Modeling of Free-Radical Polymerization Kinetics with Crosslinking for Methyl Methacrylate/Ethylene Glycol Dimethacrylate

A model has been developed to represent polymerization kinetics with crosslinking up to, and past, the gelpoint. Based upon the method of moments, the representation predicts the changes in polymer molecular weight (MW) as branching occurs, and provides a measure of the MW increase caused by the crosslinker. Loss of pendant double bonds by internal cyclization and decrease in branching rate due to diffusion limitations are included. The Ross-Laurence correlation for diffusion-controlled termination has been modified to predict the faster rate acceleration that occurs in lightly crosslinked systems and the delayed Trommsdorff effect observed upon addition of chain transfer agent. The model successfully represents gelpoint and rate data for methyl methacrylate (MMA) polymerization for a wide range of ethylene glycol dimethacrylate (EGDMA) levels, with and without the presence of chain transfer agent.