Synergia effect of grafting polymer and coating on carbon fibers surface and interface of its composites

In this work, carbon fibers were treated with epoxy-polyurethane coating to improve the interfacial properties of carbon fiber/epoxy composites. The treatment method was divided into three phases, i.e. oxidation with oxygen plasma and coating, graft with acid anhydride and coating, plasma-grafted-sizing. The physical and chemical changes were examined using X-ray photoelectron spectroscopy, contact angle measurements, and Fourier-transform infrared spectroscopy-attenuated total reflectance technique. The tensile strength of carbon fiber and the interfacial adhesion of carbon fiber/epoxy composites were analyzed by Weibull analysis of the single fiber tensile test and by the filament fragmentation experiment of the single fiber composite. The experimental results showed that the sized carbon fiber with plasticizer had better wear-resistant properties. X-ray photoelectron spectroscopy results revealed that the plasma-grafted-sizing samples showed a significant increase in oxygen-containing groups, such as C-OH, COOH, C-O-C, and COOR. The interfacial shear strength of the plasma-grafted-sizing carbon fiber increased more significantly than the carbon fiber with sizing. This demonstrated that the surfaces of the samples were more active, hydrophilic, and rough after plasma-grafted-sizing treatments using dielectric barrier discharges operating in ambient argon mixture with oxygen.