微生物对长白鱼鳞云杉木材渗透性的影响

本文利用水池贮存处理木材研究了细菌对改善长白鱼鳞云杉木材渗透性的有效性。渗透性的测定采用水上升置换气流法。试验结果表明,水池贮存处理长白鱼鳞云杉气干材10周,不仅可以非常显著地增加其边材的渗透性(渗透性平均增加29倍),而且其心材渗透性亦有明显改善(平均渗透性增加1.52倍)。但心材试样渗透性增加不均匀,仅有50％的心材试样在水池贮存处理后渗透性得到了增加。渗透性增加的原因主要是由于边材和部分心材试样受到短芽孢杆菌(Bacillus brevis)等细菌的侵蚀,据电镜观察,边材大多数具缘纹孔的纹孔塞被细菌降解后形成空洞,心材的管胞内壁及具缘纹孔的纹孔缘上有细菌存在。     

几种木材干燥方法机理及其对木材浸注性的影响*

木材干燥是木材工业应用中必不可少的一环 ,木材的浸注性或渗透性又是关系到木材改性成功与否的重要前提。因此 ,开展不同干燥方法对木材浸注性或渗透性影响的研究 ,将对开展低质人工林木材功能性改良、提高其质量和利用价值的新技术与新方法的研究 ,具有重要理论指导作用。文中就高温干燥、高频 /真空干燥、微波干燥、冷冻干燥和大气干燥等干燥方法的机理及其对木材浸注性或渗透性影响的研究工作进行了全面综述     

黄花落叶松木材超微结构及其对渗透性的影响

本文详细地介绍了黄花落叶松木材超微结构特征及其对木材渗透性的影响,心材和边材管胞具缘纹孔的超微结构及其在不同部位和不同处理方法中的变化;晚材管胞具缘纹孔超微结构的变化;细胞壁各层次中的微纤丝及其周围的基质和结壳物质等的渗入或沉积性状。同时还针对黄花落叶松木材渗透性差,及一些晚材具缘纹孔少闭塞或不闭塞的原因,从木材的超微结构特点进行了较详细的探讨。     

柳杉锯材高温干燥初步研究

为高效利用柳杉木材,采用高温干燥方法对25mm厚柳杉心材、边材及心边混合锯材进行干燥,并检测干燥速率及干燥质量。结果表明,边材干燥速率最快,心材最慢;心材-弦切板、心边混合材-弦切板的干燥质量,可以达到GB/T 6491-2012《锯材干燥质量》中的二级要求。     

杉木人工林木材的高频真空干燥工艺

对人工林杉木25mm和50mm厚板材进行了系列高频真空干燥试验.结果表明:干燥后的板材变形小,表面平整,表芯层含水率差异较小.尽管试板的初始含水率差异较大,但根据高频真空干燥靠近正极板的木材比靠近负极板的干燥速度快的特点,试板的初始含水率由低至高在负极板至正极板之间进行顺序摆放码垛,干燥后的板材含水率可达到均匀一致.     

干燥工艺对枫香木材微观结构的影响研究

研究采用5种不同干燥工艺处理枫香木材,分析对比不同干燥工艺处理材与未处理材的微观结构变化规律。结果表明:经常规、降温干燥处理后,枫香木材纹孔膜发生破裂,多发生在闭塞纹孔,且破裂程度较低;经水热预处理常规和降温干燥后,被沉积物全部覆盖的纹孔膜发生较大程度破裂;微波干燥处理后,木材纹孔膜、部分细胞壁以及导管间胞间层均出现一定程度的破裂,提高了木材内部水分迁移效率。     

汽蒸处理对木材渗透性的影响

试样（２×２×５ｃｍ）在温度１２０℃和１００℃两种饱和水蒸汽条件下分别汽蒸处理８小时，然后置于大气中干燥至含水率为１０％左右时，采用水上升置换气流法进行渗透性测定。汽蒸试样的渗透性分别与其纵向相邻接的未汽蒸、含水率约１０％的对照比较，并进行成对比较分析ｔ检验。试验结果表明，各树种的木材性质不同，汽蒸作用引起木材解剖上、化学上的变化也不同，因而汽蒸处理对木材渗透性的影响各异。红松气干边材、心材经１２０℃和１００℃汽蒸处理后渗透性分别较未汽蒸者提高约６０、９０％和４０、１３０％；长白鱼鳞云杉生材边材经１２０℃汽蒸后和气干心材经１００℃汽蒸后渗透性分别较未汽蒸者约提高３２６和８０％；成对比较分析ｔ检验，汽蒸试样与未汽蒸试样渗透性之间差异可靠性为９０－９９．９％；汽蒸试样渗透性获得提高的原因均系汽蒸后纹孔膜和纹孔塞发生开裂的结果。但汽蒸长白鱼鳞云杉生材心材、气干边材和心材及臭冷杉生材心材、气干边材和心材的渗透性则未获得提高。     

杉木阴沉木的特性

杉木阴沉木的出油率高于现代杉木,其精油检出４２种化合物。与现代杉木的具缘纹孔类型一样,都属于南洋杉Ｂ型,其木块与精油的抗白蚁性,强于现代杉木。杉木阴沉木基部边材耐腐性属耐腐等级、中部边材属稍耐腐等级,对白腐菌耐腐性好,均属耐腐等级,其抗性强于现代杉木。     

人工林杨木的高频真空干燥工艺

在人工林杨木的高频真空干燥系列试验中,通过不断改变干燥工艺参数并分析总结试验结果,从而确定杨木高频真空干燥适宜的工艺基准。结果表明,在本试验确定的高频真空干燥工艺下,初含水率较高的杨木不仅能保证干燥质量,而且干燥速度可比常规蒸汽干燥法和高温蒸汽干燥法提高数倍。     

石梓

木材性质一般性质:木材一般外观为草黄色到奶油白色。心材有淡淡的气味,粉红色;边材颜色比心材深,呈浅灰色,外观略有差异。弦切板具华丽的光泽。刚锯下来的生材含水率高。天然干燥缓慢,并会出现诸如翘曲、开裂、变色或蛀成小孔的缺点。印度、马来亚、冈比亚和尼日利亚的资料表明,在这些国家中,无论生长条件多么不同,所产的石梓其木材的容重平均每立方呎为30—31磅.接近欧洲赤松(Pinus sylvestris)的容重.可列入作多种用途的正确重量等级的木材。石梓不像松类,速生不会改变木材的容重,可使其迅速成为产量大的材质稳定的工业用材。石梓的制浆特性优良,心材的耐腐度中等,但难以用防腐剂浸注。边材     

Effect of different drying methods on liquid penetration of Chinese fir plantation wood

Chinese fir plantation sapwood and heartwood boards were treated by three drying methods: radio frequency-vacuum drying (RFVD), conventional kiln drying (KD) and high temperature drying (HTD). The maximum amount of dyeing solution uptake by the capillary rising method was used to evaluate the liquid penetration of the treated wood. The pit aspiration ratio was determined by a semithin section method. Changes in wood microstructure were investigated using scanning electron microscopy. The results show that liquid penetration of Chinese fir sapwood after RFVD is significantly higher than that after KD and HTD. Liquid penetration of Chinese fir heartwood after RFVD is higher than that after HTD. Liquid penetration of Chinese fir sapwood is significantly higher than that of heartwood after three drying treatments. Low pit aspiration ratio and cracks of some bordered pits are the main reasons for the increase in liquid penetration after RFVD treatment. __________ Translated from Scientia Silvae Sinicae, 2006, 42(10): 85–90 [译自: 林业科学]     

杉木冷冻干燥材和气干材液体浸注性的比较研究

A comparative study was conducted on liquid penetration of the freeze-drying and air-drying sapwood and heartwood lumber of plantation Chinese fir （Cunninghamia lanceolata）. The maximum amount of dyeing solution uptake by the capillary rise method was used to evaluate the liquid penetration properties of the treated wood. The pit aspiration ratio was determined by semithin section method. Changes in wood microstructure were investigated using scanning electron microscopy. The results showed that compared with air drying, the freeze drying had a significant effect on liquid penetration of sapwood and heartwood of Chinese fir. The liquid penetration of sapwood is significantly higher than that of the heartwood for both drying treatments. Low pit aspiration ratio and cracks of pits membrane of some bordered pits are the main reasons for increasing liquid penetration after freeze drying treatment.     

3种不同处理方法对木材渗透性影响的研究

本文通过对长白鱼鳞云杉和臭冷杉生材分别进行普通气干处理和酒精置换处理以及对其气干材进行水浸处理,研究了这３种不同处理方法对木材气渗透性的影响及其影响机理。研究结果表明,长白鱼鳞云杉边材、心材和臭冷杉心村的生材经普通气干处理后,其气体渗透性较低,分别约为０．１１４、０．０４５和０．１１１ｄａｒｃｙ;长白鱼鳞云杉边材、心材和臭冷杉心材的生材经酒精置换处理后,其气体渗透性分别约为１１．７１３、０．０７４和０．１４４ｄａｒｃｙ,比普通气干处理对照组试样的平均渗透性分别增加约１０１．５倍、６２％和３０％,ｔ检验表明,前者差异非常显著,但后两者差异不显著;已气干１８个月的长白鱼鳞云杉边材、心材和臭冷杉心材经水浸处理后,其平均气体浸透性较处理前分别增加约８５％、４９％、６５．５％,ｔ检验表明差异均显著。长白鱼鳞云杉生材边材经     

Profile of bordered pit aspiration in Cryptomeria japonica using confocal laser scanning microscopy: pit aspiration and heartwood color

Nine trees of Cryptomeria japonica from six elite tree clones with a broad range of heartwood colors were selected. The profiles of pit aspiration percentage (ASP) of earlywood and latewood from pith to bark for green and air-dry conditions were determined to study the relationship between heartwood color and pit aspiration. Confocal laser scanning microscopy (CLSM) observations showed that the ASP of earlywood was low in sapwood and high in heartwood in the green condition. Pit aspiration increased in intermediate wood when compared with sapwood. On the other hand, latewood pits did not aspirate during heartwood formation. Comparing the air-dry condition with the green condition, sapwood pits aspirated during drying in both earlywood and latewood; however, there was no significant difference in pit aspiration of heartwood. There was no significant difference between samples with red and black heartwoods for ASP. The difference in ASP between individual trees was larger than that by heartwood color. The general advantage of CLSM over light microscopy is that serial optical sections along the Z axis can be obtained for any moisture condition, without the need for thin sectioning or embedding.     

Wood drying process: impact on Scots pine lumber durability

There are indications that the drying process may have negative effects on the natural durability of wood. The impact of various drying processes on the durability of Scots pine lumber has been evaluated with mass loss in a decay test with brown rot fungus, Coniophora puteana, as measure of the decay resistance of sapwood and inner and outer heartwood. Drying with or without steam conditioning was performed in six different series: air drying, kiln drying at temperature ranges commonly used in Swedish sawmills at 70°C and 90°C with two different regulation principles, and one high-temperature drying at 110°C. Durability varied considerably both between and within boards. Sapwood showed considerable less durability than heartwood. No difference in durability was found between inner heartwood and outer heartwood. Air-dried heartwood showed the highest durability compared to other drying series. The lowest durability in sapwood and heartwood was found for series dried at the 90°C temperature level with high material temperature early in drying. The interpretation is that the duration of high material temperature at high moisture content (MC) is the critical combination for decay resistance in heartwood. Steam conditioning after drying decreased durability in sapwood.     

小型除湿干燥机干燥乐器用材的实践

本研究使用小型除湿干燥机对提琴用材进行了干燥工艺生产性试验。结果表明，干燥过程中试材未产生内裂和表裂；干燥后板材的含水率在材堆内分布均匀，在板材厚度方向分布有一定差异，平衡后可以使用；干燥成本在100元/m^3左右；干燥后的木材质量符合乐器制作的要求。本试验确定的干燥工艺可适用楔形不规则乐器用材，还可进行不同规格乐器用材的混合干燥。     

Liquid water absorption in dried Norway spruce timber measured with CT scanning and viewed as a percolation process

Liquid flow in dried wood is complicated to study, since wood is a nonhomogeneous, hygroscopic-porous, anisotropic material. However, liquid flow is important to understand, since it has an influence on the durability of wood and on such processes like impregnation, drying, surface treatment, etc. In this study, simulations of liquid water absorption in wood as a fibre network, percolation, were compared with experimental water absorption in the longitudinal direction in spruce timber. With CT scanning, water distribution during liquid flow can be shown visually and measured by image processing. Liquid water absorption in end grain of spruce was measured with CT scanning after 1, 3, 7 and 14?days of liquid water absorption and shown as moisture content (MC) profiles in heartwood and sapwood. It was found that the amount of water absorbed could be expressed as a linear function of the square root of time. The slopes of the lines differed between sapwood and heartwood and also varied depending on the growth condition of the trees. The simulations according to the percolation method show generally good agreement with the measured results for sapwood.     

Improvement of penetrability of sugi wood by impregnation of bacteria using sap-flow method

The sap flow method of wood impregnation was conducted to aid the movement of bacteria through the living tree, thereby accelerating their distribution through wood within a short time. When log-pond water containing mixed species of bacteria were introduced in the living trees by butt-end dipping and then laid horizontally for 6 months, bacteria could be delivered by sap flow vertically through the sapwood tracheids up to the high portions from the butt-end of trees; they could be detected in the ray parenchymal cells. The sap-flow method was assumed to deliver the bacteria to sapwood and heartwood at high levels of standing sugi (Cryptomeria japonica D. Don) trees. Degradation of the pit membranes was observed even at more than 3 m upward from the butt-end after the treatment in sapwood, as well as around the butt-end of the trees. The uptake of the aqueous dye solutions in sapwood of the treated logs were about eight times more than those of control specimens after 8h.Part of this report was presented at the 40^th annual meeting of the Japan Wood Research Society, Tsukuba, April 1990; the 41^st annual meeting of Japan Wood Research Society, Matsue, April 1991; and the IUFRO 4^th international conference on wood drying, Rotorua, New Zealand, August 1994     

Comparison of moisture distribution along radial direction in a log cross section of heartwood and mixed sapwood and heartwood during radio-frequency/vacuum drying

The purpose of this study was to compare the distribution of moisture contents (MCs) along the radial direction during radio-frequency/vacuum (RF/V) drying of log cross sections of heartwood (HLC) where sapwood was removed from a green log cross section and log cross section of mixed sapwood and heartwood (MLC) prepared with debarked logs of Japanese larch (Larix leptolepis) and locust (Robinia pseudoacacia). For Japanese larch, an even distribution of MC was observed over the entire cross section in HLC not only at the initial stage of drying but also up to the completion of drying. Furthermore, the moisture gradient between the outermost slice and the adjacent inner slice was more gradual compared with that in MLC. For locust, the moisture gradient between the outermost slice and the adjacent inner slice became severe as drying progressed. It decreased after reaching the maximum during the middle stage of drying but continued until the late stage of drying. Furthermore, despite the fact that the average initial MC of mixed slice within MLC was higher compared with that in heartwood slice, this trend reversed immediately after drying started. It was suggested that the possibility of formation of border checking would be high during drying the MLC, since it would be so complicate that the sapwood and heartwood reach fiber saturation point together because of differences in their green MCs and permeability between them.