Kazumi Fujita

Kinetics and Mechanisms of Unseeded Emulsion Polymerization of Methyl Methacrylate

ABSTRACTUnseeded emulsion polymerization of methyl methacrylate was carried out at 50 °C using sodium lauryl sulfate as emulsifier and potassium persulfate as initiator, respectively, to clarify the effects of emulsifier, initiator and monomer concentrations initially charged on the kinetic features of the polymerization such as the number of polymer particles produced and the course of polymerization. To describe the observed kinetic features, a quantitative kinetic model for particle nucleation and growth is proposed on the basis of the assumption that polymer particles are generated from emulsifier micelles. Furthermore, the rate coefficients for radical termination and propagation in the polymer particles are empirically correlated as a function of the weight fraction of polymer in the polymer particles. It is shown that by using these empirical rate coefficients and the proposed kinetic model, the observed monomer conversion versus time histories can be successfully simulated up to almost the end of ...

Crosslinking kinetics in emulsion copolymerization of methyl methacrylate/ethylene glycol dimethacrylate

Abstract A newly developed kinetic model for network structure development during emulsion crosslinking copolymerization of vinyl and divinyl monomer is used to investigate the kinetics of emulsion crosslinking copolymerization of methyl methacrylate and ethylene glycol dimethacrylate. The agreement of predicted with measured development of crosslinking density and that of monomer concentration in the polymer particles is found to be satisfactory. It is shown that the crosslinking density is fairly high even from very early stages of polymerization and that the produced polymeric networks tend to be highly heterogeneous. The kinetics of crosslinking and resulting network structure are essentially different from those for polymerizations in homogeneous media such as bulk and solution polymerization.