Fast-growing Poplar Wood Research Articles

Rapid production of high-performance unilaterally surface-densified wood through integrating mechanical compression and thermochemical modification

Enhancing the mechanical performance and dimensional stability of fast-growing wood in an efficient and eco-friendly manner remains a challenge. This study introduces a straightforward and highly efficient technique for fabricating unilaterally surface-densified (USD) wood from fast-growing poplar wood. This process involves a pre-drying treatment, high-temperature compression at 250 ℃, and subsequent cooling, all completed within a total compression time of 300s. The produced USD wood exhibits outstanding physical and mechanical properties, along with excellent dimensional stability. Notably, the USD wood achieved a hardness of 4.3 kN, a modulus of rupture of 117.0MPa, and a modulus of elasticity of 12.2GPa, representing increases of 104.7%, 72.0%, and 38.6%, respectively, compared to untreated wood, aligning with the properties of several premium hardwoods. Furthermore, the USD wood showed superior impact resistance and bending stiffness, alongside minimal irreversible thickness swelling (2.29%) under humid and high-temperature conditions, evidencing its robust mechanical and dimensional stability. These improved performances are attributed to the formation of a densified layer with an intact cell wall structure, which benefits from the favorable effects of high temperature-induced plasticization of cell walls and thermal degradation of hemicellulose. The efficacy of this high-temperature compression technique highlights its significant potential for the mass production of high-performance wood from fast-growing species. Consequently, the resulting USD wood is ideally suited for value-added applications in the furniture and construction industries, offering a pathway towards sustainable and eco-friendly manufacturing solutions.

Surface layer reinforcement modification for wood with high strength and flame retardancy performances

The high-value utilization of low-value wood can effectively address the shortage of wood resource, while also contributing to the global green sustainable development and the implementation of “dual carbon” strategy. The present study employed an innovative technology to achieve controllable surface reinforcement modification of fast-growing poplar wood, resulting in improved strength and exceptional flame retardancy for structural applications. The achievement was realized through a three-step method, involving delignification, impregnation, and surface densification, while minimizing the loss of wood volume. The results demonstrated that surface functional densification can significantly improve the mechanical properties of fast-growing poplar wood, with the modulus of rupture (MOR) and modulus of elasticity (MOE) reaching 140.6 MPa and 11.8 GPa, respectively, representing a 3.4-fold and 2.5-fold increase compared to the control group (CK). The samples were found to possess thin surface-densified layers, while the core layer remained unaltered, thereby exhibiting a sandwich structure with significant disparity in density between the layers, reaching up to a factor of 2. The pores structure of the surface layers underwent significant densification, with a gradual deformation distributed throughout its thickness direction. A process optimized for surface densification involving a 2-hour delignification duration and a pressure of 3 MPa. The sample subjected to surface functional modification exhibited a 90-second delay in the peak of heat release compared with the CK. The heat release rate (HRR) experienced a significant deceleration, accompanied by notable reductions in total heat release (THR) and smoke production rate (SPR). The mechanisms underlying the enhancement of surface functionality were elucidated from the perspectives of physical mechanics, microstructure, and flame retardancy, providing a theoretical foundation for the efficient utilization of fast-growing wood.

Integrated approach for improving mechanical and high-temperature properties of fast-growing poplar wood using lignin-controlled treatment combined with densification

Previous studies on the modification of fast-growing wood have extensively examined the effects of density and lignin content on the strength and high-temperature properties of modified wood. However, a comprehensive quantitative analysis of their effects on high-temperature performance remains insufficient. To address this knowledge gap, we applied alkali treatment and compression densification to fast-growing poplar, resulting in modified specimens with varying densities and lignin levels. The quantitative effects of density and lignin content on high-temperature properties were meticulously evaluated. Chemical changes were analyzed using Fourier transform infrared spectroscopy (FT-IR), while the mechanical and high-temperature properties were comprehensively assessed. Delignification was found to be positively correlated with treatment duration, with hemicellulose degradation also detected via FT-IR analysis. Significant enhancements were recorded in flexural strength, tensile strength, and modulus of elasticity, accompanied by improvements in ductility ratio and compressive strength. The modified poplar wood exhibited increased thermal stability at elevated temperatures. Furthermore, density and lignin content were identified as significant factors affecting high-temperature performance, establishing minimum density thresholds for various lignin contents in modified poplar wood to ensure optimal performance. This study enhances to the understanding of the intricate relationships among wood properties, modification techniques, and high-temperature performance.

An eco-friendly strategy of cell wall stapling: In situ crosslinking of acrylic acid emulsion impregnated in thermally treated poplar wood

Traditional wood modification methods often result in the release of harmful substances and energy wastage. This study proposes an efficient and environmentally friendly modification strategy for fast-growing poplar wood. The approach involves polymerizing organic linear molecules within the cell wall to form stitches, thereby enhancing the dimensional stability and mechanical properties of wood and increasing its ability to withstand various environments. Poplar wood specimens were treated via a method that combines heat treatment with acrylic emulsion impregnation. The research findings indicated an improvement in the mechanical properties of poplar wood following the combined treatment. Moreover, poplar wood subjected to this treatment approach exhibited a 35.24 % lower water absorption rate after a 7-day water immersion test, and tangential and radial swelling rates of the wood were reduced by 29.66 % and 45.68 %, respectively. Scanning electron microscopy revealed excellent penetration of acrylic emulsion into wood cells; the emulsion infiltrated the wood and adhered to the cell walls, forming a crosslinked network structure. Analysis of the modification mechanism through X-ray diffraction, Fourier-transform infrared spectroscopy, and X-ray photoelectron spectroscopy showed that the successful infusion of acrylic emulsion compensated for the lower mechanical properties of thermally treated wood, thus improving the utilization value of poplar. The acrylic emulsion is an environmentally friendly and harmless modifier, making the modified wood suitable for various applications, including indoor furniture, logistics, and outdoor facilities. This modification strategy enables efficient resource utilization and provides valuable insights for the sustainable development of the timber industry.

Strength Grading of Full-Scale Chinese Fast-Growing Poplar Wood for Structural Building Applications

Strength Grading of Full-Scale Chinese Fast-Growing Poplar Wood for Structural Building Applications

SiO2 decorated wood nanocomposite with enhanced mechanical performance, flame and water resistance

Development of lightweight and strong structural material using fast-growing poplar wood is promising for green and sustainable engineering. Herein, the overall performances of fast-growing natural poplar wood (NPW) are significantly enhanced via delignification, in situ growth of SiO2 followed by densification. The SiO2/compressed-delignified-wood (SiO2/CDW) nanocomposite obtained exhibits outstanding mechanical properties including a bending strength of 395.6 ​MPa, a tensile strength of 253.4 ​MPa, and a toughness of 7.1 ​MJ/m3, which is improved by 1548 ​%, 240 ​% and 590 ​%, respectively compared with NPW. In addition, the ignition time and burning time of SiO2/CDW nanocomposite are prolonged by 700 ​% and 112 ​% compared to those of NPW. Moreover, the specific wear rate of SiO2/CDW is 18 ​× ​10−6 mm3/Nm, which is 72.6 ​% lower than that of NPW. Moreover, the spring-back ratios of SiO2/CDW in 95 ​% and in water are 45.2 ​% and 66.7 ​%, which are lower than those of CDW (64.6 ​% and 92.4 ​%). The SiO2/CDW nanocomposite with enhanced mechanical, flame/water retardant and wear performances are promising to meet the needs of modern engineering as green and sustainable materials.

Study on the physico-mechanical properties and mechanisms of poplar wood co-modified by anoxic high-temperature heat treatment and impregnation with silica sol/phenolic resin

Addressing the challenges of fast-growing poplar wood in construction, decoration, and furniture, including low density, insufficient strength, poor toughness, and suboptimal dimensional stability, this study introduces an innovative organic/inorganic impregnation-heat treatment technique. This method significantly enhances the physico-mechanical properties of poplar wood and overcomes issues associated with thermosetting resin modification, such as reduced impact toughness, uneven resin penetration, and wood swelling. Utilizing in situ polymerization with silica sol and phenolic resin, specifically with particle sizes between 8 and 15 nm, the process markedly improves wood permeability and overall properties through vacuum pressure impregnation and heat treatment. The findings indicate a 54.42 % increase in the wood's density. Optimized heat treatment at 180 °C for 1 h significantly enhances dimensional stability and reduces water absorption, with the ASE value reaching up to 69.3 %. Furthermore, the impregnation-heat treated wood exhibits a 50.19 % increase in bending strength to 81.6 MPa, a 103.93 % increase in modulus of elasticity to 16.5 GPa, and a 29.42 % increase in impact toughness to 92.5 kJ/m2, demonstrating substantial improvements over the raw material. FT-IR analysis reveals the presence of Si-O-Si vibration peaks, indicating the effective penetration of silica sol. TGA analysis displays the treated material's superior thermal stability compared to the raw material. XRD analysis confirms that the impregnation and heat treatment processes have not adversely affected the wood's crystalline regions but have instead reduced hygroscopicity and enhanced stability. SEM analysis showed that the composite impregnation liquid effectively penetrated and distributed within the wood cells. These results open new theoretical and technical pathways for enhancing the physico-mechanical properties of fast-growing poplar wood.

Fabrication of PVA-Silica Sol Wood Composites via Delignification and Freezing Pretreatment.

The efficient exploitation of planted fast-growing wood is crucial for enhancing wood resource utilization. In this study, the fast-growing poplar wood was modified by in situ impregnation through vacuum impregnation with polyvinyl alcohol and nano-silica sol as impregnation modifiers, combined with delignification-freezing pretreatment. The samples were characterized by FTIR, XRD, SEM, and the universal mechanical testing machine. The results showed that the wrinkle deformation and cracking of the wood blocks were greatly alleviated after the delignification-freezing pretreatment and the polyvinyl alcohol and nano-silica sol were successfully integrated into the wood. The resulting polyvinyl alcohol-silica sol poplar composites exhibited about 216%, 80% and 43% higher compressive strength with respect to delignified wood, natural wood and impregnated natural wood, respectively, thereby demonstrating superior mechanical properties and potential opportunities for value-added and efficient utilization of low-quality wood.

Improving fast-growing poplar wood with furfuryl alcohol and a hyperbranched polymer

Improving fast-growing poplar wood with furfuryl alcohol and a hyperbranched polymer

Effect of steam explosion pretreatment on chosen saccharides yield and cellulose structure from fast-growing poplar (Populus deltoides × maximowiczii) wood

The aim of this study was to determine the changes occurring in the wood cellulose of the fast-growing poplar (Populus deltoides × maximowiczii) under the influence of steam explosion (SE) pretreatment. Cellulose from native wood and after pretreatment at 160 and 205 °C was isolated. Cellulose polymerization degree by size exclusion chromatography (SEC) and cellulose crystallinity index by Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR) were determined. The profiles of sugars in the native wood and in the solid fraction after pretreatment (using the acid hydrolysis method) were also determined. In addition, the profile of monosaccharides in the liquid fraction obtained after steam explosion and in the liquid fraction after acid hydrolysis of the oligosaccharides were investigated using high-performance liquid chromatography (HPLC). This allowed to determine the change in the yield of hexoses and pentoses in the studied material.The behavior of cellulose in wood subjected to steam explosion at 160 and 205 °C and isolated by the Kürschner–Hoffer method was studied by determining the absorption bands of FTIR-ATR spectra. The lateral order index (LOI) of cellulose was calculated from the ratio of the intensity of the corresponding absorption bands A1422/A896 cm−1. Total crystallinity index (TCI) of cellulose was calculated from the ratio of the intensity of absorption bands A1372/A2900 cm−1. TCI of Kürschner-Hoffer cellulose isolated from wood subjected to steam explosion at 160 and 205 °C decreased by 5.6 and 5.0%, respectively, with regard to the applied temperature. LOI increased in cellulose isolated from wood subjected to steam explosion at 160 °C (by 0.7%) and at 205 °C (by 19.2%) in relation to the index of cellulose isolated from native wood. Kürschner–Hoffer cellulose isolated from wood subjected to steam explosion at 160 and 205 °C exhibited, respectively, a reduced degree of polymerization of about 11% and about 8%. Polydispersity index in Kürschner–Hoffer cellulose was 1% lower after both pretreatments than native sample.

Abatement of environmental pollution by research on electrical resistivity and conductivity mechanism of poplar dust

Under conventional processing conditions, the resistivity of wood dust is in the range of insulating materials, which can induce a dust cloud explosion when there are static sparks. This paper took the fast-growing poplar wood commonly used in Chinese wood processing and studied the effects of moisture content, temperature, and particle size on the electrical resistivity value of sanded wood dust. Orthogonal analysis was conducted on the influencing factors. The results showed that the influence of moisture content on electrical resistivity was the most significant factor, followed by temperature and particle size. Further experiments have shown that when the moisture content increased from 6% to 32%, the resistivity decreased from 109 Ω cm to 105 Ω cm, which reached the suitable resistivity range of static discharge method. The ion concentration of wood dust extracted in cold water and hot water and the resistivity of poplar dust residue after extraction were determined. Nine metal ions (a total of 105.02 mol/g) were detected in cold-water extract, and the concentrations of K+, Na+, Mg2+ and Ca2+ accounted for 99.8%. The original poplar dust and the extracted poplar dust were measured and analyzed. The changes in water-soluble ion content, functional groups, crystallinity, and complexes of the wood dust before and after ion dissolution, jointly led to changes in the electrical resistivity of the wood dust (a difference of 2–4 orders of magnitude). It was verified that the way wood dust conducts electricity is through ion conduction. There were more abundant capillary system structures between poplar dust particles, allowing water-soluble ions to move more freely with water channels. The larger specific surface area and higher temperature also promoted the dissolution of water-soluble ions, which affected the electrical resistivity.

Study on Modification of Poplar Wood via Composite Impregnation with Silica Sol/Melamine-Glyoxal Resin.

In order to overcome the defects of fast-growing poplar wood, such as low strength and poor toughness, this paper introduces a method of modifying poplar wood via impregnation with silica sol/melamine-glyoxal (silica sol/MG) resin and explores its effects on the physical, mechanical, and thermal properties of poplar wood. It was found via scanning electron microscopy that the composite modifier covered and filled the cell lumen, cell interstitial space, and cell wall pores of poplar wood. Further, infrared spectroscopy and X-ray photoelectron spectroscopy analyses confirmed that chemical cross-linking occurred between the silica sol/MG resin composite modifier and the internal groups of poplar wood and that the Si-O-Si flexible long chains introduced in the composite modifier formed a cross-linking network with poplar wood such as Si-O-Si and Si-O-C, which led to the improvement of the physical and mechanical properties and the enhancement of the thermal stability of poplar wood. The method provides a theoretical basis for the high-value utilization of fast-growing poplar wood.

Preparation Optimization of Enhanced Poplar Wood by Organic-Inorganic Hybrid Treatment via Response Surface Methodology.

In this work, a strategy for hybrid treatment was proposed, aiming to present a hybrid impregnation agent including lignin-derived resin (LR) and surface-modified montmorillonite (GMMT) to treat fast-growing poplar wood. The treating agents could penetrate the wood, fill the cavities of the wood interior, and strengthen the cell wall structure. The optimal WPG of 36.2% was obtained upon the response surface methodology (RSM) at the conditions of 34% LR, 1.8% GMMT, 1.2 MPa impregnation pressure, and 99 min impregnation time. The density, water uptake (WU), modulus of rupture (MOR), modulus of elasticity (MOE), and compressive strength (CS) of the samples were tested to evaluate the enhancement of the physical and mechanical properties. In addition, these samples were investigated via cone calorimeter (CONE), Fourier Transform Infrared spectrometer (FTIR), and X-ray diffraction (XRD). The results showed that the density of the treated samples increased significantly up to 0.72 g/cm3. Compared with 134.8% of the control, the WU of the treated wood sample could decrease to 60.3%. In addition, the MOR and MOE of the resulting samples reached up to 131.8 MPa and 18.14 GPa, respectively, which were 62.3% and 77.7% higher than the control. Notably, the CS was 84.7 MPa with an increase of up to 94.7%. Moreover, the peak heat release rate (HRR) of the treated sample was obviously reduced to 231.33 kW/m2, a decrease of 17.5% compared to the control (271.71 kW/m2).

Nano-Silica/Urea-Formaldehyde Resin-Modified Fast-Growing Lumber Performance Study

To promote the performance of fast-growing poplar wood for furniture applications, this study proposes and investigates the feasibility of modifying fast-growing poplar wood with a urea-formaldehyde resin impregnating agent by adding nano-SiO2 as a way to improve its physical and mechanical properties. By observing the solubility of nano-SiO2 addition in urea-formaldehyde resin, determine the optimal ratio of nano-SiO2 addition to the solid content of the urea-formaldehyde resin solution. After the fast-growing poplar specimens were treated with nano-SiO2/UF resin, the water absorption, wet swelling, dry shrinkage, nail grip, flexural strength, and modulus of flexural elasticity of the fast-growing poplar specimens were compared and analyzed to determine the effect of impregnation modification and the optimal impregnation ratio. The results showed that the physical and mechanical properties of fast-growing poplar wood were significantly improved by impregnating the fast-growing poplar wood with urea-formaldehyde resin with SiO2, and the impregnation modification was beneficial to reducing the wet swelling and dry shrinkage of poplar wood, increasing its dimensional stability, improve the grip nail strength, and increase the flexural strength and flexural modulus of elasticity with the increase in nano-SiO2 concentration.

Experimental analysis of thermally-treated Chinese poplar wood with focus on structural application

The primary issues restricting fast-growing wood utilization in buildings are its low dimensional stability and lack of strength grading. Thermal treatment has been shown to improve wood dimensional stability while decreasing certain mechanical parameters. This study was aimed to optimize the thermal treatment for fast-growing poplar wood to determine its impact on the wood strength class from the perspective of structural applications. Seven temperature levels between 20 and 210 °C and 2 h heating duration were used to thermally treat fast-growing poplar wood, which was then subsequently investigated for chemical composition and color change, as well as mechanical properties, such as parallel-to-grain bending, tensile, compressive (fc,0), shear strength (fv), modulus of elasticity (M0), and perpendicular-to-grain tensile strength. In addition, characteristic values were derived to provide an initial indication of design values. Thermal treatment resulted in hemicelluloses degradation, which darkened the color and reduced strength according to chemical composition and infrared spectroscopic analyses. In general, mechanical properties decreased with temperature, except for fc,0 and M0, which increased with temperature (≤180 °C) and followed by a decrease at ≥ 190 °C. The strength class of heat-treated wood depended on the smaller values of M0 and fv. M0 determined the strength class of native and heated wood to be ≤ 180 °C and fv at ≥ 190 °C. Thermal treatment in the region of 170–180 °C was a practical approach to improving wood properties in view of their structural use. Results of this study provided a basis for developing a design guide for structural uses of thermally-treated poplar wood.

Compression performance and failure mechanism of honeycomb structures fabricated with reinforced wood

In this paper, a fast-growing poplar wood was selected as the structural raw material to construct a green, eco-friendly, and high-quality building structure. The pretreatment and hot-pressing process were designed to reinforce the poplar wood, and the reinforced poplar square honeycomb structure was further manufactured by the inlay-locking process. Quasi-static axial compression tests were conducted on the reinforced poplar and natural wood honeycomb structures. The results reveal the compression damage mode of the square honeycomb structure to be the shear damage of the honeycomb ribs due to the flexion of the core. The reduced height and increased relative density of the honeycomb structure were able to enhance the strength and elastic modulus. The specific energy absorption of the square honeycomb structures was found to be similar or better than that of other lattice structures. The results reveal that an excellent specific strength and energy absorption can be achieved through poplar reinforced designation, showing great potential for biomass material applications in construction.

Modification of poplar wood cells using 1,3-dihydroxymethyl-4,5-dihydroxyethylideneurea/alkaline lignin for enhanced mechanical properties and decay resistance

Fast-growing poplar wood was modified by using 1,3-dihydroxymethyl-4,5-dihydroxyethylideneurea (DM) and alkaline lignin (AL) to improve its mechanical properties and decay resistance. AL was first used in combination with DM for wood impregnation modification. The weight percent gain, dimensional stability, mechanical properties, decay resistance and microcosmic changes of all wood samples were evaluated systematically. The results indicated that the maximum weight percent gain and anti-swelling efficiency of poplar wood after modification with DM-AL reached 46.2 % and 52 %, respectively. Compared with the unmodified samples, the bending strength, modulus of elasticity and hardness of the wood samples modified with DM-AL increased by 40 % – 60 %. Notably, the impact strength of samples modified with DM-AL was 18–26 % higher than that of samples modified with DM only, which may be due to the fact that the AL macromolecules slowed down the infiltration of DM-AL into the wood cell walls. The decay resistance of optimal modified samples against the decay fungus was improved by ∼80 % compared with unmodified sample. Furthermore, scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) confirmed that DM-AL modifiers impregnated into wood cell lumens. Fourier transform infrared spectroscopy (FTIR) demonstrated that the DM resin crosslinked with wood cell walls and AL macromolecules. In general, this study provides a facile, low-cost and green method to improve the comprehensive performance of fast-growing poplar, including mechanical properties and decay resistance.

Acrylic Resin Filling Cell Lumen Enabled Laminated Poplar Veneer Lumber as Structural Building Material

Wood is a viable alternative to traditional steel, cement, and concrete as a structural material for building applications, utilizing renewable resources and addressing the challenges of high energy consumption and environmental pollution in the construction industry. However, the vast supply of fast-growing poplar wood has bottlenecks in terms of low strength and dimensional stability, making it difficult to use as a structural material. An environmentally friendly acrylic resin system was designed and cured in this study to fill the poplar cell cavities, resulting in a new type of poplar laminated veneer lumber with improved mechanical strength and dimensional stability. The optimized acrylic resin system had a solid content of 25% and a curing agent content of 10% of the resin solid content. The cured filled poplar veneer gained 81.36% of its weight and had a density of 0.69 g/cm3. The static flexural strength and modulus of elasticity of the further prepared laminated veneer lumber were 123.12 MPa and 12,944.76 MPa, respectively, exceeding the highest flexural strength required for wood structural timber for construction (modulus of elasticity 12,500 MPa and static flexural strength 35 MPa). Its tensile strength, impact toughness, hardness, attrition value, water absorption, water absorption thickness expansion, and water absorption width expansion were 58.81%, 19.50%, 419.18%, 76.83%, 44.38%, 13.90%, and 37.60% higher than untreated laminated veneer lumber, demonstrating improved mechanical strength and dimensional stability, significantly. This method provides a novel approach to encouraging the use of low-value-added poplar wood in high-value-added structural building material applications.

Experimental investigation into lateral performance of cross-laminated timber shear walls made from fast-growing poplar wood

ABSTRACT Structural tests for seven full-scale cross-laminated timber (CLT) shear walls were conducted under cyclic lateral loading to investigate the feasibility of using fast-growing poplar in CLT structures. Connection tests with monotonic loads were performed to calculate the later bearing capacity of CLT shear walls. The effects of wood species, artificial accelerated aging, vertical step joint, and laminate strength class on the later performance of CLT were determined. Test results show that poplar CLT panels had potential application in CLT structures, with only an 8% difference in structural properties compared to spruce CLT. Accelerated aging reduced the mechanical properties of poplar CLT and converted its failure mode from plasticity to brittleness. The elastic stiffness of a poplar CLT shear wall with a vertical step joint decreased, but the energy dissipation capacity increased 3.3-fold. The lamina strength class was not positively related with the lateral bearing capacity of these walls.

Fire Resistance Improvement of Fast-Growing Poplar Wood Based on Combined Modification Using Resin Impregnation and Compression.

Fast-growing poplar with low wood density has been generally regarded as a low-grade wood species and cannot be used as a building material due to its poor fire resistance. As the fire resistance of wood materials is positively correlated with density, combined treatment using resin impregnation, which imparts thermal resistance, and compression, which improves density, appeared to be a route toward improved combustion performance. Fast-growing poplar wood was modified with a combination of borate-containing phenol–formaldehyde resin impregnation and compression in a transverse direction at varying intensities. The effects of the combined treatment on fire resistance were then examined and discussed. Char residue morphology analysis and microscopic observations were conducted to reveal the effects and mechanism of the combined treatment on fire resistance improvement. The test results showed that fire resistance was greatly improved, including the static and dynamic bending performance at elevated and high temperatures, as well as the combustion performance. The higher the compression ratio was, the better the fire resistance of the modified wood.