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

Abstract

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 (Sestak–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.