Kinetics study of imidazole-cured epoxy-phenol resins

The reaction kinetics of diglycidyl ether of bisphenol A (DGEBA) cured with different concentrations of imidazole and bisphenol A (BPA) were investiga ted by using differential scanning calorimetry. Both dynamic and isothermal DSC were studied. Two initiation mechanisms were found to play roles in th e-curing reactions. One was based on adduct formation of epoxy groups with pyridine-type nitrogen and the other was based on ionic complexes of imidaz ole and BPA. The subsequent propagation was composed of three main reaction s, viz. the epoxide/phenol reaction, the acid/base reaction, and the epoxid e/R-O- reaction. A generalized kinetics model was developed and used to pre dict the conversion of epoxide groups using a wide range of imidazole and B PA concentrations, and cure temperature. (C) 1999 John Wiley & Sons, Inc.