| 概要 |
この研究では,木材の空気透過性を使って材質評価を行うための基礎資料を得ることを目的に,広葉樹材の組織･構造と空気透過性との関係について検討･考察した.広葉樹材では道管が主要な透過経路であるとしても,道管要素間の連絡構造およびチロースなどによる道管要素の充填が透過経路を複雑にするために,道管の占有体積だけでは透過性を決めることができない.したがって,簡単な2要素モデルを透過経路に適用して樹種による適...合性を検討した結果,透過にかかわる広葉樹材の組織･構造をおおよそ類型化できることがわかった.すなわち,道管径のバラツキが甚だしい環孔材や閉そくした道管を持つ樹種では,その適合性が悪い.一方,充填物による道管の閉そくが認められない散孔材,とくに階段せん孔を持つ樹種では,道管の径や数を十分に評価できることが明らかになった.また,道管中の閉そくの有無が評価でき,空気透過性を使って閉そく率を求める可能性を示したものの,より一層的確に評価を行うための透過モデルの検討が,さらに必要であろう.以上,広葉樹材の組織･構造を,空気透過性を使って総合的に評価する可能性を示唆できるが,空気透過性に材質指標としての位置づけを与えるための検討がさらに必要であり,今後の裸題として期待される.
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.続きを見る
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Mendeley出力
