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1.
《Wood material science & engineering》2013,8(2):59-68
Abstract Chitosan is a biopolymer derived from chitin in crustacean shells. Over the past decade it has been studied as an environmentally benign wood-protecting agent. It is assumed to act as a fungi-stat against a wide range of fungi and even as a fungicide at higher concentrations. This study investigated the properties of wood treated with modified chitosan of different molecular weights. Scots pine (Pinus sylvestris L.) and beech (Fagus sylvatica L.) samples were impregnated with two chitosan solutions differing in their average molecular weights. The chitosan solutions were depolymerized by nitrous acid to one solution of high molecular weight and one solution of low molecular weight with a concentration of 5% (w/v). The results show changes in sorption properties, antifungal properties, fire-retardant properties and mechanical properties of modified chitosan-treated wood. Heat-modified, chitosan-treated wood showed similar properties to chitosan-treated wood, except for brownish coloration, enhanced hydrophobation, and slightly reduced antifungal and fire-retardant properties. The modulus of rupture and hardness showed little or no change. The modulus of elasticity of the heat-modified, chitosan-treated wood increased by 27% compared with untreated wood. 相似文献
2.
Morten Eikenes Gry Alfredsen Bjørn Erik Christensen Holger Militz Halvor Solheim 《Journal of Wood Science》2005,51(4):387-394
Fungi cause serious problems in wood utilization, and environmentally benign wood protection is required as an alternative to traditional chemicals. Chitosan has shown promising antimicrobial properties against several microorganisms. In this study, we present the characterization of and antifungal properties of a commercial chitosan formulation developed for impregnation of wood. A broad range of chemical and mycological methods were used to evaluate the uptake, fixation, and antifungal properties of chitosan for wood preservation. The results show that the higher the uptake of chitosan the lower the relative recovery of chitosan in wood after leaching, and the higher the molecular weight of chitosan the higher the recovery. Chitosan with high molecular weight proved to be more efficient against decay fungi than chitosan with low molecular weight. The fungi tested on chitosan-amended nutrient agar medium were totally inhibited at 1% (w/v) concentration. In decay studies using small wood blocks, 4.8% (w/v) chitosan concentration gave the best protection against brown rot fungi. 相似文献
3.
《Wood material science & engineering》2006,1(3):138-145
When using chitosan as an antifungal agent in wood it is important to understand which factors contribute to a higher fixation ratio to optimize the utilization of chitosan, the active component. Small pine samples were impregnated with chitosan solutions varying in molecular weight, concentration, pH, polymerization agent, acid and degree of deacetylation. Different post-treatments such as time, temperature, moisture content and the effect of present air were applied to the samples to evaluate the effect on the relative retention. After impregnation, the samples, with a volume of 1.5 cm3, were leached in separate test-tubes according to EN-84. The samples were prepared in a paired design where both samples were impregnated, but only one was leached. Both leached and unleached samples were analysed for their chitosan content, and the relative ratio was used as a measure for the relative retention of chitosan during leaching. The results from these trials show that pH in the range of 5.1-5.9 is favourable. The molecular weight should be as high as possible yet able to penetrate the wood structure, and the use of acetic acid gives far better fixation than the use of hydrochloric acid. 相似文献
4.
The effects of a Maillard reaction between glucose and chitosan on the resultant chitosan films and the bonding properties
of chitosans with different molecular weights were investigated. In film preparation, chitosan and glucose were dissolved
in 1% acetic acid and dried in a Petri dish at 50°C. The bonding properties of the Maillard-reacted chitosan in three-ply
plywood were evaluated by a tensile shear test. The weight, color, free amino groups, insoluble fraction, and thermal properties
of the film changed significantly as the amount of added glucose increased. However, few differences in these properties due
to the use of chitosan of different molecular weights were observed. The effect of glucose addition on the tensile strength
of the film differed for chitosans of different molecular weights. Improvement of the strength by 10 wt% glucose addition
was observed in low-molecular-weight chitosans. The dry- and wet-bond strengths were significantly enhanced with increasing
glucose addition for low-molecular-weight chitosans. In addition, good bond strength was maintained even in 1% acetic acid
solution. It was thus clarified that the bonding properties of low-molecular-weight chitosan were improved markedly by the
environmentally safe method of glucose addition. 相似文献
5.
《Wood material science & engineering》2013,8(3-4):138-145
Abstract When using chitosan as an antifungal agent in wood it is important to understand which factors contribute to a higher fixation ratio to optimize the utilization of chitosan, the active component. Small pine samples were impregnated with chitosan solutions varying in molecular weight, concentration, pH, polymerization agent, acid and degree of deacetylation. Different post-treatments such as time, temperature, moisture content and the effect of present air were applied to the samples to evaluate the effect on the relative retention. After impregnation, the samples, with a volume of 1.5 cm3, were leached in separate test-tubes according to EN-84. The samples were prepared in a paired design where both samples were impregnated, but only one was leached. Both leached and unleached samples were analysed for their chitosan content, and the relative ratio was used as a measure for the relative retention of chitosan during leaching. The results from these trials show that pH in the range of 5.1–5.9 is favourable. The molecular weight should be as high as possible yet able to penetrate the wood structure, and the use of acetic acid gives far better fixation than the use of hydrochloric acid. 相似文献
6.
选用新型木材阻燃剂SLB对马尾松和南洋楹两种木材进行了阻燃处理,并用氧指数法和木垛法对处理后木材的阻燃性能进行了测试。结果表明：用SLB阻燃剂处理木材,载药量达到40 kg/m^3以上时,阻燃性能达到相关标准的要求,阻燃效果随着载药量的增大而增强。在载药量相近时,南洋楹木材比马尾松木材的阻燃效果显著。 相似文献
7.
The structural theory for cantilever beams was used to calculate the diameters and dry weights of wood that unbranched shoots must produce to support their own weights. The study was done on Picea sitchensis (Bong.) Carr., Pinus contorta Dougl., Larix decidua Mill. and Betula pendula Roth. syn. verrucosa Ehrh. The weights of wood increased in a non-linear fashion with increase in shoot length. A large investment in wood (as measured by diameter and dry weight) was required to maintain a small endpoint deflection (1-5% of the length). By contrast, the degree of linear taper had only a small effect on support costs, as did the Young's modulus of the wood (over the range 1-4 GPa) and the angle of the shoot from the horizontal (over the range 0-45 degrees ). Current year's shoots on young trees of P. sitchensis and P. contorta incur a high support cost in order to maintain small (1-5%) deflections throughout the year: similar shoots of L. decidua and B. pendula have smaller support costs because they deflect by about 20% after leaf expansion in spring. 相似文献
8.
Guangjie Zhao Wensheng Luo T. Furuno Qiang Ren Erni Ma 《Frontiers of Forestry in China》2007,2(2):231-236
In order to investigate the pyrolytic characteristics of the burning residue of fire-retardant wood, a multifunctional fire-resistance
test oven aimed at simulating the course of a fire was used to burn fire-retardant wood and untreated wood. Samples at different
distances from the combustion surface were obtained and a thermogravimetric analysis (TG) was applied to test the prrolytic
process of the burning residue in an atmosphere of nitrogen. The results showed that: 1) there was little difference between
fire-retardant wood and its residue in the initial temperature of thermal degradation. The initial temperature of thermal
degradation of the combustion layer in untreated wood was higher than that in the no burning wood sample; 2) the temperature
of the flame retardant in fire-retardant wood was 200°C in the differential thermogravimetry (DTG). The peak belonging to
the flame retardant tended to dissipate during the time of burning; 3) for the burning residue of fire-retardant wood, the
peak belonging to hemicellulose near 230°C in the DTG disappeared and there was a gentle shoulder from 210 to 240°C; 4) the
temperature of the main peaks of the fire-retardant wood and its burning residue in DTG was 100°C lower than that of the untreated
wood and its burning residue. The rate of weight loss also decreased sharply; 5) the residual weight of fire-retardant wood
at 600°C clearly increased compared with that of untreated wood. Residual weight of the burning residue increased markedly
as the heating temperature increased when burning; 6) there was a considerable difference with respect to the thermal degradation
temperature of the no burning sample and the burning residue between fire-retardant wood and untreated wood.
__________
Translated from Journal of Beijing Forestry University, 2006, 28(3): 133–138 [译自: 北京林业大学学报] 相似文献
9.
10.
人工林软质木材表面密实化新技术 总被引：16，自引：7，他引：16
采用一种新型木材改性处理剂，分别以改性异氰酸酯浓度5％、10％、15％、20％，对美国人工林火炬松（Pinus taeda）进行表面密实化处理。结果表明，随着树脂浓度的增加，无论是冷水浸泡还是煮沸，木材的吸水厚度膨胀率和压缩变形恢复率明显降低。表面密实化后，火炬松处理材的MOR和MOE值分别比素材提高43．9％和30．1％；水浸24h和煮沸2h后的湿状抗弯性能比素材略低，干状抗弯性能明显比素材高，MOR分别高28．0％和25．76％；MOE分别高22．55％和27．79％。改性异氰酸酯浸渍处理后的表面密实化木材，具有一定的阻燃效果；表面耐磨耗性能和表面硬度亦明显改善。 相似文献
11.
Prabu?Satria?Sejati Aurélia?Imbert Christine?Gérardin-Charbonnier Stéphane?Dumar?ay Emmanuel?Fredon Eric?Masson Dodi?Nandika Trisna?Priadi Phillipe?Gérardin
European beech (Fagus sylvatica L.) is a major tree species of European forest which is underexploited because of its low dimensional stability and durability. Similarly to what has been developed with radiata pine, furfurylation might be the answer to optimize the utilization of local beech wood. Beech wood furfurylation process was studied using five different catalysts: maleic anhydride, maleic acid, citric acid, itaconic acid, and tartaric acid. Optimization of the furfurylation process was investigated for different catalyst and furfuryl alcohol (FA) contents, and different duration of polymerization. The following properties were studied: weight percent gain (WPG), leachability, anti-swelling efficiency (ASE), wettability, modulus of elasticity, modulus of rupture, Brinell hardness, and decay durability. Tartaric acid, never investigated up to now, was retained as catalyst to perform furfurylation due to its efficacy compared to other catalysts and its novelty. Wood modification with FA and tartaric acid as catalyst led to samples with high WPG even after leaching, improved ASE, and lower wettability with water. Increasing the polymerization duration increased the fixation of FA in treated wood. Most of all, treatment gave a significant improvement in mechanical properties and resistance to wood decaying fungi. 相似文献
12.
《Wood material science & engineering》2013,8(3-4):79-82
Abstract This research work presents a study on the properties of finger jointing green oak wood (Quercus conferta L.) using a one-component polyurethane adhesive. The effect of finger-joint orientation (vertical or horizontal fingers) was also examined. In general, the results from the measurements of modulus of rupture and modulus of elasticity of green-glued finger-jointed specimens indicated that the green gluing of a high-density species such as oak wood is feasible. 相似文献
13.
李晓东 《林业机械与木工设备》2005,33(12):7-11,14
本研究以ZR-M-301型木材阻燃剂为浸渍药液,樟子松和水曲柳为木材试样,选择常压浸渍、压力浸渍、微波处理后常压浸渍、超声波加压浸渍和微波处理后超声波加压浸渍五种木材阻燃处理方法,经过试验,探索在生产阻燃木材的浸渍方法中引入微波和超声波技术的可行性,找到效果好的木材阻燃处理方法.本研究的创新点是将微波处理与超声波辐射技术应用于木材阻燃处理中,利用微波加热处理改善木材构造的渗透性能,利用超声波的空化作用强化阻燃剂浸入性能,并提出了新的技术路线. 相似文献
14.
FRW阻燃胶合板的DMA分析 总被引：7，自引：0，他引：7
目前世界范围内木材资源短缺的情况日益加剧,发展人造板工业已成为世界各国解决木材资源严重不足的重要途径.其中,胶合板作为室内装饰的主要材料,其产量和需求量都在急剧增长.我国胶合板产量从1980年的33.00万m3增长到2004年的2 098.62万m3,呈现大幅度增长的趋势(张文标等,2000).但由于普通胶合板具有易燃性,在许多领域的应用上受到限制.因为一旦发生火灾,不仅造成重大的经济损失,而且往往会发生人员伤亡.1950-2003年全国共发生火灾4 177 730起,直接经济损失2 434.525 1亿元,因火灾死亡174 855人,受伤329 352人. 相似文献
15.
The structural theory for cantilever beams was used to calculate the dry weight of wood that a branch of Picea sitchensis (Bong.) Carr. must produce to support its own weight plus that of laterals in different positions and numbers, and with different angles and deflections. The endpoint of the branch was maintained at 2% of its length, and constant values or functions (measured on real branches) were assumed for Young's modulus, taper and self weights of wood and foliage. Support costs (branch wood dry weights) were minimized when laterals were positioned so that the center of gravity was close to the base of the branch, and when the branch was angled upward from the horizontal. Small savings in support costs also resulted when laterals were not forward pointing, were angled upward and had endpoint deflections of at least 20% of their length. 相似文献
16.
Andrés Dieste Andreas Krause Carsten Mai Holger Militz 《Wood Science and Technology》2010,44(4):597-606
Beech wood (Fagus sylvatica L.) was modified with 1,3-dimethylol-4,5-dihydroxyethyleneurea (DMDHEU). The equilibrium moisture content (EMC) of wood modified
with DMDHEU calculated on a dry modified basis is reduced. Previous results have shown that the modification with DMDHEU does
not alter the capillary condensation; therefore, the reduction in EMC seems exaggerated. The equilibrium constants of the
Hailwood–Horrobin model (K
d and K
h) and the molecular weight of a hypothetical polymer of modified wood capable of adsorbing one molecule of water (W
i) were calculated from the EMC on a dry modified wood basis (M) and on a dry wood basis (M
R). The hypothetical polymer was also calculated by stoichiometry (W
c) and compared to W
i to estimate the number of operative OH groups. The number of operative OH groups decreased when M was used, in contradiction with the previously obtained results of differential heat of adsorption (∆H
s). Therefore, the use of M
R is recommended for the analysis of moisture sorption in wood modified with DMDHEU. 相似文献
17.
The aim of this study was to use energy-dispersive X-ray spectroscopy (EDX) to localize chitosan in the cell wall of chitosan-impregnated
Scots pine. It was of interest to investigate the concentration of chitosan in wood to gain further knowledge and understanding
of the distribution of chitosan in the wooden matrix. After deacetylation, chitosan was re-acetylated with chloroacetic anhydride
to achieve a covalent bonding of chloride to the chitosan polymer. Chloride-labelled chitosan was measured by EDX using a
scanning electron microscope and described as chloride intensity. Analysis of free chloride anions was performed by dialysis
and inductively coupled plasma atomic emission spectroscopy. There was a significant correlation between the molecular weight
of chitosan and the intensity of covalent-bonded chloride to the chitosan polymer. High molecular weight chitosan showed a
better interaction with the cell wall structure than low molecular chitosan. 相似文献
18.
Kazuya Minato Yuji Konaka Iris Bremaud Shiro Suzuki Eiichi Obataya 《Journal of Wood Science》2010,56(1):41-46
The potential of muirapiranga (Brosimun sp.) as a substitute material for violin bows was estimated in terms of vibrational properties, and the influence of extractives
on the vibrational properties was examined. The loss tangent of muirapiranga was somewhat higher and the specific dynamic
Young’s modulus was rather lower than the respective values for pernambuco, which is regarded as the best material for violin
bows. Therefore, muirapiranga is a poorer bow material in terms of vibrational properties. Impregnation of crude extractives
from muirapiranga decreased the loss tangent of other wood specimens. The main compounds of the extractives were identified
as xanthyletin and luvangetin. Impregnations of isolated xanthyletin and commercially available methoxsalen, which was tested
as an analogue of luvangetin, markedly decreased the loss tangent of other wood specimens. Methoxsalen and xanthyletin differ
from conventional loss tangent-decreasing substances, namely protosappanin B and hematoxylin, in terms of water insolubility
and the absence of hydroxyl groups. From the similarity in molecular characteristics of loss tangent-decreasing substances
found so far, restriction of molecular motion due to an impregnated substance in the wood matrix is suggested as one loss
tangent-decreasing mechanism. 相似文献
19.
20.
木材阻燃剂FRW的阻燃机理 总被引：10，自引：2，他引：10
在综合分析热分析法、锥形量热仪法和FTIR法获得的FRW阻燃机理研究结果并吸收木材阻燃机理研究现有成果的基础上,推导进而提出了木材阻燃剂FRW的阻燃机理。其主要内容是:1)FRW阻燃木材受热时,阻燃剂FRW分解产生不燃性气体和不挥发的酸性熔融物质,具有降低体系温度和氧气浓度及屏蔽热辐射的作用,降低了木材的热解速度;2)FRW的组分硼酸和GUP的酸性分解产物催化木材脱水、降解,以及木材热解产物的缩合、聚合、芳构化等反应,能改变木材的热解途径并使其向着有利于炭化的方向变化,FRW显著的催化成炭作用,使阻燃木材的燃烧放热量大大降低,这是FRW阻燃机理的主要方面;3)硼酸与GUP起阻燃作用的温度和方式不同,并且有相互补充的作用,因而表现出阻燃协同效应。 相似文献