Some Remarks on the Kinetics of Vinyl Derivative Polymerization

Abstract

The various elementary steps of vinyl polymerization reactions are discussed. Activation is considered to occur by collision of an unactivated monomer either with another monomer, a catalyst, a solvent, or a polymer molecule. It is further taken into account that certain types of active nuclei can be more easily deactivated than others. Two steps of propagation are considered: normal chain growth and chain transfer. Termination of growing chains is assumed to be possible either by collision with another growing chain, with an activated monomer, with a molecule of the catalyst, or with certain chain breaking impurities. Using the assumption that for a certain period of the reaction a steady state of activated centers is maintained, equations are derived for the initial over-all rate of the reaction and for the number average polymerization degree. These equations are compared with experiments which have been carried out on the polymerization of styrene at various temperatures, monomer concentrations, and catalyst concentrations. Comparison between theory and experiments shows that in first approximation, the initial over-all rate of the reaction and the initial number average polymerization degree can be represented by the derived equations.