阔叶树小径材热压干燥工艺的研究

通过对荷木和米槠两种华南地区常用阔叶树小径材薄板材热压干燥工艺的研究，探讨热压干燥工艺参数对小径材板材干燥质量（包括密度，厚度压缩率，尺寸稳定性及部分力学性能）的影响，试验结果表明，热压干燥工艺可以大大改善小径材的物理力学性能。     

桦木,柞木小径材刨切薄板热压干燥的研究

对桦木、柞木两树种小径材刨切薄板（２１３ｍｍ×７０ｍｍ×４ｍｍ）热压干燥工艺的研究,着重探讨了：（１）热压干燥对桦木、柞木小径材刨切薄板翘曲度的影响;（２）热压干燥工艺参数及其交互作用与板片终含水率及厚度压缩率的关系,建立多元线性回归方程;（３）通过电镜分析,确定桦木、柞木小径材刨切薄板的优化干燥工艺条件。     

马尾松速生材热压干燥的初步研究

1研究的意义马尾松速生材都来源于人工林，它的生长速度较快，但它的材性和非速生林马尾松木材相比有显著的差异，在干燥过程中易产生各种各样的干燥缺陷，如翘曲、开裂等。由于其表面硬度低、密度小物理力学性能差，在应用上也受到较大的制约。作者试图采用热压干燥的方法，在减少翘曲变形的同时适当地增加马尾松板材的密度和表面硬度，使干燥后的木材能达到一般工业和生活用材的要求。2试验材料双方法2．1试验材料马尾松（Pinusmass0niana）速生材试材取自安徽省马鞍山市濮塘林场，原木直径为15cm，试验时测得木材的平均初含水率为76％，…     

杨树,河柳速生材干燥技术的研究

为解决我国木材资源的不足，近年来对森林资源的利用正在迅速地向速生短轮伐期木材及间伐小径材等方面开拓。由于对速生材的材性及加工技术研究起步较晚，以往在利用上仅限于人造板及造纸原料。木材干燥是合理利用木材的基础，是保证木制品质量的关键，也是速生材能否取代传统商品材的一个重要技术因素，对速生材的利用将起积极的推动作用。我省速生树种中杨树、河柳占很大比例，杨树中黑杨、青杨居多，此外还普遍分布着泡桐、水杉等树种。由于多数速生材心边材含水率差异大，成材快速干燥时易产生翘曲、皱缩等缺陷，从而影响了它们的直接加…     

小径木速生材薄板层积胶合门窗的研制

采用速生意杨的旋切单板、锯制薄板和三层胶合板边条为原料，利用脲醛胶热压制成门窗的框和扇，并对其层积胶合工艺进行了研究。研究结果表明：采用对接结构和热压工艺，将小径木速生材薄板一次性层积胶合为成型门窗，可以克服实木门窗易吸湿变形和因开棒打眼造成强度降低的缺点，并且工艺简单易行，能综合利用小径木和速生材。     

短周期工业材干燥工艺试验

对８种短周期材进行了干燥基准优化试验,并最终确定了８种短周期材的干燥工艺。结果表明,这些基准是可行的,干燥质量检测指标结果均达到国家标准规定的一级锯材干燥质量要求。     

核桃楸小径材干燥工艺的研究

从探索小径材的材性入手,着重研究了核桃楸小径材的干燥工艺,制定了干燥基准。探讨了介质温度对端裂的影响。试验结果表明,核桃揪小径材在干燥过程中容易发生弯曲和端裂,主要是因为核桃楸小径材多居未成熟材,材质不稳定,髓心脱落等。     

马尾松速生材的表面强化工艺研究

对马尾松速生材汽蒸预处理后,热压干燥至一定的中间含水率,再用不同的树脂进行表面强化改性处理.考虑到汽蒸处理时间、热压温度、压力、涂胶前木材的含水率、胶的种类、涂胶量对木材的横纹抗压强度(全部)、表面硬度及耐磨性等质量指标有不同的影响,分别以它们为单一质量评价指标进行分析,最后综合各因素评选出了相应的最佳工艺.     

紫椴小径材高温干燥工艺的研究

为了合理开发利用紫椴小径材,对其材性进行了研究,进而解决干燥工艺,提高干燥质量。通过研究小径材的构造和物理力学性能,并和成材作比较,研制高温干燥基准,提高紫椴小径材的干燥合格率。一、试材、试验设备及方法试材采自黑龙江省尚志县东北林业大学帽儿山林场,条件见表1。试验设备利用自行研制的间歇式电热真空干燥机,工艺试验共进行三次,每次均对试材进行质量统计,测试试材缺陷。选取5块试验板,3块含水率检验板,包括心材板、边材板、应力检验板各1块。检验板和试验板端头用铝箔纸封涂,检验板每4h称重一次。     

五种福建阔叶树材的干燥特性

本文论述了利用百度试验法,查明福建五种阔叶树材的干燥特性,以进一步制定合理的干燥工艺。实验结果表明:这五种阔叶树材干燥特性差异显著,其中椆木干燥缺陷严重,干燥速度缓慢;润楠及枫香干燥缺陷中等;蓝果树及荷木干燥缺陷程度最轻,枫香干燥速度最快。     

有机/无机复合浸渍液对杨木的改性处理

利用脲醛树脂／丙烯酸酯乳液／硅溶胶三元复合浸渍液制备复合木材,并与杨木素材为对照。采用红外光谱研究复合木材的组成变化,热分析研究其热稳定性的变化,并研究了复合木材的力学性能。结果表明,杨木中的功能基团与复合浸渍液中的脲醛树脂可发生键合作用,使改性木材的热稳定性及力学性能均有所提高。     

End grain water absorption and redistribution in slow-grown and fast-grown Norway spruce (Picea abies (L.) Karst.) heartwood and sapwood

Abstract

Wood is susceptible to decay by rot fungi if it is exposed to high-moisture contents during long periods of time and it is therefore important to limit the duration of such periods. Critical points in outdoor wood structures are, for example, end grain surfaces in joints where water can get trapped after a rain. It is therefore of interest to study both absorption and redistribution of moisture in wood. This paper presents moisture content profiles during end grain water absorption and redistribution in Norway spruce (Picea abies (L.) Karst.) measured by computed tomography with the specimens in individual climate boxes. Heartwood and sapwood of two provenances (slow-grown and fast-grown wood) were included. No major differences were seen between the water uptake of the slow-grown and the fast-grown wood since the densities were similar despite of the large difference in growth ring width. However, for the sapwood specimens, the moisture content was higher further into the specimens than for the heartwood specimens in agreement with previous studies. For the slow-grown wood, the redistribution was also generally more rapid for the sapwood specimens than for the heartwood specimens.     

两种常温固化木材胶粘剂胶接强度分析

对两种木材用常温固化胶粘剂--单宁-甲醛胶粘剂和聚氨酯胶粘剂胶接的速生杨木的静态剪切强度进行了测试与分析.研究结果表明,以速生杨I-72为被胶接对象,自制的双组分型单宁胶压缩剪切强度范围为8.08～8.92MPa,但木破率较低,要满足日本集成材JAS标准中用胶规定,需进一步研究改进.相比较而言,聚氨酯胶粘剂的胶接强度较高,其压缩剪切强度值均在9.8MPa以上,木破率在75%以上,能够满足日本集成材JAS标准中用胶的规定.     

竹材在土木建筑中的应用

我国竹类资源比较丰富，而木材、钢材等建筑材料紧缺的问题将日益突出，在这种形势下，竹材作为一种速生的森林资源，其优越的性能将会越来越引起人们的关注。本文介绍了竹材的一些性质以及原竹在建筑中的应用情况。以竹代木、以竹代钢合理地利用好竹材，不仅能够缓解建筑材料紧缺的形势，而且将会对我国的生态环境起着重要的保护作用。     

Semi-isostatic densification of heat-treated radiata pine

Semi-isostatic densification is a useful method to increase the density and to improve the mechanical properties of fast-grown softwood species like radiata pine. A major disadvantage of this method is the almost complete recovery of the original dimensions when densified wood is exposed to moisture. Heat treatment improves the dimensional stability of wood and might be a useful method to prevent this shape-recovery after densification. However, no or only a limited effect on the shape-recovery was found when densified radiata pine was exposed to moisture.     

High temperature and chemical effects on wood stability

Summary The increasing supplies of fast-grown woods grown on short roations contain significantly higher proportions of juvenile wood with properties different from those of mature wood. Improved processes will be required to produce dried wood that is satisfactorily stable with few distortional or dimensional changes. The basic wood features affecting different forms of instability are considered. Variations in the amounts of cellulose, hemicelluloses and lignins in wood, the changes in them and the degradation products formed under different conditions are discussed. Changes in the nature of hemicelluloses appear to play an important role in conveying stability. The different volumes of heartwood in green timber have an effect on moisture levels and other properties. As industry is increasing kiln temperatures for high-temperature drying, the effect of time-temperature-moisture relationships on stability and degradation are discussed. The effect of ammonia and other chemicals on stability is considered.     

豫东平原杨农间作不同杨树品种生长性状对比研究

杨树是平原地区栽培面积最大、木材产量最高的速生用材树种之一,具有生长快、成材早、产量高的特点,是非常优良的工业用材经营树种。本文通过对民权林场四种速生杨优良性状的对比试验进行比较,得出欧美108杨的优良性状最好,为进一步提高林业经济效益和环境效益提供支持。     

VARIATION OF DENSITY IN STEMS OF DOUGLAS FIR

In a disk from the stem of a very fast-grown Douglas fir (Pseudotsugataxifolia Brit.), 19 years old, with an almost constant ring-widthof about inch, the density of the individual rings was almostconstant from pith to bark and there was no sign of any increaseoutwards such as was found by Turnbull in fast-grown South Africanpines. Similar results were also obtained with more closelygrown material (mean ring-width about 1 1/0 inch). There appearedto be no general relation between density and ring-width, butthe highest densities occurred in rings less than 6 mm. widein the centre of the fast-grown tree and at the outside of atree with access to river water.     

应力波木材无损检测技术应用及研究进展

文中概述了应力波传播机理及应力波木材无损检测技术的优缺点与工作过程,介绍了现阶段木材无损检测领域内常用的几种应力波木材检测设备,对其特点进行了分析,并从力学性能检测、内部缺陷检测和影响应力波传播速度的因素3个方面对应力波木材无损检测技术的研究进展进行总结分析,预测其发展前景,以期为该领域的进一步研究提供参考。     

木材顺纹压缩率与PDR的影响机制研究

木材顺纹压缩弹塑性和PDR(永久变形率)变化规律及机理研究是攻克木材顺纹压缩与多维弯曲技术的核心.从木材的树种、密度、软化处理条件、化学组分和相对结晶度以及压缩速度几个方面,分析了木材顺纹压缩过程中这些因素对木材顺纹压缩率和PDR的影响机制.