Preparation and mechanical properties of functionalized graphene oxide and silane coupling agent modified carbon fiber/epoxy resin composites

To improve the interfacial bonding properties of carbon fiber-reinforced polymer (CFRP) composites, this study proposes an effective surface modification strategy for carbon fibers. A CF-KH560-PGO hybrid reinforcement was fabricated through chemical grafting, employing γ-glycidoxypropyltrimethoxysilane (KH560) as a coupling agent to bridge the carbon fibers (CF) with polyethyleneimine (PEI)-functionalized graphene oxide (GO). The presence of lamellar PGO has been observed on the surface of modified carbon fibers. The presence of the –NH2 peak, in conjunction with the C–N peak, on the surface of the carbon fibers, served to verify the grafting of PGO. The synergistic effect of PGO and KH560 significantly enhanced the surface wettability of carbon fibers. This study systematically investigates the mechanical performance of composites fabricated through different CF modification approaches, along with the underlying interfacial reinforcement mechanisms. The modified carbon fiber composites exhibited remarkable tensile strength (669.7 MPa) and interlaminar shear strength (60.41 MPa), representing 49.89% and 20.36% improvements respectively over desized carbon fiber composites. Grafted PGO can provide abundant amino groups for chemical bonding with epoxy resins. That KH560 and PGO increased the thickness of the interfacial transition layer, thereby enhancing the load transfer at the composite interface.