Search Results (753)

In this study, alkali-treated wood flour/dynamic polyurethane composites were successfully prepared through a solvent-free one-pot method and in situ polymerization. The effects of the alkaline treatment process, changes in the flexible long-chain content in the dynamic polyurethane system, and the wood flour filling amount on the interface’s bonding, mechanical, and reprocessing properties were investigated. Partial removal of lignin and hemicellulose from the alkali-treated wood flour enhanced rigidity and improved interface bonding and mechanical strength when combined with dynamic polyurethane. The tensile strength was improved from 5.65–11.00 MPa to 13.08–23.53 MPa. As the composite matrix, dynamic polyurethane could not easily infiltrate all wood flour particles when its content was low or its fluidity was poor. Conversely, excessive content or overly high fluidity led to leakage and the formation of large pores, affecting the mechanical strength. As the polyol content increased, the matrix exhibited greater fluidity, which enabled it to accommodate more wood flour and penetrate the cell cavity or even the cell wall. This improved infiltration enhanced the interface bonding performance of the composites and made their mechanical properties sensitive to changes in wood flour content. The reprocessing ability of the prepared composites decreased with the increase in wood flour content, and the interface bonding was enhanced after reprocessing. The tensile strength retention rate of the composites prepared with alkali-treated wood flour was lower. This study provides a theoretical basis for optimizing the performance of wood fiber/dynamic polyurethane composites and an exploration path for developing self-healing and recyclable wood–plastic composites, which can be applied to building materials, automotive interiors, furniture manufacturing, and other fields. Full article

This study focused on investigating the flammability and thermal degradation behavior of wood fiber-reinforced composites consisting of xanthan gum (XG) and gelatin (GEL). These materials could potentially be used as novel bio-based and biodegradable topsoil covers (TSCs) to support reforestation practices. To improve the thermal properties of these composites, xanthan gum was cross-linked with citric acid (CA) or tannic acid (TA) and eventually coated with casein, while gelatin was cross-linked with tannic acid. Thermogravimetric analysis (TGA) showed that thermal degradation of all the prepared samples started at temperatures of 200 °C for xanthan-based samples and 300 °C for gelatin-based samples, which is well above the typical operating conditions for TSCs in their intended application. Single-flame-source tests demonstrated that the CA cross-linked xanthan-based TSCs coated with casein and all the gelatin-based TSCs had excellent self-extinguishing properties. Additionally, Limiting Oxygen Index (LOI) tests showed that gelatin-based composites had LOI values between 30 and 40 vol% O₂, increasing with a higher gelatin-to-wood fiber ratio. These results demonstrated the potential of cross-linked biopolymers (e.g., xanthan and gelatin) as green flame retardants for the production of wood fiber-filled TSCs for use in forestry. Full article

Wood polymer composites (WPCs) represent a rapidly growing class of sustainable materials, formed by combining lignocellulosic fibers with thermoplastic or thermoset polymeric matrices. This review summarizes the state of the art in WPC development, emphasizing the use of recyclable (or recycled) and biodegradable polymers as matrix materials. The integration of waste wood particles into the production of WPCs addresses global environmental challenges, including plastic pollution and deforestation, by offering an alternative to conventional wood-based and petroleum-based products. Key topics covered in the review include raw material sources, fiber pre-treatments, compatibilizers, mechanical performance, water absorption behavior, thermal stability and end-use applications. Full article

Climate extremes threaten the resilience of Eucalyptus plantations, yet hybridization with drought-tolerant species may enhance stress tolerance. This study analyzed xylem anatomical and functional drought responses in commercial Eucalyptus grandis (GG) clones and hybrids: E. grandis × camaldulensis (GC), E. grandis × tereticornis (GT), and E. grandis × urophylla (GU1, GU2). We evaluated vessel traits (water transport), fibers (mechanical support), and wood density (D) in stems and branches. Theoretical stem hydraulic conductivity (k_Stheo), vessel lumen fraction (F), vessel composition (S), and associations with previous hydraulic and growth data were assessed. While general drought responses occurred, GC had the most distinct xylem profile. This may explain it having the highest performance in different irrigation conditions. Red gum hybrids (GC, GT) maintained k_Stheo under drought, with stable F and a narrower vessel size, especially in branches. Conversely, GG and GU2 reduced F and S; and stem k_Stheo declined for a similar F in these clones, indicating vascular reconfiguration aligning the stem with the branch xylem. Almost all clones increased D under drought in any organ, with the highest increase in red gum hybrids. These results reveal diverse anatomical adjustments to drought among clones, partially explaining their growth responses. Full article

Rammed earth (RE), a traditional material aligned with circular economy (CE) principles, has been gaining renewed interest in contemporary construction due to its low environmental impact and compatibility with sustainable building strategies. Though not a modern invention, it is being reintroduced in response to the increasingly strict European Union (EU) regulations on carbon footprint, life cycle performance, and thermal efficiency. RE walls offer multiple benefits, including humidity regulation, thermal mass, plasticity, and structural strength. This study also draws attention to their often-overlooked ability to mitigate indoor overheating. To preserve these advantages while enhancing thermal performance, this study explores insulation strategies that maintain the vapor-permeable nature of RE walls. A parametric analysis using Delphin 6.1 software was conducted to simulate heat and moisture transfer in two main configurations: (a) a ventilated system insulated with mineral wool (MW), wood wool (WW), hemp shives (HS), and cellulose fiber (CF), protected by a jute mat wind barrier and finished with wooden cladding; (b) a closed system using MW and WW panels finished with lime plaster. In both cases, clay plaster was applied on the interior side. The results reveal distinct hygrothermal behavior among the insulation types and confirm the potential of natural, low-processed materials to support thermal comfort, moisture buffering, and the alignment with CE objectives in energy-efficient construction. Full article

This study focuses on the development of lignin-based carbon-fiber-reinforced laminated veneer lumber (LVL) beams for garden timber structures, addressing wood shortages and environmental concerns. The research consisted of three main phases: the extraction and characterization of the lignin from corn stalks; the preparation and characterization of lignin-based carbon fibers; the fabrication and testing of reinforced LVL beams. Lignin was extracted from corn stalks using a deep eutectic solvent, followed by the preparation of lignin-based carbon fibers through electrospinning. These carbon fibers were integrated with poplar veneers to create reinforced LVL beams. The test results demonstrated significant improvements in mechanical properties, with the reinforced LVL beams exhibiting a 17% increase in elastic modulus and a 30% enhancement in flexural strength compared with conventional LVL beams. Notable improvements were also observed in tensile strength, compressive strength, and shear strength. This research provides a novel approach for producing high-value-added carbon fibers from agricultural waste, advancing the development of sustainable building materials. Full article

Fabric veneer panels were prepared using ethylene-vinyl acetate copolymer film (EVA) as the intermediate layer and poplar plywood as the substrate. Eight fabrics with different compositions were selected for evaluation to screen out fabric materials suitable for poplar plywood veneer. The fabrics were objectively analyzed by bending and draping, compression, and surface roughness, and subjectively evaluated by establishing seven levels of semantic differences. ESEM, surface adhesive properties, and peel resistance tests were used to characterize the microstructure and physical–mechanical properties of the composites. The results show that cotton and linen fabrics and corduroy fabrics are superior to other fabrics in performance, and they are suitable for decorative materials. Because the fibers of the doupioni silk fabric are too thin, and the fibers of felt fabric are randomly staggered, they are not suitable for the surface decoration materials of man-made panels. The acetate veneer surface gluing performance was 1.31 MPa, and the longitudinal peel resistance was 20.98 N, significantly exceeding that of other fabric veneers. Through the subjective and objective analysis of fabrics and gluing performance tests, it was concluded that, compared with fabrics made of natural fibers, man-made fiber fabrics are more suitable for use as surface finishing materials for wood-based panels. The results of this study provide a theoretical basis and process reference for the development of environmentally friendly decorative panels, which can be expanded and applied to furniture, interior decoration, and other fields. Full article

The standardization of physical and mechanical properties is critical for the large-scale application of engineered bamboo products. In this study, the distribution characteristics of density and modulus of elasticity (MOE) were systematically examined in a large sample of flattened bamboo boards. The density and MOE ranged from 0.46 to 1.12 g/cm³ and 5.60 to 22.18 GPa, respectively. Both exhibited a decreasing trend with increasing board thickness. Based on interquartile analysis, four density grades and five MOE grades were established. A strong positive correlation was identified between density and MOE, indicating that density—closely linked to fiber volume fraction—is the primary factor influencing mechanical performance. Notably, the graded bamboo boards demonstrated significantly higher modulus values than conventional wood veneers such as hemlock and poplar, highlighting their potential for high-performance structural applications. This study proposes a practical grading framework that contributes to the standardization and broader engineering utilization of flattened bamboo boards. Full article

This study presents the design and fabrication of a glass fiber–poplar veneer composite plate, investigating how varying interlayer configurations of glass fiber (single- and double-layer) and the arrangement of poplar veneer layers (odd and even) impact the mechanical and thermal insulation characteristics of these composite plates. Compared to plywood made from natural wood, glass fiber significantly improved the properties of fast-growing poplar plywood. The highest impact strength increased by 3.62 times, while the flexural strength increased by 26.22% and the tensile strength by 29.66%. The thermal diffusion coefficient of the experimental group decreased by 40.74%, indicating better insulation. Interestingly, single-layer glass fiber is superior to a double-layer structure in terms of thermal insulation. An optimal interlayer structure was identified, comprising one veneer layer between two layers of glass fiber cloth, repeated three times. Abaqus 2019 was used for finite element analysis (FEA). The simulation results agree with the experimental data to within 5%. These findings confirm the importance of structural configuration in determining the properties of composite materials, providing a theoretical basis for the structural design of fiber–reinforced composite materials. Full article

Energy demand in the building sector has drastically increased due to rising occupant comfort requirements, accounting for 30% of the world’s final energy consumption and 26% of global carbon emissions. Thus, to improve building efficiency in heating and cooling applications, phase change material (PCM)-based passive thermal management techniques have been considered due to their energy storage capabilities. This study provides a comprehensive review of the research on PCM applications, types, and encapsulation forms. Various solutions have been proposed to enhance PCM performance. In this review, the authors suggest new methods to improve PCM efficiency by using the multilayered wall technique, which involves employing two layers of a hybrid bio-composite—specifically, the hybrid hemp/wood fiber-reinforced composite with a polypropylene (PP) matrix—along with a layer of PCM made from spent coffee grounds (SCGs). Previous studies have shown that oil extracted from SCGs demonstrates good thermal and chemical stability, as it contains approximately 60–80% fatty acids, with a phase transition temperature of approximately 4.5 ± 0.72 °C and latent heat values of 51.15 ± 1.46 kJ/kg. Full article

This study utilizes waste wheat straw fibers and discarded tea bags as novel raw materials for developing new thermal insulation and sound absorption composites. Wood adhesive (WA) is used to bind the polymer raw materials. Loose polymers and different composites are experimentally developed in different concentrations. Sound absorption and thermal conductivity coefficients are obtained for the developed boards. Bending moment analysis and the moisture content of the boards are reported in addition to a microstructure analysis of the straw fibers from wheat. The results indicate that as the wheat straw fiber’s percentage increases in the composite, the thermal conductivity coefficient decreases, the flexure modulus decreases, the sound absorption coefficient increases at some frequencies, and the moisture content increases. The range of thermal conductivity and the noise reduction coefficient are 0.042–0.073 W/m K and 0.35–0.6 at 24 °C for the polymer raw materials, respectively. The corresponding values for the composites are 0.054 and 0.0575 W/m K and 0.45–0.5, respectively. The maximum moisture content percentages for the polymers and composites are 6.5 and 1.15, respectively. The composite flexure modulus reaches maximum and minimum values of 4.59 MPa and 2.22 MPa, respectively. These promising results promote these polymer and composite sample boards as more convenient insulation materials for green buildings and could replace the conventional petrochemical thermal insulation ones. Full article

The dynamic thermomechanical properties of wood–plastic composites (WPCs) are influenced by various factors, such as the selection of raw materials and processing parameters. To investigate the effects of different wood fiber content ratios and temperature on the loss modulus of WPCs, seven different proportions of Masson pine (Pinus massoniana Lamb.) and Chinese fir [Cunninghamia lanceolata (Lamb.) Hook.] mixed-fiber-reinforced HDPE composites were prepared using the extrusion molding method. Their dynamic thermomechanical properties were tested and analyzed. The storage modulus of WPCs showed a decreasing trend with increasing temperature. A reduction in the mass ratio of Masson pine wood fibers to Chinese fir wood fibers resulted in an increase in the storage modulus of WPCs. The highest storage modulus was achieved when the mass ratio of Masson pine wood fibers to Chinese fir wood fibers was 1:5. In addition, the loss modulus of the composites increased as the content of Masson pine fiber decreased, with the lowest loss modulus observed in HDPE composites reinforced with Masson pine wood fibers. The loss tangent for all seven types of WPCs increased with rising temperatures, with the maximum loss tangent observed in WPCs reinforced with Masson pine wood fibers and HDPE. A prediction method based on the Extreme Learning Machine (ELM) model was introduced to predict the dynamic thermomechanical properties of WPCs. The prediction accuracy of the ELM model was compared comprehensively with that of other models, including Support Vector Machines (SVMs), Random Forest (RF), Back Propagation (BP) neural networks, and Particle Swarm Optimization-BP (PSO-BP) neural network models. Among these, the ELM model showed superior data fitting and prediction accuracy, with an R² value of 0.992, Mean Absolute Error (MAE) of 1.363, and Root Mean Square Error (RMSE) of 3.311. Compared to the other models, the ELM model demonstrated the best performance. This study provides a solid basis and reference for future research on the dynamic thermomechanical properties of WPCs. Full article

Sustainability and the circular economy are increasingly recognized as global priorities, particularly in industrial waste management. This study explores the development of a sustainable composite material using wood waste and natural fibers, contributing to circular economy practices. Sandwich panels were manufactured with a green epoxy resin matrix, incorporating wood waste in the core and flax fibers in the outer layers. Mechanical tests on the sandwich panel revealed a facing bending stress of 92.79 MPa and a core shear stress of 2.43 MPa. The panel demonstrated good compressive performance, with an edgewise compressive strength of 61.39 MPa and a flatwise compressive strength of 96.66 MPa. The material’s viscoelastic behavior was also characterized. In stress relaxation tests (from an initial 21 MPa), the panel’s stress decreased by 20.2% after three hours. The experimental relaxation data were successfully fitted by the Kohlrausch–Williams–Watts (KWW) model for both short- and long-term predictions. In creep tests, the panel showed a 21.30% increase in displacement after three hours under a 21 MPa load. For creep behavior, the KWW model was preferable for short-term predictions, while the Findley model provided a better fit for long-term predictions. Full article

Recycled wood fiber (RWF) obtained through the multi-stage processing of waste wood serves as an eco-friendly green construction material, exhibiting lightweight, porous, and high toughness characteristics that demonstrate significant potential as a cementitious reinforcement, offering strategic advantages for environmental protection and resource recycling. In this study, high-performance sulfoaluminate cement (SAC)-RWF composites prepared by modifying RWFs with nano-silica (NS) and a silane coupling agent (KH560) were developed and their effects on mechanical properties, shrinkage behavior, hydration characteristics, and microstructure of SAC-RWF composites were systematically investigated. Optimal performance was achieved at water–cement ratio of 0.5 with 20% RWF content, where the KH560-modified samples showed superior improvement, with 8.5% and 14.3% increases in 28 d flexural and compressive strength, respectively, compared to the control groups, outperforming the NS-modified samples (3.6% and 8.6% enhancements). Both modifiers improved durability, reducing water absorption by 6.72% (NS) and 7.1% (KH560) while decreasing drying shrinkage by 4.3% and 27.2%, respectively. The modified SAC composites maintained favorable thermal properties, with NS reducing thermal conductivity by 6.8% through density optimization, whereas the KH560-treated specimens retained low conductivity despite slight density increases. Micro-structural tests revealed accelerated hydration without new hydration product formation, with both modifiers enhancing cementitious matrix hydration product generation by distinct mechanisms—with NS acting through physical pore-filling, while KH560 established Si-O-C chemical bonds at paste interfaces. Although both modifications improved mechanical properties and durability, the KH560-modified SAC composite group demonstrated superior overall performance than the NS-modified group, providing a technical pathway for developing sustainable, high-performance recycled wood fiber cement-based materials with balanced functional properties for low-carbon construction applications. Full article

Wood is an important raw material for industrial applications. Its fiber-specific genetic modification provides an effective strategy to alter wood characteristics in tree breeding. Here, we performed a cross-analysis of previously reported single-cell RNA sequencing and the AspWood database during wood formation to identify potential xylem fiber-dominant expressing genes in poplar. As a result, 32 candidate genes were obtained, and subsequently, we further examined the expression of these genes in fibers and/or vessels of stem secondary xylem using the laser capture microdissection technique and RT-qPCR. Analysis identified nine candidate genes, including PtrFLA12-2, PtrIRX12, PtrFLA12-6, PtrMYB52, PtrMYB103, PtrMAP70, PtrLRR-1, PtrKIFC2-3, and PtrNAC12. Next, we cloned the promoter regions of the nine candidate genes and created promoter::GUS transgenic poplars. Histochemical GUS staining was used to investigate the tissue expression activities of these gene promoters in transgenic poplars. In one month, transgenic plantlets grown in medium showed intensive GUS staining signals that were visible in the leaves and apical buds, suggesting substantial expression activities of these gene promoters in plantlets predominantly undergoing primary growth. In contrast, for three-month-old transgenic poplars in the greenhouse with predominantly developed secondary stem tissues, the promoters of seven of nine candidate genes, including PtrMYB103, PtrIRX12, and PtrMAP70, showed secondary xylem fiber-dominant GUS signals with considerable spatial specificity. Overall, this study presents xylem fiber-dominant promoters that are well-suited for specifically expressing genes of interest in wood fibers for forest tree breeding. Full article