Improving the interfacial properties of carbon fiber–epoxy resin composites with a graphene‐modified sizing agent

ABSTRACT We successfully prepared a graphene‐modified carbon fiber (CF) sizing agent with good dispersity and stability by dispersing reduced graphene oxide (RGO) into an emulsion‐type sizing agent. RGO was obtained by the reduction of graphene oxide (GO) with the help of gallic acid. The influence of the graphene‐modified sizing agent on the interfacial properties of the CF–epoxy resin composites was investigated with microbond testing and the three‐point bending method. The results show that optimized interfacial properties were achieved when the size of the modified graphene was less than 1 μm, the content of RGO was 20 ppm, and the pH value of the sizing agent was 10.5. The interfacial shear strength of the composites reached 92.3 MPa, which was 29.6% higher than that of the composites with unmodified CFs. Compared with commercial‐CF‐fabric‐reinforced composites, the interlaminar shear strength of the composites treated with the RGO‐modified sizing agent increased by 21.5%. Both the interfacial and interlaminar failure morphologies of the composites were examined with scanning electron microscopy (SEM). The results show that a large amount of residual resin adhered to the surfaces of the CFs treated with the RGO‐modified sizing agent; this indicated good interfacial properties between the CFs and the resin matrix. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136 , 47122.