ANALYSIS AND COMPARISON OF THE BARRETT, FREEMAN-CARROL AND THE TIME-TEMPERATURE-TRANSFORMATION (TTT) SUPERPOSITION METHODS - THE CASE OF A HIGH T-G DIAMINE EPOXY SYSTEM/

In the present work the curing process of the epoxy system diglycidyle ther of bisphenol A (DGEBA) with 4,4'-diaminodiphenylmethane (DDM) has been studied by differential scanning calorimetry (DSC) techniques. D ynamic methods (Barrett and Freeman-Carrol) and the isothermal time-te mperature-transformation (TTT) superposition method were applied in or der to obtain kinetic features of the curing process. The time-tempera ture evolution of the glass transition temperature (T-g) and the exten t of reaction (cc) were used as parameters in order to monitor the cur ing process. Three different reaction ranges have been observed: the i nitial range of cure (0.05 < alpha < 0.35), the range prior to the vit rification (0.35 < alpha < 0.6) related to the gelation process and a final vitrification range (0.60 < alpha < 0.95). The time-temperature- transformation (TTT) superposition method was found to be more sensiti ve in the description of the vitrification process than the dynamic me thods. (C) 1997 Elsevier Science Ltd.