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

The inelastic incoherent neutron scattering technique was utilized to revea l structural changes caused by modification treatments on furnace blacks an d gas blacks. The effects of introducing disorder into the material due to oxidation, gas-phase hydrogenation or deuteration, or wet-chemical H/D-isot ope exchange and the cofuming of silicon were monitored. Partial hydrogasif ication of a furnace black induced the formation of non-extractable polyaro matic entities bound to the surface of the black. Enhanced amounts of non-e xtractable hydrogenous species either chemically bound or free recoiling we re observed whereas molecular hydrogen was missing. It follows that predomi nantly atomic hydrogen or other states of activated hydrogen at trap sites are involved. Introducing sp(3) species by cofuming of Si into the bulk str ucture 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-ex change on a gas black revealed a broad variety of protonic species which ac count for the high chemical activity of the black. Indications for relaxati on of strained sites were obtained. A sample of finely divided furnace blac k showed stronger interactions with adsorbed water molecules than grades of higher particle size. (C) 1999 Elsevier Science Ltd. All rights reserved.