▎ 摘　　要

A detailed study has been undertaken of the mechanisms of stress transfer in polymeric matrices with different values of Young's modulus, E-m, reinforced by graphene nanoplatelets (GNPs). For each material, the Young's modulus of the graphene filler, E-f, has been determined using the rule of mixtures and it is found to scale with the value of E-m. Additionally stress-induced Raman bands shifts for the different polymer matrices show different levels of stress transfer from the polymer matrix to the GNPs, which again scale with E-m. A theory has been developed to predict the stiffness of the bulk nanocomposites from the mechanics of stress transfer from the matrix to the GNP reinforcement based upon the shear-lag deformation of individual graphene nanoplatelets. Overall it is found that it is only possible to realise the theoretical Young's modulus of graphene of 1.05 TPa for discontinuous nanoplatelets as E-m approaches 1 TPa: the effective modulus of the reinforcement will always be less for lower values of E-m. For flexible polymeric matrices the level of reinforcement is independent of the graphene Young's modulus and, in general, the best reinforcement will be obtained in nanocomposites with strong graphene-polymer interfaces and aligned nanoplatelets with high aspect ratios. (C) 2017 The Authors. Published by Elsevier Ltd.