulsion polymerization of vinyl acetate have been studied in the absence of emulsifiers using potassium persulphate as the radical generator. Uniformity of particle sizes, in batch operation, indicated that nucleation of stable particles occurs early in the polymerization. The polymerization rate was proportional to the 0.69 power of the initial monomer concentration. Particle sizes were consistent with the suggestion that particles are stabilized by initiator fragments. When polymerization was carried out in the presence of a dialysed seed latex, with no added emulsifier, the polymerization rate was found to depend on the initiator concentration raised to the power 0.60 +/- 0.05 but was independent of the monomer-to-polymer ratio. New stable particles could be produced when the monomer-to-polymer ratio was high. The production of these new particles did not affect the polymerization rate significantly. Polymerization rate was insensitive to the stirrer speed unless the speed was very high. At high speed the polymerization rate was reduced.