Comparison between microwave and thermal curing of a polyimide adhesive end-caped with phenylethynyl groups

Microwave energy was investigated to cure phenylethynyl-end-capped polyimide adhesive using an industrial microwave oven at a frequency of 2.45 GHz and the adhesive properties, thermal performance and curing mechanism for bonding stainless steel were evaluated. The results are compared with those of thermal cured samples. It was demonstrated that while the lap shear strength properties and thermal performance of microwave cured samples were almost as good as those cured via a thermal process, the microwave curing process resulted in a significant reduction in the process cycle time and power consumption. The Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) analysis of the cured resin structures suggested that there was no obvious difference in the chemical reactions taking place during the microwave and the thermal cure processes.