Kinetics of emulsion polymerization of styrene—simulation model with varying free radical capture efficiency

A kinetic model has been developed and successfully applied to describe the reaction profiles of the seeded emulsion polymerization of styrene. The model incorporated a mechanism for the capture of aqueous‐phase oligomeric free radicals by latex particles. Both the collision and diffusion mechanism were considered. The experimental data agreed well with the collision mechanism. The rate of the free radical capture by latex particles is proportional to latex particle surface area (D2p), and also is a strong function of the rate of free radical generation per latex particle. The model predicts that the rate of polymerization is dependent on the latex particle diameter to the 2.5 power in the gel region. This was demonstrated experimentally by J. W. Vanderhoff et al. (J. Polym. Sci., 20, 225 (1956)). Propagation and termination rate constants for styrene in the 70–90°C temperature range were also determined.