A STUDY ON ISOTHERMAL CURE BEHAVIOR OF AN EPOXY-RICH ANHYDRIDE SYSTEMBY DIFFERENTIAL SCANNING CALORIMETRY/

Cure behavior of a catalyzed epoxy/anhydride system was investigated f or an epoxy-rich formulation using differential scanning calorimetry ( DSC). The mixture was isothermally cured at different times and temper atures, and the cure behavior of the samples was analyzed by the peak exothermic temperature (T-peak) and the extent of cure reaction (X) fr om DSC thermograms. For the excess epoxy sample, two exothermic peaks at a low temperature from esterification reaction and at a high temper ature from etherification on DSC curves appeared in the early stage of cure and shifted to a lower temperature scale with curing. However, t he esterification peak disappeared and the remaining etherification pe ak shifted to a higher temperature with further cure. The shift of the peaks may be attributed to the change of reaction mechanism from kine tically controlled to diffusion-controlled. The extent of cure of este rification and etherification was also considered separately in this a rticle. The result shows that esterification reaction mainly occurs in the early stage of cure and then etherification slowly proceeds after the completion of the esterification. (C) 1998 John Wiley & Sons, Inc .