▎ 摘　　要

Significant reinforcement of polyurethane/epoxy (PU/EP) composites in situ synthesized on the graphene oxide nanosheets (GONS) is reported for the first time. Firstly, the PU prepolymer was in situ synthesized on the GONS. Then, the EP and a curing agent were added to prepare the PU/graphene oxide/EP (PU/GO/EP) nanocomposites. Morphologic study shows that, due to the formation of chemical bonding, the GONS was dispersed well in the PU/EP matrix and formed a strong interfacial interaction between the GONS and the matrix. With the incorporation of 0.066 wt% of GONS, the tensile modulus of PU/GO/EP nanocomposites increased from 218 MPa to 257 MPa, the tensile strength and elongation at the break of the PU/GO/EP nanocomposites increased by more than 52% and 103%, respectively. Additionally, the enhancing mechanism was tentatively proposed. The thermogravimetric analysis tests show that graphene oxide slightly changed the thermal stability of PU/GO/EP nanocomposites. It is hoped that our current work could provide an effective and promising method for preparing graphene-based polymer composites. (C) 2013 Elsevier Ltd. All rights reserved.