Seeded emulsion polymerization of vinyl acetate

The study of seeded emulsion polymerization of vinyl acetate in the absence of emulsifiers, with potassium persulfate as an initiator has been conducted in order to investigate the kinetics and mechanism of particle nucleation. Poly(vinyl acetate) latex particles are stabilized by the ionic end groups from decomposition of initiator. The polymerization behaviour of vinyl acetate in the water phase has been clarified. The variation of the polymerization rate with changes in initiator concentration, monomer-polymer ratio, and stirring speed were determined. The polymerization rate of seeded emulsion polymerization of vinyl acetate is dependent on the initiator concentration to the 0.60 ± 0.05 power, however, it is independent of the monomer-polymer ratio. There was no significant change in polymerization rate when the stirring rate was changed from 50 to 150 rpm, but, the polymerization rate was considerably reduced when the stirring rate was increased to 300 rpm. New small particles were formed in the system where the monomer-polymer ratio was substantial large (that is the system containing a small amount of seed particles). The emulsifier-free emulsion polymerization of vinyl acetate in the absence of seed particles was also investigated. It was found that the polymerization rate is proportional to the 0.69 power of initial monomer concentration.