▎ 摘　　要

In this contribution, the impact of graphene oxide (GO) with different oxidation degrees on the cryogenic mechanical properties of GO/epoxy nanocomposites is investigated. GO samples with varied oxidation degrees were prepared using a modified Hummers' method. It was found that GO exhibited better dispersion in the matrix and improved interfacial interactions with epoxy resin as its oxidation degree increased. Resultantly, GO/epoxy nanocomposites showed increased tensile properties at room temperature (RT) and liquid nitrogen temperature (LNT) as GO oxidation degree increased and reached the idealist performance with appropriate GO oxidation degree. Under low GO loading of 0.10 wt% GO/epoxy nanocomposites exhibited the highest tensile strength of 78.0 MPa at RT and 123.2 MPa at LNT, 31% and 14% higher than that of neat epoxy, respectively. Based on the fractured surface investigation, toughening mechanisms of GO for epoxy nanocomposites at RT and LNT were analyzed, between which there existed significant differences.