Study on the heating mechanism and macro/micro properties of composite materials under microwave curing

Compared to composite components prepared by traditional thermal process, microwave-cured laminates exhibit superior mechanical properties under the same heating cycle, indicating a unique heating mode that differs from air circulation. To progressively replace the thermal curing process with microwave technology in the aerospace composites manufacturing field, it is crucial to elucidate the heating mechanism of microwave-cured composite materials. In this study, the microwave absorbing performance of both carbon fibers and epoxy resins was systematically compared and revealed. Drawing upon principles of organic chemical reaction and Fourier transform infrared spectroscopy, the results demonstrated the swift response of carbon fibers to microwaves, which facilitated heightened functional group transformation and more complete curing reactions at the fiber-matrix interface. Notably, as indicated by the results of the three-point bending tests and fiber push-in tests, microwave-cured laminates displayed enhanced interlaminar and interfacial bonding properties in comparison to thermally cured counterparts, resulting in a 10.74% increase in interlaminar shear strength (ILSS) and a 20.23% rise in interfacial shear strength (IFSS).