Micromechanics of reinforcement of a graphene-based thermoplastic elastomer nanocomposite

In this work, a series of graphene-reinforced thermoplastic elastomers were prepared, with the introduction of graphene nanoplatelets (GNPs) of different particle diameter. Their microstructures were characterised by scanning electron microscopy (SEM) and quantified by polarised Raman spectroscopy. Τhe GNPs were well-dispersed and their orientation across the cross-section of the injection moulded samples was consistent with the shear rate profile of fountain flow mechanism. The mechanical properties of the nanocomposites were evaluated by tensile testing and it was found that the GNPs contributed to significant improvements in both the stiffness and strength. A micromechanical model based on the combination of shear-lag theory and the rule-of-mixtures was introduced to analyse the stiffening mechanisms. Τhe effective aspect ratio of GNPs was in the order of 100 and decreased with increasing filler loading due to agglomeration. Finally, the stress transfer efficiency from the matrix to GNPs was evaluated by observing the Raman band shifts under tension.