European Journal of Wood and Wood Products最新文献

There is growing interest in developing natural wood preservatives, particularly in response to the escalating challenges posed by environmental degradation. Caffeine is a bio-based preservative that improves decay resistance of treated wood, however it is also sensitive to leaching from wood when exposed to water. Combining chitosan-caffeine formulations limits the leaching of caffeine from impregnated wood, thereby increasing its resistance even under outdoor conditions. This research aimed to evaluate the properties of wood impregnated with chitosan-caffeine formulations, focusing on wettability (contact angle measurement), mechanical properties (bending strength), and sorption behavior. The contact angle measurement revealed that wood treated with chitosan and chitosan-caffeine formulations exhibited an improvement in water resistance compared to untreated wood and wood treated with caffeine alone. However, this resistance showed only for short-term application. Both caffeine and chitosan treatments reduced the equilibrium moisture content during adsorption and desorption phases in the relative air humidity range from 0 to 0.95. The application of chitosan-caffeine formulations for wood impregnation resulted in a reduction in equilibrium moisture content, as well as hygroscopicity of the treated wood. Treatment with all formulation variants had no effect on the mechanical parameters, including modulus of elasticity and modulus of rupture. In addition, FTIR results indicated that both caffeine and chitosan interact with wood components. These findings suggest that chitosan-caffeine formulations are promising as natural wood preservatives, offering an improved hygroscopicity while maintaining the mechanical properties of the treated wood.

Previous studies on the hydrothermal liquefaction (HTL) of biomass have primarily focused on bio-oil production, overlooking the significant hydrochar by-product. In this work, the HTL of beech wood, soda lignin, and black liquor was performed at temperatures of 300 °C and 350 °C for 20 min. The effect of temperature and biomass type on hydrochar yields and properties was thoroughly investigated. The mass yields of the hydrochars varied between 25.92 wt% and 32.70 wt%. An increase in temperature from 300 °C to 350 °C led to a decrease in hydrochar mass yields. The carbon yield was found to be highest (51 wt%) at 300 °C using beech wood. The highest heating value, 30.97 MJ/kg, was obtained with hydrochar derived from soda lignin at 300 °C. Solid-state carbon NMR demonstrated that the hydrochars derived from black liquor contain condensed aromatic structures. Both the type of biomass and temperature significantly influenced the characteristics of the resulting hydrochar. This research demonstrates that hydrochar holds promise as a solid biofuel due to its advantageous energy content and carbon yield, highlighting its potential for sustainable energy applications.

The milling performance of thermally modified wood is an essential step in its actual processing and production. Accurate prediction of milling performance of thermally modified wood is significantly meaningful for subsequent parameter optimization to improve product surface quality and increase product competitiveness. Hence, based on machine learning, four models, Random Forest (RF), Support Vector Machine (SVM), Gaussian Process Regression (GPR) and Multilayer Perceptron (MLP), were established to predict two milling parameters of thermally modified wood. In addition, four characteristics factors were set up to evaluate the cutting force (F) and the surface roughness (Ra): the modification temperature (T) of thermally modified wood, the depth of cut (h), the feed rate (u), and the spindle speed (n) of the tool during the milling process. In order to reflect the scientific nature of the research process, normal distribution analysis was additionally used as a dataset preprocessing step. The final comparison found the GPR model to be the best fitting and most accurate method for predicting milling performance.

This study investigates borate treatments of Douglas fir (Pseudotsuga menziesii) and grand fir (Abies grandis) lamstock and their impact on adhesive bonding performance. Lamstock were treated using three different methods (dip, double vacuum, and vacuum/pressure) with the aim to achieve a target retention of 0.1% (w/w) B₂O₃. The degree to which B₂O₃ was sorbed by the lamstocks was evaluated using image analysis technique. Treated lamstocks were bonded with one component polyurethane adhesive, and bond performance was evaluated by a cyclic delamination and block shear test. Results revealed that the uptake of treating solution differs by treatment methods and species. Uptake by vacuum/pressure-treated lamstocks is highest while uptake in dip treated lamstocks is the lowest. Grand fir had higher uptake values than Douglas fir throughout all treatments. The level of retention of B₂O₃ was influenced by treating solution concentration and wood properties. Dip treated lamstock showed limited spread of retained B₂O₃ with bulk of the B₂O₃ retained close to the surface. All conditions of grand fir, planed or unplaned, were able to meet the requirement of ANSI A190.1-2022 for block shear wood failure and total delamination, while unplaned specimens of Douglas-fir did not meet the requirement of ANSI A190.1-2022. Borate treatments increased the hydrophilicity of the lamstocks, causing the potential formation of superficial bonds between the adhesive and the accumulated chemicals on the surface of the unplaned dip treated lamina. This study presents insightful information about maximizing the chemical treatment of B₂O₃ to have the least possible impact on adhesive bond performance.

The use of CNC machines for woodworking is becoming increasingly widespread due to advancing technology. In this study, while 3D processing is performed on wood materials using a CNC machine, the aim is to determine wood dust emissions (PM2.5, PM10) according to processing parameters and wood species. Yellow pine, spruce, chestnut, sapelli, and beech are wood species frequently preferred in furniture businesses. Utilizing a CNC machine equipped with 2 mm and 10 mm diameter cutting tools, the wooden material was machined at a spindle speed of 18,000 RPM, a plunge rate of 4000 mm/min, and a cutting speed of 8000 mm/min. For the study, a 3D-modeled motif with curved lines was selected and applied to wooden prisms measuring 30 cm × 30 cm × 30 mm (width, length, thickness).

In conclusion, Yellow pine, with its high hardness and dense structure, generates significantly more dust than spruce during CNC machining. This result reveals that different wood species exhibit different levels of environmental impact during CNC processing. This underscores the urgent need for appropriate air filtration and emission control systems, particularly for woods that produce high emissions. Fine cutting edges effectively reduce PM2.5 and PM10 concentrations, enhancing workplace air quality. By reducing exposure to wood dust, which is harmful to human health, this study plays a crucial role in addressing this pressing issue and allows for the implementation of suitable arrangements with minimal chip removal for CNC parameters.

The aim of the study was to investigate the effect of using various amounts of coffee silverskin and cocoa pod husk (5%, 10%, 15%), both unmodified and modified with methacrylic acid, as the urea-formaldehyde adhesive fillers on the properties of plywood. The attenuated total reflectance Fourier transform infrared spectroscopy showed that the performed modification was effective. Based on the contact angle measurement and the analysis of phenolic compounds content using ultra performance liquid chromatography, it was found that the modified fillers were less hydrophilic and demonstrated lower content of phenolic acids and flavonoids. The viscosity and reactivity of the adhesive mixtures were influenced solely by the filler loading, rather than by the type or modification of the filler. The use of the tested fillers enabled the achievement of the wet shear strength level required by the standard. Furthermore, it was demonstrated that modifying the fillers with methacrylic acid positively influenced the strength of the bond lines. The negative effect on density, bending strength and modulus of elasticity was observed only for variants with the lowest filler content. Furthermore, the results of formaldehyde content in the cured adhesive and formaldehyde emission of plywood demonstrated the formaldehyde-scavenging ability of cocoa pod husk.

Wood modification with 1,3-dimethylol-4,5-dihydroxyethyleneurea (DMDHEU) has been widely demonstrated to enhance the biological durability and dimension stability of wood, thus it serves a predestined technology to equip wooden products for outdoor applications. However, such technology hardly affects the fire performance of wood, a parameter which gains increasing relevance in the construction sector. Recently, the combination of curing resins with flame retardants has been proposed as a potential approach to enhance the fire performance of wood in a permanent way, hence providing a durable fire protection system. Scots pine sapwood (Pinus sylvestris L.) was impregnated with aqueous compositions of DMDHEU, a commercially available phosphate-nitrogen based fire retardant (adapted for wooden applications) and combinations thereof. The fixation of the flame retardant was assessed on the basis of a cold water leaching process according to EN 84 (2020). The fire performance of the treated wood was assessed through thermal gravimetry analysis (TGA), a Bunsen burner ignition test and mass loss calorimeter. Both wood treated with pure flame retardant and combination of a flame retardant and DMDHEU, demonstrated improvements in thermal stability, reduced flammability and decreased heat release after treatment. Notably, the THR_600s of wood treated with DMDHEU in combination with the flame retardant was reduced by 89.3% compared to wood treated solely with DMDHEU. However, after the leaching process, the flame retardant happened to leach out almost completely, which was assessed on the basis of a loss in its efficacy related to fire protection. On the contrary, DMDHEU seemed to partially fix the flame retardant inside the wood matrix, which was derived from a persistent enhancement in fire performance, even after wooden specimens passed a cold water leaching.

Bamboo, known for its rapid growth, renewability, and technological properties, has become a sustainable alternative in manufacturing eco-friendly construction and building materials. Particleboard, with an annual production of 110 million cubic meters, is currently challenging to source raw materials, which has shifted many countries to try substitute materials. The utilization of bamboo for particleboard could be beneficial in different ways. This study examines the application of bamboo-based particleboard in environmentally friendly construction, buildings, furniture, etc. focusing on processing techniques, material properties, potential benefits, and existing challenges. Throughout the review of recent studies and innovations, this paper highlights the environmental benefits, supply advantages, and challenges associated with bamboo utilization. Furthermore, it identifies key areas for future research, including developing bamboo-specific processing methods and adhesive systems. Addressing these research gaps could significantly enhance the understanding and application of bamboo-based particleboards, paving the way for more sustainable materials in construction, furniture, and interior design.

On the basis of 31 quasistatic and 27 constant-amplitude fatigue tests, the withdrawal behaviour of a self-tapping timber screw under cyclic loading is examined in two configurations with respect to the penetration length. Together with similar results from earlier withdrawal tests on threaded rods, indications of a dependence of the bearable load cycles on the penetration length are revealed. A larger penetration length was found to yield inferior performance under cyclic loads. Furthermore, combined with results from earlier axial tensile tests on the examined screw, insights into the transition point between steel tensile failure and withdrawal are gained. The results on the withdrawal failure mode are combined with results from earlier studies to develop a proposal for a holistic verification concept for the high-cycle fatigue design of connections with inclined self-tapping screws. After reviewing the relevant failure modes, the verification is reduced to the dominant failure modes, namely, withdrawal and steel tensile failure. Subsidiary effects such as bending in the fastener are inherently considered.

Automated detection of lathe checks in wood veneers presents significant challenges due to their variability and the natural properties of wood. This study explores the use of two convolutional neural networks (U-Net architecture) to enhance the precision and efficiency of lathe checks detection in poplar veneers. The approach involves sequential application of two U-Nets: the first for detecting lathe checks through semantic segmentation, and the second for refining these predictions by connecting fragmented lathe checks. Post-processing techniques are applied to denoise the mappings and extract precise lathe check characteristics. The first U-Net demonstrated strong performance in predicting lathe check presence, with precision and recall scores of 0.822 and 0.835, respectively. The second U-Net refined predictions by linking disjointed segments, improving the overall lathe checks mapping process. Comparative analysis with manual methods revealed comparable or superior performance of the automated approach, especially for shallow lathe checks. The results highlight the potential of the proposed method for efficient and reliable lathe check detection in wood veneers.