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三种树种木纤维的漆酶活化胶合 总被引:4,自引:0,他引:4
通过测定经漆酶活化处理后的思茅松、枫香和杉木纤维制成的纤维板的内结合强度,对木纤维活化后的胶合性能进行了比较.结果显示:在相同条件下进行漆酶活化处理,不同树种木纤维的自身胶合性能有一定差别,可能与其木素含量有关;不同树种木纤维进行酶活化反应时介质最佳pH值均在酸性范围,但略有差别. 相似文献
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采用漆酶活化木素或其磺酸盐制备胶黏剂用于人造板生产,可以消除游离甲醛的污染问题。以漆酶、工业木素及其磺酸盐、杨木为原料,在处理时间分别为30、45、60min,pH值分别为3.5、4.5、5.5,温度20℃条件下,分别以漆酶处理工业木素、木素磺酸钠和木素磺酸铵三种底物制备胶黏剂,然后在热压时间30min,压力4.5~5MPa,热压温度150℃条件下生产杨木胶合板。结果表明,除漆酶木素磺酸钠胶合体系外,漆酶木素和漆酶木素磺酸铵的胶合体系的胶合板胶合强度均达到并超过国家Ⅲ类胶合板的要求。 相似文献
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酶在木材胶合中的应用 总被引:4,自引:2,他引:2
介绍了酶用于木材胶合的研究及进展。利用酶可直接活化木纤维或木刨花中的木素使其自身胶合,也可使酶与制浆过程中分离出来的木素反应,得到与酚类化合物类似的胶粘剂,用以胶合木纤维或木刨花。利用酶催化氧化木素的途径生产人造板,无污染且安全可靠。 相似文献
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《林业研究》2017,(6)
White rot fungi were optimized to cultivate highly active laccase. The characteristics of laccase incubated by continuous culture were compared with those of direct culture. The enzyme activity of laccase incubated by continuous culture technology reached a higher value on the fifth day of the growth. The optimization incubation time of high activity laccase was the eleventh day. A large amount of highly active laccase can be obtained in a relatively short time by continuous culture to replace traditional laccase. After laccase treatment, the lignin composition of wood fibers were oxidation-catalyzed by laccase. The number of chemical-bonding points between the wood fibers was increased. The wood fibers treated by laccase were fabricated into boards and their mechanical properties improved with the laccase-incubation times.Compared with the fiberboards made from fibers that were pre-treated by laccase of incubation 5 days, the static bending strength of those that were pre-treated by laccase of incubation 11 days was increased by 18.95%, the elastic modulus was increased by 35.49%, and the internal bond strength was increased by 44.11%. 相似文献
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Cheng Xing S. Y. Zhang James Deng Bernard Riedl Alain Cloutier 《Wood Science and Technology》2006,40(8):637-646
The properties of medium-density fiberboard (MDF) panels as affected by wood fiber characteristics were investigated. Wood chips from three softwood and one hardwood species were refined under the same refining conditions to make four different types of fibers. The resulting fibers were characterized by fiber size distribution, bulk density, pH value, and buffering capacity. Using the same resin system and hot-pressing parameters, MDF panels were produced and evaluated for internal bonding (IB), modulus of rupture (MOR), modulus of elasticity (MOE), thickness swelling, and linear expansion. The pH values and alkaline buffering capacities of raw materials were reduced considerably after refining. IB was strongly related to the pH value of fibers. The mechanical properties increased with alkaline buffering capacity. IB, MOR, and MOE increased with the bulk density of fibers. Increased proportions of coarse fibers had negative effects on the panel mechanical properties. 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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Some of the properties of particleboard made from paulownia 总被引:3,自引:0,他引:3
The objective of this study was to determine some of the properties of experimental particleboard panels made from low-quality paulownia (Paulownia tomentosa). Chemical properties including holocellulose, cellulose, lignin contents, water solubility, and pH level of the wood were also analyzed. Three-layer experimental panels were manufactured with two density levels using urea–formaldehyde as a binder. Modulus of elasticity (MOE), modulus of rupture (MOR), internal bond strength (IB), screw-holding strength, thickness swelling, and surface roughness of the specimens were evaluated. Panels with densities of 0.65 g/cm3 and manufactured using a 7-min press time resulted in higher mechanical properties than those of made with densities of 0.55 g/cm3 and press times of 5 min. Based on the initial findings of this study, it appears that higher values of solubility and lignin content of the raw material contributed to better physical and mechanical properties of the experimental panels. All types of strength characteristics of the samples manufactured from underutilized low-quality paulownia wood met the minimum strength requirements of the European Standards for general uses. 相似文献
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Charalampos Lykidis Athanasios Grigoriou Ioannis Barboutis 《Wood material science & engineering》2014,9(4):202-208
This paper investigates the potential of utilising wood biomass from fruit tree branches and evergreen hardwood shrubs as raw materials in the production of particleboards when mixed with Greek fir wood particles. The main mechanical properties of the boards made therefrom were determined and compared with those made of typical industrial wood (IW) particles. The highest modulus of rupture and elasticity (30.0 N/mm2 and 4330 N/mm2, respectively) in bending and screw withdrawal (SW) resistance (127.8 N/mm) were reported for boards made of Greek fir and were downgraded when the fruit tree branches or evergreen hardwood shrub particles also participated. The participation of fruit tree branch particles in proportions higher than 50% improved the internal bond (IB) of fir produced boards, while the highest IB strength (0.95 N/mm2) was reported for boards made of fruit tree branches. Particleboards made of evergreen hardwood shrubs showed inferior mechanical properties compared with those made of IW particles. The latter also showed superior bending strength but inferior SW resistance compared with boards made of fruit tree branches. Hygroscopic and other properties are under determination and will be presented and discussed in the second part of the work. 相似文献
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广宁县竹香骨下脚料制备竹碎料刨花板及其复合改性研究 总被引:1,自引:0,他引:1
采用竹香骨下脚料为原料,以脲醛树脂和三聚氰胺改性脲醛树脂胶粘剂制备竹碎料刨花板,并与木纤维复合改性,检测并分析了内结合强度、静曲强度、弹性模量和吸水性。结果表明,在热压温度为160℃时,竹碎料板和竹木复合碎料板的物理力学性能均满足国标规定在干燥状态下使用的普通用板要求。当木纤维与竹碎料复合后,复合板材的静曲强度和弹性模量有一定程度提高,但内结合强度降低。 相似文献
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平面密度分布对刨花板内结合强度的影响 总被引:1,自引:0,他引:1
平面密度变异是非单板类木质人造板所共有的一种结构现象 ,其变异程度和分布特征对板材性能有一定影响。本文利用单板条模拟 4种具有不同平面密度分布的刨花板 ,讨论了随机铺装刨花板坯模型的平面密度分布规律及试件大小与密度分布的关系 ,分析了密度以及平面密度分布对非单板类木质人造板内结合强度的影响。结果表明 :随机铺装刨花板的平面密度遵循正态分布规律 ;内结合强度受密度影响较大 ,密度增加有助于内结合强度提高 ,但密度过高将导致内结合强度下降 ;试件大小影响试件之间密度变异程度 ,适当增加试件尺寸 ,可降低内接合强度测试结果的离散性。 相似文献
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MEI Changtong DAI Chunping ZHOU Dingguo . Nanjing Forestry University Nanjing P.R.China . Forintek Canada Corp. Vancouver BC VT W Canada 《中国林业科技(英文版)》2005,4(2):58-65
Along with the worldwide decrease of round woodwith high quality and large diameter day by day, theoutput of lumber and plywood used in constructionis declining year by year. But the market demand forcomposites keeps rising. Non-veneer woodcomposites (Oriented Strand Board, Flakeboard,Medium Density Fiberboard) will be the mainstreamof composites in the future. At present, OrientedStrand Board and structural flakeboard have to a largedegree replaced structural plywood in buildingconstructi… 相似文献
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《Wood material science & engineering》2013,8(1):25-29
Abstract The objective of this work was to evaluate the performance of particleboard manufactured from roselle (Hibiscus sabdariffa) stalks and eucalyptus (Eucalyptus camaldulensis) wood. The manufacturing parameters were various roselle (Hibiscus sabdariffa) ratios in the mixture (0, 25, 50, 75 and 100%) and press time (3, 5 and 7 min). Modulus of elasticity (MOE), modulus of rupture (MOR), internal bonding (IB) strength values and thickness swelling (TS) after 24-hour water soaking of the panels were determined according to the procedure of European Union (EN) Standard. The results of the study demonstrate that roselle stalks can be an alternative raw material source for particleboard industry. With an increase of roselle particles from 0% to 100%, the TS was reduced, and the IB, MOR and MOE were increased. The highest MOE, MOR, IB strength and TS values of the samples were found as 2754.18, 16.81, 0.89 N/mm2 and 15.26% for the panels made using 100% roselle with a 7-min press time, respectively. 相似文献