木材細胞の落ち込みと内腔に作用する負圧
1985 年 34 巻 383 号 p. 930-936
詳細
1985 年 34 巻 383 号 p. 930-936
The negative pressure, that is liquid-tension, to cause cell-collapse was estimated with osmotic pressure at 20°C, and the behavior of cell-collapsing and the radius of opening in the cell wall were discussed.
The concentration dependence of the osmotic pressure of polyethylene glycol (PEG-20000) was determined over a wide range of concentration up to 0.557g/ml. On the basis of this result, the shrinkage behavior of the collapsing samples in the solution was compared with the amount of cell-collapse in air-drying and with the results of compression tests perpendicular to the grain.
The results obtained were summerized as follows. When the negative pressure in the cell lumen exceeded a certain magnitude, the cells deformed and then the sample shrank abruptly, as if the sample yieled to the stress. The limiting magnitude was about 2kg/cm2 in the case of Balsa (Ochroma sp., R=60kg/m3), and 35kg/cm2 in Almon (Shorea almon Foxw., R=430kg/m3). According to the magnitude of negative pressure to cause cell-collapse and the permeability of the cell wall to PEG, it was considered that the maximum radius of opening in the cells collapsed at normal temperature was order of 10mμ at the utmost.
