Surface energy of commercial and pyrolytic carbon blacks by inverse gas chromatography

The surface properties of carbon blacks obtained by vacuum pyrolysis of different used rubbers (CBp) and of commercial carbon blacks were measured by inverse gas chromatography (IGC). The dispersive component of the surface energy (gamma(s)(d)) and the specific interaction (I-sp) of the recovered CBp were lower than gamma(s)(d) and I-sp of the virgin carbon black initially present in the rubber. However, gamma(s)(d) and I(sp )of recovered medium surface area carbon black and of virgin low-surface-area carbon black were comparable. During the pyrolysis, carbonaceous deposits are formed on the CBp surface. A correlation between gamma(s)(d) and I-sp and the amount of the carbonaceous deposits, measured by ESCA, was found, suggesting that the formation of these deposits is responsible for the decrease of gamma(s)(d) and I-sp.