Construction of modified MXene with “organic–inorganic” structure to enhance the interfacial and mechanical properties of UHMWPE fiber-reinforced epoxy composite

A type of MXene nanosheets with "organic–inorganic" structure was constructed through chemical reactions of 3-aminopropyltriethoxysilane and ethylene glycol diglycidyl ether on MXene surface to improve the interfacial and mechanical properties of ultrahigh-molecular weight polyethylene (UHMWPE) fiber-reinforced epoxy composite. The soft "organic" portion was conducive to good dispersion of epoxy-modified MXene nanosheets (M−MXene) in epoxy resin, whereas the "inorganic" part guaranteed the excellent mechanical performance of M−MXene. Then, M−MXene nanosheets were added into the epoxy matrix or deposited onto the surface of modified UHMWPE fibers to investigate the effect of M−MXene on composites' properties. Results indicated the introduction of M−MXene could increase friction force and mechanical interlocking, produce excellent wettability with epoxy matrix, and form chemical bonds with the curing agent. Then, reduced stress concentration and complicated crack path were formed due to the unique "organic–inorganic" structure. Compared with UHMWPE/Epoxy, UHMWPE-PAS@M−MXene/Epoxy and UHMWPE-PAS/Epoxy@M−MXene illustrated significant improvements of 39% and 56%, respectively, in tensile strength and 311% and 324%, respectively, in interfacial shear strength (IFSS). Improved mechanical and interfacial properties of UHMWPE-PAS/Epoxy@M−MXene were attributed to the uniform distribution of M−MXene in the epoxy matrix, which generated a longer crack path from fiber to matrix and more crack deflections compared with those of UHMWPE-PAS@M−MXene/Epoxy.