Wettability of Heat-Treated Wood

Summary 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 13C 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.

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