Electrostatic incitation on fiber surface for enhancing mechanical properties of fiber-reinforced composite

The excellent wettability contributes to the formation of mechanical interlocking morphologies at the interface as well as to the reduction of the internal defects in the composite for enhancing the mechanical properties of the fiber-reinforced composites. Herein, a facile and effective electrostatic method is proposed, where a small proportion of negative charges are merely sprayed on the fiber surface to modulate wettability. The results revealed that negatively charged fibers exhibit superior wettability for resin. Furthermore, the interfacial shear strength (IFSS) of the electrostatically treated T800H carbon fiber (T800H-ES)-based composite is 29.9% higher than that of the untreated-fiber composites. The improvement in interfacial properties is mainly ascribed to the formation of mechanical interlocking induced by surface charge-triggered Cassie-Baxter (CB) to Wenzel (WZ) transition of a liquid resin on the fiber surface, as verified by molecular dynamics (MD) simulations of carbon fiber–resin interfacial wetting. In addition, T800H-ES based composite has a 41.2% increase in tensile strength, a 22.5% increase in interlaminar shear strength (ILSS), and a 100.5% increase in fracture energy compared to as-received composite. These increases were mainly attributed to the improved interfacial adhesion and the reduction in internal composite defects. Consequently, this study reveals that the electrostatic charge-assisted wetting method is a green, cost-effective, and promising method for preparing composites with outstanding interfacial characteristics and mechanical properties.