XPS STUDY OF THE HALOGENATION OF CARBON-BLACK .2. CHLORINATION

Three furnace carbon blacks, a thermal black, and an electrically cond uctive sample were submitted as received to chlorination, at 450 degre es C, with a mix of chlorine and carbon tetrachloride vapors. The trea ted samples were examined using chemical and spectroscopic (XPS) metho ds. The interpretation of the XPS spectra is facilitated by comparison with spectra of reference materials. XPS detects various types of car bon-chloride bonds formed essentially by addition or hydrogen substitu tion processes. The amount of fixed chlorine is dependent on the origi n of the blacks, and there is no direct relationship between specific surface area and chlorine uptake. It is shown that chlorination is not limited to the external surface, nor is it to a sub-superficial layer . In fact, it proceeds inside the carbon black particles to a depth de pending on their origin.