Silane Coupling Agent Grafted onto the Oxidized Carbon Fiber to Improve the Interfacial Properties of Epoxy Composites

The silane coupling agent KH550 grafted carbon fiber (CF)/epoxy resin composites were prepared by two-step method. The effect of a new modification method combining oxidation treatment and surface coating on the properties of carbon fiber reinforced resin composites was investigated. The surface activity of carbon fiber is improved by introducing oxygen-containing functional groups on the surface of carbon fiber by oxidation. Subsequently, a silane coupling agent solution was applied to the oxidized carbon fiber to repair the surface damage of the carbon fiber while bridging the carbon fiber and the epoxy resin through a chemical reaction to improve the interfacial bonding performance of the carbon fiber and the epoxy resin. The results show that the interfacial properties of the composites treated with silane coupling agent are significantly improved. The interlaminar shear strength (ILSS), flexural strength, and transverse fiber bundles tensile strength (TFBT) reach 78.22 MPa, 1178.54 MPa and 27.55 MPa, which are increased by 49.27%, 106.57% and 35.85%, respectively. This method provides a simple idea for improving the mechanical properties of CF composites.