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。     

Finite element analyses in wood research: a bibliography

This paper gives a bibliographical review of the finite element methods (FEMs) applied in the analysis of wood. The added bibliography at the end of this article contains 300 references to papers and conference proceedings on the subject that were published between 1995 and 2004. The following topics are included: Wood as a construction material—material and mechanical properties; wood joining and fastening; fracture mechanics problems; drying process, thermal properties; other topics. Wood products and structures—lumber; glulam, panels, wood composites; trusses and frames; floors, roofs; bridges; other products/structures.     

Influence of Ammoniacal Copper Quaternary treatments on mechanical properties of blue-stained Lodgepole Pine wood

Three concentrations （2.8%, 2.0%, 1.2%） of Ammoniacal Copper Quaternary （ACQ） was selected to treat Lodgepole pine wood for evaluating ACQ treatment on mechanical properties of blue-stained wood. The bending modules of elasticity （MOE）, modules of rupture （MOR）, toughness and shearing strength parallel to grain on tangential surface, are tested according to the criteria GB1927-1943-91. Non-treated sample were also tested according to the same procedure. The results showed that the three groups specimen impregnated by different concentrations of ACQ solution met the AWPA standard 2003 of America （UC4A 6.4g/cm^3）. There were significant difference of toughness between treated wood and non-treated wood （p=0.01）, but there were no statistically significant differences among three concentrations in terms of toughness, and toughness of treated wood was approximately 20% lower than non-treated. MOR, MOE as well as sheafing strength parallel to grain were found to be not significantly different between treated wood and non-treated one, and there were no statistically significant difference among three concentrations of ACQ too. Toughness, MOR, MOE and sheafing strength parallel to grain increased with decrease of concentration of ACQ, but they were hardly affected by ACQ preservatives.     

Chemical modification of wood by non-formaldehyde cross-linking reagents

Summary The probability of bond between wood components and glyoxal was examined by means of a mechanical method, infrared (IR) spectrometry, and solid state ¹³C-nuclear magnetic resonance (NMR) spectrometry. The successive fixation of a compressed wood by the glyoxal treatment suggested the formation of cross-linkings between wood components and/or wood structures. The IR spectra showed that ester bond as well as ether bond was formed between wood components and glyoxal. The existence of linkages between glyoxal and cellulose was indicated also from the NMR spectra. The addition of glycol to the glyoxal solution was investigated from the viewpoint of stabilizing effect of the linkages. When 0.2 mole ratio of glycol was added to 5–10% glyoxal solution, weight gain and antiswelling efficiency (ASE) were largest, however the addition of excessive amount of glycol did not advance further the weight gain and ASE. When an appropriate amount of glycol was added to the impregnation solution, both weight and ASE did not largely reduce even by the repeated hot water soaking. By the treatment without glycol, the dimensional stability after water soaking was attributed to only restraint of the swelling. On the other hand, when the glycol was added, the dimensional stability was developed not only by the restraint of the swelling but also by the buckling effect.We would like to thank Associate Professor Dr. Umezawa, Wood Research Institute, Kyoto University, for his invaluable support in NMR analysis. Thanks are also due to Dr. Inoue, Wood Research Institute, Kyoto University, for his preparing the wood specimens.     

Ring-level models for predicting wood and fibre properties of Abies balsamea

Wood and fibre properties such as wood density, microfibril angle, and modulus of elasticity are industrially relevant factors in determining the mechanical properties of wood. Radial ring-level predictive models of these properties were developed using balsam fir data from a long-term trial in New Brunswick (Canada), where precommercial thinning was applied 8 years after the site was harvested. The mixed effects models developed accounted for most of the variability in wood density (68 %), microfibril angle (94 %), and modulus of elasticity (77 %) with low RMSE. This study shows that balsam fir wood and fibre properties are strongly related to distance from the pith, particularly in the first 20 mm, and much less to annual ring width. Disk height and selected weather variables related to air temperature during the growing season significantly improved the models, whereas the effect of precommercial thinning was not significant. These equations can be incorporated into computer models, such as Optitek, that simulate mill recovery and wood properties to obtain accurate information on wood products. The unexplained variation in these models is likely related in part to between-tree genetic variation, which is unknown in this study.     

Genetics of wood quality attributes in Western Larch

Context

Wood quality traits are important to balance the negative decline of wood quality associated with selection for growth attributes in gymnosperm breeding programs. Obtaining wood quality estimates quickly is crucial for successful incorporation in breeding programs.

Aims

The aims of this paper are to: (1) Estimate genetic and phenotypic correlations between growth and wood quality attributes, (2) Estimate heritability of the studied traits, and (3) Assess the accuracy of in situ non-destructive tools as a representative of actual wood density.

Methods

Wood density (X-ray densitometry), tree height, diameter, volume, resistance drilling, acoustic velocity, and dynamic modulus of elasticity were estimated, along with their genetic parameters, for 1,200, 20-year-old trees from 25 open-pollinated families.

Results

Individual tree level heritabilities for non-destructive evaluation attributes were moderate ( $ {\widehat{h}}_i^2=0.37-0.42 $ ), wood density and growth traits were lower ( $ {\widehat{h}}_i^2=0.23-0.35 $ ). Favorable genetic and phenotypic correlations between growth traits, wood density, and non-destructive evaluation traits were observed. A perfect genetic correlation was found between resistance drilling and wood density (r _G ?=?1.00?±?0.07), while acoustic velocity and dynamic modulus of elasticity showed weaker genetic correlations with wood density (r _G ?=?0.25?±?0.24;?0.46?±?0.21, respectively).

Conclusion

This study confirmed that resistance drilling is a reliable predictor of wood density in western larch, while the weak genetic correlations displayed by acoustic velocity and dynamic modulus of elasticity suggest limited dependability for their use as fast in situ wood density assessment methods in this species.     

Application of near-infrared spectroscopy to wood discrimination

 This study deals with a new nondestructive discriminant analysis by which wood can be classified on the basis of a combination of near-infrared (NIR) spectroscopy and Mahalanobis' generalized distance. Its accuracy and reasonability were examined for wood samples with various moisture contents ranging from oven-dried to a fully saturated free water state. In a discriminant analysis employing second derivative spectra, each wood group was well distinguished. Mahalanobis' generalized distances between softwoods are relatively independent of analytical pattern, whereas the distances between hardwoods are large for easy classification. There may be two reasons for selecting a wavelength: (1) when the chemical component of wood substance relates to the discriminant analysis; and (2) when the difference in moisture content with wood species relates to them. When we correctly construct the database of NIR spectra, confirming the purpose of the analysis, suitable wood discrimination should be possible. Received: January 23, 2002 / Accepted: March 15, 2002 Acknowledgment The authors sincerely thank the Tanabe Southeast Asia Nations Friendship Foundation for financial support. Part of this report was presented at the 51nd Annual Meeting of the Japan Wood Research Society, 2001 Correspondence to:S. Tsuchikawa     

Distribution of boron in wood treated with aqueous and methanolic boric acid solutions

The distributions of boron in Japanese cedar (Cryptomeria japonica D. Don) sapwood blocks treated with aqueous or methanolic boric acid [B(OH)₃] solutions were explored through Raman spectroscopy and prompt gamma-ray analysis (PGA). B(OH)₃ was the sole boron species observed in Raman spectra of the wood blocks treated with either solution. Plots of weight gain of the treated wood blocks versus boron concentration in treatment solutions were found to be linear. The results indicated that the methanolic solution makes it possible to impregnate wood with much larger amounts of boron than the aqueous solution. PGA confirmed that B(OH)₃ was highly enriched near the end grains of the treated wood blocks. Raman measurements suggested that boron content in the bulk of the wood block is not as large as expected from the weight gain of the treated wood blocks when an ordinary air-drying method is used. It was concluded that the aqueous solution impregnates the cell walls of wood with boron more easily than the methanolic solution. Part of this report was presented at the 55th (Kyoto, March 2005) and 56th (Akita, August 2006) Annual Meetings of the Japan Wood Research Society. This article follows the previous rapid communication “Analysis of boron in wood treated with boric acid solutions using Doppler broadening method of prompt gamma-rays.” J Wood Sci (2006) 52:279–281     

Monoethanolamine extraction of copper-preservative-treated wood and reuse of the extract for wood preservation

Remediation of copper-based alkaline copper quat (ACQ) and micronized copper quat (MCQ) wood-preservative-treated weathered southern pine mulch samples by monoethanolamine (Mea) extraction was studied. The potential reuse of Mea extract in ACQ wood preservative application was also evaluated. Continuous column extraction of copper-preservative-treated samples for 32 h, using 12 % Mea removed 66–86 % (between top and bottom of the column) and 65–80 % of Cu, respectively, from ACQ- and MCQ-treated wood. Mea extracts of treated wood could be reused in ACQ-treating solutions that met the American Wood Protection Association standard specifications for ACQ wood preservatives. This was achieved either by mixing the extract with industrial Cu–Mea solution at 1:4 ratio or by adding cupric acetate salt directly into the Mea extract. ACQ-treating solutions reformulated using Mea extracts of ACQ- and MCQ-treated wood performed similarly to wood treated with industrial ACQ solution and freshly prepared solution using cupric acetate. All treated wood had similar penetrations of Cu in wood during preservative treatment, Cu leaching from the treated wood in contact with water, corrosion of nails in contact with treated wood, and ability to protect wood from mold growth.     

Effects of contact with wood on blood pressure and subjective evaluation

This study examined the effects of contact with wood on the living human body using a physiological index and subjective evaluation. Consecutive blood pressure measurements were used as the physiological index, and sensory evaluation using the semantic differential (SD) method was used for subjective evaluation. Consideration was also given to cases in which materials were cooled and heated as well as kept at room temperature, to eliminate the effects of heat flux due to differences in thermal conductivity between wood and other materials. It was found that contact with wood produced coarse/natural sensations, with no associated increase in systolic blood pressure. Contact with cold wood created subjectively dangerous/uncomfortable but still coarse/natural sensations, also with no associated increase in blood pressure; therefore, there was no correspondence between subjective evaluation and physiological responses. Contact with aluminum kept at room temperature and cold acrylic plastic created flat/artificial and dangerous/uncomfortable sensations, with an associated significant increase in blood pressure; thus, there was a close correlation between subjective evaluation and physiological responses. It was therefore concluded that contact with wood, unlike artificial materials such as aluminum, induces no physiological stress even when kept at room temperature or cooled. Part of this report was presented at the 48th Annual Meeting of the Japan Wood Research Society in Shizuoka, April 1998     

Medical CAT-scanning: X-ray absorption coefficients,CT-numbers and their relation to wood density

Summary This paper describes how X-ray absorption coefficients and CT-number in medical CAT-scanning can be calculated for dry and wet wood. A comparison with earlier recorded data for dry wood showed that the deviation between calculated and measured CT-numbers was not significant. Linear regression showed that wood density could be measured with an accuracy of ±4 kg/m³. Wood having the same green density but containing different amounts of water have different absorption coefficients and CT-numbers. A linear relationship between CT-numbers and density of wood containing water was developed. Wood density could be measured with an accuracy of ±13.4 kg/m³.     

Genotypic variation in wood density and growth traits of poplar hybrids at four clonal trials

Wood density is considered as one of the most important wood properties which affects the properties and value of both fibrous and solid wood products. The present study was intended for evaluating the possibilities of improving wood quality and growth of poplar hybrids. Wood density components of individual growth rings (minimum and maximum wood density, average ring density) and growth traits (tree height, dbh, stem volume) were measured in four 10- and 12-year-old clonal trials of four poplar hybrids, Populus deltoides × P. nigra, P. trichocarpa × P. deltoides, P. maximowiczii × P. balsamifera, and P. balsamifera × P. nigra, as well as P. deltoides. Wood density components of individual growth rings were obtained from microdensitometeric profiles measured with a direct reading X-ray densitometer. Site had a moderately significant effect on wood density and a highly significant effect on tree growth. The hybrid effect was highly significant (P < 0.001) for most traits. Minimum, maximum and weighted wood densities were found to be under strong genetic control, with clonal repeatabilities varying between 0.45 and 0.81. The coefficient of genotypic variation (CV_G) for wood density at individual sites ranged from 4.0 to 6.8%, whereas CV_G for dry fiber weight (mass) reached 32.8% with repeatabilities of up to 0.67. A small but significant (P = 0.028) hybrid × environment interaction was found for dry fiber weight. The highest ecological sensitivity was found for P. deltoides × P. nigra, with ecovalence reaching 32.3%. Clonal × environment interaction was significant for weighted, average, and minimum wood density. Significant negative genotypic correlations between stem volume and wood density ranged from −0.39 to −0.74. One possible strategy in tree breeding would be to maximize wood fiber production through selection for dry fiber weight.     

Hygroscopicity of wood impregnated with linseed oil

Summary The reduction in hygroscopicity as spruce wood is impregnated with linseed oil may be accounted for using a molecular exclusion model. On the basis of the model, each linseed oil molecule appears to displace 90 water molecules and occupy 6 hydrogen bonding sites in the wood.Dr. Allen R. Sharp, Associate Professor of Physics at the University of New Brunswick and Dr. Christen Skaar, Professor of Wood Physics at Virginia Polytechnic Institute and State University freely gave essential advice and encouragement during this work. Graphical depiction of the molecular displacement model (Fig. 1) was suggested by Dr. Skaar. Much of the experimental work was carried out by Mr. Wu-Rong Perng, Scientific Technician in Wood Science and Mrs. Monica Snow, Instructor in Wood Science at the University of New Brunswick     

Longitudinal shrinkage behaviour of compression wood in radiata pine

The behaviour of longitudinal shrinkage was investigated in the corewood of a swept, 17-year-old New Zealand radiata pine stem. Wood categories in terms of normal wood, mild compression wood and severe compression wood were identified microscopically using autofluorescence of lignin. Average longitudinal shrinkage was collated according to corewood location and wood category within corewood in the leaning and the vertical parts of the stem, and then maximum radial difference of longitudinal shrinkage within growth ring was examined. The results show that the average longitudinal shrinkage is significant (2.4%) in the corewood of the leaning part of the stem. Among wood categories, severer compression wood displays the highest (2.9%) average longitudinal shrinkage. In the context of this study, growth rings may consist of one of three types of wood: (1) only normal wood; (2) a single compression wood type; and (3) mixed-type wood. Where multiple compression woods co-existed with normal wood, the maximum radial difference of longitudinal shrinkage within the growth ring was found to be 4.0%. A strong correlation (R ² = 0.90) between average MFA and average longitudinal shrinkage suggests a significant influence of the average MFA on average longitudinal shrinkage across the three growth ring types.     

Application of modal analysis by transfer function to nondestructive testing of wood I: determination of localized defects in wood by the shape of the flexural vibration wave

This study was intended to detect nondestructively some defects such as knots and grain deviations in wood using modal analysis. The shapes of flexural vibration waves at the first mode generated by the tapping of wooden beams were determined using the transfer function. The wave shapes obtained were compared with the theoretical wave shape for a uniform material; and the possibility of detecting defects in wood was examined. The results are summarized as follows: (1) The shapes of flexural vibration waves at the first mode of wooden beams free of defects coincided almost completely with the theoretical wave shape. (2) The shapes of flexural vibration waves of wooden beams containing defects such as knots clearly differed from the theoretical wave shape, especially near the defect. (3) Based on these results, it should be possible to detect the presence of defects and to determine their location in wood.Part of this report was presented at the 49th Annual Meeting of the Japan Wood Research Society, Tokyo, April 1999. This article is translated from the Japanese edition published inMokuzai Gakkaishi Vol. 47, No. 4, 1988     

Crash simulation of wood and composite wood for future automotive engineering

ABSTRACT

Multi material mix is a promising approach to reduce weight and the carbon footprint in automotive engineering at competitive costs. As a result, automotive industry is getting more venturous, exploring and applying other materials than metals and plastics – e.g. fibre reinforced plastics (FRPs). In this context, engineered wood products (EWPs) and wood composites should be considered: Wood composites provide high stiffness, strength, excellent damping, high resistance against fatigue and a very low density at low material costs. It is hypothesized that modern wood composites are competitive to metals and artificial fibre-reinforced materials when designed and applied properly. The application of wood and wood composites in automotive engineering calls for precise and reliable material data, required for initial material selection and later in numerical simulation. In this study, a material model normally used for modelling FRPs was adopted. A material database was generated for three hardwood species, to establish the required material parameters and validate material model. Results prove that wooden components can be simulated in crash situations and the selected material model is applicable, even in full vehicle simulation.     

Effect of ozone treatment of wood on its liquefaction

The effects of ozone treatment were investigated to improve the process of liquefaction of wood with polyhydric alcohol solvents. The liquefied wood having a high wood to polyhydric alcohol ratio (W/P ratio) could be prepared by using the wood treated with ozone in the liquid phase. The liquefied wood with a W/P ratio of 2 : 1 had enough fluidity to act as a raw material for chemical products. To get some information about the effects of ozone treatment toward the wood components, cellulose powder and steamed lignin were treated with ozone and liquefied. In particular, ozone treatment in the liquid phase was found to be effective for wood and cellulose powder. On the other hand, steamed lignin self-condensed during liquefaction after treatment with ozone in the liquid phase. Thus, ozone treatment provided lignin with reactive functional groups, and caused the subsequent condensation reaction. Although lignin was converted to a more condensable structure by ozone treatment, the condensation reaction was found to be suppressed for wood during its liquefaction. The wood liquefied products displayed good solubilities in N,N-dimethyl formamide (DMF) even after treatments of long duration. It was suggested that one of the main effects of ozone treatment toward wood was the decomposition of cellulose.Part of this report was presented at the 53rd Annual Meeting of the Japan Wood Research Society, Fukuoka, April 2003     

Possibilities for energy wood procurement in north-west Russia: Assessment of energy wood resources in the Leningrad region

Abstract

Methodology to assess the potential for energy wood procurement in Russia is described in this article and applied to the Leningrad region. Wood from thinnings, logging residues, non-industrial roundwood and residues from sawmilling are considered as sources for energy production. Energy wood available in the region, based on the 2004 actual cut, is approximately 4 million m³. Nearly 86% of this is non-industrial roundwood and felling residues, and 14% is by-products from sawmilling. Almost two-thirds of the non-industrial roundwood and felling residues are in cutting areas and one-third is in central processing yards. Deciduous tree species (birch and aspen) dominate in energy wood, representing about 65% of the total amount of felling residues and non-industrial wood. It is possible to intensify utilization of forest resources and thereby also to increase the use of wood in energy production. The total amount could be 54% higher if the allowable cut was fully utilized and 124% higher if thinnings were also utilized completely. There are, however, significant intraregional differences, as the current rate of utilization of forest resources varies in the region.     

Prediction of wood stiffness, strength, and shrinkage in juvenile wood of radiata pine

Development of optimal ways to predict juvenile wood stiffness, strength, and stability using wood properties that can be measured with relative ease and low cost is a priority for tree breeding and silviculture. Wood static modulus of elasticity (MOE), modulus of rupture (MOR), radial, tangential, and longitudinal shrinkage (RS, TS, LS), wood density (DEN), sound wave velocity (SWV), spiral grain (SLG), and microfibril angle (MFA) were measured on juvenile wood samples from lower stem sections in two radiata pine test plantations. Variation between inner (rings 1–2 from pith) and outer (rings 3–6 from pith) rings was generally larger than that among trees. MOE and MOR were lower (50%) in inner-rings than in outer-rings. RS and TS were higher (30–50%) for outer-rings than inner-rings, but LS decreased rapidly (>200%) from inner-rings to outer-rings. DEN had a higher correlation with MOR than with MOE, while MFA had a higher correlation with dry wood MOE than with MOR. SLG had higher significant correlation with MOE than with MOR. DEN and MOE had a weak, significant linear relationship with RS and TS, while MOE had a strong negative non-linear relationship with LS. Multiple regressions had a good potential as a method for predicting billet stiffness (R ² > 0.42), but had only a weak potential to predict wood strength and shrinkage (R ² < 0.22). For wood stiffness acoustic velocity measurements seemed to be the most practical, and for wood strength and stability acoustic velocity plus core density seemed to be the most practical measurements for predicting lower stem average in young trees.