Influence of covalently-bound graphene oxide on the mechanical properties of carbon fiber composite materials

Graphene was used as an additive in fiber-reinforced plastics. The apparent interfacial shear strength (IFSS) was improved by grafting graphene onto the fibers. In this study, the effect of graphene grafted onto carbon fiber via chemical covalent bonding on the mechanical properties of the fibers was evaluated. This method was used to link graphene and carbon fibers via ester linkages, which are stronger than physical adsorption interactions and cause little damage to the fiber strength. Before grafting through an ester linkage, an electrophoretic deposition was conducted to uniformly coat graphene onto the carbon fibers. The purpose of this study was to establish a fabrication method that could control the density and thickness of the graphene layer covalently bound to the fibers. In addition, the optimal production process and composite form of the reinforced fibers were determined by evaluating the fiber strength and IFSS of various graphene-reinforced fibers. Ultimately, it was determined that graphene could be grafted onto carbon fibers relatively uniformly, and that the graphene layer thickness affected their interfacial shear strength. In terms of optimizing the IFSS, a thin and uniform graphene layer was best, and the IFSS was improved by 42.1% compared with untreated fibers containing sizing agents.