热处理改性木材的性能分析Ⅴ——热处理木材的尺寸稳定性能

对南方松、桦木的热处理材,化学改性处理材和ACQ防腐处理材,进行木材尺寸稳定性测试.结果表明:热处理木材的吸湿率和体积膨胀(收缩)率均有较大程度的下降,尺寸稳定性得到明显的改善.     

热处理改性木材的性能分析Ⅳ——热处理木材的防白蚁性能

对南方松、樟子松、水曲柳、柞木、斯文漆木五种木材的热处理材,进行室内防白蚁性能检测和评价.结果表明:5种热处理试材的防白蚁蛀蚀等级均在3～4级,热处理工艺未能改善试材的抗白蚁蛀蚀性.     

思茅松热处理木材的研究

热处理对于提高木材的尺寸稳定性和耐久性、抵抗生物破坏等性能来说是一种非常有效的方法。作者采用油浴法对思茅松木材进行热处理工艺的探讨,分别对热处理木材的失重率、吸湿率、线性胀缩率、以及微观构造等进行了分析,研究结果表明：（1）思茅松热处理材随着处理温度和处理时间的增加,失重率逐渐增加;（2）思茅松热处理材随着处理温度和处理时间的增加,吸湿率逐渐降低;（3）思茅松热处理材随着处理温度和处理时间的增加,线性胀缩率逐渐降低;（4）在微观构造观察方面,由于早材腔大壁薄,材质较松软,经过热处理后早材部分容易引起径向开裂,早材管胞形态的变形程度要比晚材要大,早材轴向管胞壁的弯曲变形较晚材的要严重。随着热处理温度升高,热处理时间的延长,炭化程度越来越严重,为不使木材物理力学以及微观构造方面遭到严重破坏,建议木材热处理温度为160℃、热处理时间为6～12h或木材热处理温度为180℃、热处理时间为6～8h为宜。     

圆盘豆热处理材光稳定性的研究

采用热处理和氙灯照射对圆盘豆木材颜色的变化进行研究,以CIE(1976)L*a*b*表色系统表色,分析木材热处理前后、氙灯照射前后颜色变化。结果表明,热处理后木材颜色加深。随着氙灯照射时间延长,未处理材表面颜色逐渐加深,色差△E*逐渐增大。热处理材表面颜色变化不大,色差△E*值变化较小,这表明与未处理材相比,热处理材光稳定性能更好。     

马尾松热处理木材的表面特性研究

以马尾松（Pinus massoniana）为研究对象,分别在 180, 200, 220 ℃条件下对其进行水蒸气 热处理 1, 3, 5 h。借助干燥器法测试不同温度热处理材的甲醛吸附量变化,利用程序升温化学吸附法、 比表面积测试以及表面接触角方法探索不同温度处理的热处理材表面特性的变化规律。结果表明：与未 热处理的素材相比,（1）热处理后的木材甲醛吸附性能得到改善,经 180 ℃、 1 h 处理后的木材甲醛吸附 性能最好,且随处理温度升高、时间延长,甲醛吸附性能降低,总体呈降低趋势;（2）热处理木材对甲 醛的吸附不仅是物理吸附,还存在化学吸附;（3）不同温度处理后,木材的比表面积均减小;（4）经热 处理后,极性的蒸馏水在木材表面的接触角较素材大且热处理的温度越高、表面接触角越大,而非极性 的二碘甲烷在其表面的接触角变化趋势相反。     

二氧化硅联合热处理改性对橡胶木性能的影响

为弥补热处理材的力学性能损失,利用二氧化硅联合热处理改性橡胶木。在热处理橡胶木前后分别真空浸渍二氧化硅前躯体溶液,热处理温度200℃,保温时间2 h。对未处理材、热处理材、浸渍-热处理材与热处理-浸渍材的力学性能、尺寸稳定性以及热稳定性进行对比分析。结果表明,与热处理材相比,浸渍-热处理材与热处理-浸渍材的抗弯强度分别提高28.97%和18.88%,抗压强度分别提高26.65%和38.91%。与未处理材相比,热处理材、浸渍-热处理材和热处理-浸渍材的吸水性与湿胀性均有所降低。热重分析表明,浸渍热处理材的热降解速率低于热处理材,说明二氧化硅与木材的结合阻碍了热分解以及木质基的完全裂解,木材的热稳定性有所提高。红外光谱分析显示,浸渍-热处理材上出现了Si—O—Si特征峰,说明木材内部有二氧化硅生成。X射线衍射分析结果表明,木材的纤维素衍射峰位置无变化,说明浸渍二氧化硅处理未破坏纤维素的结晶结构。     

压力蒸汽热处理木材生物耐久性的研究

通过对樟子松和柞木分别在常压和压力蒸汽下进行高温热处理,比较了两种热处理材与常规对照材生物耐久性的差异。结果表明,高温热处理特别是压力蒸汽处理,可以更显著地改善木材的耐腐性,耐腐等级可由对照材的Ⅳ级(不耐腐),提高为Ⅰ级(强耐腐,樟子松)和Ⅱ级(耐腐,柞木)。热处理可以有效减轻蓝变菌对木材的侵害,但不能防止或减轻木材表面的霉变。在热处理材表面涂刷油性防水涂料,是防止表面生霉的很有效的方法。     

桉树真空热处理材表面性能分析

用真空热处理法对粗皮桉木材进行热处理,处理温度分别为160,180,200,220及240℃,处理时间均为4 h.采用接触角测定法,对素材及不同温度条件下热处理材的接触角及表面自由能进行分析;用傅里叶红外光谱分析法,研究木材在热处理过程中的化学(官能团)变化;用热分析仪分析不同温度条件下木材的热解质量损失率.结果表明:素材的表面自由能(50 mN·m-1)<160℃热处理材的表面自由能(46 mN·m-1)<240℃热处理材的表面自由能(32 mN·m-1).热处理后木材中极性的羰基官能团减少,当热处理温度≤180℃时,木材的质量损失率在1%左右;而热处理温度>180 ℃时,每升高20℃,木材的质量损失率约下降2倍.     

高温热处理木材胶合性能的研究

笔者研究了桦木、落叶松和樟子松高温热处理材的胶合性能,并与常规干燥材进行了对比。测试结果表明木材的胶合剪切强度与所用的胶黏剂有关,聚氨酯胶合的三个树种木材的剪切强度普遍大于白乳胶胶合的木材。无论是室内用的白乳胶或室外木结构用的聚氨酯胶都能与三个树种的高温热处理材很好地胶合,胶合试件的浸渍剥离率或煮沸剥离率皆为零。木材经高温热处理后,其剪切强度均有不同程度的降低,阔叶材桦木下降幅度最大,针叶材落叶松下降幅度最小。     

马尾松木材热处理研究

采用单因素试验方法对马尾松木材进行热处理研究,选用温度和时间两个因素,比较了热处理和未处理马尾松木材的物理力学性质、色差和甲醛吸收率等性能。研究认为:热处理材的颜色随着热处理温度的升高和热处理时间的增加而变黑,并且热处理温度对热处理材的影响比热处理时间的影响要大。低温热处理时生产的热处理材的湿胀率比高温热处理生产的热处理材的湿胀率高,尺寸稳定性差。热处理材的静曲强度MOR和弹性模量MOE随着热处理温度和热处理时间的增加而降低。顺纹抗压强度变化较小。热处理材对甲醛有明显的吸收作用,是用于室内装饰的良好环保型材料。     

Increase in the content of low-molecular carbohydrates at lumber surfaces during drying and correlations with nitrogen content,yellowing and mould growth

Summary In this study a quantitative analysis of the low molecular carbohydrates (predominantly sucrose, fructose and glucose) in a series of lumber samples of Pinus sylvestris and Picea abies taken at various distances from the surface has been made. The increase of nitrogenous compounds towards the surface had been shown in a previous study. Several of the lumber samples showed a marked sugar accumulation at the surface, which correlated quite well with a corresponding nitrogen accumulation. In one case, the total amount of the three sugars was as high as 4.9% of the dry matter content in the 0–1 mm layer. It was of special interest to note that samples with high nitrogen and sugar contents also had a yellow surface colour, which probably formed during the drying process by the well-known Maillard reaction — a complex of reactions occurring when sugars and amino acids, peptides and proteins are heat-treated together. Growth of the mould fungus Penicillium brevicompactum was well correlated with the content of nitrogen and low molecular carbohydrates in adjacent samples. The initial colonization was somewhat delayed in material from the outermost sapwood zone despite high nutrient contents indicating effects of antifungal compounds from the bark or toxic Maillard reaction products effective against germination. Growth of Aspergillus versicolor was likewise most elaborate on samples with the highest nitrogen and soluble carbohydrate content but the results also indicate a sensitivity to antifungal compounds present.The authors thank Mrs. Gunnel Fransson for skillful technical assistence     

山毛榉热处理材的介电式含水率仪读数校正实验

采用介电式含水率仪对山毛榉常规干燥材及热处理材的含水率进行了测量,并与烘干法测量结果进行了对比分析,采用最小二乘法,分别拟合出了180℃、195℃和210℃山毛榉热处理材的校正曲线。180℃、195℃和210℃山毛榉热处理材的介电式含水率仪校正曲线分别为, y＝1.2923 x＋0.2783, y＝1.3920 x＋0.7473, y＝1.6445 x＋1.4892。结果表明,常规干燥材的电测法结果能很好地反映其实际含水率水平,而热处理材的电测法结果则普遍大于烘干法,3种热处理材均呈现出随含水率的增高,差值随之增大的趋势,且随着处理温度的升高,差值愈大。     

杉木生材含水率分布及其对气干的影响

以人工林杉木为研究对象,研究生材状态下不同厚度锯材含水率的差异,比较含髓心、钝棱与其他类型等3类锯材的含水率差异,建立生长轮宽度与锯材含水率的关系,分析生材状态含水率对锯材气干周期的影响。研究结果显示,25mm和40 mm的锯材含水率差异极显著;含髓心锯材含水率最低,其次是其他类的,最大是含钝棱锯材;随着生长轮宽度减少,锯材含水率增大;生长轮宽度为4 mm时,是生材含水率分界线,即当生长轮平均宽度小于和不小于4.0 mm时,锯材含水率差异极显著;25 mm和40 mm厚不同含水率锯材各2组气干至含水率25%,低含水率锯材较高含水率的气干周期分别缩短57%和66%。     

Effect of high temperature heat treatment on pH value of Masson Pine wood

Heat-treated wood has good dimensional stability,corrosion resistance and visual quality,but it is prone to mold,which limits its application.Based on the pH value of heat-treated wood,this study examines the factors affecting the pathogenesis causing heat-treated wood mold.Normally,the pH value of the heat-treated wood is between 4.38 and 5.10,which is suitable for the growth of mold.However,the pH of the heat-treated copper-containing material is between 6.63 and 7.12,which deviates the treated wood from the comfortable growth conditions for the mold,thereby reducing the occurrence of mold.     

Effect of high temperature heat treatment on pH value of Masson Pine wood

Heat-treated wood has good dimensional stability, corrosion resistance and visual quality, but it is prone to mold, which limits its application. Based on the pH value of heat-treated wood, this study examines the factors affecting the pathogenesis causing heat-treated wood mold. Normally, the pH value of the heat-treated wood is between 4.38 and 5.10, which is suitable for the growth of mold. However, the pH of the heat-treated copper-containing material is between 6.63 and 7.12, which deviates the treated wood from the comfortable growth conditions for the mold, thereby reducing the occurrence of mold.     

杉木热处理材结晶度及力学性能的研究

热处理对木材力学性能的影响是多样的,这与热处理条件下木材的物理化学变化密切相关。本次研究将杉木板材在160℃、180℃和220℃常压蒸汽条件下进行热处理,考察处理材的结晶度、抗弯弹性模量、抗弯强度及相互可能的关联。结果表明,热处理使试材结晶度增加,有助于提高木材的刚性,使热处理材的抗弯弹性模量高于常规对照材;结晶度的提高对抗弯强度没有改善作用,热处理后试材的抗弯强度明显下降。     

竹重组材的X射线光电子能谱分析

应用X射线光电子能谱分析(XPS)的技术手段,以冷压热固化与热压法两种生产模式的竹重组材为研究对象,分析其竹材表面元素组成及相对含量的变化。试验结果表明,冷、热压法竹重组材表面的C、O及相对含量有明显差异。从C原子结合形式来看,冷压法与热压法相比,冷压法竹重组材CA(-C-C或-C-H)含量增加明显,CB(C-O或C-OH)含量减少明显,CC(C=O)含量减少,CD(O-C=O)变化不大。说明竹材纤维素、半纤维素、木素,以及抽提物含量等化学组分出现不同程度的变化,进而影响二类竹重组材产品的物理力学性能。     

Changes of major chemical components in larch wood through combined treatment of drying and heat treatment using superheated steam

The effects of the combined treatment of drying and heat treatment using superheated steam (SHS) were studied relative to the changes of the major chemical components in larch wood. The green lumber was dried and heat-treated in SHS conditions of 250 °C and 0.5 MPa for 18 h, and the relative percentage contents of sugars, lignin, and extractives were investigated and compared with the relative percentage contents in the lumber heat-treated in hot air conditions of 250 °C and atmospheric pressure for 18 h. After both heat treatment methods, the relative percentage contents of xylan, mannan, galactan, and arabinan were greatly decreased, whereas that of the Klason lignin was increased, additionally that of glucan and extractives remained almost unchanged. Lignin may bind with furan compounds decomposed from hemicellulose following heat treatment, thus contributing to the increase in the apparent relative percentage contents of the Klason lignin. In addition, the condensate collected in the condenser after combined drying and heat treatment using SHS was investigated qualitatively and quantitatively by high-performance liquid chromatography (HPLC). A large amount of furfural and acetic acid decomposed from hemicellulose was detected and some sugar components composed of cellulose and hemicellulose were detected in the liquid condensate.     

木材超高温热处理技术的研究及应用进展

从研究背景、生产工艺及应用前景等方面,介绍木材超高温热处理技术在国外的发展、应用及研究状况.资料表明,木材经热处理改性后,尺寸稳定性增强、平衡含水率降低,且耐候性及抗生物降解能力增强.此技术的研究及应用,对扩大人工林木材的加工利用可起到积极的促进作用.     

樟子松生材的防霉防变色处理

近年来我国从俄罗斯进口大量樟子松木材，因新采伐的樟子松原木和湿锯材极易被霉菌和变色茵感染，在温暖潮湿季节引起边材严重变色而降等。为有效防止霉菌和变色茵的侵害，采用TBQ木材防腐剂对其进行防霉、防变色处理试验。结果表明：将湿锯材样品在6％TBQ溶液中浸泡1h后，其防霉、防变色效果可达到98％．说明TBQ木材防腐剂有良好的防霉、防变色效果。建议在木材产区或进口口岸制材并就地进行防霉、防蓝变处理后再运往国内市场。