糠醇化对橡胶木性质的影响

以平衡含水率(EMC)和线性湿涨系数(LSC)为评价指标,研究了不同质量增加率(WPG)的糠醇改性对橡胶木吸湿尺寸稳定性的影响,并从尺寸稳定性角度探讨糠醇改性的临界WPG;还分析了糠醇改性对抗弯强度(MOR)和抗弯弹性模量(MOE)的影响,并探讨了减量平衡含水率(EMCR)衡量浸渍改性材吸湿性的可行性.结果表明:糠醇化可以显著降低橡胶木的EMC和LSC,EMC受WPG的影响明显,LSC随着WPG的增加而显著下降,基于LSC和胞壁充涨系数推导的临界WPG两者之间存在较大误差;改性材的MOE随WPG提高而增加,增幅约在30％ ～40％,但MOR却略有下降;与基于浸渍材绝干质量的EMC相比,基于浸渍前绝干质量的EMCR能更客观地评价浸渍改性后木材的吸湿能力,可用于吸湿性的研究中,但鉴于用户和第三方检测不方便,不推荐其作为改性产品的评价指标.     

Estimation of rubberwood production in Cambodia

We estimated the production of rubberwood from 1996 to 2011 in Cambodia. We employed data from interview surveys with three rubberwood processing companies and statistics from estate rubber plantations and wood retailing companies. The result was that the end use of rubberwood in Cambodia was the sawntimber products, being exported to Vietnam and China. The yield rate from rubberwood stumpage into sawn timber was between 11.6 and 14.9%, closely matching the rates of Malaysia and Thailand. The average production of rubberwood roundwood from 1996 to 2011 was 254,697 m³/year, of which sawn timber as well as residuals in secondary processing was 84,559 and 170,138 m³/year, respectively. Although the timber production of Cambodia has declined sharply due to the strict restriction of natural forest logging, rubberwood could explain more than 60% of the domestic industrial roundwood production from 2000. We suggest the necessity of monitoring the expansion of rubber plantations in new rubber producing countries and linking the rubberwood production with the regional wood resource management.     

Asynchronous wood formation in youngAcacia mangium planted in Malaysia

In general, tropical trees have less-distinct growth rings. Even if the trees have some concentric structures, there is little information on the timing of their formation. The objective of this report is to show the asynchronous wood formation from the observation of indistinct, ring-like structures. YoungAcacia mangium planted in Malaysia was investigated for asynchronous wood formation anatomically and macroscopically. Tree heights and girths at breast height for 28 trees were measured every other week. Wood disks from four trees were sampled at breast height for this research. The radial variation of vessel dimensions and the number of cambial cells in different radial directions and the wood anatomy of discontinuous bands were investigated using thin sectioning and soft radiographic methods. The vessel dimension was quite different in their radial variation even for four radial directions with a similar radius. There was a large variation in the number of cambial cells among radial directions in youngAcacia mangium. Bands of low density included a layer of vessels aligned in a spiral rather than in a closed circle.     

Wood-boring beetles (Coleoptera: Bostrichidae,Curculionidae; Platypodinae and Scolytinae) infesting rubberwood sawn timber in southern Thailand

Species diversity and infestation densities of rubberwood (Hevea brasiliensis Müll. Arg.)-boring beetles at sawmills in southern Thailand were investigated during July 2007 and March 2008. Twenty-two species of wood-boring beetles, nine bostrichids, eight scolytines and five platypodines, were identified. The powder post beetle, Sinoxylon anale Lesne (40%), is the single dominant rubberwood pest in the studied area. Other frequently captured species are Sinoxylon unidentatum (Fabricius) (18%), Heterobostrychus aequalis (Waterhouse) (10%) and Lyctoxylon dentatum Lesne (9%). The Shannon diversity index of rubberwood-boring beetles in the eastern coastal area was significantly (p < 0.01) greater than that in the western coastal area. The infestation density in the dry season was significantly higher than that in the wet season, but there were no significant differences between eastern and western coastal areas.     

Micromorphology of abnormal and decayed xylem in rubberwood canker

Typical symptoms of rubberwood canker found in East Kalimantan, Indonesia, differ from those of conventional rubberwood peach canker. Rubberwood canker showed a conspicuous longitudinal canker with exposed xylem that was discolored and decayed. Bark wounds, resulting from regular tapping, were enclosed within the xylem, and the tissues had become integrated. The characteristics of abnormal and decayed xylem in this rubberwood canker were analyzed by light microscopy and scanning electron microscopy. Xylem in the vicinity of the enclosed bark contained fewer vessels of smaller diameter and shorter length, and significantly wider rays compared with normal xylem. Around the wide growth zones of the canker, axial cells were disoriented and warped toward the canker zones. In view of the separation among cells, and the concentric degradation of the cell walls starting from the lumen surfaces, decayed xylem appeared to be caused mainly by white-rot fungal attack.     

Radial variation of wood cell features under different stocking densities management of two new clones of rubberwood (Hevea brasiliensis)

Wood characteristics vary from pith to bark and this can influence the final use. These variations can be related to the effects of plantation management. The radial variation in fiber cells, vessel elements, and ray cells was investigated for a commercial and fast-grown species, the rubberwood (Hevea brasiliensis), at varying stocking densities. Nine-year-old trees of two new clones (RRIM 2020 and RRIM 2025) were categorized into four stocking densities of 500, 1000, 1500, and 2000 trees ha^?1. The sample blocks were anatomically analyzed to determine the changes in wood cells from pith to bark. The results generally showed a centrifugal increase in fiber features, vessel diameter, ray height, and ray area. Vessel density and ray density showed a decreasing trend. Vessel areas revealed a radial irregular variation. The ray area showed a striking relationship with ray density and ray height. Ray cell pattern indicated enough variation for visual approval to ensure within and between stocking density changes. Most radial variation was explained by the effect of cambial age. Owing to different stem width and growth rates, the mean cell features were not at the same radial distances from the pith.     

Rapid assessment of wood chemical properties and pulp yield of Eucalyptus camaldulensis in Thailand tree plantations by near infrared spectroscopy for improving wood selection for high quality pulp

Near-infrared (NIR) spectroscopy has been demonstrated as a means for rapid nondestructive determination of the chemical composition and final pulp yield of Eucalyptus camaldulensis in Thailand tree plantations. Multiple linear regression (MLR) analysis and partial least squares (PLS) analysis were introduced to develop statistical models in terms of calibration equations for total pulp yield, screened pulp yield, and contents of -cellulose, pentosans, and lignin in wood. In MLR analysis, a reasonably good calibration equation was found only for pentosans (standard error of prediction (SEP): 0.98%). The PLS analysis improved the accuracy of prediction for every criterion variable, especially for pentosans (SEP: 0.91%) and lignin (SEP: 0.52%). Also, in the case of screened pulp yield, we were able to use such a statistical result as an indicator of the characteristics of the pulp and paper. Thus, NIR spectroscopy could be satisfactorily used as an effective assessment technique for Eucalyptus camaldulensis plantation trees.     

Assessment of the properties,utilization, and preservation of rubberwood (<Emphasis Type="Italic">Hevea brasiliensis</Emphasis>): a case study in Malaysia

Rubber trees were introduced into the Malay Peninsula more than a century ago. The normal economical lifespan of a rubber tree is about 25 years, and, traditionally, rubberwood was used as firewood by the rural community. In recent decades, rubberwood has become an important timber for wood products, particularly in the furniture manufacturing sector, due to its attractive features, cream color, and good working properties. Sapstain, mold, and wooddecaying fungi are serious threats to rubberwood. Conventional chemical control has been a successful method of preventing staining fungal growth, but the effects of these chemicals are of concern because they create problems for the environment and public health. Thus, biological control has been recognized as an alternative approach to the problem. This article reviews the properties, potential utilization, and problems of protecting rubberwood against sapstain, mold, and wood-decaying fungi, and discusses the treatment methods available. Advances in biological control, particularly biofungicides, are emphasized as an alternative method for rubberwood treatment.     

在动态中把握市场的走向——2005年我国木材进出口情况点评及2006年走势预测

2005年我国进口木材（包括原木、锯材、薄板、胶合板、纤维板、刨花板、枕木）3683．1万m^3，比上年3402．53万m^3，增加280．57万m^3，增幅8．25％；进口总值539 511万美元，比上年494 927万美元，增加44 584万美元，增幅9．01％．     

Thermo-directional movement of wood and wood composites

Summary Thermal movement of wood and wood composites was studied and compared with that of random and oriented phenolic foams. Cell orientation was a dominate factor determining the thermal response of these structures. In dried wood, thermal movement in the direction parallel to the cells (longitudinal) decreased in dimension during heating while the radial and tangential directions expanded under similar heating condition. Oriented foams showed more restraint in thermal movement in the parallel to orientation direction. These findings indicate constraining forces act on the direction parallel to the cells while more flexibility exists in perpendicular directions. Wood element size and orientation and the manufacturing process also influence the thermal response in wood composites. The experimental results also revealed the potential fire hazard of waferboard type of composites.     

Differences in wood properties between juvenile wood and mature wood in 10 species grown in China

 This study examined the intrinsic differences in various wood properties between juvenile wood and mature wood in 10 major reforestation species in China. Comparisons between juvenile wood and mature wood were made in both plantation- and naturally-grown trees. Considerable differences in most wood properties were found both between plantation-grown juvenile wood and mature wood, and between naturally-grown juvenile wood and mature wood. This suggests that wood properties of plantation-grown trees, to a large extent, depends on their juvenile wood contents, and can thus be manipulated effectively through rotation age. In general, the longer the rotation age, the lower the juvenile wood content, and the stronger the mechanical properties of the plantation-grown woods. However, the differences between juvenile wood and mature wood vary with wood properties and species. In general, juvenile wood and mature wood have less difference in chemical composition than in anatomical and physico-mechanical properties. Compared to the softwoods studied, the hardwoods appear to have less difference between juvenile wood and mature wood. Received 25 June 1999     

木材干燥产生缺陷的预防措施及补救方法

缺陷对木材的加工及使用影响很大 ,本文对木材干燥产生的缺陷及产生的原因进行了探讨 ,提出干燥引起缺陷的预防措施。     

Differential calometric analysis of wood and wood components

Summary The prolysis of cellulose, hemicelluloses, lignin preparations, and wood was studied by differential calorimetric analysis (DCA) for the range of 25° to 800° C. The test samples included powdered and filter paper celluloses; hardwood xylan; softwood galactoglucomannans, compression wood galactan, and arabinogalactan; a synthetic (DHP), sulfuric acid, Björkman, Brownell, and cellulase lignins; and unextracted and extracted hardwoods and softwoods. Heats of reaction were determined from the DCA thermal transition areas. Distinct differences were found between the thermograms of each hemicellulose and lignin sample. Although wood species could not be separated thermally, hardwood and softwood thermograms differed because of the hemicellulose degradation pattern.Trade names and company names are included for the benefit of the reader and do not imply any endorsement or preferential treatment of the product by the U.S. Department of Agriculture.Formerly Research Technologist, Forest Products Laboratory, Forest Service, U.S. Department of Agriculture. The Laboratory is maintained at Madison, Wis. 53705, in cooperation with the University of Wisconsin. Present address: The Pennsylvania State University, University Park, Pennsylvania 16802.     

传统木材生产与效益木材生产

本探讨了传统木材生产和效益木材生产的区别，并从生产方式和经营模式上具体论述了传统木材生产和效益木材生产。     

Superheated steam treatment of rubberwood to enhance its mechanical,physiochemical, and biological properties

ABSTRACT

This research was aimed to investigate mechanical properties, color and cell-wall components changes, and durability of pre-dried rubberwood (Hevea brasiliensis) after superheated steam (SS) treatment. Wood samples were treated at different SS temperatures (140–180°C) for 1–3?h. The highest compression strength parallel-to-grain, hardness and impact strength were found for samples treated at 160°C for 3?h (30.7% higher than untreated), at 150°C for 1?h (26.6% higher than untreated) and at 150°C for 2?h (52.6% higher than untreated), respectively. The surface color became darker after each treatment in comparison with the untreated wood. The number of accessible hydroxyl groups decreased and the relative cellulose crystallinity increased with SS temperature, indicating decreased hygroscopicity of the treated wood. Also, SEM micrographs of wood surface showed consistent decrease in starch particles with treatment temperature. Both decay and termite resistances of treated rubberwood improved with treatment temperature. All the analyzes showed that dried rubberwood treated with SS had some improvements in the mechanical properties, decreased hygroscopicity, and increase resistance to decay.     

酯化、醚化木材及其应用

通过适当的化学改性反应如酯化、醚化等,可以使木材转化为热塑性高分子材料。这些热塑性材料可单独或与合成高聚物按比例混合热压加工成型为各种板材或其他成型产品,这对扩大木材的加工利用途径、充分利用木材加工剩余物、提高木材利用率等都具有十分重要的意义。本文介绍了酯化、醚化木材的主要方法,产品的特点,以及今后木材及纤维素酯化、醚化的发展方向。     

Chemical composition of wood and its connection with wood anatomy in Betula pubescens

ABSTRACT

The connection between chemical composition and anatomy of wood is poorly studied. Abiotic and biotic growth conditions affect the synthesis of structural compounds and the anatomy of wood at the same time as they affect growth. In this study, the wood chemical composition, and connections between wood chemistry and anatomy were studied in downy birch (Betula pubescens Ehrh.) grown on four growth sites possessing mineral and peat soils. Lignin, holocellulose, extractive and ash contents, and effective heating value were analysed and compared with libriform fibre double wall thickness and lumen diameter, vessel size and number, and ray and axial parenchyma numbers. Measured lignin and extractive contents were exceptionally high and holocellulose content low. Correlations between wood anatomy and effective heating value were partly different on different soils. Correlations between holocellulose and anatomy were the opposite of the correlations between other chemical compounds and anatomy. The significant correlations between chemical composition and anatomy were commonly opposite in trees grown on peat than in trees grown on mineral soil. Particularly, vessel characteristics and fibre wall thickness correlated significantly with wood chemistry in trees grown on mineral soil. The connections between wood anatomy and chemistry proved to be soil-dependent.     

泰国藤家具及装饰品占主流

藤器是泰国家具中富吸引力而又廉价的一种。藤家具的朴素和优雅大受欢迎。有的以天然或色藤器配以玻璃、不锈钢或布艺大胆设计,是出口欧洲及太平洋一带的流行款式。无论是传统或现代的设计,摆放在日光浴室、餐厅,