The effect of solvent on postcuring in free radical photopolymerization.

ABSTRACT During free radical photopolymerization, with an increasing degree of conversion, the viscosity increased and vitrification occurred. The unreacted double bonds had difficulty diffusing to the reactive site in the vitrifying polymer. However, the free radicals generated in the vitrifying matrix could survive for a long time. Thus, the postcuring process occurred. In this study, free radical photopolymerization kinetics of methacrylate with or without solvent was investigated by real-time FTIR, which was combined with a heating device. Results showed that without solvent, postcuring occurred only by heating at a higher temperature than the glass transition temperature of the polymer. However, with solvent, the postcuring occurred even at room temperature, where only a small amount of solvent was enough to cause postcuring. The lifespan of the free radicals inside the polymer was over 10 h. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44223. [ABSTRACT FROM AUTHOR]