Studies of cure schedule and final property relationships of a commercial epoxy resin using modified imidazole curing agents

A commercial epoxy prepolymer (MY750) was cured with novel modified imidazole curing agents under both isothermal and dynamic scanning conditions. The thermal behaviour of the formulated mixtures was investigated using differential scanning calorimetry and thermogravimetric analysis, and glass transition temperature (T-g) values derived for polymers resulting from both cure schedules. T-g values and the thermal stability of polymers arising from the isothermal cure schedules were generally higher than those for the corresponding dynamic cure. For samples cured by the dynamic curing process, a lower heating rate resulted in higher T-g values and superior thermal stability. The same findings were obtained for samples cured by the isothermal curing process when the relatively low initial cure temperatures were optimal. The results of this study indicate that the initial and post-cure conditions may affect the final properties, and support the view that both the initial and post-cure schedules are of critical importance in governing the nature of the early network formation and the final network structure. (C) 1998 Elsevier Science Ltd. All rights reserved.