Improved interfacial properties of carbon fiber/epoxy composites through graphene oxide-assisted deposition of carbon nanotubes on carbon fiber surface

A useful reinforcement for carbon fiber (CF) composites was found by performing the assisted electrophoretic deposition (EPD) of graphene oxide (GO) for carbon nanotubes (CNTs) onto the CF surface. GO-assisted EPD of CNTs was conducted without the use any other pre-treatment or additives in order to avoid destroying the structure of the CNTs and to facilitate preparation of stable dispersion that was suitable for EPD. The presence of GO-CNTs may effectively increase both the roughness and wettability of the CF surface, resulting in an improvement to the interfacial bonding strength between the CF and the epoxy (EP). In contrast to the pristine CF/EP composite, the GO-CNTs/CF/EP composite exhibited a 64.6 % increase in interlaminar shear strength. Meanwhile, the water absorption of the composites decreased from 0.36 wt.% to 0.14 wt.%. The variable surface morphology, surface roughness, surface free energy and surface chemical composition of the CF were considered to have had an effect on the interfacial properties of the CF/EP composites; these effects could be seen using atomic force microscopes, scanning electron microscopes, X-ray photoelectron microscopes and contact angle analysis characterizations.