▎ 摘　　要

The toughening effect of graphene sheets on polycarbonate (PC) was investigated to fabricate PC composites with excellent balanced toughness, notch resistance as well as strength. The reduced graphene oxide (RGO) was incorporated into PC matrix through melt compounding. A maximum toughening effect was observed in PC/RGO (PCG) composites with 0.03 wt% or 0.07 wt% RGO. Particularly, the tensile fracture toughness of PCG composites with 0.03 wt% RGO was enhanced by 89%. The notched impact strength and K-IC of PCG composite with 0.07 wt% RGO was increased by 46% and 58%, respectively. The point of 0.1 wt% was found to be the ductile-brittle transition point in PCG composites. Meanwhile, the yield strength of these novel materials was increased by around 12% as well at loading of 0.07 wt%. Microcrack, resulting from interfacial debonding between PC and RGO as well as breakage and pulling out of graphene layer, was proposed to be the main toughening mechanism contributing to the great enhanced fracture toughness and notch resistance. Apart from the microcrack, crack pinning, crack deflection and crack arresting were also found and proposed to be toughening mechanism in notch fractured process. This work not only provides us a novel strategy to fabricate advanced PC nanocomposites but also gives us a deep understanding on the toughening role of graphene on polymers. (C) 2017 Elsevier B.V. All rights reserved.