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1.
Jian-Zhang Li Takeshi Furuno Sadanobu Katoh Tohru Uehara 《Journal of Wood Science》2000,46(3):215-221
Acetylated, propionylated, butyrylated, isobutyrylated, and hexanoylated woods were prepared at several temperatures. The reaction rate, dimensional stability, and changes in the ratios of specific gravity and dimensions in the tangential and radial directions were estimated. The reaction rate of propionylation was slow at temperatures under 90°C but increased with the temperature. The butyrylated, isobutyrylated, and hexanoylated woods showed little or no weight percent gain (WPG) and little or no antiswelling efficiency (ASE) below 110°C even for 24h, but they achieved significant WPG and ASE values at 140°C with a longer reaction time. The acetylated, propionylated, and butyrylated woods showed almost the same values for dimensional stabilization efficiency based on WPG (DSE). The specific gravity and dimensions ratios for acetylated, propionylated, and butyrylated woods compared to those of untreated wood increased with an increase in WPG. 相似文献
2.
Reaction between maleic anhydride (MA) and wood specimens was carried out in a vapor phase reaction system. Reaction conditions
such as the ratio of supplied MA to wood, initial moisture content, and reaction temperature were optimized. The MA supplied
to the reaction system was effectively absorbed by the wood, and a satisfactorily high dimensional stability was achieved
even at a low MA/wood ratio. The dimensional stability increased with rising initial moisture content. When the reaction was
conducted at an elevated temperature (180°C), high dimensional stability was attained without remarkable weight increase and
bulking. The mechanism of dimensional stabilization was discussed on the basis of the dimensional changes at high humidity
and during repeated water soaking and drying. It was shown that the dimensional stabilization arises mainly from a decrease
of hygroscopicity. When the reaction was conducted at 180°C, the formation of cross-links in the cell wall was apparent. Following
the MA treatment, the antifungal property was remarkably enhanced and met the Japanese Industrial Standard K1571. Therefore,
MA treatment in the vapor phase is an effective method to attain antifungal properties as well as high dimensional stability
with a small amount of nontoxic reagent. 相似文献
3.
Five wood species were acetylated with acetic anhydride (AA) solution of glucose pentaacetate (GPA) at 120°C for 8h, and the effect of GPA on the dimensional stability of the acetylated wood was investigated. Some GPA was introduced into the wood cell wall during acetylation. The GPA remaining in the cell lumen penetrated the cell wall effectively after heating to more than 140°C for 10min. The bulking effects of GPA resulted in a 10%–30% increase in the anti-swelling efficiency of the acetylated wood with 20% GPA/AA solution in place of AA. Hydrophobic GPA did not deliquesce under highly humid conditions and it remained in the cell wall after boiling in water.Part of this paper was presented at the 51st Annual Meeting of the Japan Wood Research Society, Tokyo, April 1988 相似文献
4.
Rubiadin (4) (1,3-dihydroxy-2-methylanthraquinone), which is one of the natural dyes from the roots of Rubiaceae, was synthesized from
phthalic anhydride (1) and 2,6-dihydroxytoluene (3) by two reaction steps, that is, a Friedel-Crafts reaction with AlCl3 and a cyclization with H2SO4/HBO2. Microwave heating resulted in remarkable acceleration of the reaction rate in the first reaction, and had an effect in reducing
the reaction time and increasing the yield of rubiadin (4) in the second reaction. 相似文献
5.
落叶松木材的高强度微波辐照法改性 总被引:1,自引:0,他引:1
LIU Hong-Hai WANG Qing-Wen YANG Lin JIANG Tao CAI Ying-Chun 《林业研究》2005,16(3):237-240
The larch wood was treated by microwave irradiation under different radiant intensity and treating duration. The microwave-treated wood specimens together with the un-treated for comparison were impregnated by water in pressure vessel and then tested for permeability, mechanical properties and microstructure change by SEM to study the modification performance of microwave treatment on larch wood. The results showed that under suitable conditions of microwave treatment the permeability of larch wood was improved without noticeable decreasing of the modulus of rupture (MOR) and the modulus of elasticity (MOE). The radial parenchyma and some pit membrane were ruptured, and tiny cracks were formed in the cell walls. The formation of tiny cracks in the cell walls serves as man-made channels of gas and liquid and this contribute to improve the permeability of the wood. 相似文献
6.
Effects of low bondability of acetylated fibers on mechanical properties and dimensional stability of fiberboard 总被引:1,自引:0,他引:1
Hideaki Korai 《Journal of Wood Science》2001,47(6):430-436
Fiberboards were prepared from acetylated fibers with various weight gains: 0, 4.7, 9.4, 18.5, and 24.8 weight percent gain (WPG). The effects of low bondability of acetylated fibers on mechanical properties and dimensional changes were determined. The decreased mechanical properties of acetylated fiberboard are mainly due to low bondability. To improve bending strength, high face density is also needed. The thickness swelling according to JIS and the linear expansion under relative humidity changes decreased with increasing WPG. As for accelerated weathering and the outdoor exposure test, the thickness changes in 4.7–18.5 WPG boards were much higher than those in OWPG board and 24.8 WPG board. The high thickness change in 4.7–18.5 WPG boards is due to low bondability. Although 24.8 WPG board also has low bondability, the thickness change of 24.8 WPG board decreased. The high dimensional stability of acetylated fibers, caused by high WPG, probably outweighs the dimensional change caused by low bondability. On the other hand, during the boiling test the thickness changes in 24.8 WPG board and the 4.7–18.5 WPG boards were higher than those in 0 WPG board. The effect of the boiling test on the boards is more severe than that seen with the accelerated weathering and outdoor exposure test; therefore, the effects of the low bondability probably cancel the effects of the high WPG. It is necessary to increase the bondability of acetylated fibers to improve the dimensional stability and the mechanical properties. 相似文献
7.
采用氢氧化钠水溶液预处理刨花,并用这些刨花压制单层酚醛刨花板。经1%碱液处理刨花30min,可提高板材尺寸稳定性,尤其是可将板材的不可逆厚度膨胀降至极小。 相似文献
8.
Wang Fenghu Yu JingNortheast Forestry UniversitySong KuiyanYichun Reconnaissance Designing Institute of Forestry 《林业研究》1993,4(2):93-97
A method of alkaline pretreatment of particles was designed to produce threetypes of chips.The pretreatmentet of particles in 1% water solution of NaOH for 30minutes offered a possibility of producing PF bonded particleboards with minimal irrecover-able swell and a reduction in thickness swelling.The method used in this work could beused to produce more stable PF particeboard. 相似文献
9.
10.
The purpose of this paper is to offer a new method for detecting stress in wood due to moisture along the lines of a theory reported previously. According to the theory, the stress in wood could be estimated from the moisture content of the wood and the power voltage of a microwave moisture meter (i.e., attenuation of the projected microwave). This seems to suggest a possibility of utilizing microwaves in the field of stress detection. To develop such an idea, the stress formulas were initially modified to the form of an uni-variable function of power voltage, and the application method of the formulas to detection was tried. Finally, these results were applied to the data of sugi (Cryptomeria japonica) lumber in the previous experiment. The estimated strains showed fairly good agreement with those observed. It could be concluded from this study that the proposed method might be available for detecting stress in wood due to moisture.Part of this report was presented at the 52nd Annual Meeting of the Japan Wood Research Society, Gifu, April 2002 相似文献
11.
农用货车在木材生产中应用的评价 总被引:1,自引:1,他引:1
从经济改革,南方林区道路状况,结合农用货车性能特点。通过与EQ1090、CA1090等车型各方面比较,对农用货车在木材生产中应用作出了评价。 相似文献
12.
13.
The vapor phase reaction of wood with maleic anhydride (MA) was investigated from the aspect of the mechanism of dimensional
stabilization. Notably the existence of cross-links was examined by detailed analyses of dimensional stability and related
properties, diffuse reflectance infrared Fourier transform (DRIFT) spectra, and changes in mechanical properties such as creep
property and vibrational property. Higher reaction temperature resulted in less leaching of reagent. Also a peak in DRIFT
spectra at 1730 cm−1 showed the esterification of wood components with MA, while that at around 1780 cm−1, which became remarkable with increasing reaction temperature, suggested the formation of cross-linking. The loss tangent
decreased and the creep deformation was restrained for the specimens treated at high temperature. From these results it is
plausible that MA mainly forms monoester with wood components at lower temperature; however, at elevated temperature cross-linking
appears in addition to formation of the monoester. 相似文献
14.
刨花蒸汽处理提高刨花板的尺寸稳定性 总被引:2,自引:0,他引:2
本研究探索用高压饱和蒸汽处理刨花来提高刨花板的尺寸稳定性。分别对云杉(Picea spp。)和桦木(Betula spp。)找出了不同的蒸汽压力和处理时间与刨花板的弹性模量、静曲强度、平面抗拉强度和线性膨胀率之间的关系,并得出结论:蒸汽处理刨花时较适宜的工艺条件为:蒸汽压力1.3N/mm~2左右,蒸汽处理时间5~6min;经蒸汽处理后桦木刨花板尺寸稳定性的改善程度优于云杉刨花板。 相似文献
15.
Ezomatsu wood blocks were acetylated in a mixture of acetic anhydride and acetic acid containing excess potassium acetate
(KAc). The mixture method enabled rapid acetylation at 120°C: a 20% weight gain (weight percent gain; WPG) was achieved within
30 min while the WPG did not exceed 18% after 120 min of conventional uncatalyzed acetylation. At 40°C, however, a satisfactory
WPG was not achieved with the mixture method because both the wood swelling and KAc concentration in the reagent solution
were limited at that temperature. In addition, the antiswelling efficiency attained by the mixture method was irregularly
low, probably because of nonuniform reaction involving shrinkage of the cell lumina. These results suggest that the mixture
method is not advantageous for low-temperature acetylation, whereas it enables simple and rapid acetylation at high temperature. 相似文献
16.
Summary This article relates to a procedure of preparing solutions for wood treatment by dissolving the condensed waste material from the baking steam of expanded cork board production in organic solvents. These solutions were applied by way of different methods inPinus pinaster wood treatment. The use of these products and methods improved the pine wood dimensional stability giving rise to lower water absorption and swelling. This cork industry waste, is mainly constituted by tannins and waxes, and their solutions are easy to obtain at low cost. A patent application was done.The authors would like to thank the collaboration of our fellow Mr. Paulo Cortiço 相似文献
17.
The purpose of this study was to use images from a microwave sensor on a pixel level for simultaneous prediction of moisture
content and density of wood. The microwave sensor functions as a line-scan camera with a pixel size of 8mm. Boards of Scots
pine (Pinus sylvestris), 25 and 50mm thick, were scanned at three different moisture contents. Dry density and moisture content for each pixel were
calculated from measurements with a computed tomography scanner. It was possible to create models for prediction of density
on a pixel level. Models for prediction of moisture content had to be based on average values over homogeneous regions. Accuracy
will be improved if it is possible to make a classification of knots, heartwood, sapwood, etc., and calibrate different models
for different types of wood. The limitations of the sensor used are high noise in amplitude measurements and the restriction
to one period for phase measurements. 相似文献
18.
Influence of heating history on dynamic viscoelastic properties and dimensions of dry wood 总被引:2,自引:2,他引:0
To obtain new information about the mechanical and physical properties of dry wood in unstable states, the influence of heating
history on viscoelastic properties and dimensional changes of dry wood in the radial, tangential, and longitudinal directions
was studied between 100° and 200°C. Unstable states of dry wood still existed after heating at 105°C for 30 min and were modified
by activated molecular motion in the first heating process to temperatures above 105°C. This phenomenon is thought to be caused
by the unstable states reappearing after wetting and drying again. Dry wood components did not completely approach the stable
state in the temperature range tested, because they did not entirely surpass the glass transition temperatures in most of
the temperature range. In constant temperature processes at 135° and 165°C, E′ increased and E″ decreased with time regardless of the direction. This indicated that the unstable states of dry wood components were gradually
modified with time at constant temperatures. On the other hand, anisotropy of dimensional change existed and dimension increased
in the longitudinal direction, was unchanged in the radial direction, and decreased in the tangential direction with time
at constant temperatures.
Part of this report was presented at the 13th Annual Meeting of the Chubu Branch of the Japan Wood Research Society, Shizuoka,
August 2003 相似文献
19.
阻燃剂WFRJ1改性木材的体积稳定性和涂饰性能 总被引:3,自引:0,他引:3
用阻燃剂WFRJ1处理大青杨木材并对处理材的阻燃性能、涂饰性能和体积稳定性进行测定。结果表明:WFRJ1可用于木制品的阻燃处理。当WFRJ1浓度为10%时,氧指数可达到50%以上,与水溶性RF树脂复配,可大幅度提高处理材的抗胀缩率和阻湿率,增加体积稳定性。经WFRJ1处理后杨木单板的涂饰性能未受影响。 相似文献