COMPARISON OF MICROWAVE AND THERMAL CURE OF EPOXY-RESINS

Stoichiometric mixtures of DGEBA (diglycidyl ether of bisphenol Al)/DD S (di-aminodiphenyl sulfone) and DGEBA/mPDA (meta phenylene diamine) h ave been isothermally cured by electromagnetic radiation and conventio nal heating using thin film sample configurations. Fourier transform i nfrared spectroscopy (FTIR) was used to measure the extent of cure. Th ermal mechanical analysis (TMA) was used to determine the glass transi tion temperatures directly from the cured thin film samples. Well-defi ned glass transitions were observed in the TMA thermograph for both th ermal and microwave cured samples. Significant increases in the reacti on rates have been observed in the microwave cured DGEBA/DDS samples. Only slight increases in the reaction rates have been observed in the microwave cured DGEBA/mPDA samples. Higher glass transition temperatur es were obtained in microwave cured samples compared to those of therm ally cured ones after gelation. The magnitude of increases of glass tr ansition temperature is much larger for the DGEBA/DDS system than DGEB A/mPDA system. The microwave radiation effect was much more significan t in DGEBA/DDS system than in DGEBA/mPDA system. DiBenedetto's model w as used to fit the experimental T(g) data of both thermal and microwav e cured epoxy resins.