共查询到18条相似文献，搜索用时 234 毫秒
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分别用氢氧化钾和亚氯酰钠处理木材原料，以移去木材原料中的一部分半纤维素和木素。些特制浆料压制的无胶纤维板，无论是板的经度性能还是板的耐水性能都比未处理木材原料制造的无胶纤维板的性能有明显的下降。这一结果表明，木材原料中的半纤维素和木素都对纤维间自生胶粘因素的形成具有重要意义。 相似文献
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干法无胶硬质纤维板制造工艺 总被引：2，自引：0，他引：2
干法无胶硬质纤维板制造工艺曹忠荣为检验干法无胶生产硬质纤维板的技术可行性，对其工艺进行了研究。１试验方法１．１试验方法此工艺过程除无施胶工序外，其余工艺过程与传统干法纤维板生产工艺相同。１．２原料意杨和桦木。意杨剥皮削片，桦木未剥皮直接削片。１．３蒸... 相似文献
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生产无胶干法硬质纤维板的特点曹忠荣（中国林科院木材工业研究所北京１０００９１）中国林科院木材工业研究所研制的无胶干法硬质纤维板生产工艺技术问世后￣［１］，受到了国内同行的广泛关注，尤其是目前处于进退维谷中的湿法生产纤维板厂。为便于对这一新工艺有比较全... 相似文献
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本文采用正交试验方法,探讨了热压工艺中的温度、压力和时间对无胶干法硬质纤维板主要物理力学性能的影响,筛选出最佳热压工艺参数。对最佳热压工艺参数进行验证试验表明,所制无胶干法硬质纤维板的主要性能,可达到湿法纤维板的水平。 相似文献
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Binderless boards were prepared from steam-exploded fiber of oil palm(Elaeis guineensis Jacq.) frond at six levels of explosion conditions. Their properties were investigated and evaluated. The mechanical properties (i.e., modulus of rupture, modulus of elasticity, and internal bonding strength) of the boards increased linearly with increasing board density as the usual hardboard. The boards made from fibers treated under a steam explosion condition of 25 kgf/cm2 (steam pressure) and 5 min (digestion period) exhibited the maximum strength. These boards at a density of 1.2 g/cm3 met the requirement of S-20 grade of JIS A 5905 — 1994 (fiberboard). Thickness swelling of the boards ranged from 6% to 14% under the JIS A 5908 — 1994 (particleboard) test condition and showed no significant changes with increasing board density. The main bonding strength of the board is believed to be due to a ligninfurfural linkage. Considering the chemical components of oil palm frond, which is rich in hemicellulose, there seems to be a good possibility for producing binderless boards using steam-exploded fibers of oil palm frond.This study was presented in part at the 2nd International Wood Science Seminar, Serpong, Indonesia, November 1998 相似文献
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Jianying Xu Ragil Widyorini Hidefumi Yamauchi Shuichi Kawai 《Journal of Wood Science》2006,52(3):236-243
Binderless fiberboards with densities of 0.3 and 0.5 g/cm3 were developed from kenaf core material using the conventional dry-manufacturing process. The effects of steam pressure (0.4–0.8
MPa) and cooking time (10–30 min) in the refining process, fiber moisture content (MC) (10%, 30%), and hot-pressing time (3–10
min) on the board properties were investigated. The results showed that kenaf core binderless fiberboards manufactured with
high steam pressure and long cooking time during the refining process had high internal bond (IB) strength, low thickness
swelling (TS), but low bending strength values. The binderless fiberboards made from 30% MC fibers showed better mechanical
and dimensional properties than those from air-dried fibers. Hot-pressing time was found to have little effect on the IB value
of the binderless board at the refining conditions of 0.8 MPa/20 min, but longer pressing time resulted in lower TS. At a
density of 0.5 g/cm3, binderless fiberboard with the refining conditions of 0.8 MPa/20 min recorded a modulus of rupture (MOR) of 12 MPa, modulus
of elasticity (MOE) of 1.7 GPa, IB of 0.43 MPa, and 12% TS under the optimum board manufacturing conditions.
Part of this article was presented at the 54th Annual Meeting of the Japan Wood Research Society, Hokkaido, August 3–5, 2004 相似文献
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Summary The effects of creep at constant conditions of moisture content and the effects of deformations occurring during cycling of
moisture content have been studied in loaded beams of particleboard and hardboard. The variations in stiffness in loaded and
unloaded beams of particleboard during moisture cycling were also determined. Contrary to the findings of some workers but
in agreement with the findings of another, the increases in the deflections of loaded beams of particleboard during cycling
of moisture content were due mainly to desorption of moisture. Qualitatively similar behaviour was found for particleboard,
hardboard and wood but quantitatively the effects were greatest in particleboard and hardboard. It appears that the basic
mechanism of the transient effects in bending, arising with the simultaneous action of load and change in moisture content,
may be similar in wood, particleboard and hardboard. 相似文献
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Chemical components are the main factors affecting the mechanical properties of wood fibers. Lignin is one of the main components of wood cell walls and has a critical effect on the mechanical properties of paper pulp and wood fiber based composites. In this study, we carried out tensile tests on single mature latewood tracheids of Chinese fir (Cunninghamia lanciolata (Lamb.) Hook.), using three different delignified treatment methods to obtain different amounts of lignin. We applied single fiber tests to study the effect of the amount of lignin on mechanical tensile properties of single wood fibers at the cellular level. The results show that in their dry state, the modulus of elasticity of single fibers decreased with the reduction in the amount of lignin; even their absolute values were not high. The amount of lignin affects the tensile strength and elongation of single fibers considerably. Tensile strength and elongation of single fibers increase with a reduction in the amount of lignin. 相似文献
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ZHOUGuanwu DUANXinfang** CAOYongjian CHENYongsheng CAO Yuanlin** .Division of Wood Protection Research Institute of Wood Industry Chinese Academy ofForestry Beijing P.R.China .Centerfor Brain CognitiveSciences Institute of Biophysics Chinese AcademyofSciences Beijing P.R. China 《中国林业科技(英文版)》2006,5(2):28-32
INTRODUCTIONLaccase (EC 1.10.3.2) is multicopper oxidase catalyzing oxidation of various phenolic compounds, aromatic amines, and even certain inorganic compounds by a one-electron transfer mechanism. The electron withdrawn from the substrates is transferred via four copper atoms to molecular oxygen (Messerschmidt 1997). Laccase is very common in nature, especially in plants and fungi (Gianfreda et al. 1999). Fungal laccases participate in plant pathogenesis, pigment production and ligni… 相似文献
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B. A.. -L. Östman 《Wood Science and Technology》1985,19(2):103-116
Summary The immediate tensile strength parameters for spruce parallel to the grain and for hardboard have been determined at equilibrium conditions at temperatures up to 250°C. Below 100°C the moisture content has been varied between 0 and 30%. Above 100°C dry samples have been studied. An increase in moisture content up to about 12% leads to a slight increase in the tensile strength of spruce whereas the modulus of elasticity remains constant. With a further increase in moisture content, both properties decrease significantly. At any given moisture content, both properties decrease with increasing temperature. The corresponding strain at rupture is constant. An increase in temperature leads to a more or less linear decrease in the tensile strength and in the modulus of elasticity up to about 200°C. Above 200°C there is a more rapid decrease due to thermal softening. It is most relevant to consider the relative strength decrease since the absolute levels may be quite high due to the fact that wood samples without any irregularities were used. Such relative strength data are compared with the small amount of similar data found in the literature. The effects on the modulus of elasticity are discussed in terms of thermal softening and of water as a softener for the cellulose/hemicellulose polymers. The glass transition temperature is determined as a function of the moisture content.A special thank to Ms. K. Bojadzijev for skillful experimental assistance, to Prof. E. L. Back for stimulating discussions and to the fund for research in woodworking industries for financial support 相似文献
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Fourier-transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) were used to study ambient-aged wood
fibers and their effects on the mechanical properties of medium-density fiberboard (MDF). It was found that MDF made with
ambient-aged fibers had poorer mechanical properties than MDF made with fresh fibers; this difference resulted from the alterations
of surface characteristics of wood fibers after ambient aging, which led to poor wettability of the urea–formaldehyde (UF)
resin applied to the aged wood fibers. After 6 months of ambient aging, the concentration of carbonyl groups in the fibers
increased by 144%, while the pH value of wood fiber decreased from 5.2 to 4.7. SEM showed that much more UF resin agglomerated
on the surface of ambient-aged fibers and the breakage of MDF made with aged fiber frequently occurred at the resin-fiber
interfaces, indicated the poorer wettability of UF resin to fibers due to the decrease in surface energy after aging. 相似文献