Research Articles

In this study, a wood-based X-type lattice sandwich structure was fabricated by an insertion glue method using medium density fiberboard (MDF) and plywood as panels. Birch was used for the core. The mechanical properties and failure modes of the wood-based X-type lattice sandwich structure were investigated by an out-of-plane compressive test, a short beam shear test, and their matching analytical models. The out-of-plane compressive test and the compression analytical model showed that the failure mode of the plywood and birch combination was mainly shear failure in the core. The cores were broken or had sliding surfaces, while the failure mode of the MDF and birch combination was mainly shear failure of the core at both ends. Although the compression properties of the MDF and birch combination were better, the specific strength and modulus of the plywood and birch combination was larger, which align with the characteristics of lightweight and strong strength. The failure mode of the plywood and birch combination was delamination at both ends of the panel or core breakage, which indicated that this combination had better short beam shear properties. The theoretical models of the compressive /short beam shear properties were in good agreement with experimental results obtained for the plywood and birch combination.

Enzymolysis is a key bioconversion process of lignocellulosic biomass. The optimization of enzymolysis is important for its efficiency and accuracy. There is potential to solve the problem of low reducing sugar in the conversion of lignocellulose to bioethanol. In this study, mixed cellulases (cellulase and β-glucosidase) were used in the enzymolysis of acid-exploded poplar wood residues. The mixed enzymolysis process was optimized by response surface area test, and its kinetics model was established based on the Michaelis-Menten equation. The optimal parameters of the mixed enzymolysis were: initial, pH 5.2; temperature, 46 °C; and cellulase to β-glucosidase ratio, 1.62. These parameters resulted in enzymatic saccharification efficiency 1.3 times as high as that of the control (conducted with un-optimized parameters). The modeling revealed that there was a strong correlation (R2 = 0.97) between substrate concentration and reaction rate. Multiple simultaneous saccharification and cofermentation (MSSCF) developed in the laboratory was also employed to verify the optimal parameters. The mixed enzymolysis process carried out with the optimal parameters achieved an ethanol concentration of 30.09 ± 0.49 g/L, which was 1.64 times higher than that conducted with un-optimized parameters. The fermentation time was also reduced by 24 h. Overall, the optimization of mixed enzymolysis process could enhance the efficiency of lignocellulosic directional conversion to bioethanol.

The wood fiber industry has a complex and sensitive supply chain. Consumers and suppliers across the wood fiber supply industry share a highly dynamic relationship, but they lack a structured technique to evaluate and improve the flow of information and materials. The goal of this study was to develop a mathematical model based on supplier selection and assessment criteria using structured, multi-criteria decision-making methods. The first method was the analytic hierarchy process (AHP) and the second method was the Technique for Order Preference by Similarity to the Ideal Solution (TOPSIS). These methods were chosen based on their acceptance and use in previous research. The hybrid model was implemented as a software tool based on Microsoft Excel and Visual Basic. The tool improved the way in which wood product firms selected their suppliers and guaranteed that the best available alternatives were selected, thus increasing the chance of a successful supplier-consumer relationship and increasing the value that the company receives from its supplier base. Seven interviews were conducted in the wood fiber industry to validate the tool. The tool was found to be applicable and a valuable approach, as reported by most participants.

A novel green approach was developed for producing silver nanoparticles (AgNPs) using lignocellulose nanofibrils (LCNF). This method does not require any additional reducing agent, and the LCNF itself serves both as a reducing agent and a supporting material. A simple autoclave procedure was employed for the synthesis. The synthetic conditions such as concentrations of reactants and reaction time were optimized. Also, the effect of lignin content in LCNF on the formation of AgNPs was evaluated. Three types of cellulose nanofibrils, i.e., HCNF (0% lignin), LCNF-5 (5% lignin), and LCNF-18 (18% lignin), were employed for the preparation of AgNPs. Three types of AgNPs were obtained and thoroughly characterized using UV-vis, Fourier-transform Infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The results suggest that LCNF can be employed as a green source for the reduction and effective stabilization of AgNPs, but an increased content of lignin can have an adverse effect on the yield of AgNPs. However, the presence of lignin greatly influenced the particle size. Therefore, LCNF with small amounts of lignin (5%) is best for producing AgNPs.

Ferromagnetic activated carbon (FAC) was prepared through impregnation of cassava peel with FeCl3 (3.75%) solution and pyrolyzed at 800 °C. Samples were characterized using iodine number, methylene blue number, X-ray fluorescence, Fourier transformation infrared, X-ray diffraction (XRD), scanning electron microscopy (SEM) coupled to energy dispersive X-ray spectroscopy, elemental analysis and N2 adsorption for surface area determination. The proximate analysis of cassava peel showed that the moisture content, fixed carbon, ash content, and the volatile matter were 3.52%, 82.97%, 4.97%, and 8.54%, respectively. The prepared FAC had a BET surface area of 405.9 m2/g, pore size of 2.03 nm and total pore volume of 0.11 cm3/g. The SEM analysis showed the presence of both micro and mesopores on the FAC sample. The XRD pattern of FAC showed the presence of characteristic peaks of magnetite–maghemite, confirming that the prepared material is ferromagnetic. According to the experimental results, the cassava peels are considered as appropriate raw material for FAC preparation.

Essential oil emulsion, which is generally functionalized to have increased antifungal activity, has high solubility in water. The objective of this research was to develop an essential oil emulsion for absorption by water hyacinth plants in order to produce an essential oil absorbent material as a carrier of essential oil vapor that can be released to control mold in an enclosed packaging system. The fresh water hyacinth adsorbed the Michelia alba oil emulsion (100 µL/mL to 500 µL/mL) through its root system, transporting it to the stems and leaves after submerging the plant into the M. alba oil emulsion for 48 h. Dried sections (root, stem, and leaf) of the water hyacinth plant with absorbed M. alba essential oil emulsion released the M. alba vapor, inhibited Aspergillus flavus growth on malt extract agar (MEA), and also Thai dessert (Ja Mongkut) with the highest antifungal activity achieved with the concentration 500 µL/mL. The maximum essential oil absorption (345 µL/g) in the fresh plant was achieved after 48 h. The dried water hyacinth (≥ 0.4 g/L air) completely inhibited the growth of A. flavus for at least 7 days. In addition, the absorbent material prevented the growth of A. flavus on the Thai dessert (Ja Mongkut) with approximately 100% effectiveness (versus the control) for 10 days, thereby extending the shelf-life 2.5-fold in when compared with the control without essential oil.

A high-density particleboard composed of peanut shells (Arachis hypogaea L.), an agro-industrial residue, and bamboo wastes of the species Dendrocalamus giganteus (branches and apical part), bonded with a two-component polyurethane resin based on castor oil (Ricinus communis L.) in the proportion of 12% of the particleboard mass, was produced. Four types of specimens were prepared according to the percentage of peanut shells: 0%, 10%, 20%, and 30%. Mechanical characteristics were evaluated through the flexural strength tests for modulus of rupture, modulus of elasticity, perpendicular traction, and screw pull resistance. The particleboard reached an average density of 917.2 kg/m3, meaning that it could be classified as high-density particleboard. The results of the mechanical tests indicated that the specimens containing a mixture in the proportion of 90% bamboo and 10% peanut hull presented the best mechanical strength. The experiment produced particleboards with a satisfactory mechanical physical performance that met the standards ABNT NBR 14.810-2 and ANSI A208-1, supporting the use of the peanut shell residue in the manufacture of particleboards to be used in internal environments and allowing the applicability of this residue through additional value.

A new type of structural element, the timber-concrete composite beam, exhibited excellent structural performance. The notched connector is widely used in timber-concrete composite systems as a result of its considerable shear capacity and stiffness. Six groups of push-out tests were performed to investigate the shear performance of the notched connectors for the timber-concrete composite beams, with consideration to the varying concrete types, the shear length of the timber, and whether the notch was reinforced. From the test results, the notched connectors that corresponded to the shear fracture of concrete or timber had a low shear capacity and poor ductility. Notched connectors that simultaneously failed at the concrete slab (via shear force), as well as at the lag screw reinforcement point during bending presented the greatest shear capacity. This was followed by the notched connectors that exhibited diagonal-compression failure at the concrete slab. Screw fasteners in the notch were shown to improve the strength, ductility, and post-peak behavior of the notched connectors. In addition, the concrete type, the shear length of the timber, and whether the notch was reinforced were found to have no major influence on the slip modulus of the notched connectors.

Wood is both renewable and natural, which are qualities that make it both environmentally sustainable and useful in terms of development. However, wood also has certain inherent defects, such as its tendencies to shrink when dried and rot when wet. These defects restrict the use and popularity of lumber as a building material. In this paper, the effects of beeswax impregnation on the dimensional stability of wood were studied. Pieces of African padauk (Pterocarpus soyauxii) (20 mm × 20 mm × 20 mm) were used as the test material. The wood was treated at a temperature of 120 °C for periods of 3 h or 6 h. Measurements of weight gain rate, size expansion coefficient, and contact angle of the control samples were compared with samples treated with beeswax for 3 h and 6 h to explain macroscopic changes in wood. The effects of beeswax impregnation were compared using scanning electron microscopy, thermal weight loss characteristic analysis, and functional group analysis. The results indicated that, to some extent, beeswax impregnation improved the dimensional stability of wood and remarkably enhanced its surface hydrophobicity.

Melamine urea formaldehyde (MUF) resin impregnation followed by heat compression is a prominent method in improving mechanical properties and dimensional stability of wood. In addition, melamine is reactive to formaldehyde, and therefore able to reduce the free formaldehyde of the treated wood. This study aimed to produce compressed sesenduk (Endospermum diadenum) wood with low formaldehyde emission using low viscosity MUF resin. The effects of treatment efficiency on the physical and mechanical properties of the wood products were evaluated. The experimental design included impregnation of sesenduk strips with 20% and 30% MUF at five different formulations. Then, it was pre-cured at a temperature of 70 °C for 90 min, followed by hot compression at 140 °C with the compression ratio of 80%. The optimum treatment combination was determined through treatability, mechanical strength, dimensional stability, and formaldehyde emission. It was also compared to other treatments, including impregnation without further compression using formulated MUF and commercial MUF. The results revealed that F4 MUF, which consisted of 30% melamine, 50% formaldehyde, and 20% urea, was the optimal MUF formulation that resulted in low formaldehyde emission and acceptable physical and mechanical properties.