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11.
To improve the impregnation of wood, the pre-treatment by compression was systematically studied in terms of effects of compression ratio, compression direction, compression speed and compression-unloading place on the liquid impregnation in poplar and Chinese fir. The results showed: the impregnation increased 0.0065 or 0.0074 g/cm3 for every 1% increase of compression ratio when the compression ratio was lower or equal to 50 and 40% for poplar and Chinese fir, respectively; it continued to increase afterwards while the variation was quite big. There existed a significant difference of the impregnation of wood compressed at different directions in Chinese fir, but not in poplar. There existed a significant difference of the impregnation of wood compressed at different speed in both species. The impregnation of wood is likely to be in favor of radial compression in terms of the amount of impregnation. 5 and 10 mm/min were recommended as a compromise of impregnation and pre-treatment efficiency. The impregnation of wood that the compression unloaded in water was about 18.2 (poplar) and 9.2% (Chinese fir) higher in amount and was much quicker in speed than that the compression unloaded in air, and the difference between them was significant, suggesting that compression unloaded in water is significant to improve the impregnation. 相似文献
12.
Liquid penetration of precompressed wood VII: combined treatment of precompression and extraction in hot water on the liquid penetration of wood 总被引：1，自引：0，他引：1
The object of this study was to determine the cause of differences in the improvement in liquid penetration of precompressed wood species. The maximum amount of water uptake by the capillary rise method and changes in the aspirated pits seen with scanning electron microscopy before and after of preextraction and precompression were investigated using heartwood samples of four softwoods. The height of penetration and the weight by the capillary rise method for preextractive wood powders are discussed. Three wood species andLarix leptolepis showed marked increases in the amount of solution uptake after precompressed treatment only.Larix leptolepis wood required compression after extraction by boiling in water. These differences among wood species were caused by the accumulation of extractive material. It was also recognized that the accumulative material inLarix wood has plasticity and that inPseudotsuga is brittle. Based on these results it was found that it is difficult to destroy aspirated pits in the former and easy in the latter. On the other hand, the difference in penetration of each wood species was caused by the quantity and quality of the extraction material in addition to the extent of the wettability of the surface of the cell cavity as well as aspirated pit.Part of this report was presented at the 46th annual meeting of the Japan Wood Research Society, Kumamoto, April 1996 相似文献
13.
Zhou Yu Iida Ikuho Minato Kazuya Kurosu Hiroshi 《中国林学(英文版)》2005,7(2):19-25
The adsorptive properties and selectivity of dyes and water molecules to cellulosic sheet, dependence of adsorptive properties of dyes on the concentration of dye solution, and discoloration of the dye solution due to the UV-ray irradiation were determined for 18 kinds of commercial dyes. The results are as follows： 1） the adsorptive properties of dyes to cellulose sheet differed greatly, but did not depend on the dye types such as acidic, basic and so on; 2） adsorptive properties of dyes to cellulosic sheet de- pended on the concentration of dye solution and were classified into 4 types： concentration-independent, increasing or decreasing with dye concentration, and having a maximum. This classification was irrelevant to the dye types; 3） the irradiation of UV-ray did not cause significant discoloration of dye solution itself, which suggested that wood components as well as dye molecules influence the discoloration of wood. 相似文献
14.
Youke Zhao Zhihui Wang Ikuho Iida Rongfeng Huang Jianxiong Lu Jinghui Jiang 《Journal of Wood Science》2015,61(2):113-119
15.
Yoshinori Kobayashi Ikuho Iida Yuji Imamura Ugai Watanabe 《Journal of Wood Science》1998,44(6):482-485
The sap flow method of wood impregnation was conducted to aid the movement of bacteria through the living tree, thereby accelerating their distribution through wood within a short time. When log-pond water containing mixed species of bacteria were introduced in the living trees by butt-end dipping and then laid horizontally for 6 months, bacteria could be delivered by sap flow vertically through the sapwood tracheids up to the high portions from the butt-end of trees; they could be detected in the ray parenchymal cells. The sap-flow method was assumed to deliver the bacteria to sapwood and heartwood at high levels of standing sugi (Cryptomeria japonica D. Don) trees. Degradation of the pit membranes was observed even at more than 3 m upward from the butt-end after the treatment in sapwood, as well as around the butt-end of the trees. The uptake of the aqueous dye solutions in sapwood of the treated logs were about eight times more than those of control specimens after 8h.Part of this report was presented at the 40th annual meeting of the Japan Wood Research Society, Tsukuba, April 1990; the 41st annual meeting of Japan Wood Research Society, Matsue, April 1991; and the IUFRO 4th international conference on wood drying, Rotorua, New Zealand, August 1994 相似文献
16.
Xiaoyang Yang Yutaka Ishimaru Ikuho Iida Hiroyuki Urakami 《Journal of Wood Science》2002,48(4):283-288
This study was intended to detect nondestructively some defects such as knots and grain deviations in wood using modal analysis. The shapes of flexural vibration waves at the first mode generated by the tapping of wooden beams were determined using the transfer function. The wave shapes obtained were compared with the theoretical wave shape for a uniform material; and the possibility of detecting defects in wood was examined. The results are summarized as follows: (1) The shapes of flexural vibration waves at the first mode of wooden beams free of defects coincided almost completely with the theoretical wave shape. (2) The shapes of flexural vibration waves of wooden beams containing defects such as knots clearly differed from the theoretical wave shape, especially near the defect. (3) Based on these results, it should be possible to detect the presence of defects and to determine their location in wood.Part of this report was presented at the 49th Annual Meeting of the Japan Wood Research Society, Tokyo, April 1999. This article is translated from the Japanese edition published inMokuzai Gakkaishi Vol. 47, No. 4, 1988 相似文献
17.
In our preceding study, we clarified that liquids having similar molecular sizes to ethanol were mainly adsorbed onto lignin
among the major constituents of wood. This suggests that most micropores or adsorption sites loosely hydrogen-bonded to each
other, which are accessible to these liquids, exist in lignin. In the present study, to examine micropores in wood and lignin,
micropore distribution was measured by CO2 gas adsorption at ice-water temperature (273 K). Dry samples prepared by gradual delignification from wood meal were used
as adsorbents. The pore-size distributions were determined by analyzing adsorption isotherms using the Horvath-Kawazoe method.
It was found that the number of micropores decreased with the decrease in residual lignin, and micropores were hardly found
in cellulose and hemicellulose. It is considered that most micropores smaller than 0.6 nm in wood exist in lignin. 相似文献
18.
Ikuho Iida Michiyasu Kudo Jyunji Onizuka Yutaka Ishimaru Yuzo Furuta 《Journal of Wood Science》2002,48(2):119-125
Previously we showed that the relaxation modulusEt of water-saturated wood during temperature reduction maintained its initial value despite the decrease in temperature, although during temperature elevationEt showed a marked decrease. In the present study, to clarify the mechanism of relaxation during temperature elevation and reduction, Young's modulus was measured in stress relaxation experiments with changes in temperature, and relaxation behavior was simulated using a Maxwell model consisting of five elements. Furthermore, the dynamic Young's modulus and dynamic loss modulus were measured during both temperature elevation and reduction. The results obtained suggested that the unique relaxation behavior during temperature reduction was caused by decreases in Young's modulus and coefficient of viscosity (i.e., an increase in fluidity) compared with those during elevation of temperature. The decrease in Young's modulus and increase in fluidity were considered to be due to an unstable structure in wood that occurred during temperature reduction. This unstable structure probably develops in the nonequilibrium state of temperature toward a true equilibrium state. Wood should be more unstable during temperature reduction than during temperature elevation because of the decrease in molecular motion when the temperature is lowered.Part of this report was presented at the 49th annual meeting of the Japan Wood Research Society, Tokyo, April 1999 相似文献
19.
The modulus of elasticity and the modulus of rupture during static bending in the radial direction, and the viscoelastic properties in the radial direction in the temperature range 20°–100°C of hinoki (Chamaecyparis obtusa) swollen in organic liquids with two or more functional groups in a molecule were compared with those of wood swollen by moisture. The wood swollen in organic liquids in or near the swelling equilibrium, but not that swollen in organic liquids distant from the swelling equilibrium, showed higher moduli of elasticity and rupture than the wood swollen to a similar degree by moisture. This suggests that wood exists in an unstable state as it approaches the swelling equilibrium, rendering it highly flexible and weak. During the first viscoelastic measurements for wood swollen in various organic liquids, thermal softening was observed in 40°–60°C range and above 80°C, though this softening disappeared during the second measurement. The softening observed in the 40°–60°C range and above 80°C was thought to have been caused by the redistribution of liquid toward the equilibrium state at a higher temperature and the swelling accompanying an elevated temperature, respectively.Part of this report was presented at the 49th Annual Meeting of the Japan Wood Research Society, Tokyo, April 1999 相似文献
20.
Stress relaxation of water-saturated wood was examined at various temperatures and during the processes of elevation and lowering of temperature. The difference between relaxation at a lower temperature and that at a higher temperature was almost same as the increase in relaxation during temperature elevation. Similar results were obtained regardless of the elevating speed of the temperature and regardless of preheating the samples. On the other hand, relaxation behavior during temperature lowering was quite different from that during temperature elevation. The relaxation moduli during the process of lowering the temperature scarcely changed, although those at various constant temperatures decreased with increases in temperature. Marked sets occurred after relaxation measurements under temperature lowering, whereas only slight sets occurred during the process of elevating the temperature or at a constant temperature of 80°C. Furthermore, it was found that the sets that occurred during the process of temperature reduction were almost recovered when the samples were heated again in water. The mechanism of the relaxation behaviors observed in the present study under nonequilibrium temperature is discussed in relation to the occurrence of set after relaxation measurements.Part of this report was presented at the 48th annual meeting of the Japan Wood Research Society, Shizuoka, April 1998 相似文献