Electrical properties of imidazole-modified MWNT/polyphenylenesulfide composites prepared by melt mixing

The electrical conductivity of surface-modified multiwalled carbon nanotubes (MWNTs)/poly-phenylenesulfide (PPS) composites prepared by melt processing is measured as a function of frequency with the MWNTs content and evaluated in terms of percolation behavior. The imidazoledithiocarboyxlic acid (imidazole) is grafted from the oxidized MWNTs, and the results of surface analysis, HRTEM and thermal analysis reveal that the MWNTs are successfully modified by imidazole. Although the imidazole-modified MWNTs are most damaged during the modification reaction of imidazole with carboxylic group onto the MWNTs as well as during the oxidation, so that the modified MWNTs are significantly shortened, the imidazole modification of MWNTs enables the PPS composites to have the lower percolation threshold and the higher electrical conductivity than the oxidized MWNTs/PPS composites. It is recognized that the better dispersion of MWNTs derived from the compatibility of PPS with sulfur moiety in the imidazole and the presence of N-H groups which may act as an assistor of the electronic conduction and/or decrease the energy barrier required for the charge carriers to hop from conducting clusters to neighbors contribute to the enhancement of the electrical properties of the imidazole-modified MWNTs/PPS composites.