Non-isothermal kinetics of epoxy resin curing reaction under compressed CO2

The non-isothermal curing kinetics of epoxy resin system consisting of diglycidyl ether of bisphenol A (DGEBA) and m-xylylenediamine (MXDA) were investigated by high-pressure differential scanning calorimetry at different heating rates of 5, 10, 15 and 20 K min(-1) under compressed carbon dioxide (CO2) of 0.1-8 MPa. The activation energies were determined by isoconversional Kissinger-Akahira-Sunose method and Vyazovkin numerical method, and the average values decreased from 53.5 to 46.8 and 54.1 to 44.5 kJ mol(-1), respectively, when the CO2 pressure increased from 0.1 to 8 MPa. It is indicated that the curing reaction of epoxy resin occurs more easily under higher-pressure CO2 due to the promoted molecular movement, especially in the supercritical state. The non-isothermal curing kinetics were investigated by nth-order model and two-parameter autocatalytic model (estak-Berggren model), and the latter one analyzed by Malek method exhibited good agreement with the experimental data except the initial and final stages of the curing reaction.