Influence of different surface treatments on the interfacial adhesion of graphene oxide/carbon fiber/epoxy composites

In this paper, four surface modifications have been applied on carbon fiber (CF) prior to graphene oxide (GO) electrophoretic deposition (EPD) for preparing GO/CF hybrid fiber reinforced epoxy (GO/CF/EP) composites, including acid oxidation, sizing coating, silane coupling coating and electrochemical oxidation. Note that electrochemical oxidation coupled with EPD was a feasible way to evenly disperse GO on CF surface and construct conductive network. In contrast, acid modification could increase surface roughness while sizing and coupling coating were responsible for chemical activity. Furthermore, after comparative analyses between different modifications, it can be concluded that surface oxygen-containing functional groups and micromechanical interlocking contributed a lot in robust strengthening and electrical conduction of GO/CF/EP composites, as proved by GO/CFs-eco and GO/CFs-acid reinforced composite samples. Based on these results, an in-depth comparison based on interfacial shear strength (IFSS) and other adopted evaluating factors on four kinds of surface modifications was proposed, demonstrating that proper treatments should be chosen for the combination of optimizing interfacial properties in GO/CF/EP composites.