Neutron spectroscopic investigations on different grades of modified furnace blacks and gas blacks

The inelastic incoherent neutron scattering technique was utilized to reveal structural changes caused by modification treatments on furnace blacks and gas blacks. The effects of introducing disorder into the material due to oxidation, gas-phase hydrogenation or deuteration, or wet-chemical H/D-isotope exchange and the cofuming of silicon were monitored. Partial hydrogasification of a furnace black induced the formation of non-extractable polyaromatic entities bound to the surface of the black. Enhanced amounts of non-extractable hydrogenous species either chemically bound or free recoiling were observed whereas molecular hydrogen was missing. It follows that predominantly atomic hydrogen or other states of activated hydrogen at trap sites are involved. Introducing sp(3) species by cofuming of Si into the bulk structure of furnace black led to highly disordered but well dispersed domains in the bulk structure. Labelling of proton-active sites by means of H/D-exchange on a gas black revealed a broad variety of protonic species which account for the high chemical activity of the black. Indications for relaxation of strained sites were obtained. A sample of finely divided furnace black showed stronger interactions with adsorbed water molecules than grades of higher particle size. (C) 1999 Elsevier Science Ltd. All rights reserved.