▎ 摘　　要

The reinforcing effect of graphene in enhancing the cryogenic tensile and impact properties of epoxy composites is examined at a weight fraction of 0.05-0.50%. The micro-structure and cryogenic mechanical properties of the graphene/epoxy composites are investigated using scanning electron microscopy, transmission electron microscopy, small-angle X-ray scattering and mechanical testing techniques. The results show that the graphene dispersion in the epoxy matrix is good at low contents while its aggregation takes place and becomes severer as its content increases. And the cryogenic tensile and impact strength at liquid nitrogen temperature (77 K) of the composites are effectively improved by the graphene addition at proper contents. The cryogenic Young's modulus increases almost linearly with increasing the graphene content. Moreover, the results for the mechanical properties at room temperature (298 K) of the graphene/epoxy composites are also presented for the purpose of comparison. (C) 2012 Elsevier Ltd. All rights reserved.