title: Characterization of a gel in the cell wall to elucidate the paradoxical shrinkage of tension wood.
abstract: Wood behavior is characterized by high sensibility to humidity and strongly anisotropic properties. The drying shrinkage along the fibers, usually small due to the reinforcing action of cellulosic microfibrils, is surprisingly high in the so-called tension wood, produced by trees to respond to strong reorientation requirements. In this study, nitrogen adsorption-desorption isotherms of supercritically dried tension wood and normal wood show that the tension wood cell wall has a gel-like structure characterized by a pore surface more than 30 times higher than that in normal wood. Syneresis of the tension wood gel explains its paradoxical drying shrinkage. This result could help to reduce technological problems during drying. Potential applications in biomechanics and biomimetics are worth investigating, considering that, in living trees, tension wood produces tensile growth stresses 10 times higher than that of normal wood.
authors.affiliation: Laboratoire de Mécanique et Génie Civil, Université Montpellier 2, CNRS, 34095 Montpellier, France. clair@lmgc.univ-montp2.fr
authors.forename: Bruno
authors.initials: B
authors.lastname: Clair
authors.forename: Joseph
authors.initials: J
authors.lastname: Gril
authors.forename: Francesco
authors.initials: F
authors.lastname: Di Renzo
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Yamamoto
authors.forename: Françoise
authors.initials: F
authors.lastname: Quignard
mesh_terms: D002473:Cell Wall / Q000737:chemistry*; D005782:Gels; D024301:Plant Bark / Q000737:chemistry; D014197:Trees / Q000737:chemistry; D014934:Wood / Q000032:analysis* / Q000737:chemistry*
chemical_list: D005782:Gels