Comparison between the thermal and microwave curing of bismaleimide resin

Microwave energy was used to cure Matrimid 5292A bismaleimide resin. The degree of cure at different cure times was determined with differential scanning calorimetry. A comparison was made with the same resin cured in a conventional oven. The resin cured faster in the microwave oven than in the conventional oven. The glass-transition temperature (T-g) depended on the degree of cure. The samples cured with a conventional oven showed slightly higher T-g's than the microwave-cured samples at higher degrees of cure. At low degrees of cure, the two heating methods yielded materials with similar T-g's. Fourier transform infrared spectroscopy and solid-state cross-polarity/magic-angle-spinning C-13 NMR spectroscopy were used to investigate the cured structures. There was no difference in the chemical reactions taking place during the microwave cure and the thermal cure. (C) 2003 Wiley Periodicals, Inc.