Improved rheological and electrical properties of graphene/polystyrene nanocomposites modified with styrene maleic anhydride copolymer

Styrene-maleic anhydride copolymer (SMA) was used as a compatibilizer to improve the interfacial interaction between graphene sheets and polystyrene matrix. SMA mediated graphene sheets are closely encapsulated by a polymer layer and uniformly dispersed compared to the graphene sheets without SMA. The presence of SMA not only improves the melt modulus and its frequency-independence, but also results in an earlier transition from liquid-like to solid-like, indicating the formation of a percolated conducting network at a low content of graphene with the assistance of SMA. Accordingly, the different frequency dependences of electrical conductivity also lead to a much lower threshold of 0.17 vol.% for SMA modified nanocomposites compared to 0.52 vol.% for the unmodified counterparts, further confirming the earlier formation of a graphene network in the matrix. The improved rheological and electrical properties of the polystyrene nanocomposites are attributed to the homogeneous dispersion of the graphene sheets and the enhanced interfacial interaction between the graphene sheets and the polystyrene matrix.