ISOTHERMAL CURE KINETICS OF A DIGLYCIDYL ETHER OF BISPHENOL A/1,3-BISAMINOMETHYLCYCLOHEXANE (DGEBA/1,3-BAC) EPOXY-RESIN SYSTEM

By employing differential scanning calorimetry, DSC, we have studied, under isothermal conditions, the kinetics of the cure reaction for a system containing a diglycidyl ether of bisphenol A (DGEBA) and 1,3-bisaminomethylcyclohexane (1,3-BAC) as a curing agent, over the temperature range of 60-110 degrees C. We have determined the conversions reached at several cure temperatures and the reaction rates. The experimental data, showing an autocatalytic behavior, were compared with the model proposed by Kamal, which includes two rate constants, k(1) and k(2), and two reaction orders, m and n. This model gives a good description of cure kinetics up to the onset of vitrification. The activation energies for these rate constants were 44-57 kJ/mol. The reaction orders present a moderate change but their sum is in the range 2.5-3. Diffusion control is incorporated to describe the cure in the latter stages (postvitrification region). By combining the autocatalytic model and a diffusion factor, it was possible to predict the cure kinetics over the whole range of conversion. (C) 1995 John Wiley and Sons, Inc.