Chemico-diffusion kinetics and TTT cure diagrams of DGEBA–DGEBF/amine resins cured with phenol catalysts

Abstract

Curing of epoxy–amine resins with bisphenol A (BPA) as an external catalyst was studied from differential scanning calorimetry analyses in isothermal and dynamic modes. Both phenomenological and mechanistic models have been tested. The mechanistic model where epoxy cure is postulated to only occur through hydroxyl-catalyzed reactions, and assuming a different reactivity of both types of hydroxyl groups (from BPA and epoxy chains) provided a reasonable fitting of the whole set of experimental data. In particular, the latter model provides good predictive behavior for changes in the mixture composition (BPA content varying in the range from 3 to 10 wt.%, relative to the weight of hardener), contrary to the model based on the same reactivity of both types of hydroxyl groups. The isothermal time–temperature–transformation (TTT) diagram including the time to vitrification and iso- T g curves of the complex epoxy system was also established.