Modeling and measurement of free radical copolymerization kinetics for high-temperature synthesis of acrylic coatings resins

In accordance with North American regulations, the volatile organic content (VOC) in coatings has been dramatically reduced in the past decades. The high molecular weight polymer solutions at 30 to 40 wt% solids have been replaced by low molecular weight, highly functionalized polymer resins at 60 to 80 wt% solids. One of the most effective ways to control molecular weight is to polymerize at temperatures greater than 120°C.; However, the classic free radical kinetics, which includes initiation, propagation, termination, and chain transfer, fails to predict the molecular weights and monomer conversion in higher temperature copolymerization of acrylate and methacrylate. Two additional secondary reactions have to be considered in order to better understand the system: methacrylate depropagation and acrylate backbiting.; This work experimentally investigates the effect of methacrylate/acrylate feed ratio on observed molecular weight and conversion profiles for high temperature solution copolymerization of butyl methacrylate and butyl acrylate. A mechanistic model, which includes all the important side reactions to further improve our understanding of the system, has been set up in PrediciRTM, a commercial software package. (Abstract shortened by UMI.)...