漆酶活化木材产生活性氧类自由基的处理条件研究

自由基对漆酶活化木材产生胶合力起着关键性的作用。通过试验分析反应体系pH值、处理温度、酶用量、处理时间及树种等因子，对漆酶处理木粉产生的活性氧类自由基的相对浓度的影响。研究结果表明：5个因子均对活性氧类自由基相对浓度有极显著影响。当采用思茅松心材木粉、处理4h、反应体系pH值为4、酶用量为1．5u／g木粉、处理温度为60℃时，漆酶活化木材产生的活性氧类自由基的相对浓度最高。     

明代南京船厂造船用材的鉴定与比较分析

对明代龙江船厂遗址出土的51个木材样本进行了树种鉴定,分析该遗址造船所用木材的树种及其来源,同时从用材的角度与宝船厂出土的造船用材树种进行了比较,并对我国古代常用造船树种选择的原因进行了分析。鉴定结果表明:龙江船厂出土木材共有9类树种,木材主要来源于长江流域及以南地区,多为我国重要的传统造船用材。其中,使用量最大的为红锥占50.98%,其次为杉木占27.45%。与宝船厂出土造船木材树种比较表明,古人不仅了解多种木材的性质,还能够针对不同船只的建造合理地选择木材。     

14个菇木树种生长量分析

对１４个菇木材种生长规律及分龄阶生长速度进行对比分析，结果按生物量、萌芽力、适应性、生长速度、种源和抗性为标准可分为３类，Ⅰ类优良菇木树种—桤木、杜英、拟赤杨、细柄蕈树，Ⅱ类优良菇木树种—南酸枣、枫香、南岭栲、钩栗、甜槠；Ⅲ类优良菇木树种—苦槠、锥栗、石栎、光皮桦、山合欢。     

水泥刨花板（CPB）生产中原辅材料适应性的评估方法与装置

ＣＰＢ生产中原辅材料的质量包括水泥的品种、树种、化学助剂的种类等直接影响水泥刨花板的质量，为寻找一种简单、快速、有效的评估方法及相应的装置，可在生产前对原辅材料进行适应性检测。研究结果表明：水泥－木屑混合物的最高水化温度△Ｔ及到达这一温度的时间△ｔ可以做为评价原辅材料适应性的指标。     

Ⅰ—214、沙兰杨、欧美杨的引种和栽培

为扩大我县优良树种资源,加速实现园林化,尽快改变木材奇缺的局面,自1963年以来,大沙河林场和本所先后开展引种试验,引进杨树90个品种,包括欧美杨类,小美杨类和白杨派杂交种。其中,Ⅰ—214杨、沙兰杨和欧美杨生长最快,在生产上已经推广,并收到显著增益。现将这三品种引种及栽培情况综述如下。     

高温热处理对欧洲云杉和花旗松吸湿特性的影响

研究了高温热处理对欧洲云杉和花旗松平衡含水率及吸湿特性的影响。采用水蒸气作为保护介质,设定160,180,200和220℃4个温度条件下进行高温热处理2 h,以双室温、湿度控制法获得等温吸附曲线,并采用GAB模型拟合,分析高温热处理对木材水蒸气等温吸附曲线线型、平衡含水率、有效比表面积的影响。结果表明:高温热处理可以显著降低2个树种试样的吸湿平衡含水率,处理温度越高,平衡含水率下降值越明显,220℃处理后试样的平衡含水率相较于未处理材的平衡含水率下降可达40%以上;利用GAB吸附模型能够较好地描述高温热处理欧洲云杉木材和花旗松木材的等温吸附过程,等温吸附线拟合度较高(拟合度决定系数均高于0.98)。高温热处理并未改变木材等温吸附线的线型,高温热处理试样和未处理试样均呈现第2类等温吸附曲线特征,但热处理会影响等温吸附曲线斜率;高温热处理后2个树种试样的有效比表面积显著降低,处理温度越高,有效比表面积下降值越明显,且试样高温热处理后比表面积相较于素材的下降比例与平衡含水率受高温热处理的影响相近。本研究可为热处理木材吸湿特性科学评价及实际高温热处理木材生产提供参考。     

热处理温度对不同树种木材材色影响的研究

以热处理木材生产企业常用3种树种为研究对象,通过研究热处理温度对宏观材色、基本材色指数和色差的影响,分析树种对热处理温度反应存在的差异以及内在相关性。结果表明:相同处理条件下,不同树种材色变化存在显著差异,明度受处理温度影响规律性最为明显,是对热处理温度最为敏感的材色参数,对色差的影响系数较高。     

24个乔灌树种苗期蒸腾强度的初步研究

本项研究用快速称重法测定了油松、侧柏、白榆、山杏、黄刺玫、沙棘等24个乔灌树种苗期的蒸腾强度,按树种建立了蒸腾强度与空气温度、相对湿度、风速、照度等气象因子间的回归方程,进行了聚类分析。按蒸腾强度的大小,将24个参试树种聚成了4类,经检验分析,各类间的差异是非常显著的。     

柠檬桉水泥刨花板若干工艺因子的研究

通过对柠檬桉制造水泥刨花板的可能性、水泥/刨花的比率、水泥种类与板材性能关系等因素的研究,结果表明:使用添加剂或对木材进行热水处理可以使柠檬桉成为适宜制造水泥刨花板的树种。     

相思类树种木材的资源、材性与加工利用

相思类树种生长速度快，适应性强，在我国南方广泛引种栽培。通过对其木材的解剖特征、天然耐腐性、干燥特性、制浆造纸性能以及人造板和细木工等加工性能的分析，结果显示，相思类树种木材不但是优良的纸浆材原料之一，而且多数树种木材也是生产人造板和实木家具等的较好原料。     

Hydration behavior of wood cement-based composite I: evaluation of wood species effects on compatibility and strength with ordinary portland cement

As an essential preliminary evaluation for understanding the hydration behavior of wood-cement-water mixtures, an isothermal calorimetry and experimental method were used to measure the hydration heat of woodcement-water mixtures. The compatibility of 38 wood species with ordinary portland cement was studied using this procedure. Based on the results, all the wood species tested were classified into two groups. The 24 species included in the first group showed a moderating influence on the hydration reaction of cement, and a maximum temperature (T _max) peak during the exothermic reaction while the cement set appeared within 24h for each species. The other 14 species inhibited cement hydration completely. According to the maximum hydration temperature (T _max) and the time (T _max) required to reach the maximum temperature of the mixture, the suitability of each species in the first group was estimated when used as a raw material during production of cement-bonded particleboard. By testing mechanical properties [modulus of rupture (MOR) and internal bonding strength (IB)] during the board-making experiment using the same composition of wood-cement-water, a positive correlation was found betweenT _max andt _max and MOR and IB. The results imply that the method can be used as a predictor of the general inhibitory properties and feasibility of using wood species as raw materials prior to manufacture of cement-bonded particleboard.Part of this report was presented at the 49th annual meeting of the Japan Wood Research Society, Tokyo, April 1999     

Study of hydration behavior of wood cement-based composite II: effect of chemical additives on the hydration characteristics and strengths of wood-cement composites

The influence of the 30 chemical additives on the hydration characteristics of birch wood-cement-water mixture was determined by measuring the maximum hydration temperature (T _max) and the time (t _max) required to reach the temperature. The chemical additives were tested and divided into two types depending on the pattern of exothermic reaction peak within the 24-h observation period. The wood-cement-water mixtures with additions of each of the 11 type I chemical additives showed a two-peak temperature-time curve similar to that for neat cement. CaCl₂, FeCl₃, and SnCl₂ reached the highestT _max above 50°C. When the 19 type II chemical additives were included, the mixtures offered only one peak hydration temperature-time curve. Among them, the 10 chemical additives caused an obvious temperature increase at the beginning of the hydration reaction. The most significant effect was with the addition of diethanolamine, where the mixture produced aT _max above 50°C. The strength values (modulus of rupture, internal bond strength) of word-cement board were tested with separate additions of the 10 chemical additives arranged by the highestT _max. There was a good positive correlation betweenT _max and the strength values. In addition, the composite chemical additives were preliminarily examined to determine if they accelerated the hydration reaction of blast-furnace slag cement. The results revealed that composite chemical additives evidently accelerated the hydration reaction and the setting of blast-furnace slag cement mixed with wood. Blast-furnace slag cement can thus be considered for use as an acceptable inorganic bonding material for wood-cement panel manufacture.Part of this report was presented at the 49th Annual Meeting of the Japan Wood Research Society, Tokyo, April 1999     

Characterizing the setting of cement when mixed with cork, blue gum, or maritime pine, grown in Portugal II: X-ray diffraction and differential thermal analyzes

It is already known by the scientific and industrial communities that lignocellulosic substrates are, to a certain extent, inhibitors of the hydration reaction of cement. The extent to which and how they influence such reactions is still a matter of debate. Several techniques, such as calorimetry, i.e., the measurement of the heat evolved or obtaining temperature profiles during the hydration, the determination of extractive contents of lignocellulosic substrates and their relation with the characteristics of the hydration curves, or even testing of the mechanical properties of the wood-cement composites, have been used in previous research. This study complements past research using two techniques that have been used in the analysis of cement hydration but are not usually applied to lignocellulose-cement mixes, namely X-ray diffraction (XRD) and differential thermal analysis (DTA). The raw materials for this study were three lignocellulosic materials of Portuguese origin: cork (the bark of Quercus suber L.), blue gum (Eucalyptus globulus Labill.), and maritime pine (Pinus pinaster Ait); and Portland cement. The two techniques allowed tracking of the evolution of the main cement constituents during hydration. It was found that all the lignocellulosic substrates had detrimental effects on cement hydration. The blue gum exhibited the fastest hydration kinetics in the initial stage of reaction, but was then overtaken by cork, which at the end gave the highest hydration conversion amongst the three lignocellulosic substrates. Although pine caused the slowest initial hydration kinetics, with the passage of time its effect approached that of blue gum. At the end of the hydration period, specimens containing either species had similar quantities of hydration reaction products. The DTA and XRD results were consistent and are in good agreement with the temperature profiles and compatibility indexes reported in a previous work.     

A new technique to classify the compatibility of wood with cement

Summary Wood-cement panels have commanded renewed interest during the last decade because of their potential application in the building industry. Several methods to classify wood of various species regarding its compatibility with cement have been established in the literature based on hydration measurements in Dewar flasks. These ranking methods lack consistency in the classification of species because the hydration conditions vary among laboratories. Three techniques for evaluating wood-cement compatibility were established and compared. The best technique is based on a wood-cement compatibility factor which is the ratio of the area under the wood-cement hydration heat rate curve to that of neat cement. The area is calculated on 24-h basis starting from the initial cement set time. This area ratio method ranks species over a 100% scale and accounts well for species that are totally incompatible.This research was supported in part by the U.S. Agency for International Development under contract number 608-0160 administered by the Hassan II Institute of Agronomy and Veterinary Sciences, Morocco, and the University of Minnesota, USA     

竹材—水泥混合物水化特性初探

本文论述湖南省4种竹材:楠竹、斑竹、慈竹、杂竹与水泥及水混合时的水化反应特性,以及化学助凝剂和竹材预处理方法(包括冷水处理、热水处理和氫氧化钠溶液处理)对竹材—水泥混合物水化特性的影响。     

Hydration behavior and compressive strength of cement mixed with exploded wood fiber strand obtained by the water-vapor explosion process

Poor compatibility was found between exploded wood fiber strand (WFS) and cement due to the excessive presence of water-soluble degraded polysaccharides in extractives of exploded WFS obtained from weathered wood waste treated by the water-vapor explosion process (WVEP). This study presents some comparative results from a continuing investigation on the compressive strengths of exploded WFS–cement mixtures. Based on results previously obtained with the hydration test, the relation between hydration behavior and compressive strength of the mixture was explored. In addition, the effect of the curing age on compressive strength development of the mixture with selected additive chemicals was examined. The results supported the results of early studies with hydration tests indicating that adding MgCl₂ to the mixtures of exploded WFS mixed with quick-curing cement or ordinary Portland cement and a composite of MgCl₂ + CaO added to the mixture of exploded WFS and furnace-slag cement effectively improved the hydration behaviors; it greatly enhanced the compressive strengths of mixtures as well. Compressive strengths were strongly correlated to maximum hydration temperatures (T_max) of wood–cement mixtures influenced by the cement type, wood wastes (treated or not with WVEP), additive chemicals, and their content levels. The results also indicated that adding selected chemicals had no significant effect on compressive strength among the mixtures of exploded WFS mixed, respectively, with three types of cement at a curing age of 180 days. X-ray diffraction, scanning electron microscopy, and energy dispersive X-ray spectroscopy were used to identify the hydration products and to probe the element distribution of the mixture in the wood–cement interface zone from a fractured surface.Part of this report was presented at the 52nd Annual Meeting of the Japan Wood Research Society, Gifu, April 2002     

Rapid production of high-strength cement-bonded particleboard using gaseous or supercritical carbon dioxide

This study deals with the effects of curing treatment with gaseous and supercritical carbon dioxide on the properties of cement-bonded particleboard (CBP) manufactured by the conventional cold-pressing method. The hydration of cement and the mechanism of improvement were examined using X-ray diffractometry (XRD), thermal gravimetry (TG-DTG), and scanning electron microscopy (SEM) observations. The results are as follows: (1) The curing of cement was accelerated concomitantly with the improvement in mechanical and dimensional properties of CBP significantly by curing with gaseous or supercritical carbon dioxide. (2) Supercritical carbon dioxide curing imparted boards optimal properties at a faster rate than did gaseous curing. (3) Accelerated formation of calcium silicate hydrate and calcium carbonate and the interlocking of those hydration products on the wood surface are potentially the main reasons for the superior strength of carbon dioxide-cured boards.     

Effect of carbon dioxide-air concentration in the rapid curing process on the properties of cement-bonded particleboard

This study deals with the effects of carbon dioxide (CO₂)-air concentration in the rapid curing method on the properties of cement-bonded particleboard manufactured using conventional cold pressing as the setting method. The hydration of cement was examined using X-ray diffractometry, thermal gravimetry, and scanning electron microscopy. The results are as follows: (1) The properties of CO₂-cured boards improved with increasing CO₂ concentration. When 10% or 20% CO₂ was applied for 10 min of curing time, the properties of the CO₂-cured boards were comparable to those obtained by conventional 2-week curing. (2) The hydration process of cement could be accelerated within several minutes using CO₂ curing, even with a low concentration of 10%–20% CO₂; a reduction in calcium hydroxide was observed followed by rapid formation of calcium carbonate.     

Study of hydration behaviors of wood-cement mixtures: compatibility of cement mixed with wood fiber strand obtained by the water-vapor explosion process

To provide information on the feasibility of using exploded wood fiber strand (WFS) obtained by the water-vapor explosion process in wood-cement mixtures, the compatibility between cement and exploded WFS and its improvement with various additive chemicals were investigated by observation and analysis on hydration behaviors in terms of hydration characteristics: maximum hydration temperature (T _max) and required time (t _max). The three types of cement, six additive chemicals, and exploded WFS (sugi, air-dried and water-soaked) were employed as raw materials in this study. The hydration behaviors of mixtures demonstrated that exploded WFS had strong retarding effects on cement hydration and completely prevented mixtures from setting. The analysis of sugar revealed that the sugar contents of exploded WFS were much higher than those in unexploded wood and increased to about 20-fold (air-dried) and 10-fold (water-soaked), respectively. The degraded polysaccharides became a major factor and played an important role in inhibiting the setting of cement. Moreover, high-performance liquid chromatography analysis proved that the main peaks representing the molecular weight of polysaccharides in extractives of exploded WFS shifted markedly to a lower range of polymerization. MgCl₂ was determined to be an effective additive chemical for restraining the inhibitory influences. Addition contents of 2%–3% and 4%–5% were available and acceptable for quick-curing cement and ordinary Portland cement, respectively. As for the furnace-slag cement, the composite additive chemicals of MgCl₂ (4%) and CaO (2%) were found to have an obvious accelerating effect.Part of this report was presented at the 51th Annual Meeting of the Japan Wood Research Society, Tokyo, April 2001     

A preliminary investigation on microstructural characteristics of interfacial zone between cement and exploded wood fiber strand by using SEM-EDS

The hydration behavior and strength performance of cement mixed with exploded wood fiber strand (WFS) obtained by the water-vapor explosion process have been studied previously. In the current study, the microstructural characteristics of cement–exploded WFS interfacial zone were examined using scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS). The Ca/Si ratios at the interfacial zones and the elemental compositions of hydration products deposited in the tracheid lumen were investigated. In addition, the morphological differences and compositional variations of hydration products that developed on the wood surfaces were examined. The results revealed that the Ca/Si ratios at the interfacial zones were strongly influenced by the mixture compositions, and that the elemental compositions of the hydration products that filled the tracheid lumen were significantly different from those of the cement paste in the mixtures. Differences in morphology and composition of hydration products at the wood surfaces were also observed to correspond to the different mixture compositions. These characteristics are considered to be directly related to the bond property, and thus, to the mechanical performance of WCM.Part of this report was presented at the 53rd Annual Meeting of the Japan Wood Research Society, Fukuoka, March 2003