Published by De Gruyter

Volume 72 Issue 6

Issue of Holzforschung

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Contents
Journal Overview

Publicly Available June 1, 2018

Original Articles

Publicly Available February 13, 2018

Improvement of enzymatic digestibility of wood by a sequence of optimized milling procedures with final vibratory tube mills for the amorphization of cellulose

Jinwu Wang, Johnway Gao, Kristin L. Brandt, Jinxue Jiang, Yalan Liu, Michael P. Wolcott

Page range: 435-441

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Abstract

A three-stage wood milling process was investigated leading to coarse, fine and amorphization of milled wood (MW) as a pretreatment for enzymatic wood hydrolysis. An eccentric vibratory tube mill (EVTM) and a spring suspended vibratory tube mill (SSVTM) were found to be suitable for wood cellulose amorphization. Both methods gave rise to highly digestible and amorphous wood powders amenable to enzymatic hydrolysis. The SSVTM had superior energy efficiency. The resulting MW afforded a 70% sugar yield via enzymatic hydrolysis and the total energy consumption was around 1.5 kWh kg −1 oven-dried wood (odW) for all three milling stages. In contrast, EVTM consumed 17 kWh kg −1 odW energy. Accordingly, SSVTM has a high potential for preparing wood for enzymatic hydrolysis.

February 1, 2018

The effect of delignification on the properties of cellulosic fiber material

Quanliang Wang, Shengling Xiao, Sheldon Q. Shi, Liping Cai

Page range: 443-449

Abstract

The behavior of pressed poplar chemi-thermomechanical pulping (CTMP) without additive the focus of our study. Four CTMPs with decreasing lignin contents were prepared by the sodium chlorite/acetic acid method and the holocellulose, α-cellulose, pentosan and Klason lignin contents of the delignified CTMPs were determined. The surface composition, aggregation structure and microstructure of the delignified fibers were characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and scanning electron microscope (SEM), and the mechanical properties of the fiber material were investigated by means of tensile and bending tests. As shown by XPS, the lignin content of the Pr-CTMP surface layer firstly increased and then decreased as the lignin content of CTMP decreased. With the delignification time increased from 0 to 240 min, the crystallinity index ( C r I ) of CTMP increased from 60.1% to 65.7%. The C r I of all CTMPs at different delignification degrees showed significant elevated values after hot-pressing. The fiber cell wall became thinner and the cells were flattened and thus elevated the contact area among fibers and, as a consequence, the density of material gradually increased at higher delignification degrees. The tensile strength increased by ca. 10%, when the lignin content decreased from 24.9% to 13.1%, and by ca. 53%, when the lignin content decreased from 13.1% to nearly zero. The bending strength increased with increasing delignification. When the removal rate of lignin increased from 47% to 54%, the bending strength increased from 101 to 122 MPa.

February 6, 2018

Optimization of polyol production via liquefaction from Acacia mangium and analysis of the polyols by traditional methods and two-dimensional correlation spectroscopy

Ismawati Palle, Naruhito Hori, Tadahisa Iwata, Akio Takemura

Page range: 451-458

Abstract

The aim was to optimize the liquefaction conditions of Acacia mangium wood flour with polyethylene glycol (PEG#400) as the solvent in the presence of sulfuric acid as a catalyst under atmospheric pressure. Reaction time (30–180 min), temperature (130–170°C), and the solvent ratio (PEG/glycerol=0–25%) were varied to obtain the lowest residue content. The resulting polyol was characterized by their hydroxyl number (OHN), acid number (AN), viscosity, molecular weight (M w ), thermogravimetric analysis, Fourier transform infrared (FT-IR) and two-dimensional correlation spectroscopy (2D-COS). The OHN was lowered, AN and M w were elevated as a function of increasing the reaction temperature and the time. Introducing glycerol in the PEG system markedly increased the OHN, AN and viscosity of the liquefied wood. The optimum condition was 80/20% ratio of PEG/glycerol at 150°C in 150 min leading to a 75% liquefaction yield. The 1730 cm −1 band was indicative for the esters in the liquefied product. The 2D-COS analysis showed that lignin is easily liquefied at high temperatures and a decreasing amount of PEG, and that the presence of glycerol significantly enhanced the 1730 cm −1 band.

March 29, 2018

Differential proteome analysis of the extracts from the xylem of Cinnamomum camphora inhibiting Coriolus versicolor

Quan Li, Liping Xu, Hui Wu, Jing Liu, Jinguo Lin, Xin Guan

Page range: 459-466

Abstract

The proteins of Coriolus versicolor treated with the acetone extracts of Cinnamomum camphora xylem has been investigated. The specific proteins found in the extract treated C. versicolor , were characterized by two-dimensional (2D) gel electrophoresis (2D-GE) and identified by matrix assisted laser desorption ionization (MALDI) combined with tandem time-of-flight microscopy, i.e. TOF-MS/TOF-MS. Most of 474 proteins detected from the pure culture were common metabolic proteins. Nineteen protein spots changed significantly and 17 spots were identified successfully. The 19 proteins were assigned to 10 functional groups including ion binding, translation factor activity, nucleic acid binding and ATPase activity. These proteins are involved in signal transduction, transport and membrane trafficking. The down regulated expression of translation elongation factor 1 alpha (EF1α), α-tubulin, and tropomyosin-1 showed that protein translation elongation, growth-stimulating signal transduction, signal transduction and material transport were suppressed, which resulted in the apoptosis of the pathogen. These findings provide a better understanding of the anti-fungal mechanism of C. camphora and indicate the way for the development of wood preservatives based on natural extracts.

Review

March 10, 2018

Nondestructive assessment and imaging methods for internal inspection of timber. A review.

Konrad J. Vössing, Ernst Niederleithinger

Page range: 467-476

Abstract

This paper reviews state-of-the-art in nondestructive testing (NDT) and semidestructive testing (SDT) methods applicable for imaging the condition of structural timber. Both NDT and SDT imaging reveal defects, damages, and decay, while the extent of wood decay can also be quantified. Combined with an appropriate data interpretation concerning the internal defects, the mechanical properties of the material can also be assessed. The possibilities and limitations of the most relevant individual NDT and SDT methods, also in combination with each other, are outlined and compared. To facilitate comparison, many observations are reported based on the same test specimen.

January 20, 2018

Effects of sample size on swelling and shrinkage of Larix kaempferi and Cryptomeria japonica as determined by digital caliper, image analysis, and digital image correlation (DIC)

So Sun Lee, Gi Young Jeong

Page range: 477-488

Abstract

Swelling (Sw) and shrinking (Sh) of Larix kaempferi and Cryptomeria japonica woods were observed with the methods digital caliper, image analysis, and digital image correlation (DIC) as a function of cubic sample sizes (20 3 , 50 3 , and 100 3 mm 3 ) and the three anatomical directions of wood. The moisture content (MC) of the samples was 19, 12, and 8%, such as MC→ and MC satur . Coefficients of swelling were significantly different at the three sample sizes. Coefficients of shrinking were significantly different by species and sample size. Results of DIC revealed that the magnitude of mixed Sw/Sh behaviors increased with increasing sample size.

February 6, 2018

Preparation of a synergistically stabilized oil-in-water paraffin Pickering emulsion for potential application in wood treatment

Jun Jiang, Jinzhen Cao, Wang Wang, Haiying Shen

Page range: 489-497

Abstract

Pickering emulsions (emulsions stabilized by solid-state additives) are attractive as they have strong similarities with traditional surfactant-based emulsions. In this study, an oil-in-water (O/W) paraffin Pickering emulsion system with satisfying stability and small droplet size distribution was developed by hydrophilic silica particles and traditional surfactants as mixed emulsifiers. The droplet morphology and size distribution were observed by optical microscopy and a laser particle analyzer. The emulsion stability was improved and the droplet size was reduced after addition of a suitable amount of silica particles. The silica concentration of 1% showed the optimal effect among all the levels observed (0.1, 0.5, 1 and 2%). Wood was impregnated with the prepared emulsion, and the chemical and morphological properties of the product were investigated by Fourier-transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) combined with energy-dispersed X-ray analysis (SEM-EDXA). Moreover, the hydrophobicity, thermal properties, surface hardness, axial compression strength (CS) and dynamic mechanical properties were tested. The silica was evenly distributed in the wood cell wall and thus there was a synergistic positive effect from the paraffin and silica in the cell wall leading to better hydrophobicity, improved surface hardness and mechanical properties including the thermal stability.

February 5, 2018

Improved wood properties via two-step grafting with itaconic acid (IA) and nano-SiO₂

Xiaoshuai Han, Yihui Yin, Qinqin Zhang, Ren Li, Junwen Pu

Page range: 499-506

Abstract

Itaconic acid (IA) with its trifunctional structure was first introduced into the wood cell lumen and cell wall, which functions as a grafting anchor for fixing various polymers via strong chemical bonds. Then nano-SiO 2 was grafted to the IA-modified wood. Field-emission scanning electron microscope revealed that the grafting experiment was successful and that the modified cell wall thickness increased by 65%. The incorporated hydrophobic nano-SiO 2 substructure reduced the wood’s hygroscopicity and improved its dimensional stability. The thermal stability of the new composite was also excellent. The presented approach is simple and efficient and the probability is high that it can be up-scaled to a level of a large-scale engineering material.

February 10, 2018

Shear moduli in the longitudinal-radial and radial-tangential planes of Sitka spruce measured by torsional vibration tests

Hiroshi Yoshihara, Makoto Maruta

Page range: 507-512

Abstract

The shear moduli (SM) of solid wood in the longitudinal-radial (LR) and radial-tangential (RT) planes of Sitka spruce are extremely different from each other and were obtained via a torsional vibration (TV) test by varying the aspect ratios and conducting subsequent numerical analyses. The SM in both planes were accurate, when the aspect ratios of the specimens were appropriately selected, even though the SM around the torsional axis were extremely different from each other.

March 19, 2018

Creep behavior of 3D core wood-strand sandwich panels

Mostafa Mohammadabadi, Vikram Yadama, Jian Geng

Page range: 513-519

Abstract

A preliminary experimental evaluation of duration of load and creep effects of lightweight wood-strand sandwich panels (lwW-SSP) was conducted following ASTM D6815-09 to determine the equivalence to the duration of load and creep effects of visually graded lumber as specified in Practice D245. The modulus of rupture (MOR) of lwW-SSP was obtained using four-point bending tests to evaluate their creep and load behavior at three stress levels (15, 40 and 65% of MOR). Two different widths were considered to observe the effect of this parameter. lwW-SSP preformed well under long-term loads, as tertiary creep was not observed at all stress levels and the strain rate decreased over time. The panels met the criteria specified in the standard. None of the specimens failed, the creep rate decreased and the fractional deflection was <2. Accordingly, the duration of load factors of visually graded lumber is applicable to these panels. For the theoretical evaluation of solid wood behavior, viscoelastic models can also be applied to describe the creep behavior of lwW-SSP with wood-strand corrugated cores. An exponential viscoelastic model consisting of five elements accurately approximates the experimental creep behavior of three-dimensional (3D) core sandwich panel.

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 72 Issue 6

Issue of Holzforschung

Frontmatter

Improvement of enzymatic digestibility of wood by a sequence of optimized milling procedures with final vibratory tube mills for the amorphization of cellulose

Abstract

The effect of delignification on the properties of cellulosic fiber material

Abstract

Optimization of polyol production via liquefaction from Acacia mangium and analysis of the polyols by traditional methods and two-dimensional correlation spectroscopy

Abstract

Differential proteome analysis of the extracts from the xylem of Cinnamomum camphora inhibiting Coriolus versicolor

Abstract

Nondestructive assessment and imaging methods for internal inspection of timber. A review.

Abstract

Effects of sample size on swelling and shrinkage of Larix kaempferi and Cryptomeria japonica as determined by digital caliper, image analysis, and digital image correlation (DIC)

Abstract

Preparation of a synergistically stabilized oil-in-water paraffin Pickering emulsion for potential application in wood treatment

Abstract

Improved wood properties via two-step grafting with itaconic acid (IA) and nano-SiO2

Abstract

Shear moduli in the longitudinal-radial and radial-tangential planes of Sitka spruce measured by torsional vibration tests

Abstract

Creep behavior of 3D core wood-strand sandwich panels

Abstract

Improved wood properties via two-step grafting with itaconic acid (IA) and nano-SiO₂