Surface activity and chemistry of thermal carbon blacks

The surface energy of thermal and furnace carbon blacks was determined by i nverse gas chromatography (IGC) at infinite dilution. In general. the speci fic surface energy decreases with decreasing carbon black specific surface area. However, there is also an influence of the concentration of impuritie s during the carbon black production. The surface energy decreases with dec reasing concentration of impurities. The carbon black surface and bulk chem istry was studied by electron spectroscopy for chemical analysis (ESCA), se condary ion mass spectroscopy (SIMS) and Raman spectroscopy. Scanning tunne lling microscopy (STM) was used for characterization of the surface morphol ogy. Thermal grades of carbon black produced from high purity natural gas f eedstock do nor contain fewer surface functional groups than the other grad es. No correlation between the concentration and nature of the oxygen and s ulphur surface groups and the carbon black surface energy was found. Instea d, a correlation between the surface energy and the polyaromatic character of the carbon black surface exists. Both increased in the order: thermal bl acks from high purity natural gas feedstock < thermal black from oil feedst ock < furnace blacks. The increase of the surface energy might be related t o the formation of active sites which are formed upon removal of non-carbon elements during the carbon black formation. There was no principal differe nce in the surface morphology of thermal blacks from high purity gas feedst ock and other blacks.