Non-isothermal curing of a diepoxide–cycloaliphatic diamine system by temperature modulated differential scanning calorimetry

The non-isothermal curing of an epoxy resin based on diglycidyl ether of bisphenol A (DGEBA) with a diamine based on 3,3′-dimethyl-4,4′-diaminodicyclohexylmethane (3DCM) was analysed by temperature modulated differential scanning calorimetry (TMDSC). The TMDSC scans were performed at underlying heating rates, q0, of between 1 and 0.1 K min−1, and at the following modulation conditions: an amplitude of 0.2 K and a period of 60 s. For values of q0 equal to or lower than 0.5 K min−1, a vitrification and further devitrification of the system was observed in the modulus of the complex heat capacity, |Cp∗|, and also in the phase angle signal. Both the time and the temperature of vitrification and devitrification are used to construct a continuous heating transformation (CHT) cure diagram. This diagram was completed by the lines that give the evolution of the temperature and the glass transition temperature over time at constant heating rate. The effect of the steric hindrance of the diamine is analysed in the curing kinetics and the maximum glass transition temperature of the resin. The thermal stability of the reacting system was studied by thermogravimetric analysis.