Enhancing the Interfacial Bonding Strength of Carbon/Epoxy Composites Using Silane-Functionalized Graphene Oxides

Silane-functionalized graphene oxides (sGOs) were fabricated with four different self-assembled monolayers (SAMs) to reinforce an epoxy adhesive, with the aim of improving the bonding strength of carbon/epoxy composites. The oxygen-containing groups on the surface of GO were converted by the SAMs to amine, epoxy, or alkyl groups. The successful reaction between the silane molecules of the SAMs and functional groups of GO was evidenced by the results of different characterization methods such as Fourier transform infrared spectroscopy, thermogravimetric analysis, X-ray diffraction, and synchrotron-radiation photoemission spectroscopy. It was found that the average thickness of the sGO flakes was higher than that of GO flakes regardless of the SAM used, which also suggested the presence of silane-functionalized groups on the GO sheets. The bonding strength of a carbon fiber/epoxy composite, tested with a single lap joint bonded with an epoxy adhesive, was increased by 53% after the addition of a sGO that contained amine groups. These results show that sGOs, especially those containing amine functional groups, can strengthen the interfacial bonding between the carbon fibers and epoxy adhesive. Therefore, it is thought that sGOs could be used in adhesive bonding applications to increase the bonding strength.

AcknowledgementsThis research was supported by the Mid-Career Research Program (2014-1051098) through the National Research Foundation of Korea (NRF), which is funded by the Ministry of Education, Science, and Technology.