Permeability to water of the cell wall material of spruce heartwood |
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| Authors: | M Anne Palin J A Petty |
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| Institution: | (1) Department of Forestry, University of Aberdeen, Scotland |
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| Abstract: | Summary The permeability to water of spruce heartwood has been measured by applying a known osmotic pressure difference across specimens
in which the cell walls were water swollen and most of the void space was filled with paraffin wax.
To ensure that solute molecules should not penetrate the cell wall aqueous solutions of polyethylene glycol of molecular weight
6,000 and dextran of molecular weight 40,000 were used to generate the osmotic pressures. The mean values of the permeability
k×1021 defined by the Darcy equation were 67.5 m2 for longitudinal flow, 7.12 m2 for radial flow and 4.03 m2 for tangential flow. Permeability was probably overestimated by about 10% owing to water entering some of the void space
not filled by wax. The measured values are 10 to 100 times smaller than those calculated assuming all water in the cell walls
is free to flow and this is probably caused by much of the water being bound to cell wall material.
This work was made possible by Research Grants from the Leverhulme Trust Fund and the Science Research Council, and we thank
both organisations for their support. We wish to thank Hickson's Timber Products Ltd for kindly supplying some of the specimen
holders and Professor J. D. Matthews for his encouragement of this work
Paper presented at the Seminar on “Flow and Permeability in Wood” of the Royal Microscopical Society, Wood Anatomy Group,
held in Princes Risborough, 17, October 1979 |
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