Coagulation phenomena in emulsion polymerisation of vinyl chloride

A kinetic model for the emulsion polymerisation of vinyl chloride monomer i s presented. Its main features are the evaluation of the complete particle size distribution in the presence of coagulation phenomena and a detailed d escription of the reaction kinetics and molecular weight distribution of th e polymer, accounting for branching mechanisms. The kinetic scheme adopted includes both particle and aqueous phase reactions and chain branching due to chain transfer to polymer. A comprehensive expression for the coagulatio n rate coefficient is used, including three different mechanisms: Brownian diffusion, particle-particle interactions, and fluid dynamics. Literature v alues were used for most of the model parameters. The missing ones were eva luated by fitting experimental data from stable reactions both from the lit erature and from the authors' laboratory. Simulation results are compared w ith experimental data and discussed. Finally, the role of the coagulation p henomena is examined parametrically. A series of simulations is presented i n order to elucidate the effect of the different mechanisms, which determin e latex stability. PRC/1555 (C) 1999 IoM Communications Ltd.