Oil-soluble initiators are usually used in suspension polymefizationreaction

the polymerization reaction is taken place in the monomer droplets．In many cases

the kinetics of suspension polymerization is the same as that of bulk polymerization It is suitable for monomers which can not dissolve in water．but there are some deviations in the kinetics of polymerization when the monomer has partiall water solubility

such as methyl methacrylate (MMA)

vinyl acetate (VAc) and aerylonitrile (AN)．The aqueous suspension homopolymerization of MMA at large water-to-monomer ratios is now investigated．Comparing with the bulk polymerization of MMA

there are large differences between the kinetic curves of suspension and bulk polymerization

and the water-to-monomer ratio will affect the kinetic curves of MMA suspension polymerization．In order to study the affecting reasons of monomer’s water solubility on the kinetics of its suspension polymerization in detail

a modified kinetic model for MMA suspension polymerization is presented on the basis of its bulk polymerization kinetic model and three assumptions．The three assumptions are：the amount of monomers dissolved in the aqueous phase should be deducted

the propagation and termination rate constants should be decreased

and a small amount of oil-soluble initiators may stay in the aqueous phase．Using the modified kinetic model

the effects of water-to-monomer ratio．polymerization temperature and initiator concentration are predicted．The simulated kinetic curves are in agreement with the experimental data．