Coagulation phenomena in emulsion polymerisation ofvinyl chloride

A kinetic model for lhe emulsion polymerisation of vinyl chloride monomer is presented. Its nnain features arc the evaluation of the complete particle size distribution in the presence of coagulation phenomena and a detailed description of the reaction kinetics and molecular weight distribution of lhe polymer, accounting for branching mechanisms. The kinetic scheme adopted includes both particle and aqueous phase reactions and chain branching due to chain transfer lo polymer. A comprehensive expression for the coagulation rate coefficient is used, including three different mechanisms: Brownian diffusion, particle-particle interactions, and fluid dynamics. Literature values were used for most of the model parameters. The missing ones were evaluated by fitting experimental data from stable reactions both from the literature and from the authorsʹ laboratory. Simulation results are compared with experimental data and discussed. Finally, the role of the coagulation phenomena is examined parametrically. A series of simulations is presented in order to elucidate the effect of the different mechanisms, which determine latex stability.