Bio-Resveratrol-Based Epoxy Resin to Improve the Interfacial Bonding Properties of Carbon Fiber/Epoxy Composites

A resveratrol-based epoxy resin was synthesized and applied as a novel bio-based sizing agent for the surface treatment of carbon fibers (CF). This paper investigated the effects of different sizing concentrations on the surface morphology of carbon fibers, the interfacial properties, and the mechanical performance of carbon fiber/epoxy (CF/EP) composites. X-ray Photoelectron Spectroscopy (XPS) tests showed that the functional groups and π-π* bonds of CFs significantly increased. Compared to untreated CF/EP composites, the interfacial shear strength (IFSS) of the sized composites increased by almost 69.7%, the tensile strength and modulus increased by 32.7% and 19.5%, and the flexural strength and modulus increased by 24.9% and 9.6%, respectively. A strong positive correlation was observed between the tensile and flexural properties of the composites and their interfacial bonding strength. This sizing agent effectively enhanced the interfacial properties of CF/EP composites. The CF/EP composites with sizing treatment exhibited ductile fracture characteristics which might have the potential to delay structural cracking.