1987 Fiscal Year Final Research Report Summary
Fundamental Study on Wood Quality by Electrical Conduction and Gas Permeability
| Project/Area Number |
61560197
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
林産学
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| Research Institution | Kyushu University |
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Principal Investigator |
TSUTSUMI Juichi Faculty of Agraiculture, Kyushu University, 農学部, 教授 (00038209)
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| Project Period (FY) |
1986 – 1987
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| Keywords | Electrical conduction / Gas permeability / Wood quality / Wood morphology / 木材組織 / 木材構造 |
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| Research Abstract |
The electrical conductivities and air permeabilities of 20 hardwood species and Larix were studied in relation to specific gravity and wood morphology in order to understand a fundamental aspect of the physical properties for evaluating wood quality.
The conductivity at a given moisture content had large variation among species. On the other hand, the effect of moisture concentration per unit wood volume was highly correlated to basic density. Therefore the conductivity variation among species was assumed to be mainly caused by the difference of moisture retention with wood specific gravity and also by the physical change of adsorbed water with moisture retention. The intra-structure of cell wall and the cell dimension may be another factors in the difference among species, because the conductivity of cell wall itself was shown to have the variation among species and to be correlated to average microfibril angle in tracheid. The results suggested that, if the relationship between moistu
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re retention and wood structure was sufficiently realized, conductivity could be a reasonable index for specific gravity as well for moisture content.
Although vessel element element and tracheid were supposed to be main flow passages in wood, air permeability could not be correlated to the volumetric percentage of their lumens. It is because the flow passages in wood should be more complicated by interelements structure and also by occlusion of vessels and pits. 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 aplying the two elements model in series. A reasonable agreement between the two was found out in the species of diffuse-porus hardwoods with scalariform perforation and without occlusion of vessels, but was not in the species with high variation in vessel radius as well as for those with occluded vessels. Furthermore the percentage of occluded area to total vessel area per unit cross sectional area may be calculated. From the results mentioned, air permeability is recognized as synthetic index for wood structural classification because of its sensibility for the difference in passage among species. Less
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