▎ 摘　　要

In this work, polyvinyl pyrrolidone (PVP) non-covalently functionalized multi-walled carbon nanotubes (MWCNTs), graphene nanoplates (GNPs) and MWCNTs/GNPs hybrids were respectively dispersed into epoxy adhesive to investigate their effects on mode I fracture toughness of unidirectional composite bonded joints through double cantilever beam tests. The synergy effects of MWCNTs and GNPs with different ratios were also studied. Testing results showed that 0.75 wt% MWCNTs/GNPs (1:4) hybrid had the highest toughening effect of 286% improvement compared with pure adhesive. In addition, PVP was proved to have a positive effect on improving fracture toughness for single nanofillers while it declined the toughening effect of MWCNTs/GNPs hybrids. Furthermore, the fracture micromorphology of adhesive layer as well as the toughening mechanisms of MWCNTs, GNPs and MWCNTs/GNPs hybrids were analyzed.