European Journal of Wood and Wood Products最新文献

The aim of the conducted research was to investigate the effect of introducing a nanocellulose (NC) functionalized with an ethylenediamine (EDA) to urea-formaldehyde (UF) adhesive on the properties of particleboard. The effectiveness of performed functionalization was confirmed using a Fourier transform infrared spectroscopy (FTIR) and amino groups quantification. Based on the outcomes of a thermogravimetric analysis and the measurements of a contact angle, it was found that the EDA-modified nanocellulose was characterized by improved thermal stability and reduced hydrophilicity. Moreover, the results of differential scanning calorimetry showed that the modification of the UF adhesive increased the enthalpy of the curing reaction, which indicates an increase in the UF adhesive reactivity. The effect was particularly distinct when the EDA-modified NC was applied. Modification of the UF adhesive also had a positive effect on the physical and mechanical properties of the produced single-layer particleboards. The applied functionalization with EDA allowed to increase the potential of NC in improving the internal bond, reducing thickness swelling and formaldehyde content of the manufactured boards. Overall, the use of 1% EDA-modified NC was selected as the optimal variant enabling the production of particleboards characterized by enhanced strength, improved water resistance and decreased formaldehyde content.

The fast-growing human demands in the world are leading to the expansion of industrialization. As wooden materials are increasingly used in industrial settings, detecting defects in wood has become crucial. Wood defects adversely affect the quality and durability of materials. A wood defect detection method, named WD Detector, is proposed in this study to identify wood defects. There are 18,284 defective wood surface images and 1,992 undefect wood images in a dataset of 20,276 wood images used for wood defect detection. 12 different classical machine learning algorithms are used to classify wood defects after extracting features from images with various CNNs and transfer learning approaches. In this study, feature extraction is performed by training the Xception CNN model. Once the features are extracted, classical machine learning algorithms are used to classify the wood defects. For the first time, a deep learning-based hybrid sensor design has been implemented on this dataset for wood defect detection. WD Detector achieved 99.32% accuracy in detecting wood surface defects using the new method. The success of this study’s method in detecting wood defects is believed to pave the way for future studies.

This article proposes a model that makes possible the seismic analysis of timber frame multistory buildings in general-purpose software. The model is entitled link frame model (LFM) and shows the following advantages in comparison to previous models: (1) it can model shearwalls only with frame elements and links with errors close to 0% with respect to analytical code models such as e.g. the special design provisions for wind and seismic (SDPWS); (2) for seismic analysis, both the static analysis method and the modal spectral analysis method can be used, in addition to the gravitational analysis; (3) the computation of the natural period shows deviations close to 0% in comparison with eigenvalues and eigenvectors; (4) it can be implemented in general purpose structural analysis software such as e.g. ETABS or SAP2000; and (5) building system effects, i.e. interaction of shearwalls with other assemblies, can optionally be captured if assigning the proper diaphragm out-of-plane flexural stiffness. Given the great impact of this last aspect in practical design, and the lack of its research, this paper does not only present the model and validation itself, but also analyzes the consequences of considering system effects in a representative case study building. The analysis demonstrates that the average shearwall tension (uplift) of regular buildings can decrease by 80% if considering system effects, which could make timber buildings much more cost competitive in seismic countries.

Wood hybrid materials have gained significant attention for advanced technical applications over the past decade. In contrast to other materials, wood’s hygroscopic nature causes swelling and shrinkage, leading to differential expansion in hybrid systems under varying humidity conditions. When wood’s swelling is restrained by surrounding materials, stresses develop within both the wood and its adjacent components. To study this phenomenon, swelling tests were conducted on kiln-dried paulownia (Paulownia elongata) and Norway spruce (Picea abies) in a climate chamber at 20 °C and 98% relative humidity, with expansion restricted in one direction. Moisture absorption initially exhibited a steep, linear increase, levelling off after approximately 2 h. Swelling pressures rose sharply, peaking after 30 h for paulownia and 19 h for spruce, before gradually decreasing due to increased moisture content and relaxation. The measured stresses were lower than the compressive strengths of both wood species at their respective moisture contents. Microscopic examinations showed no cellular damage in paulownia during moisture absorption due to swelling pressure. In contrast, spruce wood displayed cell wall deformations and ray’s kinking in the early wood region of radial samples, as well as cell wall bending in tangential samples. This indicates that maximum stress is determined by the localised failure of the wood’s cellular structure rather than its overall properties. Such local effects were more pronounced in spruce than in paulownia due to their different structure. As a result, paulownia shows excellent potential for use in hybrid structures due to its low swelling and shrinkage properties and uniform structure.

Tool condition monitoring (TCM) is essential for advancing the wood-based material processing industry, particularly in the context of rapid technological progress. Unlike metal cutting, wood-based material cutting presents unique challenges that require existing TCM systems to be carefully adapted. Despite its importance, research specifically targeting TCM in wood-based processing remains sparse, with most studies focusing on cutting mechanisms rather than monitoring solutions. This paper offers a comparative analysis, synthesizing insights from cutting mechanisms and TCM to address this gap. It further explores the broader integration of TCM into wood processing, highlighting current challenges and limitations. By bridging these knowledge gaps, the study provides a foundation for improving TCM applications in wood-based material cutting.

By using basalt fibre grids as a reinforcing material, lightweight plywood with improved bending properties could be produced by using low density hardwood veneers and phenol-formaldehyde (PF) adhesives. The improvement in flexural strength would allow it to be used in a wider range of load-bearing applications. In this study, acrylate-coated basalt fibre grids with a grammage of 200g m(^{-2}) and uncoated basalt fibre grids with a grammage of 116g m(^{-2}) were inserted into the outer glue joints of five-layer lime (Tilia cordata) plywood as reinforcement. The plywood was bonded with two formulations of PF adhesive. The evaluation of the mechanical properties showed increases for the modulus of rupture (MOR) and the modulus of elasticity (MOE). The increase in MOR was up to 25% in the parallel direction of the top layers and up to 49% in the perpendicular direction of the top layers for plywood reinforced with the acrylate-coated basalt fibre grid compared to the unreinforced reference in a raw density-adjusted comparison. After treatment to evaluate moisture resistance under cyclic test conditions (MR), the reinforced plywoods exhibited similar bending strength to the unreinforced reference after standardised climate conditioning. At the same time, the addition of coated basalt fibre grid had no effect on surface soundness (SS). Therefore, the use of coated basalt grid as a reinforcing material could be a good way to produce high-strength plywood using low-density hardwood veneers.

Oriented strand board (OSB) is widely used in construction due to its cost-effectiveness and good mechanical performances. While the relationship between processing parameters and void formation has been extensively studied, the real-time behavior of voids during mechanical loading remains poorly understood. This study investigated the dynamic relationship between void characteristics and mechanical properties of OSB using digital image correlation (DIC) technology during the three-point bending tests on 15 mm and 18 mm thick commercial panels. Results showed that the initial void sizes in the core and face layers averaged 0.019 mm² and 0.017 mm² respectively, with voidage being significantly higher in the core layer than in the face layers. The size of voids hardly changes when the loading force is lower than 0.7 times of the maximum loading force. Shear strain analysis revealed that structural changes were more pronounced in and around voids compared to other regions, especially in the core layer along the major axis. Fracture initiation was primarily associated with individual voids in face layers and areas of high void concentration in the core layer. Notably, continuous and large fractures enhance the specimen’s load-bearing capacity, resulting in high MOE and MOR values. Non-continuous fractures in the core layer, however, have limited contribution to increasing MOE and MOR of the specimens.

The current study investigated the rheological behavior of a heat-treated and phenolic resin-impregnated bamboo bundle slab during the hot-pressing process. These findings have significant implications for advancing hot-pressing technology, conserving energy, and reducing emissions in the bamboo scrimber industry. The results revealed that stress relaxation played a dominant role in the hot-pressing process after reaching the target thickness of the slab, which was influenced by compression deformation stress, hygrothermal stress, and phenolic resin polycondensation. Higher hot-pressing temperature and initial moisture content (IMC) led to increased hygrothermal stress, causing delayed stress relaxation. Increasing target thickness or reducing target density could alleviate hygrothermal stress while phenolic resin curing facilitated stress relaxation by constraining compression deformation. Both the three-element generalized Maxwell model (average R² = 0.95) and the five-element generalized Maxwell model (average R² = 0.98) effectively described the slab stress relaxation; however high IMC caused excessive vapor pressure, leading to unsatisfactory fitting of the stage.