Toughening of a trifunctional epoxy system. II. Thermal characterization of epoxy/amine cure

The cure of a trifunctional epoxy resin with an amine coreactant was studied using two thermal analysis techniques: differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA). These techniques were used to monitor the development of both the thermal and mechanical properties with cure. Detailed kinetic analysis was performed using a variety of kinetic models: nth order, autocatalytic, and diffusion-controlled. The reaction was found to be autocatalytic in nature during the early stages of cure while becoming diffusion-controlled once vitrification had taken place. By combining the results obtained from DSC and DMTA, the degree of conversion, at which key events such as gelation and vitrification take place, were determined. A TTT diagram was constructed for this epoxy/amine system showing the final properties that can be achieved with the appropriate cure history.