Volume 19 Issue 4

Microfibrillated cellulose (MFC) batches were produced using never-dried and commercial, dried microcrystalline cellulose (MCC) as raw materials. Mechanical treatment was applied with a Masuko grinder using different refining degrees and consisting of one to three passes through the equipment. The impact of the mechanical treatment on the particle size distribution, fiber swelling properties, particle morphology as well as rheology of the manufactured MFC gel products were investigated. In addition, specific energy consumption of the process was calculated. The MFC gel samples manufactured from the never-dried AaltoCell™ MCC, demonstrated more pronounced changes in material properties with various refining parameters than those produced from the commercial, dried MCC, which is likely attributable to the hornification effect. The most significant reduction in particle sizes and the greatest increase in fiber saturation point and rheological properties were achieved during the initial pass through the grinder. The use of never-dried MCC as the raw material resulted in a stronger MFC gel with higher storage and loss modulus characteristics. Specific energy consumption also indicated that the refining energy transfers better to the never-dried structure of MCC, and more fibrillation can be obtained with less energy when using the never-dried MCC as raw material for MFC production.

Oil palm is Indonesia’s predominant estate crop, but it generates a significant amount of unproductive stem waste. This study examined the anatomical characteristics and their relationship with density from core to bark across the bottom, middle, and top sections, providing insights for effective OPS utilization. Anatomical characteristics were observed with optical and scanning electron microscopy, and the density was measured using an electronic densimeter. The vascular bundle numbers (VBN) increased from core to bark and decreased from top to bottom. The fiber bundle area (FBA) increased from core to bark and from top to bottom. The fiber length (FL), width (FW), and wall thickness (FWT) decreased from bottom to top, whereas the fiber lumen diameter (FLD) increased. The FL of all sections decreased from core to bark. The radial variation of FW, FLD, and FWT varied in each section. The fiber at the inner section of the middle section and the whole top section mostly showed third-grade pulp quality, whereas the bottom section and outer part of the middle section were mainly fourth-grade pulp quality. The density was positively correlated with VBN. FBA, FL, and FW were negatively correlated with oven-dry density, although not significantly, while FWT and FLD were not correlated with OPS density.

This study aimed to investigate the influence of dammar resin on the mechanical properties of composite materials reinforced with corn husk and paper waste laminates. Different percentages of dammar resin (50%, 60%, and 70%) were added to the matrix while keeping the reinforcement constant. For all samples, the ratio was maintained at 40% matrix and 60% reinforcement. With the experimental results obtained, statistical analyses were conducted: two-way analysis of variance (ANOVA), Levene’s test, Shapiro-Wilk test, and ANOVA post hoc (with Bonferroni correction). The null hypothesis stated that dammar resin does not influence the mechanical properties. For all tests considered, the null hypothesis was rejected (p < 0.05), the variances were homogeneous (p > 0.05), and the data followed a normal distribution (p > 0.05). It was found that dammar resin had a significant influence on the mechanical properties as the percentage increased from 50% to 70% (p < 0.0083). For each test, based on already known premises, an explanation of the phenomenon that could occur due to the insertion of dammar resin was provided, serving to complement and validate the statistical estimations.

Light is essential for tree growth and development, yet some species are able, or prefer, to tolerate shady conditions without adversely affecting their development. This ecological preference prompts different strategies in these species, often involving a trade-off between performance and safety in terms of mechanical support, conductivity, and pest and disease protection. Studies on the ecological strategies of trees and their associated functional traits are essential to gain further insight into biodiversity and the processes that shape wood quality from the standpoint of technological properties useful to humans. This literature review showcases current links between ecological preferences and the main functional traits of tree species, with particular emphasis on wood properties.

This work was conducted using the PicoScope signal extraction and Adobe Audition procedure, which revealed significant insights regarding the Iban traditional drum called ketebong. Three ketebong of different lengths, i.e., long, medium, and short sizes were studied. The amplitude of the long ketebong signal remains constant, showing that it had sustained its timbre for a longer duration compared to medium and short ketebong. Considering the diameter, all ketebong are almost similar, all the ketebong yield fundamental frequency at 50.15 Hz (i.e., G1# ~51.9 Hz). Although all ketebong showed similar fundamental frequency, Adobe Audition showed that the long ketebong has a brighter sound than the medium ketebong followed by the short ketebong. The purpose of this study is to derive the musical qualities of Gendang Pampat (GP), with a particular emphasis on the ketebong performance technique. The goal is to produce a rhythmic composition that integrates and reinforces a connected, expressive, rhythmic musical arrangement. The study aims to establish a framework by investigating the interlocking of rhythmic of GP to generate musical interpretation for composing a new repertoire for GP performance.

Bamboo is a type of fast-growing and renewable natural resource that is an ideal building material. In this study, the longitudinal tensile, longitudinal compressive, flexural, longitudinal shear, transverse tensile, and transverse compressive stress-strain and strength properties of bamboo with a period of 240 days were conducted to study the time-varying deterioration performance of bamboo. The results showed that the mechanical properties of bamboo decreased gradually with the passage of time. The transverse compressive strength deteriorated the most, and the longitudinal tensile strength deteriorated the least. After 240 days of tests, bamboo CCS decreased by 52.5% and UTS decreased by 25.4%. Formulas to predict deterioration of mechanical properties were put forward and validated. It was found that the nodes of bamboo influenced its mechanical properties. The deterioration degree of the test specimens with nodes was slightly higher than that of the test specimens without nodes. These findings provide evidence about the deterioration mechanism of bamboo and are significant for promoting the development of bamboo architecture.

The functional and structural features of microbial load in soil are influenced by the presence of insecticides. This study examined the impact of two organophosphorus insecticides, dimethoate and parathion on the microbial load of soil. The colony count of fungi, actinomycetes, bacteria, and nitrogen fixing bacteria was reduced after insecticides application at 7 and 14 days, but at 28 days the colony count began to increase. The growth of two white rot fungi including Pleurotus sajor-caju and Phanerochaete chrysosporium was affected by parathion, which was reflected by a decrease in colony radius to 1.85±0.05 and 0.75±0.06 cm, respectively, and by dimethoate, reflected by a decrease in colony radius to 3.33±0.12 and 1.85±0.05 cm, respectively at 40 mg/L compared to colony radius at control 7.90±0.12 and 7.50±0.06 cm, respectively. The applied low concentration (10 mg/L) encouraged P. sajor-caju and P. chrysosporium to remove up to 87.7% and 81.8% of dimethoate, respectively, and 69.20 and 68.30% of parathion, respectively compared with the decomposition at high dose (40 mg/L) at 28 days. The presence of insecticides induced the production of ligninolytic enzymes lignin peroxidase, laccase, and manganase peroxidase.

The biological durability of oil palm trunk modified with 1,3-dimethylol-4,5-dihydroxyethyleneurea (DMDHEU) was tested after subsequent curing at elevated temperatures. The resistance against mold, decay fungi, and subterranean termites was examined. Dimethylol dihydroxyethyleneurea-modified OPT demonstrated improved resistance against mold and decay fungi; however, the effect was lesser on subterranean termite attacks. Oil palm trunk modified with 34% DMDHEU and cured at 160 °C exhibited the most effective reduction in mass loss due to biological degradation compared to the untreated controls. High curing temperature (> 180 °C) caused cracks and ruptured the cell walls, exposing the untreated zone of the OPT to biological attack. As a non-biocidal wood modification, homogeneous dispersion of DMDHEU with adequate concentration and curing temperature is important to fully prevent OPT degradation by wood-destroying fungi and termites. These results provide valuable information for technologists to enhance or streamline the experimental design of combined modification with DMDHEU and thermal treatment, supporting their practical goals. It is recommended to continue research on the leaching of DMDHEU-modified OPT to understand the prevailing effect of DMDHEU on the biological durability of OPT, whether it is due to cross-linking or filler dispersion.

The application of copper azole (CA) preservative on glulam can improve the durability of the material. The effect of CA preservative was evaluated relative to the surface bonding quality of laminates with different surface conditions. The surface morphology and wettability of CA preservative-treated laminates were analyzed. A comparison was made on the interlaminar shear strength of preservative-treated glulam under varying environmental conditions. The atomic force microscope (AFM) diagrams showed that CA preservative adhered to the wood fibers’ surface and filled some wood cell cavities, thus reducing the water permeability of the treated laminate. Planing effectively enhanced the surface wettability of the preservative-treated laminate. The tiny particles of CA preservative on the planed laminate surface were distributed relatively uniformly, with a proportion smaller than that of the unplaned laminate. Furthermore, the interlaminar shear strength of preservative-treated glulam using planed laminates was at least 15% higher than that of unplaned laminates. In both hot and humid environments and natural aging tests, preservative-treated glulam bonded with resorcinol formaldehyde (RF) adhesive outperformed those bonded with polyurethane (PUR) adhesive. To ensure reliable quality of preservative-treated glulam, it is recommended to plane the laminate by 0.6 mm and use RF adhesive.

This review explores the evolution of prestressed timber/bamboo structures across component, connection, and structural levels, and it examines the corresponding performance of prestressed specimens. Firstly, the utilization of prestress in beams is achieved through either pre-bending methods or the incorporation of additional components. Subsequently, prestress in timber/bamboo columns often appears in the form of lateral confinement, which improves the compressive performance of the columns. On the structural level, prestress is applied in self-centering structural systems and large-span string timber/bamboo structures. Detailed schematic diagrams illustrate the application methods and underlying principles of prestress in timber/bamboo components and structures. Based on the current state of research, the future research needs and development directions are outlined. The research aims to promote the broader application of prestressed timber/bamboo structures in practical engineering, contributing to the advancement of sustainable building practices.