Electrical Conduction Behavior of High-Performance Microcellular Nanocomposites Made of Graphene Nanoplatelet-Filled...

Graphene nanoplatelet (GnP)-filled polysulfone (PSU) cellular nanocomposites, prepared by two different methods-namely, water vapor-induced phase separation (WVIPS) and supercritical CO₂ dissolution (scCO₂) foaming-were produced with a range of densities from 0.4 to 0.6 g/cm³ and characterized in terms of their structure and electrical conduction behavior. The GnP content was varied from 0 to 10 wt%. The electrical conductivity values were increased with the amount of GnP for the three different studied foam series. The highest values were found for the microcellular nanocomposites prepared by the WVIPS method, reaching as high as 8.17 × 10^-2 S/m for 10 wt% GnP. The variation trend of the electrical conductivity for each series was analyzed by applying both the percolation and the tunneling models. Comparatively, the tunneling model showed a better fitting in the prediction of the electrical conductivity. The preparation technique of the cellular nanocomposite affected the resultant cellular structure of the nanocomposite and, as a result, the porosity or gas volume fraction (V). A higher porosity resulted in a higher electrical conductivity, with the lightest foams being prepared by the WVIPS method, showing electrical conductivities two orders of magnitude higher than the equivalent foams prepared by the scCO₂ dissolution technique.