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1.
To determine the independent decomposition rates of lignin and cellulose of decayed woody debris, a technique for the rapid analysis of lignin and cellulose is required. We applied a near-infrared spectroscopy (NIRS) technique to measure the lignin and holocellulose content in decayed wood. We succeeded in creating partial least-squares (PLS) models to estimate the lignin and holocellulose content in the decayed wood of five species using NIR spectra. Although the accuracy was acceptable for the estimation of a five-species mixed model (R 2 = 0.970 for lignin and R 2 = 0.962 for holocellulose), it was further improved when the model was applied to each species independently. This combination of NIRS and a PLS model is a valuable tool for the determination of the lignin and holocellulose content in decayed wood. The technique is time efficient (3 min per sample) and non-hazardous (no acid treatment is required). 相似文献
2.
In order to examine the contribution of wood components to the acetylation of wood, we acetylated wood meal that had been
partially delignified. The results were analyzed in terms of the reaction kinetics. The first-order rate equation was successfully
adjusted to the weight gain data. The rate constant for acetylation initially increased with progress of lignin elimination
and then turned to decrease; the apparent activation energy showed the reverse tendency and ranged from about 90 to 130 kJ/mol.
These results suggest that lignin elimination brings not only separation of lignin but also drastic change of the chemical
and/or physical structure in the residual lignin, and this affects the reactivity of wood meal as a whole. The ultimate weight
gain estimated by the regression of the rate equation showed a minimum when lignin was moderately eliminated, which was explained
in terms of enhanced reactivity of lignin and lower accessibility for holocellulose than predicted. The equilibrium moisture
content had a maximum when lignin was moderately eliminated. This tendency is the opposite of that observed for the ultimate
weight gain, and suggests that the sites for acetylation do not always correspond to those for moisture adsorption.
Part of this report was presented at the 54th Annual Meeting of the Japan Wood Research Society, Sapporo, August 2004 相似文献
3.
马尾松木材化学组分的遗传控制及对木材育种的意义 总被引：10，自引：0，他引：10
本文利用 1 3年生马尾松子代测定林的 2 0个自由授粉家系的木材试样 ,着重研究木材化学组分的遗传学问题。研究结果表明 ,木材化学组分、基本密度和生长性状在家系间的差异都达到了极显著水平 ,并受中等至强度的遗传控制。在 6个木材化学组分中 ,灰分、戊聚糖和 1 %NaOH抽出物含量的遗传力较高 ,木质素、综纤维素和热水抽出物含量的遗传力稍低。生长性状与木材密度呈显著的负相关 ,而与木材化学组分相关性很小 ,似相互独立。遗传相关认为灰分和热水抽出物含量可分别作为综纤维素和木质素的间接选择指标。由于综纤维素和木质素含量在家系间的绝对差异较小 ,仅为 2 %～ 3% ,对选育的实际意义不大。可选择综纤维素含量高的优株进行无性繁殖加以利用 相似文献
4.
Liquefaction and product identification of main chemical compositions of wood in phenol 总被引：3，自引：0，他引：3
Zhang Qiu-hui Zhao Guang-jie Jie Shu-jun 《中国林学(英文版)》2005,7(2):31-37
To clarify liquefaction ratios and their construction variations of the main chemical compositions of wood in phenol using phosphoric acid as a catalyst, the chemical ingredients of wood such as holocellulose, cellulose and lignin, were measured and extracted according to GB methods. With Fourier transform infrared （FTIR）, the product identification of reactant before and after liquefaction in phenol was investigated. The molecular weights and their distributions of the liquefaction results （acetone soluble parts） were studied by gel permeation chromatography （GPC）. Results show that the molecular weights and their distributions of poplar and Chinese fir are almost the same. In poplar, the distribution of cellulose is the largest, and that ofholocellulose the smallest after liquefaction. For Chinese fir, the distribution of holocellulose is the largest, and that of cellulose the smallest. After liquefaction of poplar cellulose, the change bands of FTIR spectrum observed below 1 600 cm^-1, can be attributed to new substitute groups. The same is true for poplar lignin. For Chinese fir, the spectra of liquefaction results of all chemical compositions differ from that of wood meal. This reveals the more activity groups were produced because of the reactions between Chinese fir and phenol. The research shows that the liquefaction ratios of poplar decrease in the following order： holocellulose 〉 lignin 〉 cellulose, and those of Chinese fir in the order： lignin 〉 cellulose 〉 holocellulose. 相似文献
5.
S. Lekounougou M. Pétrissans J. P. Jacquot E. Gelhaye P. Gérardin 《Wood Science and Technology》2009,43(3-4):331-341
Effect of heat treatment on extracellular enzymes involved in wood degradation by Trametes versicolor was investigated. Heat-treated and untreated beech blocks were exposed to T. versicolor on malt-agar medium and extracellular enzymatic activities investigated. A strong ABTS oxidizing activity has been detected during the first stage of colonization in both cases, while cellulase activities are mainly detected in the case of untreated beech wood. Further investigations carried out on holocellulose, isolated using sodium chlorite delignification procedure and subjected to heat treatment or not, indicate that commercially available cellulases and xylanases are able to hydrolyse untreated holocellulose, while heat-treated holocellulose was not affected. All these data suggest that chemical modifications of wood components during heat treatment disturb enzymatic system involved in wood degradation. 相似文献
6.
Eglin T Maunoury-Danger F Fresneau C Lelarge C Pollet B Lapierre C Francois C Damesin C 《Tree physiology》2008,28(11):1619-1628
From June to December, we determined the effects of variations in biochemical composition on delta(13)C of tree rings of 2-year-old oaks (Quercus petraea (Matt.) Liebl.) growing under semi-natural conditions, and the dependence of these effects of water stress during the growth season. Percent abundance, carbon concentration and delta(13)C were measured in holocellulose, lignin, extractive-free wood, starch and a water-soluble fraction. Relative concentrations of lignin and holocellulose in the extractive-free wood varied little during the season or in response to water stress, indicating that these compounds could not quantitatively explain the variations in whole-wood delta(13)C. Among all sampled tree rings, the relative concentration of each structural compound (holocellulose and lignin) accounted for less than 5% of the delta(13)C variability in whole wood. Variations in holocellulose and extractive-free wood delta(13)C between tree rings were almost identical (r > 0.95), whereas variations in lignin delta(13)C were less well correlated to these compounds. Whole-wood delta(13)C had a slightly altered isotopic signal compared with that of the structural compounds because of the presence of the extractive component. These results showed that variations in lignin delta(13)C and lignin concentration have little influence on extractive-free wood delta(13)C and whole-wood delta(13)C. Rather, holocellulose influences delta(13)C the most. Thus, we confirmed that, for climatic reconstruction from tree rings, removal of extractives by soxhlet is generally sufficient and sometimes unnecessary. Our findings also indicate that, in the case of rapid and severe water stress, the structural component did not accurately record the associated increase in delta(13)C because of dilution with previously formed organic matter and cessation of trunk growth. The effect of drought on carbon isotope ratios was more pronounced in the extractive compounds, making them good water stress indicators but only on a scale of days to months. 相似文献
7.
Participation of lignin in the reaction between vapor-phase formaldehyde and wood was examined by using gradually delignified
wood meal. A fi rst-order rate equation was successfully applied to the weight gain data. From the estimated reaction parameters
such as rate constant, k, and ultimate weight gain, a, the reactivity toward formaldehyde was discussed among wood components, and compared with that for acetylation. k decreased monotonously with progress of the elimination of lignin, suggesting that the reaction rate of lignin is dominant
over that of whole wood, and the decrease in the ratio of lignin retarded the reaction of wood as a whole. On the other hand,
a increased with decreasing lignin content. This may be attributable to the enhanced reactivity of the remaining lignin due
to some structural changes and to the increase in the number of reactive sites in polysaccharides as a result of their exposure
accompanying the elimination of lignin. The dependencies of k and a on the lignin content were not similar to the case for acetylation, probably because of the difference in the reaction phase.
In vapor-phase formaldehyde treatment, the remaining lignin reacts as it is, whereas in liquid-phase acetylation it would
undergo rearrangement or swelling of the structure in the reaction solution. 相似文献
8.
9.
采用我国木材化学成分分析国家标准,对人工林米老排木材化学成分进行了测定和研究分析.结果表明:人工林米老排木材冷水抽提物含量和热水抽提物含量分别为2.67%和3.12%,1%NaOH抽提物含量为17.08%,纤维素含量为47.49%,综纤维素含量为80.42%,木素含量为28.80%,pH值为5.44;木材冷水抽提物和综纤维素含量在树干的不同高度上略有差异,但方差分析检验,差异不显著,热水抽提物、1%NaOH抽提物、纤维素和木素含量在树干的不同高度上差异显著,达到1%显著性水平;由树基往上,热水抽提物含量略呈两端高、中间低的趋势,冷水抽提物、1%NaOH抽提物和木素的含量逐渐降低,综纤维素含量和木材pH值逐渐升高;纤维素含量在树干上的分布规律为中间高、两端低,而且从树干中部往上的降低幅度较大. 相似文献
10.
Summary Lignincarbohydrate complexes (LCC) of poplar wood obtained by sulfate pulping and containing lignin in amounts of 0.9–8.3% have been studied by X-ray diffractometry. Heterogeneous hydrolysis methods have been used to determine their reactivity. The content of the crystalline fraction in LCC depends on the lignin removal and increases with the decrease of the lignin content. The degree of crystallinity of cellulose in sawdust and in LCC is fairly high and changes slightly with the lignin removal. The presence of lignin plays a blocking role in the heterogeneous hydrolysis and decreases the rate constant. It is suggested that lignin is bonded to cellulose on the outer surfaces of the crystalline part of the cellulose fibril. Some possible variants of these bonds are discussed. 相似文献
11.
12.
Charles Antwi-Boasiako Linda Ofosuhene Kwadwo B. Boadu 《Journal of Sustainable Forestry》2018,37(4):414-428
Construction material rising cost and global demand for economically-sustainable and environmentally-friendly building resources have necessitated the use of sawdust-cement composite. Wood constituents and cement incompatibility hinder its production and need careful selection of the timber. Sawdust suitability from Triplochiton scleroxylon, Entandrophragma cylindricum and Klainedoxa gabonensis for wood-cement composite was determined by identifying their chemical constituents and their composites’ physico-mechanical properties. T. scleroxylon recorded the minimum total extractive (6.12%), lignin (29.89%) and holocellulose (56.38%) and K. gabonensis the maximum (9.31, 31.59 and 57.5% respectively). Ash content was higher for T. scleroxylon (7.6%) but lower for K. gabonensis (1.53%). T. scleroxylon boards were stronger [Modulus of Elasticity (MOE) = 696.1 N/m2] and more moisture-resistant [Moisture Absorption (MA) = 8.8%] than E. cylindricum (MOE = 625.9 N/m2; MA = 9.5%). K. gabonensis boards crushed after manufacturing due to its incompatibility with cement. T. scleroxylon sawdust is suitable for wood-cement composites due to its more compatible chemical constituents (i.e., lower extractive, lignin, holocellulose contents and more ash) and its boards’ excellent physico-mechanical properties than those for the other timbers. Its sawdust-cement composites could be utilized for cladding and walling. The use of sawdust would increase green building resource base and reduce environmental pollution. 相似文献
13.
Ulla Westermark 《Wood Science and Technology》1985,19(4):323-328
Summary It has been found that the lignin in a middle lamella fraction isolated by a sieving technique has the same reactivity to bromine as the whole wood lignin. A plataue value of 1 mole bromine/mole C9-unit was obtained for both samples. The lignin in compression wood had a considerably lower reactivity to bromine than the normal wood lignin. A plataue value of 0.68 mole bromine/mol C9-unit was obtained with such lignin. The discrepancy between this and earlier results from the bromination of middle lamella and the implication of the results for lignin determination by the SEM- and TEM-EDXA technique are discussed. 相似文献
14.
For analysis of carbon isotope discrimination in wood, cellulose or holocellulose is often preferred to whole tissue because of the variability in isotopic composition of different wood components and the relative immobility of cellulose. Most currently used methods for the preparation of wood components for stable isotope analysis (e.g., the Jayme-Wise method) produce a residue of holocellulose. The Jayme-Wise method was initially developed to extract holocellulose from small (~1 g) samples of wood, and, despite subsequent modifications, the method requires specialized glassware, considerable time and entails the risk of sample loss. For carbon isotope analysis, we adapted an acid-catalyzed solvolytic method for preparing crude cellulose by treating wood meal with acidified di-glycol methyl ether (diglyme). The one-step process requires no special glassware, is complete within 24 hours and enables over 100 samples to be processed in a day. This method gives similar delta(13)C values to the Jayme-Wise method for wood of Eucalyptus globulus Labill., Pinus radiata D. Don and Pinus pinaster Ait. The relationship between delta(13)C of wood and crude cellulose is as strong as that observed between wood and alpha-cellulose and stronger than that observed between wood and holocellulose in other species. These relationships suggest that variation in delta(13)C of wood may result from hemicellulose and that analysis of stable carbon isotopes in crude cellulose is preferable. If the consistent -0.3 bias in the value of delta(13)C of cellulose resulting from residual lignin is corrected for, then the relationship between delta(13)C of wood and crude cellulose may be used to predict delta(13)C of cellulose from a small sub-sample. The method is well suited to species with low concentrations of extractives, but further testing is needed to assess its general applicability. 相似文献
15.
Relations between various extracted basic densities and wood chemical components were investigated by their within-tree variations in Eucalyptus globulus for assistance in the prediction of the properties of wood or wood-derived products. Extraneous compounds affect the relations between various basic densities and wood chemical components such as holocellulose and the lignin syringyl/guaiacyl ratio. We also discuss the relation of various densities, the molar composition of neutral sugars constituting hemicellulose, and fiber morphology. 相似文献
16.
Patterns of variation in the chemical composition of wood,i.e.,holocellulose,cellulose and lignin contents and 1%NaOH extractives were studied in 12 natural populations of Pinus manssoniana Lamb.in Guizhou Province,China,using wood cores as experiment material.The results show statistically significant differences among provenances in holocellulose,cellulose and 1% NaOH extractive contents.The largest coefficient of variation among the provenances was found in the 1%NaOH extractive content and the smallest in the holocellulose content.Variation of lignin content occurred within provenances.Correlations between chemical compositions of wood and factors of local geography and meteorology were largely insignificant.The chemical composition of wood presented patterns of random variation.The correlation of 1%NaOH extractive content with holocellulose content was significant(r=?0.68).There was also significantly negative correlation(r=0.62)between cellulose and lignin content.On the basis of a UPGMA cluster analysis,we identified three provenances of masson pine among the 12 studied,i.e.,those of Wengan,Tongzi and Luodian with high cellulose contents,low levels of 1%NaOH extractive and moderate lignin contents,which we recommend as promising provenances for growing of pulp wood and the manufacture of paper in Guizhou Province 相似文献
17.
《Scandinavian Journal of Forest Research》2012,27(7):577-584
ABSTRACTThe 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. 相似文献
18.
Influence of process variables on the properties of pulp and paper sheets obtained by sulphite pulping of olive tree wood 总被引：1，自引：0，他引：1
Summary A central composition design was developed to study the influence of process variables (temperature, pulping time, sulphite
concentration, anthraquinone concentration and liquid/solid relation) on the properties of pulps (yield, holocellulose, α-cellulose
and lignin contents, and brightness) and the paper sheets (stretch, burst index and tear index) obtained from them, in the
sulphite pulping of olive tree wood. Equations that reproduce the properties of pulps prepared by sulphite pulping and of
paper sheets obtained from it are reported. The proposed equations fit the experimental yield and the holocellulose and α-cellulose
contents of the pulps with errors less than 5%, as well as brightness with errors less than 10%. Also, they reproduce the
lignin content of the pulps, and the stretch, burst index and tear index of the paper sheets with errors less than 15%. Obtaining
pulps with acceptably high yield, holocellulose and α-cellulose contents, and also a high brightness, in addition to low lignin
contents, entails operating at a temperature of 193 °C for 143 min, using a sulphite concentration of 19.85%, an anthraquinone
concentration of 0.1% and a liquid/solid relation of 6.24. These are also the most suitable conditions for obtaining paper
sheets with a high stretch, burst index and tear index.
Received 23 April 1998 相似文献
19.
A new approach is proposed for the evaluation of the brittleness of heat-treated Styrax tonkinensis wood. Heat treatment made wood more brittle when wood was heated at a higher temperature or for a longer time. The brittleness
increased to four times that of the control when wood was heated at 200°C for 12 h. For treatment at 160°C, the increase in
brittleness without any change in weight is thought to be possibly caused by the relocation of lignin molecules. At higher
temperatures, loss of amorphous polysaccharides due to degradation is thought to become the main factor affecting brittleness.
The crystallites that were newly formed after 2 h of treatment showed brittleness that was different from that of the inherent
crystallites remaining after 12 h of heat treatment. This inherent crystalline cellulose possibly plays a role in brittleness.
There is also the possibility of using color to predict the brittleness of heat-treated wood. 相似文献
20.
The aim of this study was to evaluate the chemical composition and the dynamic water vapour sorption properties of Eucalyptus pellita wood thermally modified in vacuum. For this purpose, wood samples were thermally modified in a vacuum oven at 160–240 °C for 4 h. Chemical composition were investigated by wet chemical analysis, elemental analysis, as well as Fourier transform infrared (FTIR) analysis, and dynamic water vapour sorption properties were evaluated by dynamic vapour sorption apparatus. The results showed that holocellulose and alpha-cellulose contents decreased and lignin and extractives contents relatively increased during the heat process. Elemental analysis showed a reduction in hydrogen content and an increase in carbon content. FTIR analysis indicated that the degradation of hemicellulose and condensation reactions of lignin occurred. In addition, the thermo-vacuum resulted in a reduction in the equilibrium moisture content of wood during the adsorption or desorption process. And the sorption hysteresis had a decreasing trend with increasing treatment temperature. The development of the hygroscopicity was related to the increase in the relative content of lignin, the degradation of the carbonyl groups in xylan and the loss of carbonyl group linked to the aromatic skeleton in lignin after heat treatment. 相似文献