▎ 摘　　要

Graphene oxide (GO) is used to improve mechanical, thermal and functional properties of epoxy, in which the challenges are to achieve strong interfacial bonding between GO and epoxy resins with a uniform dispersion of GO within epoxy resins. GO can be partially reduced and exfoliated through modification by dopamine (DA), which can improve the dispersion of DGO in epoxy resins and achieve better interfacial bonding between DGO and the epoxy resins. The purpose of this work is to investigate the effects of GO modification by DA (DGO) on the mechanical and thermal properties of a multifunctional epoxy - diglycidyl-4,5-epoxy-cyclohexane-1,2-dicarboxylate (TDE-85). First, GO and DA were mixed with deionized water and then reacted to prepare DGO. The obtained DGO without desiccation and the pristine GO are respectively dispersed in acetone with TDE-85, and TDE-85/DGO and TDE-85/GO mixture are therefore prepared by sonication and used as master batches. The master batches are then diluted by adding a certain amount of TDE-85 and cured at elevated temperature to obtain the composites of TDE-85/DGO and TDE-85/GO with varied contents of DGO and GO. Finally, the results of the modification are demonstrated, and the properties of the composites are characterized. It is found that, GO is partially reduced and exfoliated by DA modification, and the mechanical properties of TDE-85 is enhanced upon adding DGO without losing its heat resistance. Especially when the content of DGO is 0.05 wt%, the critical stress intensity factor (K-Ic), tensile strength, elongation at break, and glass-transition temperature (T-g) of TDE-85/DGO composites are improved by 284.2%, 17.59%, 13.84% and 4.0%, respectively. The strong interfacial bonding between TDE-85 and DGO owing to the functional groups of PDA on the surface of DGO, the obvious crack deflection and crack pinning exhibited at the location of the DGO observed in SEM may be responsible for the improved mechanical properties. Furthermore, the tensile strength, K-Ic and T-g of TDE-85/DGO system are compared with those of similar toughened materials by other methods, and the result suggests that the present process is an effective toughened method. Thus, this work provides a toughened epoxy for preparing fiber reinforced composites with high-strength and high-modulus.