Surface modification of carbon fibers by microwave etching for epoxy resin composite

Abstract

Microwave irradiation was applied to modify the carbon fibers immersed in water. The surface chemical composition and morphology of treated carbon fibers were investigated in detail. It showed that great numbers of oxygen-containing groups were introduced in treated carbon fiber surfaces and nitrogen heterocyclic rings of carbon fiber bulk exposed for the exfoliation of surface layers. The surface roughness of carbon fibers was enlarged by oxidative etching of microplasma excited by microwave irradiation, and some nano humps were formed on carbon fiber surfaces. Although the tensile strength of treated carbon fibers were slightly deteriorated, the interfacial shear strength of treated carbon fibers/epoxy resin composite, as compared with that of untreated carbon fibers/epoxy resin composite, was significantly enhanced. The modification mechanism is that the microplasma and the exfoliation of monolayer graphene oxide sheets lead to the variations of chemical structure and physical morphology in carbon fiber surfaces.