加压因素对杨木单板压缩率和回弹率的影响

以速生杨木的边/心材单板为研究对象,对其进行水热密实化处理,通过单因素试验方法,分别研究了加压温度和加压压力对杨木边/心材单板的压缩率、气干24和48 h的厚度回弹率的影响,初步探讨了各个因素的作用机理.研究发现:各因素水平下,杨木边/心材单板的压缩率和厚度回弹率均呈现出一定的规律性,心材单板的压缩率高于边材单板,但厚度回弹率低于边材单板,且各因素的作用机理有所差异.边/心材单板水热密实化处理的较佳条件均为:加压温度150℃,加压压力5 MPa.     

不同处理方法对人工林杨木压缩变形恢复率的研究

采用加热和水蒸气处理方法对人工林杨木进行压缩变形恢复率的研究,目的是为了改善人工林软质木材的材性,提高其尺寸稳定性。结果表明:加热和水蒸气处理都是固定人工林木材压缩变形的有效方法。     

杨树浸渍改性材物理及力学性能研究

利用聚乙烯醇缩甲醛复合改性剂对杨树木材进行浸渍改性处理,对比研究了杨树素材与改性材的物理性能及主要力学性能的变化,并利用扫描电子显微镜(SEM)分析了改性剂在改性材中的分布情况。结果表明:改性材的气干密度和抗缩系数(PASE)随改性剂浓度的上升而增加,改性材的气干密度最高为0.41 g/cm3,比素材的提高了13.9%,抗缩系数(PASE)最大提高到47.8%。改性材吸水率随改性剂浓度的上升而下降,与素材相比最大下降了19.2%。当改性剂的浓度为25%时,改性材的弹性模量和静曲强度达最大,分别为27.4%和13%。SEM分析显示改性剂填充于部分木射线以及交错纤维间的空隙中。     

杨树浸渍改性处理材尺寸稳定性研究

利用聚乙烯醇缩甲醛改性剂对杨树木材进行浸渍改性,对其改性材的尺寸稳定性进行研究。结果表明:改性材的径向、弦向和体积干缩率与素材相比均有不同程度的下降;从全干到吸水饱和状态的过程中,当改性剂达到一定浓度时,改性材的径向、体积湿胀率与素材相比有明显下降,弦向线湿胀率下降不明显。从气干到吸水饱和状态的过程中,改性材的径向、弦向湿胀率与素材相比均有不同程度的下降;改性材体积湿胀率随着改性剂浓度的上升而呈下降趋势,当改性剂浓度为30%时,改性材体积湿胀率为6.85%,与素材相比下降了5.54%。改性材吸水率随改性剂浓度的上升而下降,最低可达159%;改性材的抗干缩系数(ASE)随改性剂浓度上升而增加,最大可达47.8%。改性材的尺寸稳定性能要明显优于杨树素材。     

刨刀角度对杨木和柞木刨片流变性能的影响

以不同前角刨刀切制两种杨木和柞木刨片,根据参数分离法,对其流变性能进行了测定和研究。结果表明:刀具前角不同可导致刨片的流变性能变化;刀具前角增大,刨片流变性能的变化对提高刨花板的性能有利;刀具前角对刨片流变性能的影响在不同树种中基本趋势一致,但对刨花板性能的影响可能因树种而有所不同。     

杨木单板软化技术的初步研究

文章采用物理化学的方法,进行了三倍体毛白杨单板软化处理的实验研究。结果表明:软化剂的种类、软化时间和软化温度对软化效果都有一定的影响;本实验的最佳软化条件为:软化剂为乙二胺,软化温度为60℃,软化时间为60min。     

杨木浸渍填充改性实验

通过浸渍填充碳酸钠和氯化钙两种不同的无机盐溶液,使浸入木材的钙离子与碳酸根离子结合。在木材微纤丝间隙和管胞的胞腔中生成稳定的固体化合物碳酸钙,从而使杨木中填充了大量的无机物,得到无机复合木材。实验表明当温度为60℃、CaCl2溶液浓度为40%、Na2CO3溶液浓度为25%时,木材增重率最大,可达32.4%;而且处理过的杨木试件的硬度均比未处理高,且硬度平均提高24.36%。     

Effect of thermo-hydro-mechanical densification on microstructure and properties of poplar wood (<Emphasis Type="Italic">Populus tomentosa</Emphasis>)

This study aimed at developing a thermo-hydro-mechanical (THM) processing to compress poplar wood and investigating the effects of high temperature, moisture, and pressure during the THM processing on the changes in microstructure, porosity, mechanical properties, and dimensional stability of compressed poplar wood. The variations in these properties were correlated and their mathematical relations were determined. Poplar woods with high moisture content were compressed using different pressures at a temperature of 160 °C for different periods. The compression level was characterized by the volume compression ratio (CR), which is defined as the ratio of the compression volume and the original volume of sample before and after THM processing. The obtained results indicated that the high pressure of THM process caused the collapsing of wood cell lumens and the developing of a certain amount of fractures in the cell wall. The damage level of wood cells increased with increasing pressure and time. Moreover, the pressure narrowed the cell lumens, which decreased significantly the pore volume in wood substrate. The pore size distribution shifted from the level of macropores to those of mesopores and micropores after THM process. The THM process created superior mechanical property, especially for those with higher CR. Besides, it was revealed that the process decreased dramatically the set recovery of treated woods and improved their dimensional stability. A significant improvement was achieved in terms of the mechanical and physical properties of compressed poplar wood via the structural reformation during the THM process.     

A model of supplying poplar wood for Iranian paper ＆ wood factories

The objective of this research is to design a method for an appropriate alternative to supply poplar wood as raw material for wood and paper factories in Iran.Due to the destruction of the forests and lack of proper plantation,replacement of the forest wood by the fast growing wood is vital to satisfy all requirements of these factories.A hierarchy was used to prioritize benefits,opportunities,costs and risks (BOCR) using the Analytic Hierarchy Process (AHP) ratings approach.To evaluate the "control criteria" of the system,a control hierarchy was also created and prioritized by applying the Analytic Network Process (ANP).A total of four major control criteria in the system are prioritized where each one controls a network structure evaluated by using ANP.The final synthesis results of the system showed that internal poplar tree farming supplied by the forest product factories was the best choice among three potential alternatives (factory procurement,external procurement and mix procurement).     

长江滩地杨木密度和干缩性的研究

对安庆段长江滩地I-72杨的密度和干缩性进行了研究。结果表明:I-72杨的气干密度、全干密度和基本密度分别为0.454 g/cm3、0.415 g/cm3和0.364 g/cm3;I-72杨木材密度的径向变异为自髓心向外,最初递减,然后再向外层递增;轴向变异为沿树干向上逐渐增加;I-72杨的径向、弦向和体积全干缩率分别为3.917%、8.093%和12.138%,体积干缩系数为0.169,差异干缩为2.107;I-72杨5.3 m高度处的径向、弦向和体积全干缩率测量值均大于1.3 m高度处的测量值。     

Fungal decay resistance of wood impregnated with parahalophenyl para-tolyl sulfonamides

Summary We are investigating wood decay biocides that are both effective in protecting wood from decay and more environmentally compatible than other biocides. A series of halophenyl sulfonamides were synthesized and characterized by infrared and neuclear magnetic resonance spectroscopy. Wood impregnated with these compounds was tested for resistance to decay as well as water leaching. Wood impregnated with para-iodophenyl or para-fluorophenyl para-tolyl sulfonamides resisted decay by brown- and white-rot fungi. For wood impregnated with para-iodophenyl para-tolyl sulfonamide, threshold retention with the brown-rot fungus Gloeophyllum trabeum was 9.1 mmol/ 100 g solution for unleached blocks. For leached blocks, weight loss was very high (24.6%), which indicated that threshold retention will be substantially higher than 9.1 mmol/100 g solution. With the white-rot fungus Coriolus versicolor, threshold retentions were 2.9 and 5.6 mmol/100 g solution, respectively, for unleached and leached blocks. Leaching of the blocks treated with the iodo compound slightly decreased resistance to decay by C. versicolor. For wood impregnated with parafluorophenyl para-tolyl sulfonamide, threshold retentions with both G. trabeum and C. versicolor were very close to 9.0 and 9.2 mmol/100 g solution, respectively, for leached and unleached blocks. Leaching had a little effect on resistance to decay by both fungi. Wood impregnated with parachlorophenyl or bromophenyl para-tolyl sulfonamide was ineffective in resisting decay by both fungi.     

不同处理方法对杨树木材压缩变形恢复率的研究

采用加热和水蒸气处理方法对人工林杨树木材进行压缩变形恢复率的研究,目的是为了改善人工林软质木材的材性,提高其尺寸稳定性。结果表明:加热和水蒸气处理都是固定人工林木材压缩变形的有效方法;在处理温度相同时,水蒸气处理方法只需要4 min或8 min,而高温加热处理需要10 h或20 h。水蒸气处理方法更加经济。     

杨木应拉木微区结构可视化及化学成分分析

木材微区结构与木材宏观性质密切相关,杨木应拉木与对应木宏观性质存在较大差别,探究杨木应拉木和对应木微区结构和化学成分,可为了解杨木应力木的宏观性质提供理论根据。借助光学显微镜、荧光显微镜、显微拉曼成像光谱仪、透射电镜对杨木应拉木微区结构进行可视化研究,并借助X射线衍射技术和美国可再生能源实验室方法,分析杨木应拉木的微晶尺寸、结晶度以及化学成分。结果表明:杨木应拉木中应拉区和对应区纤维细胞微区结构差异显著。光学显微镜下显示应拉区木纤维中胶质层清晰可见,荧光显微镜和拉曼显微镜下显示胶质层的木质素浓度比对应区低。透射电镜下显示应拉区木纤维细胞壁结构由初生壁、次生壁和胶质层组成,未见次生壁外层,各层的平均厚度分别为0.61,1.22和2.53μm。对应区木纤维为典型的初生壁和次生壁结构,次生壁各层平均厚度分别为0.33,2.28和0.14μm。杨木应拉区纤维素含量(58.91%)比对应区(41.53%)高,木质素含量和半纤维素含量均比对应区的低,应拉区木质素和半纤维素含量分别为21.99%和12.01%,对应区分别为28.10%和17.08%。杨木应拉区结晶度(48.06%)比对应区(41.01%)高,应拉区晶区宽度为2.66 nm,长度为8.84 nm;对应区晶区宽度为2.65 nm,长度为9.87 nm。     

杨木应拉木在有机溶剂置换过程中的形变研究

对杨木应拉木和正常木试样在有机溶剂置换过程中的纵向和弦向形变进行测定,并从细胞壁水平对应拉木在有机溶剂中的形变机理进行了探讨。研究结果表明:在弦向上,正常木和应拉木在弦向上均发生润胀,在70%浓度附近,试样的润胀量达到最大,随后随着浓度增加,润胀量有所回落。纵向上,正常木在溶剂置换过程中发生润胀,而应拉木依置换溶剂的极性差异产生不同程度的收缩。有机溶剂置换过程中,应拉木中残余应力释放是应拉木产生纵向收缩的主要原因。     

PF树脂改性速生杨木浸注性分布规律研究

采用低分子量酚醛树脂对速生杨木进行增强浸注,改性后统计分析改性材的质量增加率情况,以了解浸注性的分布规律。结果表明:速生杨木改性后质量增加率的数据整齐,集中在平均数附近。经过假设并检验后得出,速生杨木改性材质量增加率服从均值为41.87%、总体标准差σ为0.069 0的正态分布;并由此计算出速生杨木改性后,质量增加率落在参考区间为35%～55%的概率值。     

刀具角度对杨木刨片和刨花板性能的影响

以不同角度刀具切制杨木刨片,并制成大片刨花板,对刨片的流变和强度性能及刨花板性能进行了测定和研究。主要结果是:(1)采用较大前角刀具所切出的刨片的流变和强度性能较好,刨花板平面抗拉强度有显著提高,抗弯强度亦有改善;(2)微斜面可在不显著影响刨片和刨花板性能的条件下增强刀刃,为进一步采用更大的前角提供了可能性。     

Identification of transgenes from wood of genetically transformed poplar trees

We have extracted total DNA from different fractions of fresh wood as well as from cold-stored and air-dried wood harvested from transgenic aspen grown in the field. The highest amounts of DNA were obtained from bark/cambium tissue; the DNA quality, however, was poor. Best results in PCR and Southern blot analyses were obtained from DNA extracted from early wood. Using appropriate primer pairs, amplification products were obtained from both the foreign gene (transgene) and aspen genomic sequences. In Southern blot analyses transgene-specific hybridisation signals were obtained. This is the first report on the detection of foreign genes in wood sampled from genetically modified trees.     

北美鹅掌楸漂白药剂的选择

采用几种常见的氧化型和还原型漂白剂对变色北美鹅掌楸木材进行漂白试验,对漂后试材进行目测观察及测色仪测定色度指数比较其漂白效果.试验结果表明,对于北美鹅掌楸木材的一般漂白,氧化型漂白剂优于还原型漂白剂.在考虑环保和对材面纤维的影响等因素的条件下,低浓度过氧化氢对漂白对象有很好的漂白效果,较佳的工艺条件为:H2O2质量分数6％,pH值为9,5 ～10.0,Na2SiO3质量分数0.4％,温度70℃,时间60～ 90 min.     

杨木粉末温压成形本构方程的构建

为探寻木质粉末在温压成形过程中的"应力-应变"关系,基于杨木废单板制备的杨木粉末的温压成形实验数据,以川北公式为模型,借助模拟退火优化算法反演模型参数,构建杨木粉末温压成形本构方程。结果表明:构建的本构方程精度较高,本构模型的模拟结果与试验结果高度重合,可作为木质粉末温压成形机理分析及失效成因理论判据。