Ti₃C₂T_x-MXene sizing agent surface modified high modulus carbon fiber and its epoxy resin matrix composites interface properties

In order to improve the surface wettability of high modulus carbon fibers (HMCF) and enhance the interfacial properties of their composites, a few-layer Ti₃C₂T_x-MXene aqueous dispersion with a size of 100-500 nm was mixed with an aqueous epoxy emulsion to prepare an Ti₃C₂T_x-MXene modified sizing agent for HMCF by mechanical blending method. The continuous sizing technology was used to construct a characteristic coating rich in Ti₃C₂T_x-MXene on the surface of HMCF in order to improve the interface bonding of HMCF/epoxy resin (EP) composites. The surface morphology, surface chemical state and surface wettability of HMCF were characterized by SEM, XPS and dynamic contact angle test, and the interface bonding of HMCF/EP composites was analyzed and characterized by interlaminar shear strength (ILSS) and cross-sectional morphology tests. Finally, the interface enhancement mechanism of Ti₃C₂T_x-Mxene/EP sizing agent-modified HMCF/EP composites was investigated with the shear damage models of the composites. The results show that after the surface treatment with Ti₃C₂T_x-MXene modified sizing agent, the O/C (atomic ratio) of the HMCF surface is increased, and a certain amount of nano-scale convex micromechanical structures are introduced to improve the surface wettability of HMCF. When the solid content of the epoxy emulsion sizing agent is 0.8% and the concentration of Ti₃C₂T_x-MXene is 1.0 mg/mL, the ILSS of the HMCF/EP composites increases by 23.8% to 85.9 MPa.