European Journal of Wood and Wood Products最新文献

As a valuable biological resource, wood plays a vital role in human societal development. However, wood undergoes biotic and abiotic degradation and dimensional instability, which limit its applications. Wood modification techniques, including acetylation, furfurylation, and silicification, can help enhance the durability and sustainability of wood. However, the effectiveness of these methods varies depending on the wood species and origin, emphasizing the need for further research to refine these techniques and enhance the wood performance for diverse industrial applications. This study aimed to investigate the effectiveness of three modification methods for Korean domestic wood species by assessing their effects on the weight% gain (WPG), equilibrium moisture content, water absorption, anti-swelling efficiency, and fungal decay resistance. Attenuated total reflectance (ATR)–Fourier transform infrared spectroscopy and scanning electron microscopy were conducted for the chemical and structural characterization of modified wood. The applicability of the modification methods was tested using five Korean domestic woods, sampled from Radiata pine, Korean red pine, Japanese larch, Hybrid poplar, and Sawtooth oak. The results showed that furfurylation produced the highest WPG, water resistance (WR), dimensional stability, and fungal decay resistance among the modification methods on all the tested wood materials. Acetylation and silicification also enhanced the dimensional stability and fungal decay resistance; however, the WR differed depending on the wood species and type. This study provides valuable insights into the applicability of three modification methods for improving the durability and performance of Korean domestic wood species and contributes to the sustainable utilization of wood in various industries.

This study reveals the magnitude of stress spread angles in the design of plywood gusset plates when subjected to uniaxial tension, with a specific focus on mechanical connections. Plywood plates with elevating widths at three different load-face grain angles were destructively tested. The test series continued with consecutively increased plate widths until the measured forces reached plateaus. Two models, namely, the classic and modified stress spread models, adopted from the Whitmore effective width theory, were investigated to account for the observed phenomenon. The classic stress spread model considers a rigid fastener array and an evenly distributed stress block. A closer-to-reality modified model considers the summation of stress blocks contributed from each fastener line. For both models mentioned, the magnitudes of corresponding spread angles were calibrated utilizing a fitting scheme considering maximized R-square values. The validity of both models was later examined and validated versus the previous experimental data reported in the literature. It was found that the classic model, despite some close predictions, gave over-estimations on the load-bearing capacities of several connection patterns. The modified model was found to be conservative for almost all investigated fastener patterns. Accordingly, a hybrid adoption of stress spread models was suggested.

Different tree species exhibit significant variations in physical properties, uses, and economic value, making accurate species identification crucial. Traditional methods relying on human visual inspection are time-consuming and susceptible to subjective experience and fatigue. This paper proposes an RGB image expansion method based on hyperspectral data and an optimized Mask R-CNN model for wood species identification. First, 600 hyperspectral images of wood blocks of four tree species (Larch, Spruce, Birch, and Poplar) were collected. Principal Component Analysis was used to reduce the dimensionality of the hyperspectral images, followed by spectral band recombination to enhance texture features, resulting in a dataset of 1873 RGB images. Secondly, Leaky ReLU was used in place of ReLU as the activation function for the residual blocks. The ResNet50 and ResNet101 networks, combined with Feature Pyramid Networks were served as the two foundational feature extraction networks, and Convolutional Block Attention Module (CBAM) and Squeeze-and-Excitation Network (SENet) were inserted at different layers of the feature extraction network. Experimental results show that appropriate integration of attention mechanisms at different layers of the backbone can improve model accuracy and reduce loss rates. The ResNet101-CBAM3-SENet4 model exhibited the best overall performance, with precision of 0.9574, 0.9778, 0.9592, and 0.9783 for the four wood species in the test set, and an average precision of 0.9680. The mean Average Precision was calculated as 0.9657, and the mean Average Recall was 0.9806. This research provides new directions for dataset expansion in image identification and accurate identification of wood species with similar textures.

Wooden fasteners are gaining increasing attention due to their potential to enhance automation in wood processing, recyclability, sustainability, and producing Engineered Wood Products free from metal fasteners and adhesives. The mechanical response of wooden fasteners differs significantly from conventional metal fasteners. This distinct behaviour necessitates the development of specific guidelines and standards for assessing and designing wooden fastener connections. Current standards, such as the Eurocode and National Design Specification, along with existing research, offer empirical equations that are not fully applicable to wooden fasteners. Proper evaluation of wooden fastener joints requires the determination of key mechanical properties, including maximum bending moment, maximum bending strength, shear strength, and embedment strength. However, the flexible nature of wooden fasteners and their size and geometry make the determination of these properties challenging. This review critically examines the mechanical properties of wooden fasteners, factors influencing their performance, testing methodologies, failure modes, deviations from existing metal fastener standards, and emerging trends and challenges in the design of wooden fastener-based connections. This critical comparative review of wooden fasteners and their quantitative evaluation of deviations from steel fasteners provides valuable insights that will be helpful for future standards and innovation related to wooden fasteners.

Microwave technology finds application in wood processing, particularly for improving drying and impregnation. A less explored application is the treatment of wood to reduce resin exudation. The aim of this research is to examine how microwave treatment of spruce wood specimens can change the physico-chemical properties of resin to retain it in the wood. The results demonstrated that microwave treatment can increase the glass transition temperature more rapidly than conventional heat treatment. Both the amount of volatile content and chemical composition of resin are affected. Further optimization of treatment parameters, such as duration and power density, could enhance the efficiency of this method.

Interest in paulownia cultivation is growing across Europe, highlighting the need to explore the properties of this material and its suitability for the different manufacturing processes. The study investigates the suitability of paulownia wood as raw material for plywood production, both as pure paulownia plywood and in combination with poplar, and compares the results with those of pure poplar plywood. For this research, paulownia trees were harvested from a six-year-old plantation in Northern Italy. The logs were peeled to produce veneers, which were then used to manufacture plywood panels. Veneers were classified based on surface appearance according to the European standard EN 365:1995, with the 46% rated as Excellent and the remaining 54% assigned to Class I. Plywood panels were produced using poplar, paulownia, and a mix of both species in a 5-ply configuration. These panels were evaluated for appearance, mechanical performance, and bonding quality. Bending tests were conducted in both longitudinal and transverse directions to determine the modulus of elasticity and strength; density was also measured. Bonding quality was assessed through shear tests after pretreatment, considering intended applications in both interior dry environments and exterior covered environments. Overall, paulownia plywood exhibited more surface defects, such as cracks, bubbles, and areas with adhesive exudation, compared to mixed poplar-paulownia panels. Its density was also lower than that of poplar and mixed panels. From the mechanical perspective, paulownia plywood showed lower strength and stiffness compared to poplar and mixed panels, with the mixed panels performing similarly to or slightly below poplar. While paulownia wood can be used for plywood production, it is most effective when used as internal layers in mixed panels with poplar.

Regrowth Tasmanian oak and Eucalyptus nitens are fast-growing Australian plantation hardwoods widely cultivated in Tasmania. Despite their favourable physical and aesthetic properties, their relatively low density limits use to wood-chip production and minor interior applications. This study aimed to enhance the material properties of these species through thermo-mechanical densification. The effects of compression ratio, pressing time, and pressing temperature were evaluated on color change, set recovery (wet and dry), pull-off strength, and delamination. Eucalyptus nitens showed excellent color stability under all conditions (ΔE*ab < 5), while Tasmanian oak exhibited significant darkening at 175 °C (ΔE*ab 6.17–9.06). At 175 °C and 37% compression, E. nitens responded more strongly, achieving a mean wet-use set recovery of 0.0%, compared with 2.7% for Tasmanian oak. Both species showed significantly improved dimensional stability at 37% compression ratio compared to 25%. The highest F-values observed for Eucalyptus nitens and Tasmanian oak were 25.36 and 17.91, respectively. Increased compression also improved pull-off strength in both species, but in Tasmanian oak, extractive migration at 175 °C likely reduced coating adhesion. The densification process had minimal impact on bondability overall. However, a higher pressing temperature significantly reduced delamination in Tasmanian oak (P-value 0.031), while showing negligible effect in Eucalyptus nitens. The results suggest that both Eucalyptus nitens and Tasmanian oak species were stable following the densification process and would make the densified wood serviceable under conditions in which the EMC does not exceed 17% if unprotected. Statements and Declarations. All authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by Benoit Belleville. The first draft of the manuscript was written by Benoit Belleville and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript. The authors have no relevant financial or non-financial interests to disclose. The authors have no competing interests to declare that are relevant to the content of this article. All authors certify that they have no affiliations with or involvement in any organization or entity with any financial interest or non-financial interest in the subject matter or materials discussed in this manuscript. The authors have no financial or proprietary interests in any material discussed in this article.

Raw bamboo possesses wax layer, which endows the surface hydrophobic property but makes the anti-fungal chemicals enter difficultly. In this work, lipase was utilized to remove the wax layer from bamboo epidermis for increasing the permeability of raw bamboo. The lipase treatment was optimized as 24 h reaction in buffer solution with a pH value of 8.5 and a temperature of 40 ℃. The weight percentage gain (WPG) of water characterizing the permeability of raw bamboo was used to evaluate the treatment effect. In addition, the bonding strength of bamboo surface was assessed using epoxy resin to further investigate the effect of lipase treatment. Compared with untreated bamboo, WPG increased to 14.7% after 72 h, and the bonding strength improved from 0.01 MPa to 0.73 MPa. The phenomenon could be explained by the diminished contact angle of bamboo epidermis, which decreased from 102.4 °to 73.5 °. An in-depth study on how lipase improves the permeability of bamboo epidermis was investigated using the GC-MS, TG, and DSC analyses. This work provides a green processing method to increase the permeability of bamboo epidermis, which will be beneficial for enhancing the fungal and cracking resistance of raw bamboo through chemical impregnation or modification.

Wood modification by impregnation with phenol-formaldehyde (PF) resins is a promising method to improve the woods’ fungal decay resistance, weathering resistance, and dimensional stability. Recent research indicates that 30% of the non-renewable phenol may be substituted by renewable softwood kraft lignin cleavage products obtained through microwave-assisted pyrolysis. Pinus sylvestris sapwood modified with this resin has good fungal decay resistance but slightly enhanced formaldehyde emission. While these results on solid wood indicate a high potential of the method, the properties of modified plywood may differ, and the weathering resistance has not been studied. In this study, formaldehyde emission, weathering resistance and fungal decay resistance against three basidiomycetes (Trametes versicolor, Rhodonia placenta, and Gloeophyllum trabeum) of plywood modified with pure PF resin and PF resin with 30% substitution of the phenol by lignin cleavage products were analysed. The 30% lignin cleavage product substitution didn’t affect the plywood’s fungal decay resistance, with less than 1% initial mass loss in all modified specimens. While the decay resistance improved significantly for all modified samples compared to reference samples, weathering resistance slightly declined with phenol substitution compared to pure PF resin modification. The formaldehyde emissions of the plywood modified with both resins were in similar ranges to that of unmodified reference plywood. Overall, plywood with good properties for exterior applications may be produced even with the substitution of 30% of the phenol by lignin cleavage products, allowing for increased use of renewable resources.

The increasing demand for sustainable and transparent materials in construction has intensified interest in alternatives to conventional glass, which is known for its energy-intensive production, high carbon emissions, brittleness, and environmental impact. This study focuses on guamuchil wood (Pithecellobium dulce), recognized for its rapid growth, high hardness, and adaptability to arid environments, as a candidate for transparent wood applications. Unlike traditional delignification, which can damage wood, the photooxidative method used here preserves its integrity by partially modifying the wood under milder conditions. Thus, this study explores the enhancement of guamuchil wood transparency through a photooxidative process, an approach not previously applied to this species. Visual analysis revealed a progressive increase in transparency of guamuchil wood with UV exposure, reaching maximum clarity at 10 h (GW10) due to extensive chromophore degradation. Exposure beyond this point led to undesirable yellowing due to excessive oxidation. SEM analyses revealed the photooxidative treatment of guamuchil wood-induced cell wall thinning, increased cell diameter, and enhanced structural order. EDS showed a reduction in carbon content from 44.16 to 42.14% and an increase in oxygen content from 55.84 to 57.86%, indicating partial degradation of lignin. FTIR analysis confirmed these oxidative changes, showing decreased aromatic lignin peaks and increased hydroxyl and carbonyl signals, with lignin content reduced from 27.5 to 21.9%. The water contact angle decreased from 62.4° to 12.2°, reflecting increased surface hydrophilicity due to lignin degradation and the exposure of hydroxyl groups. These changes contributed to a substantial improvement in optical transmittance, rising from ~ 6% in untreated wood (GW0) to 19% in GW10 at 7 mm thickness, achieved without polymer infiltration. This demonstrates the effectiveness of the photooxidative process in enhancing transparency through selective lignin degradation and surface modification. This study demonstrates a novel photooxidative process to enhance guamuchil wood transparency, achieving significant optical improvement without polymer infiltration. The process selectively degrades lignin, offering a sustainable alternative to glass in construction with reduced environmental impact.