Electrical conductivity of thermal carbon blacks - Influence of surface chemistry

The electrical conductivity of thermal and conductive carbon blacks with different chemistry was determined by impedance spectroscopy. Thermal blacks are suitable compounds for studying the influence of the chemistry on the conductivity since they have similar structures and surface areas, which strongly influence the conductivity. The conductivity was related to the carbon chemistry characterised by surface spectroscopic methods (ESCA and SIMS) and Raman spectroscopy, respectively. In general, the conductivity increases with decreasing concentration of surface oxygen and sulphur functional groups. However, different conductivities were observed for some samples with similar concentration of surface oxygen and sulphur functional groups. The conductivity correlated best with the polyaromatic character of the carbon black surface characterised by the C2H-/C-2(-) peak ratio of the static SIMS spectra. The surface probed by SIMS is more important for the conductivity than the surface-near region probed by the asymmetry of the ESCA carbon peak. No correlation between the carbon black electrical conductivity and the carbon black bulk structure studied by Raman spectroscopy was found. (C) 2001 Elsevier Science Ltd. All rights reserved.