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Gas-phase chlorination of carbon fiber based on polyacrylonitrile was performed and active chlorine-containing precursors were obtained, in which chlorine can be replaced by sulfur-containing functional groups. It is shown that chlorination of carbon fiber samples with carbon tetrachloride at temperatures of 300, 450 and 6000C in an argon stream leads to the introduction of 0.2-1.7 mmol g-1 of chlorine into the surface layer of the fiber. The thermodesorption properties of the modified carbon fiber samples were investigated by thermogravimetry and thermoprogrammed desorption with mass spectrometric registration of products. It was established that the obtained samples exhibit a relatively high thermal stability. The study conducted by means of thermoprogrammed desorption method showed that chlorine is desorbed from the surface in a wide temperature range (up to 8000C). It was found that the treatment of chlorinated samples with sulfur-containing reagents with subsequent oxidation produce the samples of carbon fiber with a concentration of sulfo-groups up to 0.3 mmol g-1, which are catalytically active in the dehydration reaction of isopropyl alcohol in the gas phase. The temperature of 50% conversion of isopropyl alcohol to propylene was used as a measure of catalytic activity. It was found that pre-chlorination leads to an increase in the catalytic activity of the fiber modified with sulfur-containing reagents: the temperature of 50% conversion of isopropyl alcohol to propylene is 215-2900C, depending on the concentration of sulfo-groups. [ABSTRACT FROM AUTHOR]

The structure and surface morphology of graphite nanoplatelets (GNPs) modified by bimetallic Ni-Fe phase with 80% mass. Ni and 20% mass. Fe is investigated by the methods of scanning electron microscopy and X-ray analysis. The bimetallic active phase is applied onto GNPs surface with impregnation method using nitrate solutions of metals. The prepared Ni80Fe20/GNPs composite demonstrated high catalytic performance in the reaction of CO2 methanation. At the temperature range of 350-450°C, it exhibited a high efficiency of CO2 conversion compared to bulk Ni80Fe20. The thermoprogrammed desorption study of the surface condition of the Ni80Fe20/GNPs composite after exposition in the catalytic process showed that H2O (m/z = = 18), CO (m/z = 28) and CO2 (m/z = 44) particles are desorbed from the surface. [ABSTRACT FROM AUTHOR]

Deconvolution of differential mass loss curves of epoxy polymers and epoxy-silica composites cured with anhydride in the presence of metal acetylacetonates was performed. Mass-spectra of destruction products in vacuum were obtained. Effective activation energy was determined for each destruction stage. The first stage is destruction initiation. It is affected by sol-fraction and effective crosslink density of polymer, and by oxygen presence in atmosphere. The second and the third stages are the destruction of oxypropylene chain and cycle structures respectively. [ABSTRACT FROM AUTHOR]