Strong and ductile graphene oxide reinforced PVA nanocomposites

Abstract

Graphene oxide (GO) and its derivatives have been widely used as reinforcement in polymer matrices for enhanced mechanical and electrical properties. While graphene has higher elastic modulus and tensile strength than that of graphene oxide, it is the latter’s hydrophilic nature that provides a distinct advantage as a filler in the aqueous processing of polymer nanocomposites. In this work, we have tried to disseminate the effects of GO and reduced graphene oxide (rGO) as fillers in polyvinyl alcohol (PVA) matrix. At a loading of only 0.3 wt% GO in PVA, we observed ∼150% increment both in elastic modulus and tensile strength, which is unprecedented. The property enhancement was attributed to the homogeneous distribution of fillers, and strong interfacial interactions (hydrogen bonds) between the fillers and the matrix. Composites fabricated after in-situ reduction of GO fillers had elastic modulus comparable to that of pure PVA, but had considerably improved tensile strength. The failure strain of rGO based composites was much higher than that of both pure PVA and GO reinforced PVA composites, thus showing enhanced ductility. The microstructure of the PVA-rGO composites exhibited alignment of the fillers in the plane of the polymer film, with interfacial bonds between the fillers and matrix only at the rGO sheet edges. The distribution of GO fillers in the PVA-GO composites, however, was random with no preferred orientation. A higher degree of interfacial interactions and the homogeneous distribution of the fillers led to enhanced elastic modulus and strength, along with considerable ductility for the PVA-GO composites.