Two step model for crosslinking polymerization with account of diffusion

Abstract

The proposed model includes two parallel reactions, initiation and propagation that respectively follow the reaction order and autocatalytic kinetics. The effect of diffusion is accounted for in both steps by introducing a term that depends linearly on conversion. The term is introduced into the exponential part of the rate constants. Determining the magnitude of this term allows for estimating the diffusion effect on the overall activation energy in the final stages of crosslinking polymerization. The model is tested on five previously published datasets. It appears to fit all data very well and yield physically meaningful fit parameters. Algorithms for successful fitting of the model are suggested. It is also demonstrated that disregarding the effect of diffusion gives rise to markedly inferior results. The model is quite general and expected to be applicable to any polymerization complicated by diffusion or other processes that involve the interplay between the reaction and diffusion kinetics.