Relationship of Hardwood Morphology to Air Permeability

Kuroda Naohiro, Tsutsumi Juichi, Watanabe Hironori

doi:10.15017/10836

In this study, the relationship between morphology and permeability of hardwood was discussed in order to understand a fundamental aspect of air permeability for evaluating wood quality. Although vessel element was supposed to be a main flow passage in hardwood, permeability could not be correlated to the volumetric percentage of vessel. It is because the flow paths in hardwood should be more complicated by inter-elements connection and also by occulusion of vessels. Therefore the measured values of vessel radius and total number of vessels per unit cross sectional area were compared with the estimated values from permeability measurement by applying the two elements model in series proposed by PETTY. A reasonable agreement between the two was found out in the species of diffuse-porous hardwoods with scalariform perforation and without occlusion of vessels, but was not in the species of ring-porous woods with high variation in vessel radius as well as for those with occluded vessels. The presence of tyloses and deposits in vessels was able to be estimated by permeability measurement, and the percentage of occluded area to total vessel area per unit cross sectional area may be calculated. But it will be necessary for more precise estimation of the percentage to make the permeability model more prefitable for hardwood by particular consideration on the variation in radius and length of vessel. The results made it clear that it is possible to estimate the morphological indices from gas-flow measurement: a further problem is whether permeability is effective as a wood-quality index.

Relationship of Hardwood Morphology to Air Permeability

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