The aim of this work was to study the wettability and chemical composition of heat-treated wood. Heat treatment was performed at 240°C under inert atmosphere on four European wood species (pine, spruce, beech and poplar). Contact angle measurements before and after treatment indicated a significant increase in wood hydrophobicity. Advancing contact angles of a water drop were in all cases systematically higher for heat-treated than for untreated wood. Chemical modifications of wood after heat treatment were investigated using FTIR and 13 C NMR analysis. FTIR spectra indicated little structural change which could be attributed either to carbon-carbon double bond formation or to adsorbed water. NMR spectra also revealed little chemical change except for the degree of cellulose crystallinity which was considerably higher in heat-treated wood and could explain the higher contact angles. KeywordsWettability Contact angle Heat-treated wood Chemical modification Brought to you by | Tokyo Daigaku Authenticated Download Date | 5/30/15 2:47 PM

No abstract

Hydrolysis of Si(OC2H5), by ammonia has been investigated using 'H and I3C NMR measurements in alcoholic media. Use of deuterated CD3CD20D and CD30D solvents proves the absence of transesterification by alkoxy exchange between silicate and alcohols. The rate constant increases when CD30D replaces CD3CDZOD as the solvent (k = 2.8 X L mol-' min-' in CD3CD20D; 7.5 X

The adsorption of two alkyl-phenyl-polyethoxy phosphate (APPEP) with ethoxy chains containing 6 and 10 units was investigated in relation with the dispersion and rheological properties of suspensions of CaCO 3 and TiO 2 particles. Data were compared to these properties of related compounds alkyl-phenyl-polyethoxy (APPE) and polyethoxy-diphosphonate (PE2P). As with APPE, APPEP gave high affinity isotherms, which are attributed to the ligand effect of the phosphate head group. The adsorption plateaus of APPEP and APPE were significantly higher than for PE2P due to the cooperative effect of the alkyl chains. The adsorption on TiO 2 decreased at higher pH up to pH 13 and decreased by addition of phosphate ions; it increased with the addition of calcium ions. Investigations showed that the dispersion with APPEP molecules was not only linked to the surface charge, but also to the formation of a thick surfactant layer. This article aims to illustrate the respective role in adsorption and dispersion of the different parts of the amphiphilic molecules: ionic head, hydrophobic tail, and ethoxy chain.

Four independent parameters : solvent (ROH, R = CH3, C2H5, C3H7, n-CqHg) ; NH3 and H20 concentrations and temperature have been varied and consequently the final diameter of silica particles determined. The bigger the solvent, the larger the particles (210 nm : CH30H-550 nm : butanol). Increasing H20 and NH3 contents lead to an increase of the diameter. Following both the particle size (MET) and the weight evolution of silica as time enables to prove that Ostwald ripening does not occur, since the number of particles does not decrease during the growing. Measurements at 20, 30, 40°C give an Arrhenius law relating the speed rate and the temperature, the activation energy being 3.5 Kcal/mole. Raising temperature increases the kinetics as well as the nuclei generation, so that smaller homodisperse particles can be obtained ( 0 -120 nm at 20°C to 70 nm at 40°C in C2H50H).