Enhanced interlaminar fracture toughness of carbon fiber/bismaleimide composites via microwave curing

Carbon fiber-reinforced polymer composites have been widely used in the aerospace industry. However, they are extremely sensitive to crack initiation, propagation and interlaminar delamination which severely reduce their service life. This paper demonstrated that the Mode-I interlaminar fracture toughness could be significantly improved in carbon fiber/bismaleimide composites using a microwave curing process. An increase of about 53.5% in critical load and an increase of approximately 133.5% and 61.2% in fracture toughness and fracture resistance have been achieved, respectively. The microwave manufacturing cycle for composites was cut to 44% of the thermal processing cycle. Dynamic mechanical thermal analysis was performed to investigate the enhanced interfacial strength in microwave-cured composites. The improvement in fracture toughness was attributed to a better interfacial adhesion between resin and fiber, which was investigated by the observation of fracture surfaces with optical microscopes.