Solvent polarity and internal stresses control the swelling behavior of green wood during dehydration in organic solution

Shan-Shan Chang (1) , Françoise Quignard (2) , Francesco Di Renzo (2) , Bruno Clair (1)

1 MAB - Mécanique de l'Arbre et du Bois
2 ICGM ICMMM - Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier

The dimensional variations of green wood samples induced by organic solvents have been studied. The solvents used (ethanol, isopropanol, acetone, and acetonitrile) covered a wide range of polarity and were studied pure and in aqueous solutions over a wide range of concentrations. Samples of normal and tension wood of poplar were used in order to minimize the effect of hydrophobic extractives on the wood-solvent interactions. The evolution of wood volume and of tangential strain with the concentration of the organic solvents shows a behavior similar to gels, with a significant swelling for solutions of intermediate polarity. The similarity of volume obtained in water and less polar pure organic solvents strikingly contrasted the different effects of water and organic solvents on dry wood. Low-polarity solvents were extremely effective in the stress release of tension wood, as indicated by the pattern of longitudinal shrinkage. Solvent exchange does not affect the mesoporous structure of the cell walls of tension wood and is a promising way to reduce internal stress in wood products.

Mots clés: Tension wood; Organic solvant; Longitudinal strain; Tangential strain; Stress realease

Domaines: Mécanique des matériaux [physics.class-ph]; Mécanique des matériaux [physics.class-ph]

Shan-Shan Chang, Françoise Quignard, Francesco Di Renzo, Bruno Clair. Solvent polarity and internal stresses control the swelling behavior of green wood during dehydration in organic solution. Bioresources, 2012, 7 (2), pp.2418-2430. ⟨hal-00697482⟩