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Volume 66 Issue 3

Issue of Holzforschung

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Contents
Journal Overview

Original Papers

September 13, 2011

Refiner bleaching in a peroxide-based ATMP process compared with conventional bleaching

Dmitri Gorski, Lars Johansson, Per Engstrand

Page range: 275-281

Abstract

The aim of this study was to compare refiner bleaching with conventional laboratory bleaching by means of hydrogen peroxide and magnesium hydroxide. Refiner bleaching in this study was a part of the ATMP (advanced thermo mechanical pulping) process, in which bleaching chemicals are added to the first stage refiner. Unbleached reference pulp which underwent similar mechanical treatment as refiner bleached pulp was used for laboratory bleaching. Bleaching efficiency was found to be almost equal for pilot scale refiner bleaching and conventional laboratory bleaching. A brightness increase of 10 ISO% was reached with addition of 26 kg t -1 hydrogen peroxide leading to a final brightness of 66 ISO% using both methods. Slightly more COD (52 kg t -1 compared with 46 kg t -1 ) was generated in refiner bleaching compared with conventional laboratory bleaching to equal brightness with the same chemicals added.

September 17, 2011

Chemical characterization of polymerized products formed in the reactions of matairesinol and pinoresinol with the stable radical 2,2-diphenyl-1-picrylhydrazyl

Annika I. Smeds, Patrik C. Eklund, Evanthia Monogioudi, Stefan M. Willför

Page range: 283-294

Abstract

Polymerization reactions of the lignans matairesinol and pinoresinol with the stable radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) were studied. The reactions were rapid and almost quantitative. The molecular weight distribution (MWD) of the formed lignan dimers and polymers was determined by high-performance size-exclusion chromatography (HPSEC) combined with evaporative light-scattering detection (ELSD), and the compounds were characterized by HPLC-MS, pyrolysis-GC/MS, NMR, MALDI-ToF-MS, and GC-MS of the monomeric and dimeric units formed by KMnO 4 oxidation. The yield of high-MW polymers is higher for pinoresinol (69%) than for matairesinol (43%). According to the HPSEC-ELSD analyses, the MWD is also broader for the pinoresinol polymers. The latter seem to consist mainly of hepta-hexacontalignans (MW 2.5–21.4 kDa), whereas the matairesinol polymers are mainly penta-pentadecalignans (MW 1.8–5.3 kDa). The polymers seem to contain mainly unmodified lignan units linked by 5-5′ bonds.

September 17, 2011

Characterization of MWLs from Tamarix ramosissima isolated before and after hydrothermal treatment by spectroscopical and wet chemical methods

Ling-Ping Xiao, Zheng-Jun Shi, Feng Xu, Run-Cang Sun

Page range: 295-302

Abstract

To improve enzymatic hydrolysis, hydrothermal treatment was carried out on the shrub Tamarix ramosissima . Milled wood lignin (MWL) was isolated from T. ramosissima stems before and after hydrothermal treatment, and its chemical structure was characterized by carbohydrate analysis, elemental analysis, methoxy group determination, FT-IR spectroscopy, quantitative 13 C NMR spectroscopy, 2D heteronuclear single quantum coherence spectroscopy, and gel permeation chromatography. The analyses confirmed that T. ramosissima MWL is very rich in syringyl units. It was found that the main reaction responsible for the lignin degradation is the homolytic cleavage of aryl-ether bonds resulting in a reduced amount of β-O-4′ interlinkages and, as a consequence, in elevated amounts of β-β′ and β-5′ linkages. The MWL isolated from the pretreated solid residue was more condensed and had a lower molecular weight than the MWL isolated from untreated material.

August 31, 2011

Studies on electrooxidation of lignin and lignin model compounds. Part 1: Direct electrooxidation of non-phenolic lignin model compounds

Takumi Shiraishi, Toshiyuki Takano, Hiroshi Kamitakahara, Fumiaki Nakatsubo

Page range: 303-309

Abstract

The direct anodic oxidation of non-phenolic lignin model compounds was investigated to understand their basic behaviors. The results of cyclic voltammetry (CV) studies of monomeric model, such as 1-(4-ethoxy-3-methoxyphenyl)ethanol, are interpreted as the oxidation for C α -carbonylation did not proceed in the reaction without a catalyst, but a base promotes this reaction. Indeed, the bulk electrolyses of the monomeric lignin model compounds with 2,6-lutidine afforded the corresponding C α -carbonyl compounds in high yields (60–80%). It is suggested that deprotonation at C α -H in the ECEC mechanism (E=electron transfer and C=chemical step) is important for C α -carbonylation. In the uncatalyzed bulk electrolysis of a β-O-4 model dimeric compound, 4-ethoxy-3-methoxyphenylglycerol-β-guaiacyl ether, the corresponding C α -carbonyl compound was not detected but as a result of C α -C β cleavage 4-O-ethylvanillin was found in 40% yield. In the electrolysis reaction in the presence of 2,6-lutidine (as a sterically hindered light base), the reaction stopped for a short time unexpectedly. These results indicate the different electrochemical behavior of simple monomeric model compounds and dimeric β-O-4 models. The conclusion is that direct electrooxidation is unsuitable for C α -carbonylation of lignin.

August 31, 2011

Studies on electro-oxidation of lignin and lignin model compounds. Part 2: N-Hydroxyphthalimide (NHPI)-mediated indirect electro-oxidation of non-phenolic lignin model compounds

Takumi Shiraishi, Toshiyuki Takano, Hiroshi Kamitakahara, Fumiaki Nakatsubo

Page range: 311-315

Abstract

The N -hydroxyphthalimide (NHPI)-mediated indirect electro-oxidation of non-phenolic lignin model compounds has been investigated for selective C α -carbonylation of lignin. A cyclic voltammogram of NHPI in 0.1 M LiClO 4 /CH 3 CN with 2,6-lutidine interpreted that NHPI can act as a mediator in the indicated process in the range 0.5–0.8 V vs. Ag/Ag + . The corresponding C α -carbonyl compounds was obtained in high yields (85–97%) in the case of the monomer 1-(4-ethoxy-3-methoxyphenyl) ethanol in 0.1 M LiClO 4 /CH 3 CN or 0.1 M LiClO 4 /(CH 3 CN/H 2 O=7/3) with a small amount of 2,6-lutidine at 0.7 V vs. Ag/Ag + . The processing of the dimeric lignin model compound (4-ethoxy-3-methoxyphenylglycerol-β-guaiacyl ether) also gave the corresponding C α -carbonyl compound in high yield (88–92%). The reaction proceeds through hydrogen atom transfer in the NHPI-mediated electro-oxidation. On the other hand, the direct electro-oxidation and indirect electro-oxidation mediated by ABTS [2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonate)] of the dimeric compound preferentially gave the corresponding C α -C β cleavage product in low or moderate yields (5–40%). The conclusion is that NHPI is an excellent mediator for selective C α -carbonylation of non-phenolic β-O-4 structures in lignin in electronic mediator system.

November 17, 2011

Shaped hemocompatible aerogels from cellulose phosphates: preparation and properties

Falk Liebner, Ramona Dunareanu, Martina Opietnik, Emmerich Haimer, Martin Wendland, Carsten Werner, Manfred Maitz, Philipp Seib, Marie-Alexandra Neouze, Antje Potthast, Thomas Rosenau

Page range: 317-321

Abstract

Hemocompatible, shaped cellulose phosphate aerogels were obtained from phosphorylated cellulosic pulps of low degree of phosphorylation (DS P ≤0.20) by dissolution in stabilized NMMO×H 2 O, shaping, reprecipitation with ethanol and subsequent scCO 2 drying. The novel aerogels were found to be promising materials for cell scaffolding and bone grafting. Special features include their interconnected and spread porosity, highly porous surface and microstructure, good hemocompatibility, and suitable hydroxyl apatite-binding environment. Adsorption of Ca 2+ ions to the phosphate groups did not invert the negative inflammatory response observed after phosphorylating cellulose, but increased platelet-dependent parameters of hemostasis.

Open Access November 16, 2011

The effects of combining guaiacol and syringol on their pyrolysis

Mohd Asmadi,, Haruo Kawamoto, Shiro Saka

Page range: 323-330

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Abstract

Pyrolysis of guaiacol/syringol mixtures was studied in an ampoule reactor (N 2 /600°C/40–600 s) to understand the reactivities of the aromatic nuclei in hardwood lignins. By comparing the results with those of pure guaiacol or syringol, significant effects of their combination were observed during early stage pyrolysis: charring and gas formation were markedly suppressed. Yields for the tar fractions (MeOH-soluble) were increased by combination but the contents of GC/MS-detectable products with low molecular weight were dramatically decreased in these fractions, especially catechol-type compounds diminished, which are formed through the O-CH 3 homolysis reaction and subsequent donation of hydrogen atoms. These observations are discussed at the molecular level. Inhibition of the charring reaction, which can act as a strong hydrogen donor, would increase the probability of radical coupling reactions of the O-CH 3 homolysis products instead of the formation of catechol and pyrogallol and their derivatives. The latter compounds are important intermediates for gas formation, especially for CO. Based on these lines of evidence, a hypothesis is proposed according to which poly\xadaromatization during carbonization activates the pyrolytic reactions of guaiacol and syringol.

May 13, 2011

Multi-steps degradation method for β-O-4 linkage in lignins: γ-TTSA method. Part 1: Reaction of non-phenolic dimeric β-O-4 model compounds

Daisuke Ando, Toshiyuki Takano, Fumiaki Nakatsubo

Page range: 331-339

Abstract

The so-called γ-TTSA method has been developed for the cleavage of β-O-4 linkages in lignin. It consists of four steps: (1) γ-tosylation, (2) thioetherification (substitution reaction with 1-dodecanethiol to γ-thioether), (3) sulfonylation (oxidation from γ-thioether to γ-sulfone), and (4) mild alkali degradation of γ-sulfone. The method was tested on non-phenolic dimeric β-O-4 lignin model compounds: 1G (4-benzyloxy-3-methoxyphenylglycerol-β-guaiacyl ether), 1S (4-benzyloxy-3,5-dimethoxyphenylglycerol-β-syringyl ether), and 1H (4-benzyloxyphenylglycerol-β-phenyl ether). It is demonstrated that the mild alkali degradation of the γ-sulfone group proceeds efficiently, i.e., the electron-withdrawing sulfone group at γ-position contributes to the cleavage of β-O-4 linkages. The γ-TTSA method may be especially useful for the elucidation of lignin-carbohydrate complex structures containing benzylether bonds.

September 26, 2011

Optimization of Burkholderia sp. ZYB002 lipase production for pitch control in thermomechanical pulping (TMP) processes

Zhengyu Shu, Jiguang Wu, De Chen, Lanxing Cheng, Yi Zheng, Jianping Chen, Jianzhong Huang

Page range: 341-348

Abstract

Production and process optimization of a thermostable lipase from Burkholderia sp. ZYB002 and the application potential of this lipase for pitch control of thermomechanical pulp (TMP) has been investigated. The optimized physical and nutritional factors of Burkholderia sp. ZYB002 were found to be (all units in%, w v -1 ): 0.5 peptone, 0.025 urea, 0.5 glycerol, 0.1 NaHCO 3 , 0.2 K 2 HPO 4 , 1.5 Tween 80, 1.1 olive oil, four inoculum volume, and initial pH 8.5. The lipase production process was carried out at 30°C at 250 rpm for 36 h in 250 ml Erlenmeyer flasks containing 35 ml fermentation medium and five glass beads. Under the optimized conditions, lipase activity reached 216.5 U ml -1 . In a TMP of Pinus massoniana , 39% of triglycerides were hydrolyzed by the lipase under optimized conditions [pulp concentration 6% (w v -1 ), lipase dose 20 U g -1 based on dry TMP, pulp initial pH 7.5, and 65°C for 30 min]. The lipase in question displayed a great potential for pitch control of TMP.

September 17, 2011

Evidence that release of internal stress contributes to drying strains of wood

Bruno Clair

Page range: 349-353

Abstract

Wood shrinks during drying, with the departure of bond water. Along the fibre direction, the magnitude of this shrinkage is mainly governed by the orientation of cellulose microfibrils (MF) in the cell wall. However, tension wood has an unexpectedly high longitudinal shrinkage considering the fact that MFs are oriented nearly parallel to the cell direction. This effect is thought to be caused by the gel collapse of the G-layer; however, some species producing a tension wood without a G-layer also exhibit a higher longitudinal shrinkage than normal wood. The aim of this study is to analyse the contribution of maturation stresses to drying shrinkage. Longitudinal and tangential drying shrinkage of tension wood and normal wood were measured on two sets of matched chestnut wood samples. The first set was directly oven-dried, whereas on the second set, a hygrothermal treatment released the maturation stress before oven-drying. The analysis of the strains during each step of the procedure revealed that part of the drying shrinkage is caused by the release of internal stresses during the desorption process. Finally, a tentative schematic model is proposed, taking into account the cumulative contributions to longitudinal drying shrinkage.

September 17, 2011

Structure of oak wood from the Swedish warship Vasa revealed by X-ray scattering and microtomography

Kirsi Svedström, Ingela Bjurhager, Aki Kallonen, Marko Peura, Ritva Serimaa

Page range: 355-363

Abstract

The degradation of oak wood of the historical warship Vasa was studied, focusing on cellular structure by X-ray microtomography (μCT) and on the nanostructure of the cell wall by wide- and small-angle X-ray scattering (WAXS, SAXS). Solid samples [polyethylene glycol (PEG)-, impregnated and PEG-extracted] were submitted to X-ray analysis and the results compared to those of recent oak. The cellular structure of the Vasa oak was surprisingly well preserved at the micrometer level, according to the μCT images. As revealed by WAXS, the fraction of crystalline cellulose was lower in the Vasa samples compared with recent oak, but the average length and width of cellulose crystallites (25±2 nm and 3.0±0.1 nm, respectively), and the mean microfibril angles (4–9°), showed no significant differences. Accordingly, the crystalline parts of cellulose microfibrils are well preserved in the Vasa oak. The SAXS results indicated a declined short-range order between the cellulose microfibrils and a higher porosity of the Vasa oak compared with recent oak, which may be explained by modification of the hemicellulose-lignin matrix.

November 25, 2011

Physical properties of simul (red-silk cotton) wood (Bombax ceiba L.) chemically modified with styrene acrylonitrile co-polymer and nanoclay

Rashmi Rekha Devi, Manabendra Mandal, Tarun Kumar Maji

Page range: 365-371

Abstract

Wood plastic composites have been prepared based on simul wood ( Bombax ceiba L.), which was vacuum impregnated with the styrene acrylonitrile (SAN) co-polymer nanoclay (nnc) intercalating system in the presence of glycidyl methacrylate (GMA), a crosslinking agent. The impact of nanoclay was investigated on the mechanical, thermal, dynamic mechanical behavior, and the biodegradability of the resultant wood polymer nanocomposite (WPC nnc ) was investigated. The tensile strength, tensile modulus, flexural strength, and flexural modulus of the composite were relatively higher in the presence of 2 phr nanoclay. The limiting oxygen index values showed self-extinguishing behavior of the WPC nnc . Furthermore, the storage moduli (E′) and damping index (tan δ) of these products were high. WPC SAN/GMA/nnc exhibit higher biodegradability compared to WPC SAN/GMA .

March 1, 2012

Characterisation of moisture-dependent plasticity of beech wood and its application to a multi-surface plasticity model

Stefan Hering, Susanne Saft, Eckart Resch, Peter Niemz, Michael Kaliske

Page range: 373-380

Abstract

The moisture-dependent stress-strain behaviour of European beech wood ( Fagus sylvatica L.) has been determined under compression, analytically described for the radial and tangential direction using a modified Ramberg-Osgood approach and realized numerically by a multi-surface plasticity model. The conspicuous decrease of the stress-strain characteristic perpendicular to the grain with increasing moisture content is similar to the behaviour of the presented ultimate strength values in the longitudinal direction. Based on input parameters previously quantified by means of an inverse finite element analysis, the simulation of a crosswise laminated two-layer arrangement during moistening was carried out. A distinct development of plastified regions can be observed due to the resulting swelling stresses.

November 16, 2011

Vibration method for grading of large cross-section coniferous timber species

Francisco Arriaga, Guillermo Íñiguez-González, Miguel Esteban, Ferenc Divos

Page range: 381-387

Abstract

The non-destructive testing (NDT) of timber using the longitudinal vibration method is based on the natural frequency of wood which is in relation to its quality. In the present paper, the suitability of this tool is investigated and the results of grading 395 pieces are presented. Structural timber of Radiata pine ( Pinus radiata D. Don.), Scots pine ( Pinus sylvestris L.), and Laricio pine [ Pinus nigra ssp. salzmannii (Dunal) Franco] from Spanish sources were investigated. The specimens were tested for bending according to the European standard EN 408 (2003) and the values of strength and stiffness were compared with the results estimated by means of NDT. The vibration equipment applied permits the measurement of the longitudinal natural frequency and mass of the specimen, and then the density and the dynamic modulus of elasticity can be calculated. There is a strong relationship between the static modulus of elasticity obtained from the bending test and the dynamic modulus of elasticity obtained by the NDT technique. There is an acceptable relationship between modulus of rupture and dynamic modulus of elasticity if the visual defects (knot sizes) are taken into account. Acoustic measurements have become widely acceptable, and they have great potential for stress grading of coniferous timber.

November 16, 2011

Ultrastructural evaluation of compression wood-like properties of common juniper (Juniperus communis L.)

Tuomas Hänninen, Pekka Tukiainen, Kirsi Svedström, Ritva Serimaa, Pekka Saranpää, Eero Kontturi, Mark Hughes, Tapani Vuorinen

Page range: 389-395

Abstract

To date, very little is known about the ultrastructure of common juniper, Juniperus communis L (juniper). In this study, the mechanical properties of juniper, its chemistry and ultrastructure has been analyzed. The data are presented in comparison to the normal wood (NW) and compression wood (CW) of spruce. Helical grooves, which are a characteristic of CW, were clearly visible in micrographs of juniper. The angle of the grooves with respect to the fiber axis was ca. 40°, which correlates with the microfibril angle determined by X-ray diffraction. Data from 4-point bending tests show that juniper and spruce CW exhibited similar behavior. The elastic moduli of both species were only ca. half from that of NW spruce. The composition of juniper fibers resembled that of CW fiber with respect to high lignin and hemicelluloses contents. However, the galactose content in CW of juniper was low and in CW of spruce was high. Raman imaging clearly revealed that the lignin/cellulose ratio in the fiber cell wall of juniper was similar to that of NW spruce.

September 17, 2011

Effect of ammonia addition to alkaline copper quaternary wood preservative solution on the distribution of copper complexes and leaching

Sedric Pankras, Paul A. Cooper

Page range: 397-406

Abstract

The effects of ammonia (NH 3 ) addition to monoethanolamine (Mea)-based alkaline copper quaternary (ACQ) on the predicted distribution of cupric (Cu 2+ ) species in solution and copper leaching from treated wood were investigated. Addition of ammonia in higher proportions reduced the amount of neutral copper-Mea complex at high pH and increased the amounts of divalent copper-NH 3 complexes. At lower pH, the amounts of high-ligand copper-Mea complexes were reduced. These effects should promote better fixation and diminish copper leaching. However, ammonia addition also reduced the monovalent copper-Mea complex and the amount of copper fixed by precipitation at lower pH. This effect could, potentially, reduce fixation and leach resistance. Ammonia addition to the ACQ formulation from a Cu:Mea:NH 3 ratio of 1:4:0 (normal Mea formulation, pH=9) to 1:4:2 (pH 10–10.2) and 1:4:4 (pH 10.4–10.5) did not significantly affect the amount of copper leached. However, a further increase in ammonia to 1:4:6 (pH 10.6–10.7) resulted in a significant reduction in copper leaching. At pH 9, an increase in the proportional amount of ammonia increased the amount of copper leached by reducing the amount of monovalent copper-Mea complex and increasing the divalent copper-NH 3 complexes. Ammonia addition with a lower amount of Mea, 1:2.5:4 formulation (pH 10.5–10.7), significantly reduced copper leaching as a result of higher amounts of divalent copper-NH 3 complexes adsorbed at higher pH (higher cation exchange capacity) without compromising the amount of copper precipitated at lower pH.

September 30, 2011

Morphological responses of Betula protoplasts in fiber spinning

Tomoko Seyama, Tetsuo Kondo

Page range: 407-411

Abstract

In a previous article, it was reported that, under stress conditions caused by Ca 2+ ions, isolated protoplasts of Betula platyphylla leaves release a bundle of hollow fibrils as a stress-induced response. In the present article, details of this phenomenon have been investigated. As a special method, light microscopy combined with a ‘through focus variation’ technique was applied. In a regular culture medium, protoplasts could regenerate the cell walls, whereas protoplasts submitted to Ca 2+ stress could not. Under stress conditions, the protoplasts inflated and formed a huge vacuole and, after 28 days, secreted the peculiar gigantic fibril with a diameter of 150 μm. The giant fibril is composed of (1→3)-β-glucan chains, i.e., the material of callose tissue.

Erratum

March 1, 2012

Surface chemistry of vessel elements by FE-SEM, μ-XPS and ToF-SIMS

Page range: 413-413

Abstract

No abstract availbale.

Meetings

March 1, 2012

Meetings

Page range: 415-415

Abstract

No abstract available

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

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Original articles, Reviews, Short notes

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