The Effect of Graphene Dispersion on the Electrical Properties of Polyimide Nanocomposites

Graphene-based polymer nanocomposites have attracted widespread industrial interest as the electrical conductivity of the material can be precisely controlled due to the unique conduction properties of graphene. In this paper, we show the effect of exfoliation methods and dispersion time on the particle dispersion, aggregate size and the overall electrical conduction of polyimide/graphene nanocomposites. A set of polyimide films with a varying graphene nanoflake content were prepared by thermal imidization and electrically characterised to assess the impact of the composition of the nanocomposite on the electrical percolation threshold. Three dispersion techniques were investigated (i.e. high shear mixing, ultrasonication probe and planetary mixing) and it was found that the size of the graphene nanoflakes was reduced by increasing the dispersion time in each case. The highest dispersion quality was obtained using the high shear mixing technique which yielded an electrical percolation threshold of 0.03 wt%.