Fluorination of carbon blacks. An X-ray photoelectron spectroscopy study .2. XPS study of a furnace carbon black treated with gaseous fluorine at temperatures below 100 degrees C. Influence of the reaction parameters and of the activation of the carbon black on the fluorine fixation

The fluorination of a furnace carbon black (N115 from Degussa) with gaseous F-2, diluted in N-2, at room temperature was studied by XPS. The influence of the reaction parameters (% of F-2 in the gaseous mixture, duration of contact) and activation (O-2 at 450 degrees C) of the carbon black on the amounts of fluorine fixed, in the bulk and at the surface and subsurface zone of the carbon particles has been investigated. By analyzing the Cls and Fls peaks, different forms of C and F were evidenced and their relative contributions in fluorinated black determined. Information concerning the nature of the C-F bond formed and the effect of the fluorination on the structure of the pristine carbon black is given. It is shown that the fluorinated product obtained is of polyphasic nature. Fluorinated islands of limited thickness alternate with non-fluorinated zones that have kept their original structure. F is mainly covalently bonded to reactive C atoms of the surface and subsurface shell of the particles. (C) 1997 Elsevier Science Ltd.