Evaluation of capacillary radii distribution in wood by the balance of water potential.

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If the dehydration behavior were investigated under centrifugal fields, water potential which were caused in wood was calculated. The water potential in wood means to load the stress between outside and inside of cell. We must consider the damage at the weakest place in cell such as bordered pit pairs.1. The relationship between the water saturation ratio (SR) after the centrifugal treatment and the measure of water potential (Y) in the specimen was expressed by a following simple linear regression. LogィイD210ィエD2SR = αY + 2. "α" is new expression of the permeability under non-steady flow. The results showed that Sugi had a larger variation of water permeability than Douglas fir and was estimated to have a good water permeability than Douglas fir from the comparison of the slope2. Judging from the dehydration behavior under the centrifugal fields, it is estimated that torus were aspirated to pit border by the pressure differential of 0.119 to 0.178 Mpa. And then it is calculated that the stress which is subject to damage on torus is 0.248 to 0.68 Mpa.3. Torus in Sugi wood have more weak than that in Douglas fir, namely, the overlapped area between torus and pit border in sugi was less than Douglas fir and the thickness of torus is thinner. Damaged torus in sapwood were statistically measured in drying process and under centrifugal fields. In drying process, the number of damaged torus depended on the length of specimen. It decreased with the increase of temperature. On the other hand, it increased with the increase of temperature in the centrifugal fields. Damaged torus in microwave drying were less than in convective drying. The ratio of damaged torus had the closely relation with impregnation of dye solution.