Describing non-Fickian water-vapor sorption in wood
Wadso, L.
Journal of Materials Science, 29(9): 2367-2372
Wadso, L."Describing non-Fickian water-vapor sorption in wood", Journal of Materials Science, 29(9): 2367-2372.
Abstract:
Moisture transport and sorption in wood may not be accurately described by Fick's law of diffusion. The problem of making a model of non-Fickian behavior (NFB) for wood is discussed. Some measurements in which NFB in wood is clearly seen are also reviewed. Four criteria, which must be satisfied by a model describing sorption in wood cell walls, are presented; (1) the model should not only describe the response to step changes in vapor pressure; (2) it should be able to predict sorption with more than one time scale; (3) the sorption rate should not depend on the thickness of the cell wall; (4) small rapid changes in vapor pressure should give slower fractional weight change rapid changes. A review of models of NFB in synthetic polymers indicates that there is presently no model of NFB which fulfills the above criteria. More measurements of the sorption behavior of the cell wall are needed to construct such a model for wood. This model can then probably be used, together with a Fickian diffusion model, to model the sorption behavior of whole wood. [Author abstract; 58 Refs; In English]