Effects of oxygen plasma treatment on the surface of graphitized carbon black

Sterling FT carbon black was oxidized in a cool oxygen plasma to various burn-off degrees ranging between 6 and 84%. Plasma-treated samples were characterized by nitrogen and carbon dioxide adsorption, scanning electron microscopy and contact angle measurements. Following the oxygen plasma treatment no changes in BET surface area or porosity were detected. SEM examinations evidenced an absence of fractures or other changes in the morphology of the particles, suggesting that carbon black oxidation by an oxygen plasma takes place through smooth, progressive etching of successive layers of the material. Some heterogeneity in the consumption of spheres was clear at high burn-offs. The contact angles with water decreased at low burn-offs and then remained approximately constant. The oxygen plasma treatment can be tentatively proposed as a suitable method to change carbon black surfaces from hydrophobic to hydrophilic. (C) 1998 Elsevier Science Ltd. All rights reserved.