木竹材糠醇树脂改性技术及其机理研究

发布时间：2018-06-10 01:01

本文选题：木材 + 竹材　；参考：《中国林业科学研究院》2016年博士论文

【摘要】：速生木材和竹材的优势是生长速度快,轮伐期短,但性能缺陷也十分明显。如何克服人工林木材、竹材的天然性能缺陷,延长使用寿命,提升其使用和商业价值,是我国林业产业可持续发展面临的一个重大难题。加强速生人工林木材和竹材的科学利用也是缓解我国木材供需矛盾,保障国家木材安全的的重要途径之一。木材糠醇树脂改性技术是近年来再次兴起的一种环境友好、商业化前景极为广阔的木质材料改性技术。本文作者在课题组自主研发糠醇处理液配方的基础上,以我国人工林木材代表杨木和杉木,特色速生资源毛竹为研究对象,开展木、竹材糠醇树脂改性技术及改性机理研究。研究内容包括两部分:(1)木竹材糠醇树脂改性技术研究。根据速生针、阔叶材代表杨木和杉木及竹材自身的材性、结构特点以及产品目标用途,以增重率、吸湿性、尺寸稳定性、部分力学性能、防霉、耐腐、抗白蚁等性能为主要评价指标,对糠醇树脂改性技术关键参数,如浸渍方式、改性溶液浓度、固化时间及固化温度进行优化。(2)木竹材糠醇树脂改性机理研究。采用环境扫描电镜观察糠醇树脂在木、竹材细胞腔中的分布;应用激光共聚焦显微镜观察糠醇树脂在细胞壁和细胞腔中的分布差异;采用纳米压痕仪测试改性前后木、竹材细胞壁微观力学性能,进一步明确糠醇树脂是否进入细胞壁,并测试改性对木竹材细胞壁力学性能的影响。应用红外光谱和核磁共振等理化性能表征技术,明确糠醇树脂与细胞壁组分之间是否存在化学键结合。论文主要研究结论如下:低分子量、极性糠醇改性溶液极易浸入木竹材内部。经一次真空加压浸渍处理,杨木、杉木和竹材的改性材增重率最高可达60%、85%和32%。糠醇树脂改性显著降低了木、竹材的吸湿性,使其平衡含水率降低40~50%(65%RH,25℃)。糠醇树脂改性显著提高了木、竹材的尺寸稳定性。杨木的弦向、径向和体积的抗湿胀系数分别提高79.98%、91.88%和90.32%;杉木分别提高71.3%、78.74%和74.86%;室温浸泡处理的竹材的弦向、径向、顺纹方向和体积的抗湿胀系数分别提高49.28%、51.28%、52.44%和50.99%。糠醇树脂改性技术赋予木、竹材优异的抗生物劣化性能。糠醇树脂改性木、竹材拥有高效防霉性能。改性材增重率仅为20%的改性杨木和杉木试样和增重率仅为10%的竹材试样,经三种霉菌和变色菌侵染后,表面没有任何菌丝残留,防霉效率达100%。实验室耐腐测试结果显示,糠醇树脂改性木、竹材属强耐腐等级。增重率20%的改性杨木和杉木试样,经三种腐朽菌侵蚀后,失重率低于3%;增重率仅为10%的改性竹试样,失重率低于7%,且测试后改性木、竹材均保持完好无损。抗白蚁性能测试证明糠醇树脂改性木、竹材对白蚁有很好趋避能力。增重率达20%以上的改性木材经白蚁蛀蚀后,失重率低于0.7%,且表面没有出现任何蛀蚀痕迹,显示出优异的抗白蚁性能。对于改性竹材,增重率较低时(wpg=5.4%),白蚁蛀蚀等级为“1”级。中等增重率(wpg=15%)的改性竹材,白蚁蛀蚀等级为“0”级。糠醇树脂改性对木竹材力学性能的影响因树种不同而存在差异。本研究发现相同工艺条件下,改性杨木的抗弯强度和顺纹抗压强度可显著提高、弹性模量略有改善或影响不明显。但仅少许工艺条件下改性杉木的力学性能获得改善,部分工艺条件下,改性杉木的力学性能反而呈降低趋势。综合考虑改善木竹材尺寸稳定性和抗生物耐久性,且对力学性能影响较小等因素。推荐糠醇树脂改性杨木较优工艺为:50%糠醇浓度,固化温度105℃,固化时间8h;杉木改性工艺:50%糠醇浓度,固化温度115℃,固化时间5h;真空加压浸渍竹材改性工艺:15%糠醇浓度,固化温度105℃,固化时间3-5h;室温浸泡竹材改性工艺:50%糠醇浓度,固化温度105℃,固化时间5h。环境扫描电镜和激光共聚焦显微镜观察发现糠醇树脂填充在木材管胞、导管和木射线细胞中,且将细胞内壁完全覆盖,阻塞了胞壁上大部分纹孔。竹材薄壁细胞中丰富的淀粉粒被溶解脱除,并有部分胞腔被树脂填充。树脂的填充阻塞了水分进入孔道,并润胀细胞壁,从而使改性后木竹材吸湿性降低、尺寸稳定性显著改善。纳米压痕技术测试发现,糠醇树脂改性后杨木、杉木和竹材细胞壁的硬度和模量比对照样分别提高32%、24%、65%和4%、51%、53%,从细胞壁微力学角度证明糠醇树脂浸入细胞壁。糠醇树脂在木竹材细胞腔和细胞壁中的填充润涨改变了微生物和昆虫的寄生环境,从而提高木竹材的抗生物劣化性。红外光谱测试发现木材纤维素、半纤维素和木质素的特征峰减弱变宽,证明木竹材细胞壁组分在糠醇树脂改性过程中可能被降解。此外,代表羰基的特征峰显著加强和偏移,说明糠醇树脂改性木竹材可能发生了酯化反应。当然,糠醇聚合物的引入也是重要原因。核磁共振波谱分析发现,改性木竹材谱图上除未改性材和糠醇树脂对应化学位移处特征峰叠加外,并无新的特征峰出现。因此,本研究尚可证明糠醇树脂填充与木竹材细胞腔和细胞壁中,可推测糠醇树脂在细胞壁中可能发生酯化反应,但因实验仪器的分辨率及知识积累有限,尚不能确切证明糠醇树脂与木竹材胞壁组分发生化学反应。
[Abstract]:The advantages of fast-growing wood and bamboo are fast growth rate and short cutting period, but the performance defects are also obvious. How to overcome the natural performance defects of wood, bamboo and prolong the use and commercial value of bamboo is a major problem for the sustainable development of forestry industry in China. The use of science is also one of the important ways to alleviate the contradiction between the supply and demand of wood in China and ensure the safety of the country. The technology of the wood furfuryl alcohol resin modification is a kind of environmentally friendly and highly commercialized wood material modification technology in recent years. The author of this paper is based on the basis of the author's research group to develop the formula of furfuryl alcohol treatment solution. The study on the modified technology and modification mechanism of wood and bamboo furfuryl alcohol resin was carried out in China. The research contents included two parts: (1) study on the modification technology of the furfuryl alcohol resin of wood bamboo. Structure characteristics and product target use, with weight gain, hygroscopicity, dimensional stability, mechanical properties, mildew proof, corrosion resistance, termites and other properties as the main evaluation indexes, the key parameters of furfuryl resin modification technology, such as impregnation mode, modified solution concentration, curing time and curing temperature are optimized. (2) the modification mechanism of the furfuryl alcohol resin of wood bamboo The distribution of furfuryl alcohol resin in the cell cavity of wood and bamboo was observed by environmental scanning electron microscope, and the distribution difference of furfuryl alcohol resin in cell wall and cell cavity was observed by laser confocal microscope, and the micromechanical properties of the modified wood and bamboo cell wall were tested by the nano indentation instrument and whether the furfuryl alcohol resin entered the cell or not. The effects of modification on the mechanical properties of the cell wall of wood bamboo were tested. The chemical bonds between the furfuryl alcohol resin and the cell wall components were determined by using the physical and chemical characterization techniques such as infrared spectrum and nuclear magnetic resonance. The main conclusions are as follows: low molecular weight, polar furfuryl alcohol modified solution is easily immersed inside wood bamboo. The maximum weight gain of the modified wood, Chinese fir and bamboo was up to 60% in vacuum pressure impregnation treatment. The modification of 85% and 32%. furfuryl alcohol resin significantly reduced the moisture absorption of wood and bamboo, and reduced the balance water content by 40~50% (65%RH, 25). The modification of furfuryl alcohol resin significantly improved the dimensional stability of wood and bamboo wood, the chord direction, radial and volume resistance of poplar wood. The expansion coefficient increased by 79.98%, 91.88% and 90.32%, and the Cunninghamia lanceolata increased by 71.3%, 78.74% and 74.86%, respectively. The wet expansion coefficient of the bamboo material treated at room temperature was increased by 49.28%, 51.28%, 52.44% and 50.99%. furfuryl resin modified technology. The excellent biodegradation properties of bamboo were given to wood and bamboo. The modification of furfuryl alcohol resin was improved. Wood and bamboo have high anti mildew resistance. The modified wood and Cunninghamia lanceolata with the weight increase rate of only 20%, and the bamboo samples with only 10% weight gain. After three kinds of mould and chromotropic bacteria, there is no mycelium residue on the surface. The anti mould efficiency is shown by the 100%. laboratory corrosion test results, the furfuryl resin modified wood, and the bamboo is strong corrosion resistance grade. The weight loss rate of the modified poplar and Cunninghamia lanceolata samples with the weight increasing rate of 20% was less than 3%, the weight gain rate was only 10%, the weight loss rate was less than 7%, and the bamboo material remained intact after the test. The test proved that the termite modified wood, the bamboo material had a good avoidance ability to the termites. The weight gain rate was 20%. After termite decaying, the weight loss rate of the modified wood was less than 0.7%, and there was no erosion mark on the surface, showing excellent resistance to termite. For the modified bamboo, the grade of termite decay was "1" when the weight gain was lower (wpg=5.4%). The modified bamboo with medium weight gain (wpg=15%), the grade of termite decay was "0" grade. Furfuryl alcohol resin was modified. The effect of sex on the mechanical properties of wood bamboo varies with the tree species. Under the same technological conditions, it is found that the flexural strength and the compressive strength of the modified poplar can be significantly improved, the modulus of elasticity is slightly improved or the influence is not obvious. However, the mechanical properties of the modified Chinese fir are improved under only a few technological conditions, and under some technological conditions. The mechanical properties of the modified Cunninghamia lanceolata have been reduced. The factors such as the improvement of the size stability and the Biological durability and the mechanical properties of the wood bamboo are considered. The better technology of the modified Poplar with furfuryl alcohol resin is 50% furfuryl alcohol concentration, the curing temperature 105 degrees C, the curing time 8h, and the Cunninghamia lanceolata modification process: 50% furfuryl alcohol concentration and 11 curing temperature. 5 C, curing time 5h, vacuum pressure impregnating bamboo material modification process: 15% furfuryl alcohol concentration, curing temperature 105 degrees C, curing time 3-5h; room temperature soaking bamboo material modification process: 50% furfuryl alcohol concentration, curing temperature 105 degrees, curing time 5h. environment scanning electron microscope and laser confocal microscope observation found that furfuryl alcohol resin filling in wood tracheids, ducts and wood rays In the cell, the inner wall of the cell is completely covered and most of the grain holes on the wall of the cell are blocked. The rich starch grains in the bamboo parenchyma cells are dissolving and removed, and some of the cavities are filled with resin. The filling of the resin blocks the water into the channel and expands the cell wall, thus reducing the moisture absorption of the modified wood bamboo and improving the dimensional stability significantly. The hardness and modulus of the cell wall of poplar, Cunninghamia lanceolata and bamboo were increased by 32%, 24%, 65% and 4%, 51%, 53% respectively after the modification of the furfuryl alcohol resin. The filling and swelling of furfuryl alcohol resin in cell wall and cell wall of bamboo wood changed the microorganism and Kunming. The parasitic environment of the insects increased the biodegradability of wood bamboo. The infrared spectrum test found that the characteristic peaks of wood cellulose, hemicellulose and lignin weakened and broadened. It proved that the cell wall components of wood bamboo could be degraded in the process of furfuryl alcohol resin modification. In addition, the characteristic peaks representing carbonyl groups were significantly strengthened and offset, indicating the furfuryl alcohol resin. There may be an esterification reaction in the modified wood bamboo. Of course, the introduction of the furfuryl alcohol polymer is also an important reason. The NMR spectroscopy analysis shows that there is no new characteristic peak in the modified wood bamboo spectrum except the unmodified material and furfuryl alcohol resin, and there is no new characteristic peak. In the cell wall and cell wall of bamboo, it is presumed that the esterification of furfuryl alcohol resin may occur in the cell wall, but because of the limited resolution and knowledge accumulation of the experimental instrument, the chemical reaction of the furfuryl alcohol resin and the cell wall component of the bamboo wood can not be confirmed.
【学位授予单位】：中国林业科学研究院
【学位级别】：博士
【学位授予年份】：2016
【分类号】：S781.7

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