Volume 11 Issue 1

This paper presents an evaluation of the acoustic ultrasound and stress wave methods for investigating the mechanical properties of wood and the factors that can affect the results, such as the type of device used, the wood species (Scots pine, Norway spruce, Silver fir), the cardinal direction relative to the direction of the plant growth, and the longitudinal measuring position in the trunk (the height of the trunk). The experiments were done using planks of selected species, with the aim of establishing the extent to which the values of the basic mechanical properties of wood could be predicted. These properties included compression strength parallel to the grain (MORL), modulus of elasticity in compression parallel to the grain (MOEL), modulus of elasticity perpendicular to the grain (MOER), compression strength perpendicular to the grain (MORR), hardness in the particular anatomical directions (HardR, HardT, and HardL), and density.

Microcrystalline cellulose (MCC) has the advantage of a high specific surface area as compared to that of conventional cellulose fibers. In this study the monomer methacrylamide (MAM) was used to treat MCC by grafting copolymerization. SEM, FTIR, and solid 13C NMR were used to characterize the morphology and composition of MAM-g-MCC. After the chlorination of MAM-g-MCC with 10% sodium hypochlorite solution, the grafted MCC exhibited antibacterial activity as a result of the formation of N-Cl bonds. The thermal stability, antibacterial ability, and storage stability of chlorinated MAM-g-MCC were also studied. The results showed that the chlorinated MAM-g-MCC had excellent storage stability and could inactivate all S. aureus and E. coli O157:H7 within 10 min.

Wall heating is an alternative method for residential heating that is used in a limited part of Europe. The goal of this study was to show the feasibility of this method for the Nordic market and to provide a comprehensive picture of wall heating and its functionality compared to traditional methods, i.e. radiators and floor heating. The study was conducted using a literature review, calculations, and a survey. Simulations were made using the computer software EnergyPlus (US Department of Energy). Results showed that placement of wall heating panels in interior walls results in a lower heat loss than placement in outer walls, and that wall heating can have equal or better energy-efficiency compared to floor heating and conventional radiators. Wall heating provides a more comfortable indoor climate, in regard to dust allergies, and there is no need to remove air from each individual heating panel. A disadvantage is the need for hidden installation, which creates a problem for a safe water installation and difficulties in the attachment of fixtures. Also, the wall heating system has difficultly in handling cold drafts. Though wall heating could compete with floor heating and radiators, its disadvantages are sufficient to explain why the system is not yet used in Sweden.

Carbon fibers were pretreated by ultrasonic agitation and then were used to manufacture carbon fiber-reinforced wood composites (CFRWCs) . The modulus of rupture (MOR) and the modulus of elasticity (MOE) for the CFRWCs were measured. The effects of the compounding pattern and proportion of carbon fiber on the dynamic performance were investigated by dynamic thermomechanical analysis (DMA) and finite element analysis (FEA). Finite element modeling was performed to simulate composite dynamic analysis using ANSYS commercial software. DMA results showed that the critical parameters for the mixed boards appeared to initially increase and then decrease as the content of carbon fiber increased. ANSYS simulations showed that the first-order natural frequency increased for single-sided and two-sided boards as the composite’s carbon fiber content increased, whereas it initially increased and then decreased for mixed boards. In general, the mixed board with 20 wt.% carbon fiber had maximum dynamic performances. ANSYS simulation results were very close to those of the static test, which demonstrated that the finite element model was accurate.

Extracellular laccase was produced by Trametes versicolor IBL-04 using corn cobs as a substrate under pre-optimized culture conditions. A 64-kDa laccase enzyme was purified and immobilized on calcium alginate beads using glutaraldehyde as a cross-linking reagent. Maximum enzyme immobilization efficiency (89%) was observed with 2-mm calcium-alginate beads that were developed using 4% (w/v) sodium alginate in 2% (w/v) calcium chloride solution. Immobilization of laccase enhanced the optimum temperature but caused an acidic shift in the optimum pH of the enzyme. The immobilized enzyme showed optimum activity at pH 3.0 and 60 °C as compared to pH 4.5 and 45 °C for free laccase. The kinetic constants Km and Vmax of laccase were significantly altered by immobilization. The affinity of enzyme toward its substrate increased (Km decreased), leading to enhanced catalytic efficiency (Vmax increased). Scanning electron microscopy (SEM) was performed to characterize the free and enzyme-bound immobilization matrix. Free and immobilized enzymes also were used for decolorization of the Reactive T Blue dye (030905 GWF) for three days. The free and immobilized laccases decolorized the dye by 65% and 92%, respectively, in 72 h. The immobilized enzyme retained 68% of its original activity after three cycles of repeated reuse for dye decolorization, indicating the usefulness of immobilized laccase in repeated industrial batch operations.

Veneers are used as overlaying material for various types of composite substrates for the production of veneered panels and furniture. There is a strong correlation between color and quality for the acceptability of a product, which is currently an industrial preoccupation. The aim of the present study was to evaluate the color variability of veneers produced from high-quality European oak logs exhibiting the best production yield. Defect-free logs cut from a Quercus spp. forest in Romania were sliced into veneers. Color measurements were made at various locations on veneer sheets. All data were statistically analyzed. As expected, heartwood highly influenced the final color of decorative oak veneers, in which yellow and red were highlighted. The statistical analysis also revealed the homogeneity of lightness and yellow degree within the veneer collectivity. The color homogeneity within the sectors confirmed the wood quality for veneer production. Therefore, individual veneer sheets can be segregated based on color measurement to provide accurate results for sorting pieces of different colors.

The dulling of cemented carbide cutting tools after milling five African wood species was studied. The wood specimens investigated varied in high temperature corrosivity (HTC), hard mineral contamination (HMC), and density (D). Attempts to replace the combustion method of evaluating the content of natural HMC in wood with spectral mass analysis methods, such as energy dissipative spectrum (EDAX) or atomic absorption spectrometry (AAS), failed. Experiments showed that scanning electron microscope (SEM) analysis of the ash yielded information on the size and shape of small-dimension, natural HMC particles present in the wood specimens. Employing theoretical multi-variable simulation, the combined effects of the HTC, the HMC, and the D on the cemented carbide tool wear was modeled and appeared to be a good explanation of the results observed.

Wood is a natural raw material that is an integral part of many production processes. By changing the input characteristics of native wood, the qualitative characteristics of the final product can be affected extensively. This article is concerned with examining several factors’ effects (thickness of the material; number of loading cycles) on the bending strength of beech wood during bending in the radial direction. A three-point bending test was used on the sample. The examined properties were investigated on samples of varying thicknesses that were not cyclically loaded, and the results were compared to those acquired from samples that were cyclically loaded. Thirty percent densification of the samples was achieved by rolling. Material fatigue was not achieved as an effect of examined number of cycles, nor did the examined characteristics change as an effect of cyclic loading. Densification of the wood by rolling had no effect on the changes in the examined mechanical properties at the determined level of densification. With an increase in the material’s thickness, the values of the examined characteristics decreased, which was caused by the fact that the increase in the cross-sectional modulus of the material was greater than the increase of the affecting force.

The combination of hemicellulose pre-hydrolysis by dilute acid or steam-explosion followed by kraft pulping was one approach evaluated in this work to generate pulps from radiata pine wood chips amenable to saccharification by enzymatic hydrolysis. Dilute acid (combined severity factor, CS = 1.67) and steam explosion (severity factor, log Ro = 4.09) treatments were able to solubilize approximately 53% and 63% of the original hemicelluloses content in wood, respectively. Extracted wood chips were subjected to kraft cooking (170 °C, 16-18% active alkali, 30% sulfidity and 1200 H-factor) to produce pulps that were further saccharified by cellulases. Lignin removal increased with increasing active alkali, affording delignification levels 28% for dilute acid and 68% for steam explosion extraction pretreatment pulps. Enzymatic digestibility of P. radiata pulps were low, and only samples pretreated by steam explosion reached glucan-to-glucose conversion near to 75%; this treatment was 31% and 37% higher than that obtained with wood chips that were pretreated by dilute acid extraction.

Non-destructive evaluation (NDE) techniques have been shown to be effective for evaluating mechanical properties of wood-based materials. In this study, transverse vibration of a beam under the two ends free boundary condition (FBV) was employed to measure the modulus of elasticity (MOE) in different strength directions of laminated strand lumber (LSL). It was found that the MOE values measured by the FBV were slightly higher than those measured using the three-point bending test (TPB), and the correlation coefficients between the MOE values along the major and minor strength directions measured by the two methods were 0.845 and 0.938, respectively. The effect of the length/depth ratio on measured MOE values by the FBV method was also investigated. With the decrease in the length/depth ratio of LSL, the measured MOE in the major and minor strength directions decreased. The results of the ANOVA test showed that the length/depth ratios had a significant effect on the measured MOE. The experimental values of MOE of LSL in the diagonal strength direction matched well with the theoretical values calculated by the Hankinson-type formula.