Die Sorption von Wasserdampf durch die chemischen Bestandteile des Holzes

A review of wood thermal pretreatments to improve wood composite properties

“…The hemicelluloses and the non-crystalline region of the cellulose chains are more prone to attract water due to the availability of hydroxyl groups. Christensen and Kelsey (1959) estimated that cellulose, hemicelluloses, and lignin in Eucalyptus regnans are responsible for approximately 47, 37, and 16 % of the total water sorption of this wood species. In theory, most, if not all, of the hydroxyl groups in hemicelluloses are accessible to moisture (Rowell 2005b).…”

“…Three parts can be identified: (a) chemisorption, which predominates at low relative humidity and is characterized by the buildup of a monomolecular layer of water held by the free hydroxyls of the non-crystalline regions, (b) physisorption, which is characterized by the formation of a polymolecular layer of water, and (c) capillary condensation, which occurs when water vapor condenses in the void space of the cell wall at relatively high humidity (Hansen 1986;Fengel and Wegener 1989;Tsoumis 1991;Niemz 2010) [i.e., higher than 90 % (Boonstra 2008)]. Sorption isotherms can be obtained experimentally using saturated salt solutions (Acharjee et al 2011) and environmental chambers, or can be predicted using sorption models such as the Hailwood- Adapted from Christensen and Kelsey (1959), Skaar (1972), Eckelman (1998), Suchsland (2004), and Niemz (2010 Horrobin model (Papadopoulos and Hill 2003) or the parallel exponential kinetics (PEK) model (Hill et al 2012). The sorption characteristic of wood is quite similar irrespective of the wood species, except in woods with high extractives content (Skaar 1972).…”

Anisotropy of Dielectric Constant in Coniferous Wood

“…2. In this figure triangles represent the Sorption isotherm at 25° C of hemicellulose from Eucalyptus regnans (Christensen and Kelsey 1959). Since the sorption isotherm of noncrystalline cellulose compares well with that of hemicellulose, it may be assumed that the sorption isotherms of hemicelluloses are equivalent to that of noncrystalline cellulose.…”

Effects of Cell Structure on Water Sorption for Wood

“…The isotherm curve of wood is difficult to analyze, though it includes information on the interaction between wood and water, because the sorption process shows a sigmoid curve and consists of complex processes due to its complicated structure (Stamm 1953;Christensen and Kelsey 1959;Weichert 1963;Kollmann and Cote 1968). The dual-mode sorption model has successfully been applied to various polymers for such complex sorption processes (Hailwood and Horrobin 1946;Meares 1954Meares , 1957Barrer et al 1958;Michaels et al 1963;Koros and Paul 1978;Chiou et al 1985;Kamiya 1997).…”