Photo-DSC cure kinetics of vinyl ester resins. I. Influence of temperature

Isothermal DSC was employed to monitor the photopolymerization kinetics of a commercial vinyl ester resin (VER) photoinitiated by the camphorquinone/amine photoinitiator system. The maximum rate of photopolymerization was found to increase tenfold as the isothermal cure temperature was varied from −30 to 90 °C due to faster propagation and greater initiator efficiency counterbalanced by a faster termination rate. After photopolymerization, the samples were temperature ramped in the DSC to monitor the dark polymerization reaction. The reduced polymerization rate increased with the scan temperature due to an increase in propagation rate. The summation of the isothermal and residual polymerization heats indicated that the final degree of cure after postcure was independent of the isothermal cure temperature. The onset temperatures for the recommencement of cure during the dark temperature scanning experiments were found to correspond closely with their respective isothermal cure temperatures as expected due to vitrification during the isothermal cure stage.