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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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喻云水 《中南林业科技大学学报(自然科学版)》1997,(4)
用正交试验法研究了施胶量、热压温度和热压时间3个因素对复合竹碎料板物理力学性能的综合影响.结果表明:热压温度是影响板材物理力学性能的主要因素.较佳工艺参数为,施政量12%,热压温度150℃,热压时间22min,板材物理力学性能能满足混凝土模板材料性能的需要. 相似文献
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不同热压方法对无胶竹碎料板力学性能影响 总被引:1,自引:0,他引:1
分别采用普通热压和喷蒸热压两种热压方法制备了无胶竹碎料板,对它们的物理力学性能进行了对比研究与分析.结果表明,与普通热压法相比,喷蒸热压法制备的无胶竹碎料板的静曲强度、弹性模量与内结合强度明显提高,吸水厚度膨胀率显著减小,这可能是因为两种热压法热压过程中竹碎料发生的化学变化不同所致. 相似文献
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干法蔗渣中密度纤维板热压工艺的研究 总被引:5,自引:0,他引:5
通过正交试验法,分析了热压中温度、压力和时间对干法蔗渣MDF各项物理力学性能的影响。确定了蔗渣MDF(板厚为12mm)热压的较佳工艺参数为:热压温度175℃,热压时间8.5min,热压压力4MPA。 相似文献
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漆酶/碳源系统预处理对稻草碎料板性能的影响 总被引:2,自引:0,他引:2
利用添加少量碳源与漆酶组成的体系对稻草进行预处理,以改善其压板性能,研究了漆酶预处理的最佳工艺条件、漆酶/碳源系统(LCS)与漆酶/介体系统(LMS)预处理结果比较及酶处理对稻草碎料板性能的影响。结果表明:LCS完全可以代替昂贵的LMS来降解稻草中木质素;预处理最适条件为pH值5.0,温度45℃,液比1:7,时间4-6h,酶用量20-30IU/g;当酶用量为20IU/g,时间4h条件下预处理稻草碎料板的各项力学性能均有显著改善,与粗碎料板相比,酶处理对细碎料板的性能改善效果更是明显:内结合强度(IB)增加20%,静曲强度(MOR)增加21%,弹性模量(MOE)增加31%,吸水厚度膨胀率(TS)降低35%,甲醛释放量可达到F1级标准。 相似文献
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许国强 《林业机械与木工设备》2007,35(1):17-20,28
研究了以3 mm以上厚度的竹篾片编织竹帘生产厚帘竹胶合板模板的工艺条件,讨论了热压时间、热压压力、热压温度及浸胶的胶液浓度对覆膜厚帘竹胶合板模板物理力学性能的影响,总结确定出最佳的可供生产应用的热压工艺条件.结果表明,在热压压力1.4 MPa、热压时间60 s/mm板厚、热压温度135 ℃、浸胶胶液浓度26%的条件下生产出的产品各项力学性能指标均达到或超出竹胶合板模板国家标准. 相似文献
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戴恁 《林业机械与木工设备》2012,(5):32-36
探讨了以竹材为主要原料的竹重组板材热压工艺的优化,研究了热压工艺对竹重组板材力学性能的影响,讨论分析了热压压力、热压时间、热压温度对竹重组板材吸水厚度膨胀率、耐沸水性、静曲强度、弹性模量、耐磨性、耐化学腐蚀性、浸渍剥离率和甲醛释放量等性能的影响。通过正交试验,得出的优化热压工艺为:①热压压力2.0MPa、热压温度145℃、热压时间1.7min/mm,热压压力对竹重组板材耐酸性、静曲强度和弹性模量等影响显著,对耐沸水性、耐碱性、耐盐性、耐磨性和浸渍剥离率等影响不显著。②热压时间对竹重组板材静曲强度有显著影响,对其他试验指标影响不显著。③热压温度对竹重组板材各试验检测指标均有一定的影响,但不显著。 相似文献
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Binderless particleboards were manufactured from sugi (Cryptomeria japonica D. Don) heartwood and sapwood by hot-pressing (pressure: 5 MPa; temperatures: 180°, 200°, and 220°C; times: 10, 20, and 30
min), and the board properties [internal bonding (IB), thickness swelling (TS), water absorption (WA)] were investigated to
evaluate the self-bonding ability. The IB, TS, and WA of the boards from sugi heartwood were better than those of the boards
from sugi sapwood at any hot-pressing condition. Therefore, it was suggested that the self-bonding ability of sugi heartwood
was superior to that of sugi sapwood. Then, sugi heartwood and sapwood powder with grain size 10 βm were used as a binder
for plywoods. Four kinds of plywood were manufactured from the combination of powder and veneer, both of which were prepared
from sugi heartwood and sapwood under the same hot-pressing conditions as the binderless particleboard, and the adhesive shear
strength and wood failure of the plywood were investigated. As a result, the plywood composed of sugi heartwood veneer met
the second grade of JAS for plywood, when either powder was used as a binder, when they were pressed at 200°C for 20–30 min
and 220°C for 10 min. 相似文献
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《Wood material science & engineering》2013,8(2):205-214
AbstractFive-ply self-bonded boards were obtained by pressing beech veneers parallel to the grain without additional adhesives, steam or pre-treatment. Fifteen different combinations of pressing parameters were tested, including temperature (200°C, 225°C and 250°C), pressure (4, 5 and 6 MPa) and pressing time (240, 300 and 360 seconds). Due to severe pressing conditions, the new product showed a higher density and different properties compared to a conventionally glued laminated wooden board. The self-bonding quality was assessed through dry shear strength tests, through a three-point bending test and a water-soaking test at 20°C. The dimensions in the cross section of the boards were measured after soaking in water. Results show that the choice of pressing parameters affects all the mechanical and physical properties tested. A statistical analysis revealed that the pressing temperature is the most influential parameter. Boards pressed at 200°C delaminated rapidly in water, whereas boards pressed at 225°C delaminated only at core-positioned layers after 48 hours and boards pressed at 250°C did not delaminate at all in water. Compared to panels pressed at lower temperatures, boards pressed at 250°C had the highest density, a higher shear and bending strength and a lower water absorption. 相似文献
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Summary A procedure is presented to estimate the relative vapor pressure, equilibrium moisture content, average flake temperature, and average flake moisture content in a flakeboard mat during hot-pressing. This method is based on measurements of temperature and total gas pressure in the mat during hot-pressing. A heat and mass transfer model was adapted from the literature to predict the temperature and moisture content inside an individual flake. Significant moisture gradients are predicted to develop within flakes. Convective heat transfer appears to control the change of moisture content within a flake. Thermodynamic equilibrium between the gas phase and the wood component is not achieved during hot-pressing.This work was funded by the USDA Competitive Grant Program for Forest and Rangeland Renewable Resources, Project No. 85-FSTY-9-0106 and 87-FSTY-9-0253 相似文献
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Florence Hiu Yan Lui Yoko Kurokochi Hiroe Narita Yukie Saito Masatoshi Sato 《Journal of Wood Science》2018,64(3):246-255
Binderless boards are composite boards that rely on self-bonding mechanisms for inter-fibre bonding. Quercus acutissima and Quercus serrata logs degraded by Lentinula edodes (shiitake fungi) were used in this study to investigate whether physical and chemical changes induced by shiitake fungi can enhance board mechanical properties. Binderless boards were manufactured with 0.8 g/cm3 target density, 220 °C pressing temperature, 5 MPa pressure, and pressing duration of 10 min. Boards made from logs degraded for ≥?26 months were stronger than control boards and met modulus of rupture (MOR) and internal bonding (IB) requirements for fibreboards. Chemical composition and particle size distribution of the wood powder used to make the boards were determined to elucidate the drivers of board mechanical properties. The proportion of small particles (<?150 µm) showed a strong positive correlation with MOR for both species and hot water extractives showed a strong positive correlation with IB for Q. acutissima boards. Introduction of shiitake fungi pre-treatment to the production process may enhance the mechanical strength of binderless boards. 相似文献
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Ragil Widyorini Takashi Higashihara Jianying Xu Takashi Watanabe Shuichi Kawai 《Wood Science and Technology》2005,39(8):651-662
We investigated optimum self-bonding conditions of kenaf core composites manufactured by steam treatment, and discussed on
the roles of cinnamic acids in the self-bonding mechanism. The presence of cinnamic acids in the kenaf core and its composites
were analyzed by pyrolysis gas chromatography-mass spectrophotometry in the presence of tetramethyl ammonium hydroxide (TMAH/Py-GC-MS).
The results showed that the optimum bonding properties of kenaf core composites were achieved under these conditions: steam
pressure of 0.8–1.0 MPa and pressing time of 10–15 min were able to provide shear strength of 0.40–0.42 MPa while having 2–5%
of weight loss. Lignin analysis showed that steam-treated kenaf core composites had a lower proportion of syringyl- to guaiacyl-derived
moieties and also cinnamic acids to guaiacyl-derived moieties than its native counterpart. The results indicated that some
parts of the ester-linked cinnamic acids were also cleaved due to the degradation of hemicelluloses and lignin during steam
treatment. Based on these results, it was concluded that in addition to three main components, the cinnamic acid was also
suggested to participate in the self-bonding mechanism of non-wood lignocellulosic binderless boards. 相似文献
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To provide basic information on self-bonding in kenaf core binderless boards, a series of chemical analyses was conducted
on binderless boards and their chemical changes during hot pressing were examined in our previous study. In this study, binderless
boards were manufactured under conditions that may accelerate the supposed chemical changes to investigate their effect on
the board properties. First, to investigate the influence of the chemical bonds formed by carbonyl compounds on self-bonding,
the influence of acetic acid addition prior to board manufacturing was studied and the effect of methanol extractives (containing
the carbonyl compounds) was also examined. Second, the influence of the condensation reaction in lignin was discussed from
the viewpoint of board density. Last, to examine the influence of thermal softening of lignin, the influences of temperature
condition and moisture content, as well as those of microwave pretreatment, were investigated. As a result, the estimated
chemical changes were suggested to influence the binderless board properties. 相似文献
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笔者使用的植物蛋白胶是以富含蛋白质的生物质为主要原料制备的无甲醛释放的胶粘剂。由于其初粘性不如"三醛胶"大,因此不能利用传统细木工板的生产工艺。针对该胶粘剂的特点,通过研究新的施胶工艺,确定木材含水率8%~12%,第1次预压15 min,热压第一阶段最佳工艺参数:施胶量170 g/m2,热压时间8 min,压力17 MPa,温度105℃;第2次预压15 min,热压第二阶段最佳工艺参数:施胶量155 g/m2,热压时间4 min,施胶量155 g/m2,温度100℃,压力15 MPa,板材外观能达到优等品标准,理化性能符合GB/T5849-2006的要求。 相似文献
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This study was carried out to elucidate the effect of defibration temperature in the range 171–202°C on the properties of 12-mm thick MDF boards made without synthetic resins from softwood fibers activated by laccase treatment for the generation of phenoxy radicals on the fiber surfaces. Laccase treatment generated radicals in the fibers. An increase in defibration temperature improved the reactivity of fibers during laccase-catalyzed oxidation. The number of radicals detected in the fibers after laccase treatment in water suspension and the fiber oxygen consumption during the treatments increased with an increase in defibration temperature, while a concurrent improvement was observed in the mechanical strength and thickness swell of dry-process MDF boards made from fibers refined at different temperatures and treated with laccase in the refiner blowline. The different fiber reactivities or board properties were not due to a presence of different amounts of lignin remaining on the fiber surfaces after acetone extraction. The probable reason for them was the fact that the amount of low-molecular weight lignin, a reactive substrate for laccase, increases with increasing defibration temperature. The adhesion occurring during pressing is thus likely to involve coupling or other reactions of radicals located on adjacent fibers, whereby interfiber covalent bonds are formed. 相似文献