Multi-scale structure construction of carbon fiber surface by electrophoretic deposition and electropolymerization to enhance the interfacial strength of epoxy resin composites

In order to improve the interfacial strength of carbon fiber composites, a simple and efficient carbon fiber/graphene oxide (GO)/polymer mull-scale reinforcement material was prepared by electrophoretic deposition (EPD) and in-situ electropolymerization technique. The effects of surface treatment on the microstructure of CF and the properties of composites were systematically studied. Microscopic image revealed a fight and uniform coverage of the GO/polymer, which significantly increased the physical and chemical binding sites of the fiber surface, thereby improving wettability and mechanical interlocking with epoxy resin. In addition, the GO/ polymer multiscale structure on the fiber surface can be regulated by adjusting the electropolymerization time. The optimal interlaminar shear strength (ILSS) of the composites with an electropolymerization time of 120 s (CF-GO-EPI120s) was 61.9 MPa, which is 37.6% higher than that of original carbon fiber reinforced composites (45 MPa). Moreover, the tensile strength of carbon fiber monofilament was increased from 3.01 to 3.22 GPa. The failure surface of interlaminar shear strength test and dynamic mechanical properties of the composite confirmed the improvement of interface properties and formation of a good interfacial layer. This work shows that EPD of GO and electropolymerization is a simple and efficient method for the preparation of carbon fiber composites with good interfacial properties, and the process is simple and continuous, which is a potential application in industry.