Published by De Gruyter

Volume 70 Issue 7

Issue of Holzforschung

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Contents
Journal Overview

Publicly Available June 29, 2016

Original Articles

Open Access January 6, 2016

Characteristics of guaiacyl-syringyl lignin in reaction wood in the gymnosperm Gnetum gnemon L.

Deded Sarip Nawawi, Wasrin Syafii, Takuya Akiyama, Yuji Matsumoto

Page range: 593-602

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Abstract

Gnetum gnemon L. is a unique gymnosperm species showing angiosperm-like features in terms of its morphology and chemical composition of the cell wall. Xylan is the main hemicellulose component, and its lignin is primarily composed of syringyl (S) and guaiacyl (G) units and small amounts of p -hydroxyphenyl (H) units. In the present study, in addition to branch, root, bark, and leaf samples, the reaction wood (RW) taken from the leaning stem of G. gnemon , was investigated mainly by alkaline nitrobenzene oxidation, ozonation and NMR spectroscopy. The leaning stem was wider on the lower side of the wood stem (lsW) than on the upper side (usW), similar to the case for compression wood (CW) in gymnosperms. The usW contained lignin with a higher S/G ratio, and β-O-4 structure had a higher erythro/threo ratio, while both ratios decreased around the periphery of the stem towards the lsW. The lignin content was higher towards the lsW. Overall, the lignin composition in the RW of this tree was similar to that in the tension wood of angiosperms. The H - units were minor components in the lignin, but the content was higher towards the lsW, which resembles the distribution of the H-units in a gymnosperm CW.

January 6, 2016

Sodium sulphite pulping of Scots pine under neutral and mildly alkaline conditions (NS pulping)

Saara Hanhikoski, Elina Warsta, Antero Varhimo, Klaus Niemelä, Tapani Vuorinen

Page range: 603-609

Abstract

Sodium sulphite pulping of Scots pine chips in the initial pH range of 7.5–9 was investigated at 180°C and 165°C (for 120–240 min), using chemical charges between 25 and 50% and anthraquinone (AQ) charges 0–0.2%. As a result, pulps with yields of 52–73% and kappa numbers of 35–106 were produced. Delignification was accelerated by higher Na 2 SO 3 charges and temperatures, and by AQ addition, whereas the effect of initial pH was negligible. The high pulp yields at a given kappa number were attributable to high retention of hemicelluloses, especially that of galactoglucomannan. The relatively low viscosities of pulps were apparently caused by depolymerisation of cellulose by sulphite. The sulphonic acid groups in the pulps correlated well with the residual lignin content, although some sulphonation of polysaccharides may also be possible. The results indicate that pulping of softwood in buffer-free (without Na 2 CO 3 and/or NaOH) sodium sulphite liquor may result in pulps with tailored characteristics.

January 22, 2016

Characterization of dissolving pulp by fibre swelling in dilute cupriethylenediamine (CUEN) solution in a MorFi analyser

Benoît Arnoul-Jarriault, Raphaël Passas, Dominique Lachenal, Christine Chirat

Page range: 611-617

Abstract

The swelling of dissolving pulps has been investigated by a new method based on the Morfi R analyser, which is measuring the width variation of thousands of fibres in a cupriethylenediamine (CUEN) solution in a few minutes. Pulps from various origins were analysed coming from softwood, birch wood, eucalyptus wood, kraft pulps, sulphite pulps and ECF and TCF bleached pulps, which were modified by several treatments including chemical (cold caustic extraction, hypochlorite) or enzymatic (cellulase) methods. The swelling was much affected by the crystalline form of cellulose and the hemicellulose content but did not depend neither on the cellulose DP nor on the fibre structure (hardwood vs. softwood). The dissolving pulp reactivity in the viscose process was also assessed by swelling in dilute solutions of cupriethylenediamine (CUEN) instead of the Fock’s method.

December 16, 2015

Hot water extraction of Norway spruce (Picea abies [Karst.]) bark: analyses of the influence of bark aging and process parameters on the extract composition

Sauro Bianchi, Gerald Koch, Ron Janzon, Ingo Mayer, Bodo Saake, Frédéric Pichelin

Page range: 619-631

Abstract

The hot water (HW) extraction of Norway spruce ( Picea abies [Karst.]) delivers condensed tannins and considerable amounts of other compounds. Yield and composition of the HW extracts were investigated as a function of natural weathering for up to 15 months. Total phenol monomers and oligomers were detected by Folin-Ciocaltau assay after fractionation by solid phase extraction (SPE). Procyanidins (PC) were determined by HPLC-UV after acid thiolysis and carbohydrates by HPLC combined with acid hydrolysis. Topochemistry of the bark before and after extraction was investigated by UV-microspectrometry (UMSP) and non-extractable PC analyzed by direct thiolysis on the bark. The influence of the parameters on the yield and composition of the extracts were evaluated, such as the extraction temperature, time and the addition of sodium sulfate and urea. Prolonged weathering resulted in a considerable decrease of the total extraction yield, partly because of leaching of phenolic monomers, mono- and oligosaccharides. The yield of phenolic oligomers also decreased at a moderate rate, while the yield of polysaccharides (pectins) was almost stable. Non-extractable and non-leachable compounds deposited in the cell lumens represent the majority of the phenolic extractives in spruce bark. Sequential extractions performed at increasing temperature proved to be a suitable method for the recovery of tannin-rich extracts.

April 15, 2016

Statistical modeling of pressurized hot-water batch extraction (PHWE) to produce hemicelluloses with desired properties

Marjatta Kleen, Andrey Pranovich, Stefan Willför

Page range: 633-640

Abstract

The pressurized hot-water extraction (PHWE) process of Norway spruce sawdust has been optimized aiming at the production of a hemicellulose-rich fraction consisting mainly of galactoglucomannans (GGM). The independent process parameters temperature, reaction time, and liquid-to-wood (L/W) ratio were in focus of the statistical modeling. The main target product properties were the average molecular mass (Mw) and the GGM content of the dissolved solids in the extracts and the yield of polymeric hemicelluloses with Mw larger than 4 kDa in the ethanol-water precipitate. According to the model, the highest Mw (>30 kDa) of the total dissolved solids in the extract can be obtained at a low extraction temperature (E T ), a short extraction time (E t ), and a low L/W ratio. The best result was 37 kDa, corresponding to a degree of polymerization (DP) about 230. The highest GGM content of the extract (>11% of the sawdust, which is about 70% of the GGM in sawdust) can be obtained with a high E T , a long E t and a high L/W ratio. According to the model, the PHWE process gives rise to the largest possible amount of polymeric hemicelluloses at 170°C, 11 min reaction time, and at L/W 5. Provided that a large-scale extraction apparatus works under these conditions with the same efficiency, it should be possible to produce around 60 g polymeric hemicelluloses (mainly GGM) with a Mw around 15 kDa from 1 kg spruce sawdust, which is roughly 25% of the original hemicelluloses in the sawdust.

Publicly Available December 10, 2015

Lignification of ray parenchyma cells (RPCs) in the xylem of Phellodendron amurense Rupr.: quantitative and structural investigation by TOF-SIMS and thioacidolysis of laser microdissection cuts of RPCs

Peiming Zheng, Dan Aoki, Yasuyuki Matsushita, Sachie Yagami, Yuzou Sano, Masato Yoshida, Kazuhiko Fukushima

Page range: 641-652

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Abstract

Lignification of ray parenchyma cells (RPCs) in the sapwood (sW), transition zone (TZ), and heartwood (hW) of Phellodendron amurense Rupr. has been investigated by time-of-flight secondary ion mass spectrometry (TOF-SIMS) and thioacidolysis. The results of TOF-SIMS indicate that the relative ion intensity of lignin in RPCs increased from sW to hW, while there was almost no difference in the case of axial wood fibers. The ratio of syringyl (S) to guaiacyl (G) lignin units (S/G value) in RPCs was higher than that in wood fibers. Samples containing more RPCs were prepared by laser microdissection (LMD) and analyzed by thioacidolysis, including also the subsequent Raney nickel desulfurization, and the resulting monomers and dimers were quantitatively analyzed by GC/MS. The monomer analysis shows that lignin content and S/G values in RPCs rich samples increased from sW towards hW. The dimer analysis reveals that the S-S dimers are dominant in all types of samples. The results of TOF-SIMS and thioacidolysis of LMD samples are interpreted that the lignification of RPCs progresses from the sW towards the hW and that the chemical structure of lignin in RPCs is different from that in axial elements.

December 17, 2015

Relationship between the hydrophilicity of lignin dispersants and their performance towards pesticide particles

Yuxia Pang, Xiaoyu Li, Mingsong Zhou, Yuan Li, Wei Gao, Xueqing Qiu

Page range: 653-660

Abstract

The correlation between the hydrophilicity of sodium lignosulfonate (NaLS) and its dispersing performance towards pesticide particles has been investigated. NaLS was classified into three fractions by adsorption chromatography on macroporous resins. A positive correlation has been found between the hydrophilicity and the contents of phenolic hydroxyl and sulfonic acid groups. On the other hand, the NaLS fraction with high carboxyl content is not strong hydrophilic. With decreasing the hydrophilicity of NaLS, its amounts on pesticide particles surface increased and the dispersing performance of pesticide particles was improved. Obviously, NaLS and pesticides with similar hydrophilicity match better according to the “similarity-intermiscibility” theory. Carboxymethylated alkali lignin (CML) is not as hydrophilic as NaLS. The adsorption and dispersing performance of CML for hydrophobic pesticide particles are better than those of NaLS, demonstrating that lignin formulations with lower hydrophilicity are an alternative to obtain excellent pesticide dispersants.

December 16, 2015

Preparation of electric double layer capacitors (EDLCs) from two types of electrospun lignin fibers

Xiangyu You, Junlei Duan, Keiichi Koda, Tatsuhiko Yamada, Yasumitsu Uraki

Page range: 661-671

Abstract

Electrodes has been prepared for application in an electric double layer capacitor (EDLC) based on polyethylene glycol lignin (PEGL) and soda lignin (SL) derived from cedar wood. Fibers with a diameter of 23 μm were prepared by direct melt electrospinning of PEGL. Much finer fibers of 3.6 μm diameter were obtained by dry electrospinning of 70% PEGL in a dimethyl formamide (DMF) solution at 145°C. The dry electrospinning of SL alone in an alkaline aqueous solution was not achievable, but this was possible of a mixture of SL and polyethylene glycol (M w =500 000) at a ratio of 99/1, which resulted in thin SL fibers with a diameter of 0.85 μm. These fibers were converted into activated carbon fibers (ACFs) by thermostabilization, carbonization, and steam activation. The specific Brunauer, Emmett and Teller (BET) surface areas of the resulting PEGL-ACFs and SL-ACFs were 1880 m 2 g -1 and 1411 m 2 g -1 , respectively. PEGL-ACFs electrodes with an organic electrolyte exhibited an impedance of 1.6 Ω and a specific capacitance of 92.6 F g -1 at a scan rate of 1 A g -1 , and the SL-ACFs electrodes had an impedance and specific capacitance of 4.5 Ω and 55.6 F g -1 , respectively.

December 17, 2015

Simultaneous measurement of elastic constants of full-size engineered wood-based panels by modal testing

Jianhui Zhou, Ying Hei Chui, Meng Gong, Lin Hu

Page range: 673-682

Abstract

Engineered wood-based panels are widely used in structural applications. Accurate measurement of their elastic properties is of great importance for predicting their mechanical behavior during structural design. In this study, an efficient non-destructive test method for measurement of effective elastic constants of orthotropic wood-based panels is proposed based on a modal testing technique. An algorithm was developed based on an improved approximate frequency equation of transverse vibration of orthotropic plates under the boundary condition, in which two opposite sides are simply supported and the other two are free (SFSF). The method is able to predict the frequency ranges and mode indices as well as corresponding normalized sensitivity to elastic constants based on initial estimates of orthotropic ratios with uncertainties and measured fundamental natural frequency. Full-size engineered wood-based panels including cross laminated timber (CLT), oriented strand board (OSB), and medium density fiberboard (MDF) were tested with the proposed method. In general, the measured elastic constants of the three types of panel based on modal test agreed well with those corresponding values measured by static tests. More tests are needed with a range of panel sizes and types for further validation of the proposed test method.

December 2, 2015

Development of an industrial applicable dielectric barrier discharge (DBD) plasma treatment for improving bondability of poplar veneer

Minzhi Chen, Rong Zhang, Lijuan Tang, Xiaoyan Zhou, Yang Li, Xuehui Yang

Page range: 683-690

Abstract

Dielectric barrier discharge (DBD) plasma treatment in a larger scale, which has the potential for industrial application, was studied for modification of poplar veneer surface for enhancing its interface adhesion. Chemical property, morphology, surface wetting, adhesion property and the stability of the activation after plasma treatment were investigated. ESR, XPS, AFM, contact angle (CA), and shear strength test were carried out to evaluate the effect of plasma treatment. The following properties increased after treatment: the surface free radical concentration, O/C ratio, surface roughness of wood fiber, veneer surface wetting, and surface free energy. Consequently, the plywood composite prepared after plasma treatment showed higher adhesion strength than that prepared from untreated veneer. The best plywoods were obtained from veneers treated at processing power of 4.5 kW of DBD. The time-dependent analysis by surface wetting indicated a modified stability in the first two days after plasma treatment, after which the polar component of the surface decreased and its dispersive component kept the level observed after plasma treatment. In summary, veneer surface modification by DBD plasma is promising for industrial application.

Publicly Available December 9, 2015

Mode of action of brown rot decay resistance of thermally modified wood: resistance to Fenton’s reagent

Reza Hosseinpourpia, Carsten Mai

Page range: 691-697

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Abstract

The resistance of heat treated (HT) wood to brown rot fungi has been investigated, while the role of the Fenton reaction (FR) in the initial phase of degradation was in focus. Micro-veneers made of Scots pine, were HT with various intensities and their mass losses (ML HT ) were determined before soaking with a solution of Fenton’s reagent containing Fe ions and hydrogen peroxide. The mass loss of the veneers treated that way (ML FT ), their tensile strength loss (TSL FT ) and the H 2 O 2 decomposition were observed. The ML FT , TSL FT , and H 2 O 2 loss decreased with increasing ML HT of the veneers. Soaking of the veneers in acetate buffer containing only Fe without H 2 O 2 revealed that the heat treatment (HT) strongly reduces the Fe uptake by the cell walls. FTIR spectroscopy indicated oxidation of the unmodified control veneers but did not reveal predominant decay of cell wall components; the HT veneers were not changed at all due to FR. It was concluded that the reason for the enhanced resistance of HT wood to FR is attributable to hindered diffusion of Fe ions into the wood cell wall.

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

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Volume 70 Issue 7

Issue of Holzforschung

Frontmatter

Characteristics of guaiacyl-syringyl lignin in reaction wood in the gymnosperm Gnetum gnemon L.

Abstract

Sodium sulphite pulping of Scots pine under neutral and mildly alkaline conditions (NS pulping)

Abstract

Characterization of dissolving pulp by fibre swelling in dilute cupriethylenediamine (CUEN) solution in a MorFi analyser

Abstract

Hot water extraction of Norway spruce (Picea abies [Karst.]) bark: analyses of the influence of bark aging and process parameters on the extract composition

Abstract

Statistical modeling of pressurized hot-water batch extraction (PHWE) to produce hemicelluloses with desired properties

Abstract

Lignification of ray parenchyma cells (RPCs) in the xylem of Phellodendron amurense Rupr.: quantitative and structural investigation by TOF-SIMS and thioacidolysis of laser microdissection cuts of RPCs

Abstract

Relationship between the hydrophilicity of lignin dispersants and their performance towards pesticide particles

Abstract

Preparation of electric double layer capacitors (EDLCs) from two types of electrospun lignin fibers

Abstract

Simultaneous measurement of elastic constants of full-size engineered wood-based panels by modal testing

Abstract

Development of an industrial applicable dielectric barrier discharge (DBD) plasma treatment for improving bondability of poplar veneer

Abstract

Mode of action of brown rot decay resistance of thermally modified wood: resistance to Fenton’s reagent

Abstract