木材干燥皱缩机理及其特性研究

本文从理论上探讨了木材干燥皱缩的机理．并通过对红柳桉和多枝桉进行干缩性试验，阐述了木材干燥皱缩的特征、特性及其影响因子．揭示了木材干燥皱缩受外界环境影响的规律，对在生产中克服和防止木材干燥皱缩有一定的参考价值．     

木材皱缩评价指标的研究

近年来 ,国内外学者对木材皱缩缺陷开始关注 ,澳大利亚学者Ｔ .ＣＩｎｎｅｓ( 1 995,1 996)、中国学者王喜明 ( 1 989)、刘　元 ( 1 994)等分别研究了澳大利亚产桉木如多枝桉、细叶桉和赤杨、山杨等木材的干燥皱缩缺陷。他们从调湿处理对皱缩的作用 ;皱缩材组织结构的变化 ;皱缩机理 ;皱缩极限温度 ;预冻处理对皱缩的作用等方面做了大量深入而细致的工作。所取得的成果公开发表后得到同行学者的认可 ,对进一步研究避免皱缩的干燥工艺打下了较好的基础。但在众多有关木材皱缩的研究报告中 ,普遍遇到一个同样的问题就是如何定量地去评价和测量…     

热处理对桉材皱缩的作用

多枝桉、细叶桉、赤桉采用恒温调湿干燥法测绘含水率－收缩曲线，探求热处理对改善桉材皱缩的效果。结果多枝桉、细叶桉是否热处理均具典型的“皱缩”型含水率－收缩曲线，但热处理材少有“二段”皱缩，“肩点”处收缩率和全收缩率比未热处理材小，处理效果明显；赤桉则无区别。同时，论述了“皱缩”型曲线出现“肩点”的必然性；提出了“二阶段”皱缩理论；并对寺尺＾［１］等的“导管二次皱缩”论的局部性进行了探讨。     

桉属16种木材的比较解剖学研究

本文研究了桉属(Eucalyptus L'Her.)16种木材的显微结构。导管是从小到大变化的。最大弦径从栓皮桉的78μm 到巨桉的195μm。导管分子的平均长度从纤脉桉、梅县薄皮桉和合浦薄皮桉的0.26mm 到萄萄桉和伞房花桉的0.46mm。每平方毫米导管数目2到10。大部分导管都是单管孔,而且不同程度地排成斜向列。侵填体大都缺少,有的种丰富。桉树胶滴一般是缺少的,只有少数种中比较普遍。穿孔板均为单穿孔,并且主要是水平的。管间纹孔大部分是粗糙的,具缘的,附物的。轴向薄壁组织有傍管的和离管的两种类型。傍管的从少数与导管连接的如蓝桉很少,到广叶桉、巨桉中有丰富的环管状的。离管的在许多种中是罕见的,在另一些种中是星散的。在横切面上,每毫米射线的数目平均7到10根。在大部分种中,射线是由单列到2列,少数种中有3列的。多列部分最大局度最多达10个细胞。射线是弱的异形细胞射线,边缘的1到几列横卧细胞在垂直方向上比中间的细胞大。桉树胶滴一般比较丰富,有的聚集在中间的横卧细胞中。导管射线间纹孔是大的,半具缘的,具有圆的到椭圆的纹孔口。纤维平均长度的变化从锥果桉的0.68mm 到四川产的大叶桉的0.92mm。直径从广东产的大叶桉的9μm 到赤桉的16μm。纤维是不分隔的,在弦向和径向两个方向上一般都有具缘纹孔。纤维壁的厚度与腔的直径有关。纤维的壁一般是中等厚度到厚壁的,偶然也有薄壁的。在所有种中都有环管管胞,从稀少到丰富。产于我国广东和四川的与产于澳洲的同种相比木材组成分子一般略小些这可能与生态环境有关。     

热水处理对王桉木材干缩率和皱缩的影响

研究了热水处理的温度和时间对王桉（Eucalyptus regnans）木材全干干缩率和皱缩的影响。结果表明：随着处理温度的升高,王桉木材的全干干缩率呈增大的趋势,70℃和80℃时,处理时间对王桉木材的各向干缩率的影响不大;90℃和100℃时,处理时间对王桉木材的各向干缩率影响明显。经100℃热水处理6 h后王桉木材体积、弦向和径向全干干缩率分别增大了78.3%、116.1%和44.4%,分别达到25.5%,18.8%,7.8%。王桉木材的皱缩深度随处理温度的升高显著增大,处理时间对王桉皱缩深度的影响不明显。     

按树木材干燥特性与工艺及其皱缩研究现状

本文回顾和分析了桉树木材与干燥有关的材性和干燥特性，指出按木的密度、含水率和干缩率变异性大、渗透性差，在干燥过程中易产生皱缩、开裂等干燥缺陷，若采用预冻处理和前后期调温处理可减少木材的皱缩；同时建议研究各种桉木不同规格板材的干燥基准和两段式干燥工艺。     

17种樟属树种木材比较解剖研究

利用光学显微镜和扫描电子显微镜 ,对国产樟属 17种木材结构进行了观察。结果如下 :管孔排列为散孔材和半环孔材 ;较高的单管孔率 ;具有梯状穿孔和单穿孔两种类型 ,管间纹孔式主要为互列 ,少数种具对列。单列射线稀少、细而短 ,多列射线量多 ,形状差异较大 ;射线组织以异形Ⅲ和ⅡB型为主 ,射线 -导管间纹孔式主要为刻痕状。轴向薄壁组织以稀疏傍管状和星散状为主 ,部分种具环管束状、翼状 ,数量差异较大。樟属所有木材的射线或轴向薄壁组织中含油细胞或粘液细胞。木材的上述特征表明 ,樟属木材内部结构具有明显差异 ,并可作为种级分类依据。另外 ,根据木材结构的显著差异 ,建议光叶桂和细叶香桂按两个种处理。     

微波改性木材的超微观察

对微波改性处理后的杨木和水曲柳进行超微观察发现，处理后木材的纹孔膜破裂，导管内的侵填成分明显减少并重新分布。     

樟科1O属14种木材解剖学特征的比较研究

利用光学显微镜和扫描电子显微镜,对樟科10属14种木材结构进行观察。结果表明：除檫木外,其它木材的管孔分布均为散孔材,具较高的单孔率;导管分子穿孔板兼有单穿孔和梯状穿孔2种或者仅具有单穿孔;导管间纹孔式为互列;导管-射线间纹孔式类型丰富,主要为刻痕状和大圆状。木射线有单列和多列射线2种类型,单列射线稀少、短,多列射线数量多;射线组织主要为异形Ⅲ和异形Ⅱ;轴向薄壁组织以傍管状为主,少数有带状或轮界状。油细胞和粘液细胞普遍存在于射线薄壁细胞或轴向薄壁细胞中。木纤维由韧性纤维和纤维管胞组成,部分树种具分隔纤维。从樟科木材结构特征与系统演化关系看出：樟科木材结构表现为过渡型,即不完全低级,也不完全进化。     

樟科10属14种木材解剖学特征的比较研究

利用光学显微镜和扫描电子显微镜,对樟科10属14种木材结构进行观察.结果表明:除檫木外,其它木材的管孔分布均为散孔材,具较高的单孔率;导管分子穿孔板兼有单穿孔和梯状穿孔2种或者仅具有单穿孔;导管间纹孔式为互列;导管-射线间纹孔式类型丰富,主要为刻痕状和大圆状.木射线有单列和多列射线2种类型,单列射线稀少、短,多列射线数量多;射线组织主要为异形Ⅲ和异形Ⅱ;轴向薄壁组织以傍管状为主,少数有带状或轮界状.油细胞和粘液细胞普遍存在于射线薄壁细胞或轴向薄肇细胞中.木纤维由韧性纤维和纤维管胞组成,部分树种具分隔纤维.从樟科木材结构特征与系统演化关系看出:樟科木材结构表现为过渡型,即不完全低级,也不完全进化.     

桉树木材干燥特性与工艺及其皱缩研究现状

本文回顾和分析了桉树木材与干燥有关的材性和干燥特性 ,指出桉木的密度、含水率和干缩率变异性大、渗透性差 ,在干燥过程中易产生皱缩、开裂等干燥缺陷 ,若采用预冻处理和前后期调湿处理可减少木材的皱缩 ;同时建议研究各种桉木不同规格板材的干燥基准和两段式干燥工艺     

赤桉材干燥皱缩的热处理调控

以人工林赤桉材为研究对象,根据皱缩评价指标对比研究了热水浸泡和汽蒸预处理对皱缩发生程度的影响,以及干燥中的热处理对皱缩回复的影响。研究表明：包括4 h常压预汽蒸处理和80℃热水处理在内的预热处理可以有效地预防皱缩;在板材平均含水率18%时进行3 h的汽蒸处理可以有效回复皱缩材。     

Evaluation of Strength Performance of Finger-jointed Lumbers Using Three Kinds of Nondestructive Techniques

Resonance flexural vibration（Fast Fourier Transform, FFT）, ultrasonic wave（Pundit） and stress wave（Metriguard） techniques were examined as means of evaluating the static modulus of elasticity （MOE） and predicting the modulus of rupture （MOR） of finger-jointed lumber specimens made with four kinds of Eucalyptus （Eucalyptus. citriodora, E. exserta, E. grandis x E. urophylla and E. grandis）. Dynamic MOE was calculated from frequency and time obtained from forced vibrations and sounds induced in the four species of finger-jointed specimens. It was found that correlation coefficients between density and static MOE and dynamic MOE were statistically significant at the 0.01 level. And it was also found that the three nondestructive techniques can provide rapid and accurate means to determine the MOE, and the dynamic MOE was more accurate to predict static MOE than density. But the correlation coefficient between dynamic MOE, static MOE and MOR were lower than results reported by other researchers for solid wood, and were not statistically significant. It can be concluded that the three nondestructive techniques are useful for evaluating the MOE, but not suitable for predicting the MOR of finger-jointed.     

马占相思木干燥工艺的研究

马占相思属速生树种,其人工林木材径级小,幼龄材含量高,易干燥,但容易产生皱缩及内裂,宜采用低温软基准,且干燥过程中要增加调湿处理次数,减少表层的干燥应力及塑性变形,采用气干和窑干联合干燥方式时,不仅有效避免皱缩及内裂等干燥缺陷,而且可缩短干燥时间,减少能源消耗,降低干燥成本。     

Mechanical behaviour of Eucalyptus wood modified by heat

Summary  Eucalyptus wood (Blue gum) shows very high mechanical performances, presents very few knots and gives strong glued joints, reasons that justify its interest for structural uses, carpentry and furniture components or even building construction. The inconveniences of this species are its slow and difficult drying process and its low dimensional stability – with very high swelling and shrinkage coefficients. The drying process has been studied at INETI and the problem revealed to be solved with appropriate drying schedules and the stresses released by a steam treatment. Heat treatment of Eucalyptus wood has been identified as one of the most promising techniques to increase its dimensional stability. Studies in this area still proceed. This paper presents some test results that show the influence of heat treatment in the strength properties of this wood, namely the bending modulus of elasticity and tensile strength perpendicular to grain, in addition to the explanation of dimensional stability evaluation and some results of dimensional stability treatments. Received 15 June 1998     

吴钰琳尾巨桉废料的白背毛木耳栽培技术

通过专业调查,发现尾巨桉是栽培白背毛木耳的好原料之一,据此介绍尾巨桉栽培白背毛木耳的菌种、生产工艺流程、栽培关键技术。分析认为：利用尾巨桉锯末、边角料种植白背毛木耳,既开辟了桉树新用途,又改善了工厂卫生环境;而种植白背毛木耳的废料,又可用作育苗轻型基质、有机肥等,是循环经济的一种好的利用模式。     

Characterization of viscoelastic,shrinkage and transverse anatomy properties of four Australian hardwood species

Abstract

Several key wood properties of four Australian hardwood species: Corymbia citriodora, Eucalyptus pilularis, Eucalyptus marginata and Eucalyptus obliqua, were characterized using state-of-the-art equipment at AgroParisTech, ENGREF, France. The wood properties were measured for input into microscopic (cellular level) and macroscopic (board level) vacuum-drying models currently under development. Morphological characterization was completed using a combination of environmental scanning electron microscopy and image analysis software. A clear difference in fibre porosity, size, wall thickness and orientation was evident between species. Viscoelastic properties were measured in the tangential and radial directions using dynamic mechanical analysis instrumentation. The glass transition temperature was markedly different for each species owing to anatomical and chemical variations. The radial direction showed higher stiffness, internal friction and glass transition temperature than the tangential direction. A highly sensitive microbalance and laser technology were used to measure loss of moisture content in conjunction with directional shrinkage on microsamples. Collapse shrinkage was clearly evident with this method for E. obliqua, but not with other species, consistent with industrial seasoning experience. To characterize the wood–water relations of E. obliqua, free of collapse, thinner sample sections (in the radial–tangential plane) are recommended.     

小径巨尾桉干燥特性与干燥工艺

通过百度试验法研究小径巨尾桉(Eucalyptus grandis×E. urophylla)的干燥特性,制定巨尾桉材干燥基准,进行干燥工艺优化试验.结果表明:小径巨尾桉材初期开裂等级为3级,内裂等级为2级,截面变形等级为5级,属中等难干材;采用制定的巨尾桉材干燥基准,试件从初含水率115.13%降至8.50%的干燥周期为16.3 d,除瓦弯变形外,其他可见干燥缺陷指标均达到国家标准GB/T 6491—2012 《锯材干燥质量》规定的一级要求.     

Drying Characteristics and Drying Schedule Establishment of Eucalyptus pellita Wood

The key problems of preparing water-based nano TiO₂ wood preservatives are the particle’s agglomeration and dispersion.The influences of adding titanate NDZ-105 and sodium hexamet aphosphate on transmittance,effects of dispersion modification on crystal type,distribution and interface characteristics of modified TiO₂ in wood were studied by photometric,XRD,SEM and FTIR analysis,respectively.The results show that the dispersion of nano TiO₂ suspension firstly increased, then decreased as the amount of the two kinds of dispersed agent increased,when addition amount of titanate N DZ-105,six partial sodium were separately 5%and 3%-5%,the nano TiO₂ wood preservatives were obtained that their dispersive property were stabilized.After dispersion modification,the TiO₂ maintained the crystal diffraction characteristics of anatase;the nano TiO₂ distributed in wood successfully,showing a granule or ball-shaped,and the hydrogen bond and covalent bond were combined between wood and nano-TiO₂,but only hydrogen bond was combined between wood cellulose and IPBC.