▎ 摘　　要

A high-performance piezoresistive strain sensor can be used to monitor the deformation and damage in the structural composites. We developed the sensors with high sensitivity by structuring a 3D graphene network into an epoxy matrix. One-pot synthesis of amino-functionalized graphene nanoplates (f-GnP) was realized from graphite oxide and polyether amine, so that the dispersion of graphene in epoxy was well improved. The f-GnP/epoxy composite with lower percolation threshold, i.e. similar to 1.31 vol%, exhibited relatively high gauge factor of similar to 45 and Young's modulus of similar to 2.2 GPa. Importantly, the studied sensor with f-GnP network structure could help to detect the initiation and accumulation of damage in the structure materials under tensile loading. The normalized electrical resistance change (Delta R/R-0) of the composite sensor initially almost increased linearly, then shown nonlinear drift and irregular ladder-shaped growth with the appearance of irreversible damage and deformation. These results suggest that the graphene/epoxy piezoresistive sensors show promising applications for the damage monitoring of structural materials in the field of aerospace. (C) 2015 Elsevier Ltd. All rights reserved.