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.

Cellulose Nanocrystals vs. Cellulose Nanofibers: A Comparative Study of Reinforcing Effects in UV-Cured Vegetable Oil Nanocomposites

“…The steepest curing and the highest DBC% were received for the neat resin. After 2 s of irradiation, 67% of the double bonds were converted, followed by the highest 78% DBC% reached after 8 s. Herein, achieved curing time characteristics were considerably enhanced compared to the curing of poly(methyl methacrylate) and 1,6-hexanediol dimethacrylate formulations discussed by Zhang et al [ 42 ], where after 5, 10, and 15 s of UV-light irradiation, the DBC% reached 18, 55, and 72%, respectively. Steyrer et al showed that the additional post-curing at elevating temperatures of the UV-light irradiation had increased DBC% by 2-fold [ 41 ].…”