Effect of graphene oxide/graphitic nanofiber nanohybrids on interfacial properties and fracture toughness of carbon fibers-reinforced epoxy matrix composites

Abstract

The fracture toughness of carbon fiber-reinforced epoxy composites (CFRPs) is greatly dependent on the interfacial adhesion between the carbon fibers and the epoxy matrix. Introducing nanofiller reinforcements into the interface is an effective approach to enhancing the interfacial adhesion of CFRP. In the present study, a simple and efficient method is proposed for the deep and stable penetration of graphene oxide/graphitic nanofiber nanohybrids (GO-GNFs) into an epoxy matrix as a CFRPs. To confirm the efficiency of the proposed method, CFRPs are fabricated with various amounts of (i) untreated GNFs, (ii) dry-ozonized GNFs, and (iii) GO-GNFs. For all three types of composites, the optimal nanofiller content is found to be 0.8 wt%. The addition of GO-GNFs is shown to increase the inter-laminar shear strength by 159.5%, and the fracture toughness by 102.8%, compared to those of the pristine CFRPs. The reinforcing mechanisms are explored by analyzing the surface properties of GO-GNFs and the wettability between fiber and nanofillers within the epoxy matrix, are ascribed to the maximal polar component of surface free energy and the minimal contact angles. This approach shows that the GO-GNF composite is a simple and efficient method for the preparation of CFRPs with excellent interfacial adhesion, which has potential applications in the structural composite industry.