Reinforcing effects of functionalized graphene oxide on glass fiber/epoxy composites

Abstract

Glass fiber (GF)/epoxy (EP) matrix composites containing graphene oxide (GO) nanoplatelets were manufactured for improving the mechanical properties. GO nanoplatelets were functionalized using dodecylamin (DA) and 1‐(3‐aminopropyl) imidazole (IL) to improve their dispersion in the matrix and to reinforce EP adhesive. The structural properties of GO and functionalized GOs (FGOs) were characterized by Fourier‐transform infrared spectroscopy (FT‐IR), X‐ray diffraction and BET surface area measurements. In the sample preparation, 3‐ply composites were prepared by hand lay‐up process, using a fiber‐to‐resin ratio of 40:60 (w:w). The high performance GO and FGOs were next incorporated into EP matrix resin to generate the reinforced GO/EP/GF and FGO/EP/GF composites. The GO and FGO contents varied in the range of 0.3, 0.5, and 0.8 wt%. Decreasing of oxygenated functional groups on FGOs and the appearance of aminated groups were proved by the FT‐IR spectra. The specific surface area of DA‐GO (295.8 m2/g) was much larger than IL‐GO (42.88 m2/g) or GO (2.49 m2/g), indicating a better interfacial interlocking of the DA‐GO in EP matrix. In addition, the BET surface areas of the FGOs were increased as compared to that of GO, which could be ascribed to the addition of functional groups on the GO sheet. Results showed that the mechanical properties, in terms of tensile and flexural properties, were mainly dependent on the type of GO functionalization followed by the percentage of modified GO. As a result, both the tensile and flexural strengths are effectively enhanced by the FGOs addition. However, the reinforcing effect of DA‐GO on the mechanical properties was much better than IL‐GO and GO nanoparticles. The tensile and flexural moduli are also increased by the FGO filling in the EP resin due to the excellent elastic modulus of FGO. Although incorporating FGO into the EP matrix effectively improves mechanical properties, this improvement comes at proper loading. The optimal DA‐GO and IL‐GO contents for effectively improving the mechanical performance were found to be 0.5 and 0.8 wt%, respectively. Scanning electron microscopy confirmed that the failure mechanism of GFs pulled out from the EP matrix contributed to the enhancement of the mechanical performance. These results show that FGOs can strengthen the interfacial bonding between the GFs and the EP adhesive. POLYM. COMPOS., 39:E2324–E2333, 2018. © 2017 Society of Plastics Engineers