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 s ystem containing a diglycidyl ether of bisphenol A (DGEBA) and 1,3-bis aminomethylcyclohexane (1,3-BAC) as a curing agent, over the temperatu re range of 60-110 degrees C. We have determined the conversions reach ed at several cure temperatures and the reaction rates. The experiment al data, showing an autocatalytic behavior, were compared with the mod el 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 descriptio n of cure kinetics up to the onset of vitrification. The activation en ergies 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. Diffus ion 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 t he whole range of conversion. (C) 1995 John Wiley and Sons, Inc.