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  • Author: M. Pétrissans x
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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.

Abstract

The exceptional natural durability of Prosopis africana heartwood was investigated to find potential new biocides for wood preservation. Extractions carried out with different solvents indicated high levels of extractives which explained wood durability towards fungal and insects attacks. However, the extractives were not enough to explain the durability. The hydrophobic character of the wood also likely had a significant effect. Contact angle measurements before and after extraction, indicated that extractives have only a minor effect on wood hydrophobicity. Microscopic analysis reveals the presence of high levels of gums filling the wood cell lumens, limiting the penetration of water.