共查询到18条相似文献,搜索用时 125 毫秒
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《林业工程学报》2016,(5)
采用常压冷等离子体处理杨木单板制备非结构用单板层积材(LVL),研究处理功率、处理速率对单板层积材性能的影响。结果表明:常压冷等离子体处理能明显改善杨木LVL的胶合性能,当处理功率为4.5 k W、处理速率为2 m/min时LVL的浸渍剥离率降低了59.3%;常压冷等离子体改性可以明显影响杨木单板表面的物理化学性质,提高单板表面润湿性,当处理功率为6 k W、处理速率为8 m/min时脲醛树脂胶在杨木单板表面接触角的初始角下降25.4%、平衡角下降36.8%;红外光谱分析表明,杨木单板经常压冷等离子体处理后表面羰基数量有所增加,并产生少量的酮基,杨木表面的共轭羰基或羧基数量增加,C—O数量也有所增加。 相似文献
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以蔗渣纤维为原料,通过热压成型工艺制备了无胶蔗渣纤维板。研究了板材密度、热压温度以及热压时间对其物理力学性能的影响,并通过傅里叶红外光谱及X射线衍射等分析了板材成型机理。结果表明:随着板材密度、热压温度以及热压时间的增加,无胶蔗渣纤维板静曲强度、弹性模量、内结合强度逐渐增大,2h吸水厚度膨胀率逐渐减小。热压过程中,蔗渣纤维中的纤维素和半纤维素基环甙键产生裂变,部分木素降解,产生活性羟基并在纤维间形成氢键,同时,蔗渣纤维中的半纤维素发生水解,生成起胶合作用的缩聚呋喃树脂。热压温度升高,活性羟基及氢键数量增加,缩聚呋喃树脂生成量增大,无胶蔗渣纤维板力学性能更好。 相似文献
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《林业工程学报》2017,(6)
单板在高温干燥条件下表面会发生钝化,表面活性下降,从而影响胶合性能。利用常压低温等离子体处理高温干燥杨木单板,以改善其表面特性,提高胶合性能。主要研究了等离子体处理功率和处理速率对高温干燥杨木单板表面特性及界面胶合性能的影响。研究结果表明:等离子体处理可明显提高单板表面的润湿性,当处理功率为4.5 k W、处理速率为2 m/min时,脲醛树脂胶和酚醛树脂胶在杨木单板表面的初始接触角和平衡接触角分别降低了18.2%,17.8%和40.4%,38.8%,脲醛树脂和酚醛树脂胶所制胶合板的胶合剪切强度分别增加了56.0%和51.5%。等离子体处理后脲醛树脂在高温干燥杨木单板所制胶合板的胶合界面中的渗透深度明显提高,胶合界面的平均渗透深度和有效渗透深度增幅分别为80.0%和61.9%。等离子体处理后,高温干燥杨木单板表面羰基数量有所增加。 相似文献
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用电子显微镜研究干法无胶硬质纤维板的结构 总被引:2,自引:0,他引:2
用扫描电子显微镜对未浸水和浸水后的干法无胶硬质纤维板进行观察,以获得有关无胶纤维板内在结构的变化,这可以更好地了解无胶纤维板的强度和耐水性能,在制造纤维板过程中,通过热磨使木材纤维在胞间层分离,并在热压时受压力作用再次结合,纤维重新结合的状况决定了纤维板的物理力学性能,经电镜观察的无胶纤维板,纤维间相互交织且结合紧密,即使是浸水后,纤维间的结合仍未出现松散现象,这表明不施加胶粘剂制造的干法硬质纤维板可以具有优越的强度和耐水性能。 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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通过不同浓度微纳纤丝/MF混合液对秸秆纤维板进行不同浸注时间处理后,分析可知:微纳纤丝的浓度越大,对提高秸秆纤维板的静曲强度和弹性模量效果越好;而增加浸渍时间虽然有利于提高秸秆纤维板的平均密度,但同时会提高其密度梯度。较佳的工艺参数分别是秸秆纤维板密度:0.8g/cm~3;微纳纤丝浓度:1.0%;浸渍时间:8h。 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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Surface chemical characteristics of straw fiber have a great effect on the properties of interfacial conglutination between
straw fiber and adhesives. In our study, straw was treated by four different methods—hot water, acetic acid, sodium sulfite
and sodium hydrid sulfite. Our results show that the main chemical group of straw fiber, under the four different treatments,
has not changed significantly. The acetic acid treatment reduces pH values of straw fibers and has a significant effect on
the internal bonding strength of straw fiberboards. The modulus of rupture and modulus of elasticity did not clearly improve
with the four different treatments. The thickness swelling of straw fiberboard treated in different ways is higher than that
of standard values. It is concluded that acid treatment is optimal for producing good quality straw fiberboard.
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Translated from China Forest Products Industry, 2006, 33(4): 24–26 [译自: 林产工业] 相似文献
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研究了麦秆在不同预热处理条件下,其纤维化学性质以及制得的中密度纤维板的性能,同时结合施胶量对不同预热处理麦秆纤维板性能的影响,探讨了在麦秆纤维/脲醛树脂胶中密度纤维板生产中施胶量对板性能影响的重要性。结果表明,采用预热温度为160℃左右、预热时间5~7min的处理条件获得的麦秆纤维在16%左右的施胶量时,可获得满足GB/T 11718-1999标准的麦秆纤维/脲醛树脂胶中密度纤维板。 相似文献
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