Super Heat-Resistant Conductive Nanocomposites Based on Polysulfone–Carbon Nanofillers

The present article describes the morphology, mechanical, thermal, electrical, and dielectric properties of polysulfone (PSU) nanocomposites filled with different concentrations of multiwalled carbon nanotubes (MWCNT) and carbon nanofibers (CNF) [Only one carbon material per each]. The tensile strength and tensile modulus of both MWCNT- and CNF-filled nanocomposites increased with the increase in filler loading up to 3 wt.%. The addition of 3 wt.% CNF led to increase in tensile strength and modulus by 22% and 46%, respectively. Similarly at the same loading of MWCNT, the tensile strength and tensile modulus increased by 16% and 44%, respectively. Thermogravimetric analysis indicated continuous upgrade in thermal stability compared to pure PSU matrix up to 3 wt.% nanofiller loading. Electrical conductivity of both nanocomposites obeyed a power law model of the percolation theory having very low percolation threshold of 0.0079 (0.9 wt.%) for PSU/CNF nanocomposite and 0.014 (1.5 wt.%) for PSU/MWCNT nanocomposite. Dielectric properties of nanocomposites were enhanced significantly with increasing MWCNT/CNF concentration, but decreased with increasing frequency. The dielectric constant reached to 8.5 × 109 (100 Hz) at 5 wt.% MWCNT and 5.4 × 1010 at 5 wt.% CNF, respectively, from the neat PSU matrix (2.1 at 100 MHz). The current (I)–voltage (V) characteristics exhibited ohmic conduction at and above the percolation threshold for both MWCNT- and CNF-filled nanocomposites.