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柠檬桉木材中二氧化硅的分布和含量的测定 总被引：5，自引：0，他引：5
生物矿化所形成的木材-无机质复合材是当前木材科学研究的热点之一，要实现木材一无机质复合材的人工模拟，其关键还在于研究和探讨木材生物矿化的机理，因此要对木材中无机物的分布及其含量进行研究，从而获取生物矿化所形成的木材一无机质复合材料的形成机理，以此来指导木材的生物改性或木材一无机复合材的仿生合成。本研究采用光学显微镜对柠檬桉木材中二氧化硅的分布进行观察，得出柠檬桉木材中二氧化硅主要分布在射线细胞中，同时大量的晶体存在于轴向薄壁细胞中，早材中的硅石多于晚材中的硅石。采用重量法对木材轴向分布、径向分布中灰分和二氧化硅的含量进行的分析表明：柠檬桉木材中灰分和二氧化硅的含量随着高度的增加而降低，柠檬桉木材灰分和二氧化硅的含量从边材部位向心材部位逐渐减少。 相似文献
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木材细胞中二氧化硅的吸收、运输与聚积 总被引：1，自引：0，他引：1
硅石在很多木材细胞中都可见(如紫果冷杉、樟科等),它与木材本身构成了一种复合材料即木材/无机质复合材,使木材的物理力学性能得以改善,克服了木材自身的一些缺陷(如易腐、易燃、尺寸不稳定性、各向异性等).作者根据前人对木材细胞中二氧化硅(SiO2)的分布、形态和含量的初步分析,归纳总结木材细胞中二氧化硅(SiO2)的形成过程及其影响因素即木材细胞中SiO2的吸收、运输及聚积,影响木材细胞中SiO2的吸收、运输及聚积的因素,为进一步研究木材细胞中硅生物矿化的形成过程做准备. 相似文献
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将硅石溶液经有机硅烷杂化后浸渍人工林杨木,再对其进行热处理,测试分析改性材的物理力学性能、化学结构及形貌特征,探讨木材联合改性机理。结果表明:1)复合硅石溶液改性使杨木的密度、强度和阻燃性均显著提高,但尺寸稳定性欠佳,热处理可明显增强其尺寸稳定性和阻燃性;2)改性剂填充固化于木材细胞腔,甚至渗入细胞壁中,可起到有效的增强作用;3)热处理可促进改性剂与木材组分发生稳固的Si—O—Si化学结合;4)联合改性材中Si原子配位数增多,缩聚固化程度更高,稳定性增强。复合硅石溶液/热处理联合改性是一种应用前景广阔的绿色木材改性技术。 相似文献
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生物矿化原理与木材纳米结构复合材料 总被引：11，自引：0，他引：11
为促进传统木材改性技术产生新的发展 ,将生物矿化概念导入到木材科学与技术的研究领域中。本文综述了生物体系中生物矿化作用的基本内涵 ,探讨了基于这些原理之上的木质基纳米材料控制合成的构想 ,即通过立木形成层细胞分生的有机分子和无机离子在界面处的相互作用来设置矿化位 ,调节微环境 ,建立饱和溶液、提供有机质、搬运离子、加入添加剂等来控制生物矿化作用的方向和过程 ,实现用活立木制备木材纳米结构复合材。 相似文献
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《西部林业科学》2019,(6)
樟树除常规枝叶蒸油外,综合利用樟树木材,可有效减少资源浪费,同时弥补木材资源的不足。以15年生材用和油材两用樟树木材为研究对象,利用年轮年代仪测定其生长轮宽度;木材解离后在光学显微镜下观察测量木纤维长度和宽度,计算木材纤维长宽比;采用Ifju法测定木材组织比量;研究材用和油材两用樟树木材构造的差异。结果显示:材用和油材两用樟树木材年轮平均宽度分别为7.9mm和6.4mm,木纤维长度、宽度、双壁厚材用樟树分别为1 182μm、23μm、7.8μm,油材两用樟树分别为974μm、25μm、6.3μm;木材纤维长宽比、壁腔比、腔径比材用樟树分别为52、0.51、0.66,油材两用樟树分别为39、0.34、0.75;木纤维、油细胞、薄壁细胞、导管、木射线的组织比量材用樟树分别为50.66%、4.37%、8.63%、16.84%、18.81%,油材两用樟树分别为45.45%、5.5%、13.69%、16.21%、18.53%。两种木材年轮宽度径向变异均由髓心向外先增加后减小,且表现为材用樟树径向生长速度大于油材两用樟树;根据木材解剖分子分级规定:材用和油材两用人工林樟树的木纤维均属于"中"级;纤维宽度均属于"中等";木纤维细胞壁厚度均属于"薄"级,但材用樟树比油材两用樟树木纤维更长、宽度更小、细胞壁更厚,更加适用于纤维制品原料;材用樟树木材导管和木射线组织比量相近、木纤维组织比量大于油材两用木材、油细胞和薄壁细胞组织比量小于油材两用樟树,且两类木材的油细胞、薄壁细胞纵向变异波动均较小,可作为识别材用和油材两用樟树或材质评价的参考因子;材用樟树和油材两用樟树具有非常相近的亲缘关系,材用樟树可能为油材两用樟树的一个变种。该结果为区别油用和材用樟树木材和樟树培育提供了科学依据。 相似文献
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木射线作为木材显微构造中的一个重要特征,在木材构造和树种识别的研究中具有重要意义。以针叶材为研究对象,基于计算机视觉技术对木射线特征快速提取方法展开研究,最终构建一套完整的算法,从而使研究人员在向计算机传入针叶材的弦切面图像和比例尺后,即可快速得到木射线细胞数和高度的微观特征。首先对50种针叶材树种的弦切面图像数据集构建U-Net网络模型进行语义分割,对比了在不同放大倍数下木射线的分割效果,发现放大倍数大于10倍时分割效果较好;在此基础上,设计和编写计算分割后图像中的木射线最小覆盖圆算法,可以快速提取木射线的高度,进而得到射线平均高度;再将分割后的木射线图像数据集进行目标检测模型训练,实现射线细胞的目标检测及自动计数功能,并将二值图像阈值分割法和YOLOv3、YOLOv5算法进行比较。结果表明,YOLOv5对射线细胞的检测效果最好。采用本研究方法所提取的木射线高度和细胞数与人工实测结果相比,木射线高度值的偏差不超过4%,细胞计数误差不超过6%。 相似文献
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Summary In a study on the SiO2 wood-inorganic composites prepared by the sol-gel process with tetraethoxysilane (TEOS), it is more appropriate to use safer agents than TEOS, considering the operational and processing environments. In this study, therefore, methyltrimethoxysilane (MTMOS) was used to prepare the SiO2 wood-inorganic composites, and comparative studies were made with TEOS. Resultingly, SiO2 wood-inorganic composites could be successfully prepared from MTMOS reaction system, as in TEOS system, with its lower concentration, and both composites had SiO2 gels specifically formed within the cell walls from moisture-conditioned wood specimens. On this SiO2 composites, the water-repellent properties were added most effectively with a molar ratio of 2-heptadecafluorooctylethyltrimethoxysilane (HFOETMOS) to alcohol being 1/250 and 1/180 for TEOS and MTMOS reaction systems, respectively. On the other hand, fire-resisting properties were tried to add to SiO2 composites with several fire-resisting agents. The fire-resisting agents in the obtained composites are not, however, stable and leached out readily. Therefore, a small addition of HFOETMOS was tested to the MTMOS and TEOS reaction systems with fire-resisting agents. The obtained results clearly indicated that HFOETMOS could restrain the fire-resisting agents to be leached from the composites, and that composites from MTMOS system were superior to TEOS system on the antileachability. Therefore, MTMOS can be appropriate for displacement of TEOS as a chemical agent to prepare SiO2 wood-inorganic composites.This research has been performed in Department of Wood Science and Technology, Faculty of Agriculture, Kyoto University, Kyoto, Japan.This research was supported by a Grant-in-Aid for Scientific Research (B) (No. 06453176, 1994.4–1996.3) from the Ministry of Education, Science, and Culture, Japan. 相似文献
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Nanoscale in Wood,Nanowood and Wood—Inorganic Nanocomposites 总被引：4，自引：0，他引：4
ZhaoGuangjie LuWenhua 《中国林学(英文版)》2003,5(1):44-48
In order to introduce nano science and technology(NST) into the research field of wood science and technology,and promote the research of wood science and wood-inorganic composites to nanoscale ,some new concepts,such as the nano space in wood,nano structure units of wood and nanowood are put forward in this paper based on the layer structure of wood cell wall and the pile-up model of its main components.Furthermore,the process of preparing nanowood is discussed,and wood-inorganic nanocomposites may be operated in three ways with wood (matrix) and inorganic filler phase in 0-2,0-3 or 2-3 dimensions respectively.The following results are obtained:(1) The nanoscale voids in wood indicate that wood has inherent space to accommodate nanosized materials,such as nanoparticles,nanotubes and nanosticks;(2) According to the size from top down,the nano structure units in wood can be classified as :nanolayers,nano CMF (cellulose microfibril) and matrixd,nano crystallite units and cellulose chain clusters,and these can theroretically from nanowood;(3) The preparation of wood-inorganic nanocomposites can be operated on 0-2,0-3 or 2-3 dimensions. 相似文献
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Summary A study of the wood-inorganic composites prepared by the sol-gel process with a metal alkoxide indicated that an inorganic modification of wood with TiO2 gels from tetraisopropoxytitanium (TPT) can not improve its properties due to the formation of the gels in the cell lumina by high hydrolysis rate of TPT. In this study, therefore, titanium alkoxides or titanium chelates which have the lower rate of hydrolysis and subsequent polycondensation than TPT were used for preparing TiO2 wood-inorganic composites to study the topochemical effects of the TiO2 gels for the property enhancement of wood. As a result, it was found by SEM-EDXA analysis that the TiO2 gels deposited within the cell walls could improve the properties of wood in dimensional stability and fire-resistance, whereas for the gels in the cell lumina, property enhancement could not be achieved, as observed in SiO2 wood-inorganic composites.This research has been performed in Dept. of Wood Sci. & Technol., Kyoto UniversityThis research was supported by a Grant-in-Aid for Scientific Research (B) (No. 06453176, 1994.4–1996.3) from the Ministry of Education, Science, and Culture, Japan. The authors were grateful to Nippon Soda Co., Ltd. for providing titanic reagents. 相似文献
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Brita Unger Michael B��cker Stefan Reinsch Thomas H��bert 《Wood Science and Technology》2013,47(1):83-104
It has been shown that tetraethoxysilane-derived precursors are suitable solutions for impregnating pine sapwood to improve its dimensional stability. Tailored sol?Cgel syntheses result in precursors with nano-scaled silica species which are able to penetrate into the cell walls of wood. The physical fixation of those species inside the cell walls was verified by ESEM/EDX investigations. There is evidence that the silica species are chemically bonded to wood components. Non-reacted alkoxy groups can exist in the wood composites after impregnation. The amount of these organic residues depends on the composition of the precursors, especially their condensation degree and reactivity. Treatments for finishing the composites after the impregnation step to get clean products and stable properties are discussed in this context. An explanation of the complex relationship between solids content in the impregnation solutions and percentage weight gain and bulking of the composites is given. It can be demonstrated that high WPG values (>20?%) are pre-conditions for an effective protection of the resulting composites but they only guarantee efficient improvements if connected with the incorporation of the inorganic component inside the cell walls. Therefore, the sol?Cgel syntheses have to be carried out in such a manner that very small (<2?nm) as well as reactive species are sufficiently available. This demands syntheses using sub-stoichiometric water contents (H2O/TEOS?<?4, better <2). 相似文献
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很多木材细胞中含有大量的二氧化硅、草酸钙、碳酸钙等无机晶体,这些无机物质在木材细胞壁中的沉积,起到了提高木材自身机械强度、物理强度的作用,并克服了木材自身的一些缺陷(易腐性、易燃性、尺寸不稳定性、各向异性、变异性、不耐候性)。本文就硅化合物在木材细胞壁中的沉积、运输以及影响硅化合物存在的条件进行了分析。 相似文献
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For enhancing fire-resistant properties, a binary system to prepare wood-inorganic composites was studied by adding sodium methoxide (SM) or sodium acetate (SA) to a reaction system for SiO2 composites. Compared with the SiO2 composites, both the Na2O-SiO2 composites prepared could be greatly improved up to 600°C-700°C (glowing). From scanning electron microscopic observations, this enhanced fire resistance was assumed to be due to chemical and physicochemical effects, such as dehydration and carbonization of wood by Na2O gel. The glassy layer and intumescent structure formed over the cell walls were thought to prevent oxidation and heat transfer from proceeding into the inner portion of the wood cell walls. However, the reaction medium with SM to prepare Na2O-SiO2 composites was basic, whereas that with SA was rather neutral. In addition, in the latter composites, most of the inorganic gel was formed within the cell wall, retaining the porous structure characteristic of wood. Therefore, the Na2O-SiO2 composites prepared with SA can be concluded to be preferable for practical purposes.Part of this report was presented at the 50th annual meeting of the Japan Wood Research Society, Kyoto, April 2000 相似文献