Research Articles

This work investigated the possibility of using a local wood Kayu malam (Diospyros maingayi) to construct a marimba, a musical instrument. The marimba was constructed as similar as possible to the commercial rosewood marimba. The sound and established frequencies were compared with a commercial rosewood marimba. The findings showed that although the peak value of the spectrum from the prototype marimba differs from pitch to pitch, it is useful to note that the prototype marimba was tuned according to piano standard. The commercial marimba only has peaks at the lower end of the spectrum whereas the prototype marimba contained peaks up until the higher end of its spectrum. The marimba made of Kayu malam (D. maingayi) produced the same pitch as the marimba made of rosewood.

Kraft lignin is produced in great quantities in many countries, but is mainly used as an energy source. To valorize its potential end-use applications, softwood kraft lignin was modified via sulfuric acid and sodium sulfite treatments in this study. The modification of kraft lignin through a sulfuric acid treatment resulted in a modified lignin (SA-lignin) with a charge density of 0.8 meq/g but with a limited water solubility. The sulfonation of the kraft lignin through a sodium sulfite treatment induced a soluble sulfonated lignin (SS-lignin) with a charge density of 1.4 meq/g, which was obtained under the conditions of 90 °C, 4 h, and 0.67 Na2SO3/lignin molar ratio. The elemental compositions, molecular weights, and thermal and rheological properties of modified lignin samples were characterized.

The behaviors of the mechanical, hydrophobic, and thermal properties of the molded fiber product (MFP) were examined after the removal of residual lignin. The fibers resulting from the chemi-thermomechanical pulping and bleaching processes were treated by extended delignification, namely by their reaction with glacial acetic acid and sodium chlorite. The changes in surface composition, chemical structure, crystallinity, microstructure, and thermal stability of the MFP were investigated by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA), respectively. Results showed that the composition and structure of carbohydrates on the fiber surface were not changed significantly, the lignin in fibers was almost completely removed, the relative content of intermolecular hydrogen bonds in cellulose and the contact area between fibers was increased, and the crystallinity index increased from 79.5% to 81.4% after the extended delignification. When the content of lignin decreased from 5.78% to 0.02%, the tensile strength of the MFP increased 25.6%, but little changes were found in the bending strength. The onset thermal decomposition temperature of MFP increased from 242 °C to 250 °C and the maximum rate of degradation temperature increased from 347 °C to 350 °C.

Lipophilic extractives naturally occurring in wood tend to coalesce during pulping to form pitch deposits, which have particularly undesirable effects on the pulping process and quality of pulp produced. A chemical characterization of different eucalypt species [Eucalyptus nitens, E. grandis, and E. dunnii (of different site qualities)] wood and generated pulp was performed. This study aimed at determining the effects of wood storage at -20 °C (for 6 months), by examining their chemical composition and indigenous microflora. Fatty acids were the main lipophilic compounds among E. dunnii (SQ3 and SQ4) and E. grandis wood extractives. The wood of E. nitens posed the least risk for pitch deposit formation, making it the most suitable Eucalyptus species for pulping. Storage of wood chips at -20 °C had a similar effect as the traditional method of seasoning (storage of wood outdoors prior to pulping) used for the reduction of lipophilic extractives. A 25 to 44% reduction of total extractives was observed in the raw material after storage. Variations in bacterial and fungal communities were observed after storage, and should be taken into consideration when conducting lab scale trials. If storage of wood chips is necessary for lab testing, it should be retained for a maximum of 3 months at -20 °C.

Material alternatives to wood, such as rape straw, are needed for the production of composite materials. This study performed an analysis of rape straw as a composite material source for production. There were three types of rape straw particle modification: untreated particles as reference variant, boiling in water, and soaking in sodium hydroxide (NaOH) solution. The pH and calorific value were highest for the variant soaked in NaOH. The total elemental content and the elements on the rape straw surface varied between variants. The modification method chosen influenced the pH, calorific value, elemental composition, and contact angle.

1,2-propanediol was selectively produced by electroreduction of glycerol in a two-compartment reactor. Two new kinds of cathode electrodes were evaluated: (i) mixed carbon black-activated carbon electrodes and (ii) mixed carbon black-diamond electrodes. These electrodes were compared with a conventional platinum electrode. With a reaction temperature of 80 °C, an electric current of 2.0 A, and ambient pressure, the mixed carbon black-activated carbon electrode demonstrated excellent performance and successfully reduced glycerol to 1,2-propanediol with a high selectivity of 86% and 74% glycerol conversion.  The selectivity of 1,2-propanediol on the mixed carbon black-diamond electrode and the platinum electrode was 68% and 61%, respectively, with 88% glycerol conversion on the mixed carbon black-diamond electrode and 67% glycerol conversion on the platinum electrode. The authors propose a possible reaction mechanism for the formation of 1,2-PDO.

Laminated bamboo (LB) is a processed bamboo-based composite fabricated by gluing bamboo strips under controlled temperature and pressure. It has many superior mechanical properties compared to commonly used wood products and is well suited for use as a construction material. The present work consisted of two parts. The first part aimed at studying the bending performances of LB beams. The stress-strain relationship of the LB composite had approximately perfect elasticity under tension, yet exhibited more complicated behavior under compression (i.e., linearity in the prior-proportional limit and nonlinearity in the post-proportional limit). The strength in tension was significantly higher than that during compression. Damage of LB beam began with the fiber yielding in the compressive zone until failure occurred when the fibers at the outermost part of the tensile zone broke. Hence, LB beams always underwent a long nonlinear process before failure. An empirical stress-strain relationship was proposed on the basis of a bilinear model. In the second part of the study, an analytical model for calculating the load-carrying capacity and deflection of LB beams was developed. Experimental results confirmed that the model had enough accuracy for design calculation.

The effect of alkyl ketene dimer (AKD) on plywood properties was studied. AKD is widely used in the paper industry as a sizing agent and can esterify wood cell wall components. Two types of veneers obtained from alder (Alnus glutinosa subsp. barbata (C. A. Mey) Yalt.) and beech (Fagus orientalis L.) wood logs were used. Two different treatment processes and two different concentrations (1% and 3%) of AKD were tested. The first method was AKD-dispersion, which was mixed with glue and sprayed onto veneers. The second method was dipping veneers into the AKD solutions (1% and 3%) for 25 min. Water uptake after 2 h, 24 h, and 48 h was reduced by the AKD treatment. Plywood produced from AKD impregnated veneers showed the lowest thickness swelling versus untreated plywood and plywood produced from AKD blended in glue. The AKD treatment generally reduced the mechanical properties of the plywood. However, AKD treatment considerably improved the biological resistance against brown rot fungi (Coniophera puteana BAM Ebw. 15) and white rot fungi (Trametes versicolor CTB 863A). Increased methyl/methylene and carbonyl groups of the alkyl chain were determined in the Fourier transform infrared (FTIR) spectra of specimens subjected to the AKD-dispersion method.

Changes in the chemical composition and selected physico-mechanical properties of pedunculate oak (Quercus robur L.) wood samples were assessed after thermal treatment. Heat treatment was performed at 160, 180, and 200 °C in an oxidizing atmosphere. The contents of the extractives, lignin, cellulose, holocellulose, and saccharides, and the structural changes in the functional groups were determined. Changes in the colour traits, wood density, compression strength parallel to the grain, and compression modulus of elasticity were also determined. The decrease in the holocellulose content caused by the degradation of non-glucosic saccharides was observed during thermal treatment. The contents of both the extractives and lignin increased. The syringyl to guaiacyl (S/G) ratio in the lignin increased because of the preferential condensation of guaiacyl units. The physical and mechanical properties of pedunculate oak wood, such as density, equilibrium moisture content, colour lightness, and yellowness, decreased as the temperature increased. The compression strength and redness varied during thermal treatment, and reached maximum values during the treatment at 180 °C. The modulus of elasticity showed non-significant differences. Three groups of heat treatment clusters were distinguished in the multivariate wood trait analysis and were clearly segregated from each other.

If given enough time, the moisture content of wood will reach an equilibrium with its surrounding environment. The temperature and relative humidity (RH) of the surrounding air will establish equilibrium moisture content (EMC) conditions, and the moisture content of the wood in that environment will approach a value determined by the RH. This article introduces an Excel spreadsheet that will calculate an estimate of the EMC based on any one of the following three pairs of data: RH and dry-bulb temperature, wet-bulb temperature and dry-bulb temperature, or dew-point temperature and dry-bulb temperature.