A kinetic model for the emulsion polymerisation of vinyl chloride monomer is presented. Its main features are 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 the 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 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 authors' 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. PRC/1555 (C) 1999 IoM Communications Ltd.
Coagulation phenomena in emulsion polymerisation of vinyl chloride
STORTI, GIUSEPPE;MORBIDELLI, MASSIMO
1999-01-01
Abstract
A kinetic model for the emulsion polymerisation of vinyl chloride monomer is presented. Its main features are 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 the 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 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 authors' 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. PRC/1555 (C) 1999 IoM Communications Ltd.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
