Despite being studied for over a century, the reason for the sigmoidal shape of the sorption isotherm of wood and the origin of sorption hysteresis are still the subject of debate in the literature. Recently, there have been advances in our understanding of how moisture interacts with wood. This research has been greatly helped by the use of dynamic vapour sorption (DVS) apparatus, of which there are several examples on the market. Although such instruments are primarily designed for the determination of sorption isotherms at equilibrium, they can also be used (with caution) to determine the kinetics of the sorption process. The examination of the kinetics of adsorption and desorption has led to a new understanding of sorption hysteresis. A model will be presented, based upon an understanding of the molecular dynamics processes occurring within the cell wall during sorption. The latest DVS experimental work will be presented. The reasons for the sigmoidal shape of the sorption isotherm will also be discussed.
Keywords: Water vapour, sorption isotherm, sorption hysteresis
Authors
Hill C.A.S.
Norsk Institutt for Skog og Landskap, Ås, Norway
Popescu C.-M.
“Petru Poni” Institute of Macromolecular Chemistry of Romanian Academy, Iasi, Romania
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