Volume 15 Issue 3

The biological resistance of 21 tropical wood species against bacteria and molds was studied. The gram-positive bacterium Staphylococcus aureus and the gram-negative bacterium Escherichia coli had none or negligible activity on surfaces of zebrano and maçaranduba (up to 1 ×106 CFU/mL), and they had negligible or medium activity on surfaces of macassar ebony, ovengol, santos rosewood, and iroko (from 1 ×106 up to 1 ×107 CFU/mL). These bacteria had high activity on surfaces of okoumé, tineo, doussié, makoré, and both reference woods, beech and Scots pine (usually over 1 ×107 CFU/mL). The mold growth activity (MGA) of Aspergillus niger and Penicillium brevicompactum was minimal on surfaces of ipé, yellow balau, macassar ebony, doussié, bubinga, and merbau, but it was strong on surfaces of okoumé, cerejeira, ovengol, wengé, sapelli, and both reference woods. When comparing individual biological tests of (a) bacterial and mold but also (b) bacterial, mold and rot with decaying fungi C. puteana and T. versicolor, no significant relationships were found. These results confirm that the bio-durability of woods is influenced not only by their molecular structure, but also by the attacking biological pest group.

As petrochemical products (including plastics) contribute to the destruction of the natural environment, the use of such products must be reduced. Plastics account for 90% of the insulation materials used in Korea, including extruded polystyrene (EPS), expanded polystyrene (XPS), and urethane foam. Wood-fiber insulation board (WIB) is a promising natural alternative to petrochemical insulation. This study aimed to determine the optimal amount of adhesive resin required for manufacturing WIB. Fire-resistant WIB was prepared with a melamine-urea-formaldehyde (MUF) resin (ranging from 20% to 35%), and the physicochemical and fire-resistant properties were determined. Higher resin content led to improved physical properties, while the thermal conductivity was unaffected. With the exception of 35% resin content in the WIB, the formaldehyde emissions of the WIB samples complied with the Korean Industrial Standards requirements for Super E0 grade (less than 0.3 mg per L). The physicochemical properties of the WIB samples were sufficient for use as an insulating material, even at 20% resin content. A perpendicular flame test revealed that all samples formed a carbonized layer to prevent flame penetration, except for the specimen with 20% of the resin content. The cone calorimeter testing indicated that the MUF adhesives acted as an effective fire retardant at resin contents above 25%.

Circular economy production, or upcycling of traditional waste products, has evolved in alignment with consumer driven accountability and demand for environmentally friendly alternatives. In recent years, industries have emerged to upcycle materials for value-added production. This paper presents case study interview results used to gather information about current marketing practices within the urban and reclaimed wood industries, which upcycles trees felled in urban areas and wood generated through construction and demolition. Firms reported entering the industry for a variety of reasons, most frequently surrounding intangible raw material and product attributes. Interviewees reported generating primarily made-to-order products, made-to-stock furniture, mantels, slabs, lumber, beams, flooring, millwork, and other products priced largely in line with their competition. Promotion consisted primarily of word of mouth, company webpages, social media, and event participation, such as craft fairs or trade shows. Firms relayed messages of sustainability, local production, quality, and emotional value. Companies primarily participate in direct, retail, or online sales, which have become increasingly prevalent. This paper outlines opportunities to explore, as well as barriers to overcome through examination of strengths, weaknesses, opportunities, and threats present in the internal and external environments of the urban and reclaimed wood industries.

Calotropis procera (CP) fiber is a natural and renewable material with great lumen and hydrophobic-oleophilic characteristics, providing it with a good oil absorption capacity. In order to increase the absorption efficiency of organic oils and solvents, CP fiber was treated with either 0.1 M NaOH (CPNaOH), 1% NaClO2 (CPNaClO2), or hydrothermal conditions (CPHT) in an effort to improve its ability to remove crude oil from leaks or spills. The fibers were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy with field emission (SEM-FEG), and wettability for water and diesel. The fibers CPHT, CPNaOH, and CPNaClO2 showed excellent hydrophobic-oleophilic properties and good crude oil absorption capacity in water 99.2 g/g, 103.9 g/g, and 92.0 g/g. The absorption after 60 min for most fibers in dry systems or with a layer of oil floating on water exceeded 90% of its absorption capacity for the time of 1440 min. The CPNaOH after 6 runs absorbed 445.8 g of crude oil per gram of fiber. Based on the results, the treated fibers can be considered an alternative for the removal of oil from leaks and spills due to the high availability and excellent absorption property for various oils.

Chemical compositions (fatty acids, total phenolic compounds, flavonoids) and the in-vitro biological activities (antioxidant and antimicrobial activity; and growth induction of edible fungal strains) were compared for four varieties of mango seeds. Hexanic extract (HE) showed a fatty acid profile with a higher proportion of oleic acid. In the ethanolic extract were found variable total phenolic contents (103 to 125 mg GAE/g dry weight) and flavonoid contents (0.72 to 0.8 mg QE/g dry weight). This study reports for the first time the presence of procyanidin B1 in ethanolic extracts. The antioxidant activity showed IC50 values ranging from 3.09 to 3.42 μg/mL for ABTS•+ and 12.17 to 13.93 μg/mL for DPPH•. The ethanolic extract from the seed of the Yulima variety showed the highest percentages of inhibition against Staphylococcus aureus. Residues removed from ethanolic extraction of the seed kernel (EKR) induced the growth of edible fungal strains: Lentinus crinitus and Pleurotus tubarius. The data obtained show the potential of the seeds from these mango varieties, which could lead to alternative uses in various industry sectors and the use of this agricultural byproduct.

Wet-storage is the most common way to maintain sugarcane bagasse in the pulping and paper-making industry, although there are few studies focused on the selectivity of delignification in pulping for bagasse treated by wet-storage. In this study, wet-storage of bagasse was carried out before alkali-oxygen pulping. The influence of wet-storage pretreatment on the chemical compositions, morphology of bagasse, and the consumption of NaOH in alkali impregnated bagasse meal were investigated. The wet-storage of bagasse resulted in significant improvement in delignification selectivity of alkali-oxygen pulping. After the bagasse was pretreated by wet-storage with bleaching water, the screened yield and crystallinity of the resulting alkali-oxygen pulp were increased.

The demand for noise control in residential environments is steadily increasing, but the currently available noise-reducing materials used in walls and floors are unsustainable and expensive. As an alternative, wood-fiber could be a good resource to manufacture eco-friendly acoustic materials. In this study, fiberboards were prepared by mixing wood-fibers (Pinus densiflora) with melamine-urea-formaldehyde resin adhesive, obtaining specimens with different final densities and resin contents. The acoustic, physical, and morphological properties of the fiberboards were investigated. The sound absorption was greatly influenced by the density of the fiberboard: lower densities showed higher sound absorption performances. Furthermore, the low-frequency absorption coefficient was higher for lower resin contents. The materials met all the criteria required by the Korean standards for fiberboards. As the density increased, the dimensional stability and the bending strength increased; in contrast, the physical properties were not affected by the resin content. Microscopy observations confirmed that specimens with different densities and resin contents had different porosities; the porosity was assumed to be the main property that governs the noise-reducing ability. Due to their eco-friendliness and inexpensiveness, these fiberboards offer themselves as efficient and effective alternative sound-absorbing materials.

To investigate the effect of seawater degradation on the mechanical, wear, and thermal properties of plant fiber-reinforced polymer composites, the seawater immersion test was performed on four types of straw fiber (wheat straw (WS), rice straw (RS), corn straw (CS), and sorghum straw (SS))-reinforced polyvinyl chloride (PVC) composites. The results revealed that seawater immersion would result in poor mechanical, wear, and thermal properties, and lower two-phase bonding quality, thermal mass loss, and thermal residual mass, as well as more serious abrasive wear. The SS/PVC and CS/PVC composites had the highest and lowest seawater degradation resistance, respectively. After 12 d seawater immersion, the tensile strength of the SS/PVC and CS/PVC composites decreased from 17.3 to 9.7 MPa and from 12.3 to 7.2 MPa, respectively; and the flexural strength of the SS/PVC and CS/PVC composites decreased from 34.2 to 20.1 MPa and from 28.0 to 15.3 MPa, respectively. However, the friction coefficient of the SS/PVC and CS/PVC composites increased from 0.21 to 0.27 and from 0.24 to 0.30, respectively; and the specific wear rate of the SS/PVC and CS/PVC composites increased from 0.73 × 10-5 mm3/N·m to 21.7 × 10-5 mm3/N·m and from 1.77 × 10-5 to 28.3 × 10-5 mm3/N·m.

The cell wall mechanical properties are an important indicator for evaluating the overall mechanical properties of natural bamboo fibers. Using the nanoindentation technique, the variation of the mechanical properties of the fiber cell wall of Bambusa pervariabilis culms with different ages and different positions (both radial and longitudinal) was studied. Moreover, x-ray diffraction (XRD) was employed to measure the microfibril angle (MFA), and the correlation between the MFA and the mechanical properties of the fiber cell wall. The results showed that there was a remarkable difference in the fiber cell wall mechanical properties at different ages and at different radial and longitudinal positions. However, at different ages and at different positions, the absolute value of variation of MFA was less than 1° and was very minor. Furthermore, there was no significant correlation between the fiber cell wall mechanics and MFA, indicating that the mechanical property of the fiber cell walls might be synergistically affected by many factors.

Cross-laminated timber (CLT) is a wood panel product that can be arranged in different ways. The advantage of utilizing CLT is the ability to use lamination even with low density materials or those that have defects, like knots. This study evaluated the bonding and bending performances of CLT utilizing domestic species in a shear wall or floor via a face bonding test of layers and a three-point bending test. The tests were carried out with three-layered CLT made up of Japanese larch and/or Korean red pine in various configurations. The layer arrangement for lamination was divided according to the species and grade of the wood. The out-of-plane and in-plane bending tests were conducted on the CLT according to the applicable direction in a wooden structure. The results of the bonding test showed that the block shear strength and delamination of all types of CLT met the BS EN 16351 (2015) standard requirements. The results of the bending test based on two wood species showed that the bending strength of the larch CLT was higher than that of the pine CLT in single species combinations. For mixed species combinations, the bending properties of CLT using larch as the major layer was higher than those using pine as the major layer. This demonstrated that the major layer had more influence on the bending properties of CLT and that Korean red pine was more suited for the minor layer of CLT.