Abstract
The effect of air-,kiln-, and high-temperature drying on the radial permeability ofPinus radiata D. Don was studied. It was found that for both heartwood and sapwood the permeability increased as the severity of drying increased. The sapwood permeability rose from 5.3×10−14m2 for air-dried timber to 10.9×10−14 m2 for high-temperature-dried timber, an increase of approximately 100%. The rise in heartwood permeability was approximately 280%, with the air-dried permeability being 1.3×10−14 m2 and the high-temperature-dried permeability being 5.3×10−14 m2. It is considered that this higher radial permeability of high temperature-dried wood is responsible for its increased ease of impregnation with preservatives. As the predominant route for gas movement inP. radiata is the resin canal network, it is suggested that this increase in permeability is due to movement and modification of the resin. The flow through the samples was entirely laminar, with no evidence of either molecular or turbulent flow for pressure differentials from 10 to 100 kPa.
Zusammenfassung
Der Einfluß von Luft-, Ofen- und Hochtemperatur-Trocknung auf die radiale Durchlässigkeit von Kiefernholz wurde untersucht. Sowohl im Kernholz als auch in Splintholz stieg die Durchlässigkeit mit der Trocknungsschärfe an. Im Splintholz stieg die Durchlässigkeit um 100% von 5,3×10−14 m2 bei luftgetrocknetem Schnittholz auf 10,9×10−14 m2 nach Hochtemperatur-Trocknung. Diese nach Hochtemperatur-Trocknung erhöhte Durchlässigkeit wird als Ursache für die leichtere Tränkbarkeit diese Proben mit Holzschutzmitteln angesehen. Weil die Hauptbewegung des Wassers als gas durch die Harzkanäle erfolgt, ist anzunehmen, daß die erhöhte Durchlässigkeit durch Verlagerung und Veränderung der Harze bedingt ist. Der Gasfluß durch die Proben war völlig laminär ohne irgendwelche Anzeichen von molekulare oder turbulenter Strömung für Druckunterschiede zwischen 10 und 100 kPa.
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Booker, R.E., Evans, J.M. The effect of drying schedule on the radial permeability ofPinus radiata D. Don. Holz als Roh-und Werkstoff 52, 150–156 (1994). https://doi.org/10.1007/BF02615211
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DOI: https://doi.org/10.1007/BF02615211