Kinetics and Modeling of Batch and Semibatch Aqueous-Phase NVP Free-Radical Polymerization

Aqueous-phase free-radical batch and semibatch polymerizations of NVP have been carried out with varying initial monomer and initiator concentrations. The rate of conversion was observed to increase as the initial monomer concentration was lowered, a result explained by the dependence of the propagation rate coefficient, k(p), on monomer concentration. A kinetic model with termination and conversion-dependent k(p), rate coefficients taken from independent studies provides a good description of the conversion profiles. A reasonable representation of polymer molecular-weight averages and the complete MWD was obtained by assuming that the rate coefficient for transfer to monomer also varies as a function of monomer concentration and that a small amount of chain transfer to polymer occurs.