Electrical conductivity and thermal stability of surface-modified multiwalled carbon nanotubes/polysulfone/poly(p-phenylenediamine) composites

Abstract

Abstract Multiwalled carbon nanotubes (MWCNTs) were functionalized with acid then coated with poly(p-phenylenediamine) (PpPD). Various concentrations of modified multiwalled carbon nanotubes (MWCNTs@PpPD) were introduced to a polysulfone (PSU) and poly(p-phenylenediamine) (PpPD) blend providing nanocomposites in form of sheets. Chemical oxidative polymerization was used to polymerize p-phenylenediamine. PpPD is then applied as a compatibilizer in such heterogeneous system to facilitate a successful percolation for MWCNTs in the polymeric matrix as an enhanced conductive filler. The morphological investigations showed homogeneous distribution for MWCNTs in the polymeric matrix. The prepared composites were investigated demonstrating favorable thermal and electrical properties. Thermogravimetric analysis (TGA) emphasized that MWCNTs@PpPD contributed in enhancing the thermal stability of the prepared sheets. The electrical conductivity of PSU/PpPD/MWCNTs@PpPD nanocomposites boosted upon raising the magnitude of loaded MWCNTs. The existence of MWCNTs@PpPD in the polymeric matrix extended the interfacial polarization effects with elevating the conductance. The loaded composite with (7.5 wt%) MWCNTs@PpPD showed the optimum electrical conductivity values. It was then treated with HCl to protonate the amine groups in PpPD showing higher conductivity value than its corresponding untreated one. PpPD and MWCNTs contributed synergistically in modifying the insulation feature of PSU to a favorable electrical conductivity one.