Published by De Gruyter

Volume 59 Issue 6

Issue of Holzforschung

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Contents
Journal Overview

November 1, 2005

Page range: I-VI

November 1, 2005

Species index (scientific names)

Page range: XII-XIV

November 1, 2005

Ultrastructural changes in a holocellulose pulp revealed by enzymes, thermoporosimetry and atomic force microscopy

Jesper Fahlén, Lennart Salmén

Page range: 589-597

Abstract

To increase our knowledge of the ultrastructure within softwood fibres, enzymatic treatment, thermoporosimetry, light microscopy, and atomic force microscopy with image analysis were used to investigate the structure of holocellulose softwood pulp fibres. The size of the average cellulose fibril aggregates and the width of pore and matrix lamellae were found to be uniform across the secondary cell-wall layer in the transverse direction of the wood fibre wall. In holocellulose, these dimensions were very similar to those in the native wood, whereas in kraft pulp the cellulose fibril aggregates were larger and the pore and matrix lamellae broader. These differences between holocellulose and kraft pulp fibres suggest that a high temperature is needed for cellulose fibril aggregation to occur. Neither refining nor drying of the holocellulose pulp changed the cellulose fibril aggregate size. Upon drying and enzymatic treatment, a small decrease in the pore and matrix lamella width was evident throughout the fibre wall. This indicated not only uniform distribution of pores throughout the fibre wall, but also enzymatic accessibility to the entire fibre wall. The holocellulose pulp had a somewhat larger pore volume than the kraft pulp. Refining of the holocellulose pulp led to pore closure, probably due to increased mobility of the fibre wall. The enzymatic treatment revealed that during hydrolysis of one hemicellulose, part of the other was also dissolved, indicating that the two hemicelluloses are to some extent linked to each other in the structure.

November 16, 2005

Development of wet strength additives from wheat gluten

Dakai Ren, Kaichang Li

Page range: 598-603

Abstract

Glyoxal-polyacrylamide (GPA) resin is widely used as a wet strength additive for various paper and paperboard products. However, GPA resin is derived from petrochemicals and contributes to contaminants in the recycling of papers. Wheat gluten is one of the most abundant proteins in nature. This research investigated how to convert gliadin, a key component of wheat gluten, to an effective temporary wet-strength additive. Gliadin was first modified with glycidyltrimethylammonium chloride (GTA) to generate positively charged GTA-gliadin. Further reaction of GTA-gliadin with glyoxal yielded GTA-gliadin-glyoxal resins. Conditions for these two reactions were investigated to maximize the dry and wet strengths of GTA-gliadin-glyoxal-treated paper. At a dosage of 1 wt.%, GTA-gliadin-glyoxal resin was comparable to GPA resin in terms of enhancing the dry and wet strengths of treated paper.

November 16, 2005

Characterization of electrolyzed magnesium spent-sulfite liquor

Okko Ringena, Bodo Saake, Ralph Lehnen

Page range: 604-611

Abstract

Spent sulfite liquor derived from magnesium bisulfite pulping of beech was electrolyzed in a pilot-plantelectrolysis cell. During the electrochemical treatment (125 mA cm −2 ; 60°C; 180 min), desalination of the anolyte took place and the magnesium concentration was reduced to approximately 60%. In addition, the pH decreased from 5 to 1. Three differently treated liquors (SSL pH 5; SSLe pH 2.5; SSLe pH 1) were chosen for further analysis. The average molar mass of the fractions was determined by size exclusion chromatography. Extended electrolysis time increased the molar mass of the lignosulfonates ( M w : SSL pH 5, 5700 g mol −1 ; SSLe pH 2.5, 6500 g mol −1 ; SSLe pH 1, 7400 g mol −1 ). The content of phenolic hydroxyl and sulfonic acid groups did not undergo significant changes. Nevertheless, lignosulfonates obtained after electrolysis showed higher charge densities than the unmodified product (SSL pH 5, 1590 μeq g −1 ; SSLe pH 2.5, 1760 μeq g −1 ; SSLe pH 1, 1920 μeq g −1 ). Separation of the liquors into five fractions was performed using four ultrafiltration membranes (100, 50, 10 and 1 kDa). This allowed detailed structural analysis of high- and low-molar-mass lignosulfonate fractions in terms of the modifications induced by electrolysis.

November 16, 2005

Molecular weight-functional group relations in softwood residual kraft lignins

Keiichi Koda, Keiichi Koda, Armindo R. Gaspar, Liu Yu, Liu Yu, Liu Yu, Dimitris S. Argyropoulos

Page range: 612-619

Abstract

An integrated picture of the distribution of functional groups should be provided as a function of molecular size within residual kraft lignins. With this goal we developed a reliable and reproducible method for determination of the molecular weight and molecular weight distribution of residual kraft lignins (RKLs) over the whole delignification range. In general, our data indicate that for reliable measurement of the molecular weight and its distribution of residual lignin in pulps, the lignin-carbohydrate bonds have to be cleaved prior to size exclusion chromatography. The recently developed method for isolating residual lignins, which involves cellulolytic treatment followed by a mild acid hydrolysis step, was found to be the most suitable approach to achieve this. The molecular weight and polydispersity of all RKLs decreased as a function of delignification. As anticipated, the observed decrease in molecular weight was clearly reflected in the concomitantly decreasing amount of β-O-4 structural linkages present. Similarly, the total phenolic hydroxyl content increased as the molecular weight of the RKLs decreased during kraft pulping. Despite the smaller size of the lignin remaining on the kraft fiber at the end of delignification, the preponderance of condensed phenolic structures within these lignins offers an explanation for delignification problems during bleaching.

November 16, 2005

Structure-activity relationships of cadinane-type sesquiterpene derivatives against wood-decay fungi

Chi-Lin Wu, Shih-Chang Chien, Sheng-Yang Wang, Yueh-Hsiung Kuo, Shang-Tzen Chang

Page range: 620-627

Abstract

Cadinane-type sesquiterpenes have a wide spectrum of biological activity, but their use as wood preservatives and the structure-activity relationships of their derivatives have not yet been reported. A total of 13 compounds were synthesized from T-cadinol, T-muurolol, and α-cadinol and their chemical structures were confirmed by IR, MS, and 1 H and 13 C NMR. The antifungal properties of 16 compounds against three wood-decay fungi were evaluated in vitro . α-Cadinol showed strong antifungal activity against Lenzites betulina , Trametes versicolor , and Laetiporus sulphureus (total mean IC 50 0.10 mM). Among the derivatives synthesized, 3β-ethoxy-T-muurolol (0.24 mM), 4ξ H -cadinan-10β-ol (0.25 mM), 4ξ H -muurolan-10β-ol (0.29 mM), and 4ξ H -cadinan-10α-ol (0.25 mM) showed good antifungal activity against all fungi tested. Correlation was observed between the antifungal activity of the compounds tested and log P . Furthermore, the presence of an unsaturated double bond and oxygen-containing functional groups in the compounds plays a key role in their antifungal activity. The stereo configuration of cadinane-type sesquiterpenes also influences their antifungal activity. Understanding how the structure of natural compounds relates to their antifungal function is important and may facilitate their application as novel wood preservatives.

November 16, 2005

Effect of water on wood liquefaction and the properties of phenolated wood

Seung-Hwan Lee, Siqun Wang

Page range: 628-634

Abstract

The effects of water on wood liquefaction were investigated under various reaction conditions: reaction temperature, time, and wood/phenol weight ratio. Although the addition of water decreased the reaction temperature and reduced the liquefaction rate and combined phenol content of the resulting phenolated wood, residue of <20% and a combined phenol content of >95% were obtained by controlling the reaction conditions. The addition of water suppressed an increase in the combined phenol content and molecular weight by a recondensation reaction observed in liquefaction in the absence of water under the same reaction conditions. Phenolated wood obtained in the presence of water showed comparable thermoflow properties and slightly higher activation energy for cure when compared with phenolated wood obtained in the absence of water. Moldings from both phenolated woods showed comparable flexural properties to those of moldings from commercial Novolak resin.

November 16, 2005

Effect of wood species and molecular weight of phenolic resins on curing behavior and bonding development

Guangbo He, Ning Yan

Page range: 635-640

Abstract

In this study, dynamic mechanical analysis (DMA) was used to investigate the curing behavior and bonding performance of phenolic resins with different molecular weights as a function of three wood species. The curing process of the resin was characterized by both gel point and tanδ. The change in storage modulus before and after curing was used to characterize the bonding development. Resin molecular weight was found to significantly influence the curing process, while the effect of wood on the curing behavior among the three species was not clear. The resin should contain a low-molecular-weight fraction and a high-molecular-weight fraction to achieve the best bonding performance. The optimum molecular weight and molecular weight distribution was found to be different among the different wood species studied.

November 16, 2005

Contact-free measurement and non-linear finite element analyses of strain distribution along wood adhesive bonds

Erik Serrano, Bertil Enquist

Page range: 641-646

Abstract

The strain distribution along wood adhesive bonds was studied using a contact-free measurement system based on a white-light digital image correlation (DIC) technique. Two different specimen geometries and three different adhesives were investigated. The specimen geometries were according to the standards EN302-1 and ASTM D905. The adhesives tested were a phenolic resorcinol (PRF), a one-component polyurethane (PUR) and an epoxy (EPX). In addition to the experimental investigation, a finite element study using a non-linear fracture mechanics model for the adhesive bond line was carried out, aimed at investigating whether deformation measurements could predict differences in the mechanical behaviour of the adhesives. The measurement technique was found to be capable of distinguishing, in terms of their strain distributions at a given load, adhesives that differed markedly from one another. For example, the brittle PRF adhesive showed more localised strains than the more ductile EPX and PUR adhesives did at the same load level. Another conclusion from this study is that the measurement technique used is applicable to situations in which large strains occur. Thus, the technique used here is of great interest for use in the calibration of finite element models and constitutive theories and for the design of test set-ups.

November 16, 2005

Comparison between HT-dried and LT-dried spruce timber in terms of shape and dimensional stability

Robert Kliger, Charlotte Bengtsson, Marie Johansson

Page range: 647-653

Abstract

The performance of timber studs from Norway spruce ( Picea abies ) in terms of shape and dimensional stability was evaluated. The shape stability studied included three modes of distortion, i.e. twist, bow and spring. The dimensional stability was assessed by measuring longitudinal shrinkage and swelling properties. The study comprised 96 studs measuring 45 mm×70 mm×2500 mm from 15 butt logs. Half the studs from each log were dried using a high-temperature method (HT) at 115°C, while the other half were dried using a conventional low-temperature method (LT) at 70°C. Distortion in the studs was measured at moisture contents of 14% and 9%. The HT-dried timber had significantly lower distortion values than the LT-dried timber. As a result, 80% of the high-temperature-dried studs were able to pass the limits for distortion, while only 60% of the low-temperature-dried studs passed the same limit. Studs cut close to the pith displayed the largest twist, independent of the drying method. A simple model for predicting twist that was used in previous studies was also valid for HT-dried timber. The most important parameters in this model for both HT- and LT-dried timber were grain angle, annual ring curvature and tangential shrinkage.

November 16, 2005

Physical properties of earlywood and latewood of Pinus radiata D. Don: Anisotropic shrinkage, equilibrium moisture content and fibre saturation point

Shusheng Pang, Alfred Herritsch

Page range: 654-661

Abstract

Anisotropic shrinkage (tangential and longitudinal), equilibrium moisture content (EMC) and fibre saturation point (FSP) were measured for separated earlywood (EW) and latewood (LW) of a 0.75-m-long log of 20-year old Pinus radiata that was cut at breast height from a selected tree in the forest of Central North Island, New Zealand. The experimental results have shown that at 12% moisture content (MC), tangential shrinkage was 3.23% for EW and 3.90% for LW, with an overall average of 3.56%. Longitudinal shrinkage was 0.23% for EW and 0.21% for LW with an overall average of 0.22%. Shrinkage for the oven dry (OD) state showed similar trends to those at 12% MC in terms of the differences between EW and LW. The tangential and longitudinal shrinkage varied significantly along the radius from pith to bark. The EW tangential shrinkage increased from pith to the seventh growth ring and then remained relatively constant until the last ring adjacent to the bark. The LW tangential shrinkage also increased from the pith outwards until the seventh growth ring, but beyond that was more variable than the EW shrinkage. Both EW and LW showed similar longitudinal shrinkage, with the highest values in the second growth ring, from which the shrinkage decreased exponentially towards the bark. LW had a slightly higher EMC than EW at a relative humidity (RH) below 80%, but the trend was reversed for RH above 80%. The EMC differences between EW and LW were less than 0.6%. The overall average FSP for Pinus radiata was 29.1%, with actual values varying from 25% to 32.8%. The earlywood FSP (28.9%) was slightly lower than that of the latewood (29.4%).

November 16, 2005

Effect of stress levels on compressive low-cycle fatigue behaviour of softwood

Meng Gong, Ian Smith

Page range: 662-668

Abstract

Low-cycle fatigue (LCF) of spruce under parallel-to-grain compression was investigated to simulate the damage that occurs during extreme events such as hurricanes. Load control was used, with peak stress levels of 75%, 85% and 95% of static compressive strength ( C max ). Changes in the residual cyclic modulus, cyclic creep strain and modified work density were correlated with the number of load cycles to assess their suitability as damage indicators. Creep tests were also carried out and the strain compared with cyclic creep strain under LCF load. Fatigue and creep tests had a total duration of 10 min. A three-element mathematical model was used to predict the cyclic creep strain. Some key findings were that: (1) the residual cyclic modulus varies with the number of load cycles at a given stress level and decreases with an increase in stress level; (2) cyclic creep strain and pure creep strain are strongly influenced by the peak stress level; and creep specimens fail but fatigue specimens do not at a 95% peak stress level; and (3) the three-element mathematical model is appropriate for predicting cyclic creep strain.

November 16, 2005

Comparison of morphological and chemical properties between juvenile wood and compression wood of loblolly pine

Ting-Feng Yeh, Barry Goldfarb, Hou-min Chang, Ilona Peszlen, Jennifer L. Braun, John F. Kadla

Page range: 669-674

Abstract

In conifers, juvenile wood (JW) is always associated with compression wood (CW). Due to their similar properties, there is a common belief that JW is the same as CW. To resolve whether JW is identical to CW, 24 rooted cuttings of one loblolly pine clone were planted in growth chambers under normal, artificial bending, and windy environments. The results show that the morphology of JW is significantly different from CW. Furthermore, chemical analyses revealed that JW and CW are significantly different in chemical composition. Our results indicate that JW is different from CW, and the wood formed under a controlled windy environment is a mild type of compression wood.

November 16, 2005

Ultrastructure of commercial recycled pulp fibers for the production of packaging paper

Jonas Brändström, Jean-Paul Joseleau, Alain Cochaux, Nathalie Giraud-Telme, Katia Ruel

Page range: 675-680

Abstract

Transmission electron microscopy was used to investigate the ultrastructure of recycled pulp fibers originating from a household collection plant and intended for the production of packaging paper. Three recovered paper grades and recycling processes, including pulping, screening, cleaning and refining, were assessed with emphasis on surface and internal fibrillation as well as xylan localization. Results showed a large heterogeneity with respect to fiber ultrastructure within and between the grades. Screening and cleaning steps had no detectable effects, but refining clearly increased cell-wall delamination and surface fibrillation. Immunolabeling of xylans showed that they were distributed rather evenly across the cell walls. They were also present on fines. Two different mechanisms for fiber delamination and surface fibrillation were found, one which implies that internal and external fibrillation take place simultaneously across the cell wall, and another which implies successive peeling of layers or sub-layers from the outside towards the inside. It is suggested that recycled fibers of chemical pulp origin undergo the former mechanism and recycled fibers that contain lignin binding the cell wall matrix give rise to the latter peeling mechanism. Because several recycled fibers were severely delaminated and almost fractured, we suggest that to produce a good packaging paper, it is important that recycled pulp should contain a significant proportion of fibers with high intrinsic strength.

November 1, 2005

Oxalate regulation by two brown rot fungi decaying oxalate-amended and non-amended wood

Jonathan S. Schilling, Jody Jellison

Page range: 681-688

Abstract

Oxalic acid secretion by brown rot wood-degrading fungi has been proposed to function in pH control and non-enzymatic biodegradation. Although oxalate production in liquid cultures of brown rot fungi commonly correlates with glucose oxidation, excess oxalate accumulation in wood during oxidative decay could impede Fe 3+ reduction by fungal-derived chelators and thus inhibit brown rot. In this study, we pre-treated spruce wood with various oxalate concentrations and subjected it to brown rot decay by Fomitopsis pinicola and Meruliporia incrassata in agar- and soil-block trials. In agar-block microcosms containing wood pre-treated with 0, 1, 10 or 100 mM sodium oxalate, test fungi equalized wood oxalate and pH at week 12 of decay by either increasing or reducing wood oxalate, depending on the pre-treatment. Oxalate reductions in wood were not accompanied by increases in agar oxalate. During soil-block decay of wood pre-treated with 0 or 50 mM oxalate, oxalate and pH regulation were time-dependent and more variable. Wood oxalate levels did not increase with increasing fungal biomass (per ergosterol); however, decreases in oxalate were not explained by enhanced oxalate catabolism activity, Ca 2+ import, or translocation of oxalate into the soil. Our results suggest that brown rot fungi may optimize extracellular oxalate during wood decay, and that soil characteristics may influence this dynamic.

November 1, 2005

Pine and spruce roundwood species classification using multivariate image analysis on bark

David Nilsson, Ulf Edlund

Page range: 689-695

Abstract

Wood discs from 67 pine and 79 spruce logs were collected from a forest clearing. Three different 24-bit red-green-blue (RGB) images were acquired from the radial surface of each disc. The first image contained bark, the second image was a mixture of bark and wood surface, and the third image consisted only of wood surface. The image texture was compressed into vectors of Fourier-transformed wavelet coefficients. These were assembled in matrices and analysed by principal component analysis (PCA) and partial least-squares projections to latent structures (PLS). Classification using Fourier-transformed wavelet scales showed that the wood species could be predicted with 90% accuracy. A thorough examination of this classification showed that the predicting power of these models was mostly due to wavelet scales that represented the mean value of each colour channel. The prediction accuracy that could be obtained from coefficients representing image texture was generally low. The use of grey-level co-occurrence matrices prior to the wavelet transformation showed, however, that it is possible to classify the wood species of pine and spruce with an accuracy approaching 100%.

November 1, 2005

Detection and species discrimination using rDNA T-RFLP for identification of wood decay fungi

Ulrika Råberg, Nils O.S. Högberg, Carl Johan Land

Page range: 696-702

Abstract

In the present work PCR technology was used as a tool to detect the early stages of wood decay and was compared with microscopic evaluation. The wood decay fungi Postia placenta and Coniophora puteana were detectable in interior wood samples by terminal restriction fragment length polymorphism (T-RFLP) after 2weeks of incubation with monocultures, while microscopic detection of hyphae was not possible until after 7 weeks. A potential problem when fungal communities are studied with T-RFLPs of rDNA is that intra-specific variation complicates data analysis. In this work, we show that intra-specific sequence variation in the internal transcribed spacer of the rDNA in Coniophora puteana allows T-RFLP identification of this species. This is due to intra-specific variations in fragment length, in combination with the absence of point mutations in the selected restriction sites.

November 1, 2005

Personalia

Minoru Terazawa

Page range: 703-704

November 1, 2005

Award presentation on the occasion of the 13th International Symposium on Wood, Fibre and Pulping Chemistry, May 16–19, 2005, Auckland, New Zealand

Page range: 705-705

November 1, 2005

NMR studies on Fraser fir Abies fraseri (Pursh) Poir. Lignins

Mikhail Yu Balakshin, Ewellyn A. Capanema, Barry Goldfarb, John Frampton, John F. Kadla, John F. Kadla

Page range: 706-706

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
Original articles, Reviews, Short notes

> Information on submission process

Volume 59 Issue 6

Issue of Holzforschung

Contents

Species index (scientific names)

Subject Index

Acknowledgement

Author Index

Ultrastructural changes in a holocellulose pulp revealed by enzymes, thermoporosimetry and atomic force microscopy

Abstract

Development of wet strength additives from wheat gluten

Abstract

Characterization of electrolyzed magnesium spent-sulfite liquor

Abstract

Molecular weight-functional group relations in softwood residual kraft lignins

Abstract

Structure-activity relationships of cadinane-type sesquiterpene derivatives against wood-decay fungi

Abstract

Effect of water on wood liquefaction and the properties of phenolated wood

Abstract

Effect of wood species and molecular weight of phenolic resins on curing behavior and bonding development

Abstract

Contact-free measurement and non-linear finite element analyses of strain distribution along wood adhesive bonds

Abstract

Comparison between HT-dried and LT-dried spruce timber in terms of shape and dimensional stability

Abstract

Physical properties of earlywood and latewood of Pinus radiata D. Don: Anisotropic shrinkage, equilibrium moisture content and fibre saturation point

Abstract

Effect of stress levels on compressive low-cycle fatigue behaviour of softwood

Abstract

Comparison of morphological and chemical properties between juvenile wood and compression wood of loblolly pine

Abstract

Ultrastructure of commercial recycled pulp fibers for the production of packaging paper

Abstract

Oxalate regulation by two brown rot fungi decaying oxalate-amended and non-amended wood

Abstract

Pine and spruce roundwood species classification using multivariate image analysis on bark

Abstract

Detection and species discrimination using rDNA T-RFLP for identification of wood decay fungi

Abstract

Personalia

Award presentation on the occasion of the 13th International Symposium on Wood, Fibre and Pulping Chemistry, May 16–19, 2005, Auckland, New Zealand

NMR studies on Fraser fir Abies fraseri (Pursh) Poir. Lignins