Electrical behavior of a graphene/PEKK and carbon black/PEKK nanocomposites in the vicinity of the percolation threshold

Abstract

Graphene and carbon black have been dispersed in a high performance thermoplastic polymer, the poly(ether ketone ketone), to improve its electrical conductivity. The dispersion of graphene has a significant influence on the percolation threshold. A simple exfoliation protocol to obtain graphene monolayers has led to a significant decrease of the percolation threshold from 4.2 to 1.9 vol%. To the best of our knowledge, it is one of the lowest percolation values for unfunctionalized graphene dispersed by melt blending in a high performance thermoplastic matrix. The conductivity value above the percolation threshold (1.2 S·m−1) means that graphene was not degraded during the elaboration process. Below the percolation threshold, Maxwell-Wagner-Sillars phenomenon increases the dielectric permittivity from 2.7 to 210 for PEKK/6 vol% graphene at 180 °C and 1 Hz. Dynamic mechanical analyses have shown that mechanical moduli were not significantly modified by conductive particles until 6 vol%.