Blends of an epoxy/cycloaliphatic amine resin with poly(ether imide)

By employing differential scanning calorimetry we have studied, under isothermal and dynamic conditions, the kinetics of the cure reaction for an epoxy based in the diglycidyl ether of bisphenol A (DGEBA) modified with different contents of poly(ether imide) (PEI) and cured with 1,3-bisaminomethylcyclohexane (1.3-BAC), over the temperature range of 80-105 degrees C. Kinetic analysis were performed using three kinetic models: Kissinger, Flynn-Wall-Ozawa and the phenomenological model of Kamal as result of its autocatalytic behaviour. Diffusion control is incorporated to describe the cure in the latter stages predicting the cure kinetics over the whole range of conversion. The values of the activation energies for all the PEI/epoxy blends are higher than the values for the neat system. The autocatalytic mechanism was observed in the neat system as in its blends. The reaction rates are higher with PEI, however the reached conversions decrease with the PEI content. A different behaviour was found between the neat system and the systems with 5 and 7.5 phr of PEI, and the systems with higher content in PEI, being more pronounced in the system with 15 phr of PEI. (C) 1999 Elsevier Science Ltd. All rights reserved.