Kinetic modeling of bulk free-radical polymerization of methyl methacrylate

The free-radical bulk polymerization of many monomers is characterized by a sudden rise in the rate of polymerization, a phenomenon called autoacceleration. Many mathematical models have been developed to describe this phenomenon. In this paper, the development of a new kinetic model is described. The model very successfully describes experimental data obtained by differential scanning calorimetry of the bulk free-radical polymerization of methyl methacrylate. The proposed model is composed of two contributions to the conversion of the monomer, one originating from polymerization according to the classical theory of radical polymerization and the other originating from polymerization during the autoacceleration. The rate constant of the autoacceleration (second contribution) is about eightfold higher than the rate constant of the first-order reaction (first contribution). Bulk free-radical polymerization of methyl methacrylate was studied by differential scanning calorimetry (DSC). Dependence of monomer conversion on time was calculated from the experimental DSC data. Proposed model, composed of two contributions to the monomer conversion was found to excellently describe experimental data. First contribution originates from polymerization according to classical theory of radical polymerization and the other from polymerization during the autoacceleration.