Volume 72, Issue 6

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.