不饱和聚酯树脂改性对杨木尺寸稳定性的影响

以杨木为试材,以不饱和聚酯树脂为改性剂,采用真空浸渍方法,研究了木材改性对杨木湿胀率、干缩率和吸水率的影响。结果表明:杨木经过改性后,湿胀性、干缩性明显提高且径向尺寸稳定性提高率大于弦向,吸水率显著降低,杨木的尺寸稳定性得到提高。不饱和聚酯树脂改性剂对杨木的尺寸稳定性具有明显的改良效果。     

木蜡油改性木材的研究进展

木材是一种可再生材料,被广泛使用在家装建材等领域。木材随外部环境因素的改变,易吸湿滋生真菌,导致稳定性和强度下降。木蜡油由天然蜡和天然油组成,具有无毒无害、绿色天然的特点。总结了木蜡油和植物油的特性与区别,以及木蜡油常用改性木材的方法——表面涂饰和浸渍;阐明了常压普通浸渍和真空浸渍的应用与区别。真空浸渍利用负压加快浸渍速度,在制造透明木材、高性能木材、超疏水木材等方面具有诸多应用。木蜡油改性木材能够降低其吸湿性,增加木材表面的疏水性、木材尺寸稳定性和耐候性。对木蜡油改性研究进行了展望,为进一步研究高性能木蜡油木材改性方式提供了思路和建议。     

不同预处理条件对负离子浸渍材物理特性的影响

本文以杉木(Cunninghamia lanceolata(Lamb.)Hook)为实验材料,分别对木材进行高温热处理和超声波预处理,然后再分别对预处理材进行负离子浸渍处理,并对不同预处理条件下得到的浸渍处理材的尺寸稳定性、负离子释放过程和微观结构进行探究,并对负离子释放过程进行模拟。结果表明,两种预处理方式均能提高浸渍材的尺寸稳定性,并且浸渍材的负离子释放效果显著。其中,高温热处理对尺寸稳定性改善效果最佳,且其负离子释放量最为理想;另外,通过电镜图片看出,负离子能够进入木材内部。本研究对提升杉木等速生材的附加值具有重要价值。     

高温热处理改性橡胶木的初步研究

橡胶树木材易腐朽、虫蛀,本文采用过热蒸汽作为传热介质和保护气体于180℃及210℃热改性橡胶木,结果表明高温热处理后橡胶木的尺寸稳定性得到提高,木材的弹性模量和抗弯强度减小,颜色加深。热改性后橡胶木对褐腐菌GT的重量损失率由55.93%减少到11.63%,耐久性由不耐腐等级提高到耐腐等级。     

高温热改性对7种国产阔叶材心边材颜色的影响

以过热蒸汽作为介质于185℃～215℃热改性7种国产阔叶材,分析窿缘桉、马占相思、荔枝木、刺槐、春榆、臭椿、橡胶木等木材热改性后心边材颜色的变化,考察不同处理对几种阔叶材心边材颜色的影响,为几种阔叶材工业热改性生产工艺优化及木材热变色规律提供试验依据。结果表明,(1)几种阔叶材185℃和200℃热改性后,对于心材树种,其心边材明度都显著降低,200℃明度低于185℃,且心材颜色仍较边材颜色深;(2)对于边材树种,热改性后木材明度也显著降低,200℃处理颜色亦比185℃深;(3)热改性后,马占相思等含有抽提物的心材树种木材颜色比橡胶木等不含抽提物的边材树种深;(4)热改性后窿缘桉木材的颜色变化,除了处理温度与处理时间对木材颜色有影响外,心边材也对其材色差异有显著影响。     

提高多层实木复合地板尺寸稳定性的方法

随着地暖技术的普及,人们越来越多的应用多层实木复合地板,它各层相互垂直的纹理克服了天然木材各向异性的缺陷,同时也提高了自身的尺寸稳定性。文章论述了改善实木复合地板稳定性的方法:如浸渍处理、化学改性、碳化处理、应力释放等,以及国内外的发展研究现状,为以后的研究工作奠定一些基础。     

家居用速生材改性现状研究

我国是一个森林资源贫乏的国家,随着人工速生林的大面积种植,速生材将成为主要的家居制造用木材。本文论述了速生材改性的研究现状,包括尺寸稳定化处理和强化处理的方式、微波和超声波等辅助处理手段以及纳米技术和超临界流体技术在木材改性中的应用,并针对目前改性速生材在家居中的应用提出了家居用速生材改性未来的研究方向应该以环保、高效为主,并且适应企业的实际生产,同时对于改性速生材在家居中的应用也进行结构、视觉等设计研究,以此来拓展速生材的使用范围。     

实木家具尺寸稳定性的处理方法

作为一种天然生成的有机体,木材具有一定的吸湿性,当外界环境温度变化时,木材也会随之产生干缩湿胀现象。因此,对于实木家具来说,保持良好的尺寸稳定性显得尤其重要。本文分析了木材尺寸不稳定的原因,以及减少木材细胞壁胀缩的传统方法,最后介绍了用热处理或热改性方     

大豆蛋白基明胶复合膜性能稳定性分析

以大豆蛋白和明胶为主要原料,采用戊二醛溶液交联方式和戊二醛饱和蒸汽交联制备大豆蛋白基明胶复合膜,通过对两种交联方式制备的复合膜机械性能稳定性和降解性测定,比较分析戊二醛不同交联方式对复合膜机械性能稳定性、降解性及微观结构影响。结果表明,在3个月贮藏期内,戊二醛溶液交联改性、蒸汽交联改性处理复合膜拉伸强度稳定性提高了20.58%、38.51%,延伸率稳定性提高了31.71%、54.49%,水蒸气透过系数稳定性提高了31.74%、52.19%,透氧率稳定性提高了0.24%、18.01%,降解实验中降解速率分别为未经改性处理大豆蛋白基明胶复合膜溶液交联改性处理复合膜蒸汽交联改性处理复合膜。同时,蒸汽交联复合膜表面及拉伸断面形成结构致密的三维立体网络结构。因此,戊二醛蒸汽交联制备的大豆蛋白基明胶复合膜机械稳定性能及微观结构均优于戊二醛溶液交联改性处理复合膜。     

结构用大片刨花板用低毒改性脲醛树脂胶的研制

针对三倍体毛白杨木材大片刨花板尺寸稳定性低的问题,在前人研究的基础上研制出了两种改性脲醛树脂胶,并用其压制大片刨花板。研究结果表明,采用合适的制板工艺,用这两种胶压制大片刨花板,其物理力学性能均能达到国家标准要求。建议用BZ-1号改性脲醛树脂胶作为三倍体毛白杨木材大片刨花板的专用胶。     

Chemical characterzation of fine particle emissions from the fireplace combustion of woods grown in the Southern United States

The fireplace combustion of wood is a significant and largely unregulated source of fine particle pollution in the United States. Source apportionment techniques that use particulate organic compounds as tracers have been successful in determining the contribution of wood smoke to ambient fine particle levels in specific areas in California. To apply these techniques to the rest of the United States, the differences in emissions profiles between different wood smoke sources and fuel types should be resolved. To this end, a series of fireplace source tests was conducted on six fuel wood species found in the Southern United States to determine fine particulate emission factors for total mass, ionic and elemental species, elemental and organic carbon, and over 250 individual organic compounds. The wood species tested, chosen for their high abundance and availability in the Southern U.S. region, were yellow poplar, white ash, sweetgum, mockernut hickory, loblolly pine, and slash pine. The differences in the emissions of compounds such as substituted phenols and resin acids help to distinguish between the smoke from hardwood and softwood combustion. Levoglucosan, a cellulose pyrolysis product which may serve as a tracer for wood smoke in general, was quantified in the emissions from all the wood species burned. The furofuran lignan, yangambin, which was emitted in significant quantities from yellow poplar combustion and not detected in any of the other North American wood smokes, is a potential species-specific molecular tracer which may be useful in qualitatively identifying particulate emissions from a specific geographical area where yellow poplar is being burned.     

Influence of different aging systems and oak woods on aged wine color and anthocyanin composition

The evolution of a red wine, Cigales appellation in origin, was studied during its storage in three different aging systems (barrels, chips, and staves) made of different kinds of oak wood (American, French, and Hungarian). The results obtained were analyzed in order to determine the content of anthocyanins in wine according to the aging system used. The studied variables were monoglucosides of delphidin, cyanindin, peonidin, petunidin and malvidin (as acetic and p-coumaric esters), as well as vitisin A, malvidin-3-O-caffeylglucoside, and color variables. The relationship between the anthocyanins and color variables stressed the importance of these compounds during the formation of pigments characteristic of aged wine, and highlighted how they are affected by the aging system chosen.Analysis of the results allowed us to define the evolution of the wine accordingly to the aging system and the botanical species of wood used. Wine treated with chips evolved more quickly than wines treated with the other two systems, because there was a higher loss of anthocyanins and an increase in brownish tonalities. On the other hand, wine treated with Hungarian oak wood suffered a slightly higher loss of anthocyanins than those aged with French and American oak wood.     

烟熏工艺对熏肉挥发性风味物质的影响

以熏猪肉为对象,研究传统木熏工艺和现代液熏工艺对熏肉挥发性风味物质的影响。对其挥发性风味物质进行GC-MS分析,重点比较两种烟熏方式产品的特色挥发性风味物质的差别。结果表明,传统木熏工艺产品的挥发性风味物质在种类和数量方面都明显高于现代液熏工艺的产品,传统木熏工艺的产品检测出130种挥发性风味物质,而现代液熏工艺检测出121种,酚类物质作为烟熏产品的特色挥发性风味物质,传统木熏工艺的产品检测出15种,含量达到22.85%,而现代的液熏工艺的产品检测出14种,含量仅为7.87%。因此,传统的木熏工艺在风味方面仍然具有一定的优势。     

液液萃取结合气-质联机分析景芝白干酒中的挥发性成分

采用不同的溶剂,通过液液萃取法结合气-质联机对景芝白干酒中的香气成分进行分析,并通过NIST 11 谱库 检索和保留指数进行了鉴定。结果表明,不同种类和极性的有机溶剂,其萃取出来的成分也不相同。采用正戊烷作为 萃取剂,共发现30 种物质,采用乙醚作为萃取剂,共发现29 种物质,采用二氯甲烷作为萃取剂,共发现35 种物质。 3 种溶剂一共萃取出65 种物质,其中醇类化合物9 种、酯类化合物19 种、酸类化合物11 种、烃类化合物14 种、芳香 族化合物3 种、呋喃类化合物3 种、醛类化合物3 种、酮类化合物1 种、含氮化合物1 种、含硫化合物1 种。     

Der Einfluß von Holzinhaltsstoffen auf die Erhärtung von Stuckgips und bei der Herstellung gipsgebundener Spanplatten

The influence of the water extract of 21 wood species and spruce bark and also of 24 wood extractives on the hardening of gypsum plaster was examined. Wood species containing hydrolyzable tannins have strong retarding effects. Neutral saccharides showed negligible effects. Weak until moderate retarders are organic acids and their lactones, simple phenols, flavonoid compounds, condensed tannins and saponin. A very weak solution of conidendrine has an acceleration effect, whereas a concentrated one retards the hardening. During the manufacture of gypsum-bonded particleboards from spruce, poplar, and birch, different amounts of tannin, as a retarder, had to be added. The poplar boards showed the highest bending strength, followed by those made from spruce and birch.     

Aromatic potential of Castanea sativa Mill. compared to Quercus species to be used in cooperage

The composition of volatile and semi-volatile compounds of chestnut (Castanea sativa Mill.) was studied and compared to oak wood species frequently used in cooperage (Quercus alba, Quercus petraea, Quercus robur and Quercus pyrenaica) to evaluate its aromatic potential. Chestnut was found to be a suitable wood for use in ageing processes, based on the large, diverse number of detected compounds (e.g., lactones, furanic compounds, terpenes, lignin derivatives and triterpenic compounds). Chestnut wood possessed high levels of volatile phenols and phenolic aldehydes, specifically vanillin and its derivatives. Each wood species exhibited a characteristic, quantifiable composition of volatile compounds, and therefore, the sensorial profile of each wood species is expected to be different. The levels of certain volatile compounds were also useful for discriminating among the studied wood species.     

Measurement of emissions from air pollution sources. 3. C1-C29 organic compounds from fireplace combustion of wood

Organic compound emission rates for volatile organic compounds (VOC), gas-phase semivolatile organic compounds, and particle-phase organic compounds are measured from residential fireplace combustion of wood. Firewood from a conifer tree (pine) and from two deciduous trees (oak and eucalyptus) is burned to determine organic compound emissions profiles for each wood type including the distribution of the alkanes, alkenes, aromatics, polycyclic aromatic hydrocarbons (PAH), phenol and substituted phenols, guaiacol and substituted guaiacol, syringol and substituted syringols, carbonyls, alkanoic acids, resin acids, and levoglucosan. Levoglucosan is the major constituent in the fine particulate emissions from all three wood types, contributing 18-30% of the fine particulate organic compound emissions. Guaiacol (2-methoxyphenol), and guaiacols with additional substituents at position 4 on the molecule, and resin acids are emitted in significant quantities from pine wood combustion. Syringol (2,6-dimethoxyphenol) and syringols with additional substituents at position 4 on the molecule are emitted in large amounts from oak and eucalyptus firewood combustion, but these compounds are not detected in the emissions from pine wood combustion. Syringol and most of the substituted syringols are found to be semivolatile compounds that are present in both the gas and particle phases, but two substituted syringols that have not been previously quantified in wood smoke emissions, propionylsyringol and butyrylsyringol, are found exclusively in the particle phase and can be used to help trace hardwood smoke particles in the atmosphere. Benzene, ethene, and acetylene are often used as tracers for motor vehicle exhaust in the urban atmosphere. The contribution of wood smoke to the ambient concentrations of benzene, ethene, and acetylene could lead to an overestimate of the contribution of motor vehicle tailpipe exhaust to atmospheric VOC concentrations.     

传统熏烤木材中木质素结构表征及其热解特性

为探究传统熏烤肉制品熏烤时所采用不同化学组成及结构的木材类型对产生有害物质多环芳烃的种类和生成量的影响,以传统熏烤肉制品生产时常用的松木、杨木、榉木、枣木、苹果木5种木材为研究对象,通过红外光谱、拉曼光谱、热重及热重-红外联用分析,考察5种木材中木质素的结构特征及其热解特性。结果表明：5种木材中木质素含量,以及木质素中愈创木基结构单元（G）、紫丁香基结构单元（S）含量均存在差异;热解过程基本可分为3个阶段,主要发生在200～500℃范围内,但是5种木质素的质量损失速率、质量损失温度、热解速率、热解温度均不同,说明不同木质素的热稳定性存在显著差异。熏烤木材中木质素含量,S/G结构含量及侧链结构上差异可导致其热稳定性的不同,而热解特性的不同则进一步影响多环芳烃等有害物的生成。     

不同乳酸菌发酵对酸菜的风味物质形成及品质指标的影响

为研究不同乳酸菌对于酸菜发酵效果的影响,以白菜为原料,采用植物乳杆菌（Lactobacillus plantarum）、干酪乳杆菌（Lactobacillus casei）和肠膜明串珠菌（Leuconostoc mesenteroides）作为发酵剂进行酸菜发酵,并分析不同乳酸菌发酵体系中的理化指标、感官指标和挥发性风味物质。结果表明,在发酵30 d时,肠膜明串珠菌（L. mesenteroides）发酵酸菜中pH值（3.28）和还原糖含量（2.14 g/L）最低,总酸含量（8.69 g/L）最高,但亚硝酸盐含量无显著差异（P＞0.05）。肠膜明串珠菌（L. mesenteroides）发酵酸菜中乳酸（7.59 g/L）和柠檬酸（1.84 g/L）含量最高,且乳酸占总有机酸的65%。3种乳酸菌发酵酸菜中共检出挥发性风味物质65种,主要包括醛类13种、酯类12种、酸类12种、醇类7种、异硫氰酸酯类5种和酮类4种。主成分分析（PCA）结果表明,不同乳酸菌发酵酸菜的挥发性物质种类和含量差异显著。     

Chemical investigations on boiling process waters in face veneer production

Boiling processes in veneer industry generate large amounts of process water replete with dissolved wood extractives. In the present study the chemical composition of boiling waters from 18 industrially treated wood species were investigated. Contamination levels of the boiling waters varied within a wide range depending on the different extractive contents of the processed wood species and operational conditions. Boiling wood species with high extractives content, heated over several days at temperatures above 80 °C, generate highly loaded waste waters with chemical oxygen demands (CODs) of up to 7000  mg l^-1. The determination of the elemental composition, using optical emission spectrometry (ICP-OES), showed iron contents of up to 10 mg l^-1. Phenolic compounds were in a range of 40 to 900 mg l^-1. Flavonoid compounds and phenolic acids were identified in the boiling waters by liquid chromatography (RP-HPLC-UV). The results confirm the need for water treatment facilities to establish a recycling process and to avoid discolourations of the wood by accumulated wood extractives.