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Volume 55 Issue 1

Issue of Holzforschung

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Journal Overview

June 1, 2005

Genetic Variation in the Decay Resistance of Siberian Larch (Larix sibirica Ledeb.) Wood

M. VenälÄinen, A.M. Harju, T. Nikkanen, L. Paajanen, P. Velling, H. Viitanen

Page range: 1-6

Abstract

The aim of the study was to estimate the degree of genetic determination in the decay resistance of Siberian larch ( Larix sibirica Ledeb.) wood and its correlation to other wood traits. The wood samples were taken from 25-year-old grafted seed orchard clones with an increment core borer, dried, weighed, and subjected to a laboratory decay test using a modified method based on the standardised EN 113 method. One brown rot fungus, Coniophora puteana (Schum. ex Fr.) Karst., was used as the decaying organism. The advantages of the method were the savings in time, the possibility to study standing trees, and the potential for screening large numbers of samples at reasonable costs. The clonal repeatability was used to estimate the degree of genetic determination. The genetic determination appeared to be stronger for decay resistance than for growth characteristics or heartwood formation, but weaker than for wood density or latewood formation. Decay resistance and the growth characteristics did not correlate.

June 1, 2005

Chromated Copper Arsenate Preservative Treatment of North American Hardwoods. Part 2. CCA Leaching Performance

T. Stevanovic-Janezic, P.A. Cooper, Y.T. Ung

Page range: 7-12

Abstract

Seven North American hardwood species were vacuum or vacuum/pressure treated with 2% CCA-C solution and fixed at temperatures of 21°C and 50°C under conditions of high relative humidity (95%). The rates of fixation results are presented in Part 1 of this study. Red maple ( Acer rubrum L.), red oak ( Quercus rubra L.), American beech ( Fagus grandifolia Ehrh), white birch ( Betula papyrifera Marsh.), trembling aspen ( Populus tremuloides Michx.), basswood ( Tilia americana L.) and yellow poplar ( Liriodendron tulipifera L.) were evaluated. The softwood red pine ( Pinus resinosa Ait.) was included for comparison. Adequately fixed wood blocks (99.9% chromium reduction) were exposed to leaching by the AWPA E11 procedure. All CCA components were leached in high quantities from oak wood, while from red maple and beech, high arsenic leaching occurred. Leaching losses from aspen, basswood and yellow poplar were low and comparable for both fixation temperatures. In most species, the amount of leaching was affected by the treating method, with lower leaching from pressure treated wood blocks than from vacuum treated blocks. Removal of extractives from maple and oak blocks before treatment affected the CCA leaching performance in these species. Extracted red oak had lower chromium and copper leaching, but higher arsenic leaching. In contrast, extracted red maple had reduced leaching of all CCA components compared to unextracted wood. The examined hardwoods can be classified into three groups according to their CCA fixing and leaching characteristics: fast fixing/high leaching group (beech, red oak and red maple), intermediate fixation rate and leaching group (white birch and red pine) and slow fixing and low leaching group (aspen, yellow poplar and basswood).

June 1, 2005

Interaction of Copper-Containing Preservatives with Wood. Part 1. Mechanism of the Interaction of Copper with Cellulose

N. Druz, I. Andersone, B. Andersons

Page range: 13-15

Abstract

In the present work, the state of the copper ions absorbed by cellulose from aqueous solutions with different pH values has been studied by electron spin resonance (ESR), X-ray photoelectron spectroscopy (XPS) and energy-dispersive X-ray analysis (EDXA) methods. It has been shown that the curve of copper sorption has a S-like shape characteristic for weak acid sorbents. At all pH values in ESR-spectra, an anisotropic Cu(II)-signal is registered. At pH > 4, the anisotropy of ESR-spectra decreases. At pH = 10, complexes connected by exchange interactions and diamagnetic clusters are formed. After the leaching of specimens, the ESR-signal practically disappeared. The decrease of the copper content in cellulose did not correlate with the change of the integral intensity of the spectra. The changes in ESR-spectra of copper-containing cellulose after leaching were explained by the formation of the Cu(II) diamagnetic clusters.

June 1, 2005

Identification of Cupric and Cuprous Copper in Copper Naphthenate-Treated Wood by X-Ray Photoelectron Spectroscopy

P. Kamdem, J. Zhang, A. Adnot

Page range: 16-20

Abstract

X-ray photoelectron spectroscopy (XPS) was used to monitor the modification on copper naphthenate (Cu-N) treated Southern pine and the effect of a post treatment steaming on Cu-N treated samples. The atomic ratio of oxygen to carbon (O 1s /C 1s ) decreases with Cu-N treatment, confirming the coverage of the sample surface with Cu-N, which is rich in -CH 2 - groups. XPS spectra and Auger parameters were successively used to identify and quantify Cu (I) and Cu (II) on the surface of Cu-N treated samples. The peak at 935 eV and the presence of shake up satellites are a good indication of the presence of cupric copper, while the peak at 933 eV and the disappearance of shake-up satellites are attributed to the presence of cuprous copper. The post-treatment steaming of Cu-N treated Southern pine cubes results in the conversion of 52 percent of the cupric copper into cuprous copper on the wood surface.

June 1, 2005

Measurement of Wood Wettability by the Wilhelmy Method. Part 1. Contamination of Probe Liquids by Extractives

M.E.P. Wålinder, I. Johansson

Page range: 21-32

Abstract

This work focuses on the influence of extractives during wetting measurements on wood. Fresh and aged veneers of extracted and non-extracted heart- and sapwood of pine were prepared, and the Wilhelmy method was used to study the wettability of these veneers. In this method, the force acting on the veneers was measured during immersion in and withdrawal from a series of probe liquids. The results suggest that some of the probe liquids become severely contaminated by extractives during the measurements on the non-extracted veneers, and that this strongly affects the wood wetting measurements. The contamination is effectively detected as a distinct decrease in the surface tension of the liquids caused by dissolution or presence of wood extractives at the wood-liquid interface. It is important to note that such contamination may also occur during wetting studies on wood using other contact angle measurement techniques. The most obvious contamination occurred in the case of measurements on non-extracted veneers immersed in water and formamide. Generally, no contamination was detected in the case of measurements on extracted wood veneers. The Wilhelmy method may provide an efficient means for recording and control of any contamination of the probe liquids that may arise during wetting studies on wood.

June 1, 2005

Measurement of Wood Wettability by the Wilhelmy Method. Part 2. Determination of Apparent Contact Angles

M.E.P. Wålinder, G. Ström

Page range: 33-41

Abstract

This work focuses on the determination of apparent contact angles on wood by the Wilhelmy method. In this method, the force acting on an object is measured during a test cycle involving immersion in and withdrawal from a probe liquid. Fresh and aged veneers of extracted and non-extracted heart- and sapwood of pine were investigated. The results indicate that wicking of the probe liquids, into and along the porous wood veneers, occurs during the test cycles and that this strongly affects the determination of contact angles. It is suggested that two different wicking phenomena occur. First, when the veneer contacts the liquid, an instantaneous ‘initial wicking’ occurs. It is suggested that this initial wicking is influenced primarily by the liquid density and structural properties of the specimen (such as porosity and surface roughness), and not by surface energetics. An initial wicking constant was therefore estimated for the different veneer samples based on measurements in octane. Second, after the initial wicking, a continuing ‘secondary wicking’ is observed. In some cases, this may result in zero contact angle after a certain immersion depth. Contact angles should, therefore, be estimated from the initial part of the immersion, where the secondary wicking can be neglected. This may also reduce any contamination of the probe liquids by extractives. The Wilhelmy method seems to be a valuable tool for estimating the wetting properties of wood, permitting reproducible measurements of apparent contact angles provided that there is efficient control of wicking and contamination effects.

June 1, 2005

Biomechanical Pulping of Agave sisalana

G. Idárraga, J. Ramos, R.A. Young, F. Denes, V. Zuñiga

Page range: 42-46

Abstract

The effect of biological pretreatment of sisal with several white rot fungi on the energy consumption in refining and on the mechanical properties of the pulps was evaluated in this investigation. Improvements were realized in all the mechanical properties (22–66 %) and a reduction in the energy consumption of > 39% was realized for the treated pulps with the different fungi. The best strength improvement and energy reduction results overall were obtained with the white-rot fungus, Ceriporiopsis subvermispora . The incubation time was optimized for this fungus with the optimum mechanical properties obtained with a two week treatment time.

June 1, 2005

Oxidation of Benzyl Alcohols by the Laccase-Mediator System (LMS) a Comprehensive Kinetic Description

A. Potthast, T. Rosenau, K. Fischer

Page range: 47-56

Abstract

Investigations into the reaction kinetics of the laccase-mediator system (LMS) have been carried out. Two widely used mediators, 2,2′-azino-bis(3-ethyl-benzothiazoline-6-sulfonic acid) (ABTS, 3 ) and 1-hydroxybenzotriazole (HOBT, 4 ), were compared by means of a model reaction, the oxidation of 2,4-dimethoxybenzyl alcohol (DMBA, 1 ) to 2,4-dimethoxybenzaldehyde (DMA, 2 ). The consumption of dioxygen was recorded electrochemically, substrate consumption and product formation were monitored by GLC. With ABTS as the mediator, the LMS reaction proceeded in two clearly distinguishable stages. The first phase is characterized by a fast decrease in oxygen with zero-order kinetics and no detectable formation of 2,4-dimethoxybenzaldehyde ( 2 ). ABTS is converted into oxidized species, the cation radical 6 and the dication 7 , respectively. In the second phase, oxygen consumption was considerably slower and followed a second-order kinetics, while the benzaldehyde was produced according to a zero-order rate law. According to the kinetic studies, the ABTS dication, but not the enzyme itself, is acting as the actual oxidant. The rate of oxidation product formation increased with increasing mediator / benzyl alcohol ratio. Less oxygen than the equivalent amount was consumed in the second reaction stage indicating that the oxidized ABTS formed in the first stage acts as an oxidant reservoir, being reduced to ABTS in turn. The LMS reaction with HOBT ( 4 ) as the mediator did not exhibit distinguishable phases, and was characterized by a comparatively slow oxygen uptake with zero-order kinetics throughout. Enzymatic oxidation of HOBT to the HOBT radical ( 5 ), which acts as the actual oxidant towards the benzyl alcohol, was the rate-determining step. The production of 2,4-dimethoxybenzaldehyde thus followed a zeroorder rate law as well. The reaction rate increased with increasing HOBT / benzyl alcohol ratios. Increasing concentrations of 4 caused less oxygen to be consumed per equivalent of benzaldehyde formed, indicating the occurrence of another reaction pathway at high mediator charges. At low HOBT / benzyl alcohol ratios the HOBT radical ( 5 ) acts as one-electron oxidant and is reduced to HOBT in a reversible process. In contrast, at higher HOBT / benzyl alcohol ratios 5 acts as a three-electron oxidant, being irreversibly reduced to benzotriazole. At commonly employed mediator concentrations, a superposition of both mechanisms results. The pure borderline cases can only be observed at HOBT / benzyl alcohol ratios below 1 and above 6, respectively.

June 1, 2005

Chemical Modification of Wood by Polyglycerol/Maleic Anhydride Treatment

C. Roussel, V. Marchetti, A. Lemor, E. Wozniak, B. Loubinoux, P. Gérardin

Page range: 57-62

Abstract

Polyglycerol (PG), an agricultural by-product of diester industry, was reacted with maleic anhydride (MA) to give heat curable compounds which are useful for impregnating wood to improve biological resistance, dimensional stability and strength. The relationships between reaction conditions of polyglycerol/maleic anhydride (PG/MA) adduct treatment and performance of treated solid wood were investigated. Conditions recommended for producing PG/MA treated wood durable for a long time are vacuum/pressure impregnation of aqueous solutions of PG/MA adduct (30%) in the presence of 2-butanone peroxide (2%) and cobalt naphthenate (2%).

June 1, 2005

Relationship between Released Strain and Growth Rate in 39 Year-Old Tectona grandis Planted in Indonesia

I. Wahyudi, T. Okuyama, Y. Sudo Hadi, H. Yamamoto, H. Watanabe, M. Yoshida

Page range: 63-66

Abstract

In order to clarify the growth stress mechanism of tree species in tropical forest, peripheral and internal longitudinal released strains in 39 year-old teak (Tectona grandis) trees planted in West Java, Indonesia were investigated using the strain-gauge technique. Results showed that both of the peripheral and internal longitudinal released strains were not affected by the rate of growth of the trees. However, released strains distribution inside tree stem, from pith to periphery, were significantly affected by growth rate; slow growing trees generate steeper released strain gradients.

June 1, 2005

Reduction of Residual Stresses in Medium Density Fibreboard. Part 1. Taguchi Analysis

J. van Houts, D. Bhattacharyya, K. Jayaraman

Page range: 67-72

Abstract

This paper demonstrates how the Taguchi method of experimental design can be utilised to investigate methods for relieving the residual stresses present in medium density fibreboard (MDF). Panels have been subjected to heat, moisture and pressure, and after equilibration to room conditions, the changes in residual stresses through various layers have been measured using the dissection method. The application of heat and/or moisture has reduced the magnitude of residual stresses while generally the application of pressure has no effect on these stresses. The subsequent paper in this series uses Taguchi analysis to investigate how other board properties such as thickness swell, internal bond strength, surface layer tensile modulus and surface layer tensile strength are affected by the different treatment methods.

June 1, 2005

Reduction of Residual Stresses in Medium Density Fibreboard. Part 2. Effects on Thickness Swell and Other Properties

J. van Houts, D. Bhattacharyya, K. Jayaraman

Page range: 73-81

Abstract

The Taguchi method of experimental design has been utilised to investigate various treatments for relieving the residual stresses present in medium density fibreboard (MDF). These treatments involved subjecting panels to different combinations of heat, moisture and pressure. This paper reports on the Taguchi analysis of the internal bond strength, surface layer tensile modulus, surface layer tensile strength and thickness swell of the treated specimens. These properties were measured to indicate whether the treatments had any effect on panel strength and dimensional stability. A strong correlation between residual stresses and thickness swell has been identified. When the change in residual stress through the outer layers of a panel is almost completely removed, a reduction in thickness swell of approximately 20% for a 24 hour water soak is observed.

June 1, 2005

Evaluation of Pettys Nonlinear Model in Wood Permeability Measurement

J. Lu, F. Bao, Y. Zhao

Page range: 82-86

Abstract

To calculate the effective radii of two conductive elements in series in wood specimens by using the gas permeability measurement, the four parameters from the curvilinear relationship of superficial specific permeability against reciprocal mean pressure as illustrated in Petty's model must be evaluated. This paper describes a detailed procedure for obtaining such parameters by using the least-squares fit calculated from a statistical analysis system (SAS) program. Three different iterative optimization algorithms and starting points were used separately to fit the Petty's nonlinear model based on the same experimental data from one specimen of birch. The estimate of the parameters: A = 35.38 darcy, B = 80.51 darcy, l = 0.19 darcy atm, m = 6.34 darcy atm was recommended for the fitted model. Compared to the results on the estimate of parameters obtained in the previous papers, this estimate for the parameters was a global minimum, thus it was a refinement and more accurate. Since the Gauss-Newton method resulted in almost the same convergence results for all the three sets of starting values with the least iterations in the evaluation, it was the preferred optimization algorithm both for simplicity and accuracy in solving the Petty's model. Because the same solutions for all three iterative optimization algorithms were obtained by using two different sets of starting points produced from the grid search, a grid search seemed to be very helpful for finding reasonable starting values for various iterative optimization techniques.

June 1, 2005

Dielectric Relaxation Based on Adsorbed Water in Wood Cell Wall under Non-Equilibrium State 2

C. Jinzhen, Z. Guangjie

Page range: 87-92

Abstract

In order to explain, on molecular level, the unusualness of wood physical properties under moisture non-equilibrium state, the dielectric temperature and frequency spectra of Sikkim spruce ( Picea spinulosa Griff.) specimens were measured during the adsorption process in 20°C, 60% R.H. environment. Furthermore, the dielectric relaxation based on adsorbed water was separated from that based on the methanol groups in the amorphous region of wood cell wall, so that the thermodynamic quantities of adsorbed water associated with the adsorption process could be evaluated. Consequently, the molecular reorientation model of adsorbed water molecules during the dielectric relaxation process was constructed. The results show that the activation enthalpy ∆H and activation entropy ∆S of adsorbed water both increase linearly with the adsorption time. During the initial adsorption period ∆S appears as a negative value. According to the values of thermodynamic quantities, especially the ∆H values, it can be inferred that the average number of hydrogen bonds formed between each adsorbed water molecule with its surrounding wood adsorption sites increases gradually with developing adsorption. The model based on the obtained data in this experiment shows that after 7 hours' adsorption the number is between two and three, after 24 hours it is three and later it approaches four.

June 1, 2005

Preparation and Properties of Acetylated and Propionylated Wood-Silicate Composite

J.-Z. Li, T. Furuno, S. Katoh

Page range: 93-96

Abstract

Acetylated wood-silicate (AWS) composites and propionylated wood-silicate (PWS) composites were prepared and their dimensional stability and flame resistance evaluated. The results displayed that: (1) With the existing of silicate gels, the AWS and PWS composites showed lower values of bulking coefficient (B), antiswelling efficiency (ASE) during water and moisture absorptions, and moisture excluding efficiency (MEE) than the corresponding acetylated wood and propionylated woods, but the AWS and PWS composites still exhibited a fairly good dimensional stability. (2) The oxygen indexes (OIs) of the AWS and PWS composites were higher than those of untreated wood specimens, and increased with an increase in weight percent gain (WPGs) of silicate gel, endowing them with flame-resistance.

June 1, 2005

The Flakes Alignment Efficiency and Orthotropic Properties of Oriented Strand Board

S.Y. Wang, B.J. Chen

Page range: 97-103

Abstract

This study was designed to investigate the efficiency of flake's alignment and orthotropic properties of oriented strand board (OSB) by using ultrasonic wave method. It was designed also to discuss the correlation among ultrasonic velocity (V), dynamic modulus of elasticity (E d ), modulus of elasticity in bending (MOE) and modulus of rupture (MOR). Results are summarized as follows: The flake's aligned angle (θ) : the angles between flake length direction and mechanical alignment direction on the face layer of OSB within 0°–30° were 93–97% for JSP(OSB made from 100% of Japanese cedar flakes), JMP(OSB made from 50% of Japanese cedar flakes and 50% of Taiwan paulownia flakes) and CMP(OSB made from 50% of China fir flakes and 50% of Taiwan paulownia flakes) groups OSB, and on the bottom layer, 76–85% for these three groups OSB, respectively. The ultrasonic velocity (V) at 0° of angle between flake's length direction and mechanical alignment direction (V 0 ) was the highest, decreasing rapidly with increase of aligned angle (θ). The lowest value of ultrasonic velocity occurred at 90° of angle between flake's length direction and mechanical alignment direction (V 90 ) and the relationship between θ and V could be represented by Hankinson's formula, and Jacoby equation. The orthotropic properties of OSB, defined as the ratio of V 0 /V 90 were 2.4–3.2 for the full piece specimens, and 2.4–2.6 for the bending tested specimens. Interrelationships between V, E d , MOR and MOE were positive linear regression formulas.

July 27, 2005

Walter Liese 75 Years Young

Olaf Schmidt

Page range: 104-105

July 5, 2005

Literature Reports

Page range: 106-110

About this journal

Objective
Holzforschung (HF) is an international scholarly journal that publishes cutting-edge research on the biology, chemistry, physics and technology of wood and wood components. High quality papers about biotechnology and tree genetics are also welcome. Rated year after year as one of the top scientific journals in the category of Pulp and Paper (ISI Journal Citation Index), Holzforschung represents innovative, high quality basic and applied research. The German title reflects the journal's origins in a long scientific tradition, but all articles are published in English to stimulate and promote cooperation between experts all over the world. Ahead-of-print publishing ensures fastest possible knowledge transfer.

Topics

Biology, chemistry, physics and technology of wood and wood components
Biotechnology and tree genetics

Article formats
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