Solid Wood Research Articles

Effect of wood chips and wood board-ends of Gmelina arborea on yields and process of slow pyrolysis using a semi-industrial reactor prototype

Pyrolysis of biomass residues can generate savings in the value chains of forest products due to the potential uses of its products in the forestry sector. The aim of this study was to determine the performance during slow pyrolysis process and the yields of different products of two types of residues, wood chips and solid wood board-ends from Gmelina arborea. Results showed no significant differences in yields of charcoal (26 to 28%), wood vinegar (28 to 30%) and non-condensable gases (37%), but bio-oil yield was higher for the solid wood board-ends residues (7.7%). The evaluation of energy charcoal characteristics and wood vinegar was similar for two types of residues. So, results suggest that two types of residues provided similar charcoal, condensable and non-condensable gases yields, but solid board-ends are recommended to obtain higher yield of bio-oil and complete the process in less time. Charcoal and vinegar characteristic were affected by type of residues.

Research of physical and chemical characteristics of alternative fuel containing synthetic polymers

RELEVANCE. This paper presents the research of physical and chemical characteristics of combined fuel briquettes consisting of solid wood waste and laminated paper production waste obtained by innovative technology. THE GOAL of the research is to develop a technology for processing and utilization of pulp and paper industry waste containing synthetic polymers by their joint use in the form of combined fuel briquettes of the 2nd generation, consisting of solid wood waste and laminated paper production waste, with subsequent utilization in a boiler plant with a low-temperature vortex furnace. Minimizing harm to the environmental component and maximizing energy and economic efficiency. METHODS. To realize the set goal, the following research methods were used in the work: study of thermoplasticity of synthetic polymers and moisture plasticity of polymeric components of wood in the process of briquette formation, determination empirically of the optimal composition of the combined briquette to obtain high calorific value of fuel, low concentration of harmful emissions, high strength and density of the finished product, determination of the lower heat of combustion of the obtained briquette with the help of calorimetric installation. RESULTS. The paper presents the results of the conducted research and experiments, in particular, the obtained values of density, strength and calorific value of the obtained briquette at different compositions of feedstock. CONCLUSION. The fuel briquettes obtained in the course of work have high indicators of density, strength and calorific value of fuel. In addition, the innovative technology of processing wood waste and waste packaging laminated paper will minimize the harm to the environmental component and increase the maximum energy and economic efficiency. The use of the obtained fuel and the technology of its production will make it possible to reduce the load on landfills with currently unutilized waste and use the obtained fuel energy for own needs.

Determining the quantity and quality of wood recovered from building demolitions to enable effective allocation

The goal of this study was to determine the quantity and quality of wood extracted from the structural parts of wooden buildings to facilitate the most appropriate allocation of the material. An additional aim was to provide a reliable and consistent characterisation procedure for recovered wood, according to its physical characteristics, such as dimensions, the presence of cracks etc. From a sample of recovered wood collected from the demolition of a wooden building in Espoo, Finland, it was found that around 30% of the total volume of material could be recovered for repurposing or remanufacturing into solid wood products, provided structural integrity can be ensured. The samples of recovered wood were relatively short compared to virgin timbers, averaging 88 cm. Further, it was determined that removing metal contaminants does not necessarily improve material recovery, because cracks, wane, warping, as well as machining the recovered wood to standard dimensions, impact material recovery the most.

Evaluating the Potential of Birch Bark Suberinic Acids for Solid Wood Impregnation

Evaluating the Potential of Birch Bark Suberinic Acids for Solid Wood Impregnation

Bending Performance of Plantation Teakwood and Its Mechanism Based on Radial and Tangential Directions

Curvilinear components made from solid wood bending not only enhance the use value of wood but also add a unique aesthetic to solid wood products, in line with the concept of green and sustainable development. In this study, we focused on the influence of the direction of the wood growth rings on the bending performance of teakwood and its bending mechanism, and radial and tangential bending experiments were conducted on teakwood using the synergistic softening method of a triethanolamine compounding solution and steaming. The results showed that the radial bending coefficient of the teakwood after softening treatment was 1/9.26, 41.39% higher than that for chordwise bending, 1/15.8. Through a macroscopic analysis, the stress distribution of the teakwood during radial bending was found to be uniform, while during tangential bending, the stress was mainly borne by many longitudinal growth rings, which are prone to the bending “destabilization” phenomenon. From SEM and AFM observations, it was found that the earlywood zone and latewood zone on the outermost tensile surface of the tangential bending are longitudinal; the stress redistribution problem still exists in the bending process; and ray parenchyma are the most vulnerable part, gradually extending to the earlywood zone and causing more serious bending tearing. It can be seen that the bending performance of teakwood is not only affected by the softening process but also obviously constrained by the direction of the growth rings, which is of great significance for the optimization of hardwood bending processing technology and product design.

Metallic wood-based phase change material with superior anisotropic thermal conductivity and energy storage capacity

In this study, metallic wood-based phase change material (MWM) with high performance anisotropic thermal conductivity and energy storage capacity was developed by impregnating wood with myristic acid, and subsequent introducing low melting point alloy (LMA) into the wood through a facile alternating high and low temperature heat treatment. The heat-driven LMA was rapidly squeezed into the cell lumens of the wood so as to effectively inhibit the leakage of the internal myristic acid during melting. Benefited with the well-aligned and hierarchical porous structure, the filled LMA formed a continuous heat transfer network along the highly oriented transport tissue of wood, which could greatly reduce the interfacial thermal resistance and promote heat transfer. Compared with untreated wood, the thermal conductivity of MWM in longitudinal and radial directions were improved by more than 67 % and 75 %, respectively. In addition, it exhibited superior energy storage capability, with the latent heat of 90.23 J/g and 86.42 J/g during melting and solidification. The thermal stability and anti-leakage performance were satisfied. The phase change temperatures, enthalpies and chemical structure of MWM remained unchanged after 100 thermal cycles, demonstrating outstanding cycling reliability. With excellent energy storage performance and favourable thermal conductivity, the prepared MWM shows a promising application in energy saving buildings and solid wood floors.

Study on the flexural load bearing performance of nail-laminated I-beams

ABSTRACT Using nail fastening technology to produce engineered wood by optimizing the combination of solid wood laminates is an effective means to optimize material utilization and reduce manufacturing complexity. This study explored the reliability of nail fastening technology in wood I-beam and analyzed that the connection method between the flanges and webs impacts the bending performance of the I-beam. The results showed that the connection method between the flanges and webs had important influence on the bending performance of the I-beam. The I-beams connected with nails and adhesive had better performance compared to those connected only with nails. Nail and adhesive combination laminated I-beams had a 159.85% and 495.84% increase in ultimate load and initial stiffness, respectively, compared to nail-laminated I-beams. The type of nail was an important factor to the bending performance of nail-laminated I-beams. Compared to round steel nails, self-tapping screws with stronger holding power were more suitable for the construction of I-beams. Installing stiffening ribs at the supports and loading points on both sides of the web enhanced the lateral stability and load-bearing capacity of the I-beams. The ultimate load and initial stiffness of I-beams with stiffening ribs increased by 28.26% and 5.74%, respectively, than the ones without stiffening ribs. The model established based on composite material mechanics theory could accurately predict the ultimate load capacity of self-tapping screw and adhesive combination laminated I-beams.

Sodium hypochlorite–based binderless technology for solid wood adhesion: application of a commercial bleaching agent for adhesion and observation of surface characteristics

In this study, several methods for a novel binderless technology were explored, the effects of treatment conditions on the adhesive performance were examined and the surface was characterized during adhesion. The method entailed a three-step process for bonding solid wood, which involved immersion in sodium hypochlorite–containing treatment solutions, surface scratching, and drying with pressing. Various treatment conditions were investigated, including solution types, immersion durations, scratch treatment materials, and pressing methods. The resulting shear strength was 9.7 MPa, which is well above the Japanese Agricultural Standards value for laminated wood (6 MPa). In this method, the specimens were immersed in a bleach solution containing a surfactant for 16 h, followed by pressurization at 1 MPa for 24 h at 60 ℃ using a pressure-controlled press. Around the bonding area in the specimens, the cells in the immersed area were significantly compressed, and the aldehyde groups of the coniferyl aldehyde in the lignin were denatured or lost. Based on these findings, a new binderless technology was developed for solid wood without a high-temperature, high-pressure pressing step.

Crack growth stabilization in the eccentric three-point end-notched flexure test of solid wood using side-grooved samples

A three-point eccentric end-notched flexure (3EENF) test was conducted on Sitka spruce to characterize the Mode II resistance curve (R-curve). To extend the range for stabilized crack growth, grooves were cut along both side surfaces of the sample to reduce the region around the neutral axis. The R-curve was determined by varying the initial crack lengths, and fracture toughness values were measured at both the onset and during growth. Additionally, the effect of side grooves on stabilizing crack growth in the 3EENF test was investigated by comparing numerical simulation results with those from four-point end-notched flexure (4ENF) tests. The grooves effectively stabilized crack growth, and the stabilization range was equivalent to that of the 4ENF test when the initial crack length was appropriately determined. The grooved sample exhibited behavior indicative of a longer crack than the actual length.

Research on the veneer defect image enhancement algorithm based on AMEF-AGC+

Aiming at the veneer defect image acquisition process is prone to the problems of blurred edges, inconspicuous contrast and distortion, which cannot show the defects clearly.To improve image analyzability and clarity, a veneer defect image enhancement method based on AMEF-AGC is proposed herein. First, a veneer defect image is subjected to Gamma correction to obtain multiple underexposed image sequences for which Gaussian and Laplacian pyramids are constructed to determine the weights of the multiple exposure sequence group images.Multiscale fusion is then performed based on these weights. Second, the fused image is converted into the HSV color space, where contrast and brightness enhancements are performed for the luminance component, and then converted back to the RGB color space to obtain an enhanced veneer defect image. Solid wood panels selected herein were pine, poplar and birch with defects including live knots, dead knots, and cracks.Compared with those obtained using several algorithms including AMEF, AGC, improved AGC and GC, this algorithm achieved 6.93% and 5.4% improvements in PSNR and SSIM metrics, respectively.Results demonstrated that the proposed method effectively enhanced veneer defect images with blurred and distorted edges, improved image clarity and visual quality, and made defect parts and details of the image clearer

Lacquered Wooden Painted Double-headed Tomb Beast The Aesthetics of Chu Antiquities

Tomb stabilizing beasts, commonly used as burial objects in ancient Chu tombs in China, are an important component of Chu burial customs. Tomb keeping beasts are generally divided into three parts: body, base, and antlers. The overall appearance of the Tomb Beast is fierce and solemn, with a terrifying and terrifying face. The antlers of the deer on its head are intertwined, with complex and orderly patterns. The solid wood on its base has sparked the thinking of many scholars for the mysterious and beautiful portrayal of this woodcarving double headed Tomb Beast.

Clustering of tropical species through multivariate analysis of the bonding properties of edge-glued panels (EGP)

Tropical woods have high added value, and the use of waste for panel production is an initiative to add more value to this material, typically consisting of various species. The use of raw materials from tropical solid wood waste in the Amazon region contributes to the reduction of carbon emissions associated with the burning of this material. In this context, this study aimed to cluster species based on the bonding properties of Amazonian woods by applying multivariate analysis. The apparent density 12% and strength of finger joint and edge-glued joints of Cedrela odorata, Enterolobium schomburgkii, Erisma uncinatum and Qualea paraensis was evaluated which were joined in homogeneous and hybrid configurations with the adhesives PVA and EPI, as spreading rate of 180 g/m2. The treatments were compared by multivariate analysis of variance and discriminant analysis. The discrimination of species and combinations based on wood density (low, medium, and high) revealed that this is the most important characteristic for grouping different species that make up tropical hardwood waste for the production of EGP panels. In practice, the separation of species into groups according to wood densities can contribute to a better definition of the indications for use of edge glued panels of each density class, and assertive targeting for applications according to the strength ranges required. In the static bending, parallel tensile and shear tests all species and their combinations met the minimum requirements normative, indicating the approval of species and combinations studied for the production of EGP panels.

Texas trade in forest products industry

Texas boasts abundant forest resources, providing substantial economic and ecological benefits statewide. This study examines the trends in forest product trade within Texas over the past two decades, focusing on key disruptions during this period. The analysis categorizes the forest products industry into two main markets: solid wood and paper and pulp, further dividing the industry into five core sectors. The findings indicate that Texas operates as a net importer of solid wood and wood furniture products while serving as a net exporter of wood pulp and, paper and paperboard products. Both import and export values have generally shown a gradual increase over time. Notably, Mexico emerged as Texas’s primary trade partner for both imports and exports in 2023. Additionally, Texas ranks as the second-largest exporter of paper and paperboard products nationally while also being the second-largest importer of solid wood products and wood furniture products. The study highlights the profound impact of the COVID-19 pandemic response on Texas’s trade dynamics, emphasizing the crucial need for ongoing monitoring of trade policies and international relationships. These factors have the potential to exert significant influence on Texas’s trade landscape in the foreseeable future.

Development of automatic CNC machine with versatile applications in art, design, and engineering

The area of computer numerical control (CNC) machines has grown fast, and their use has risen significantly in recent years. This article presents the design and development of a CNC writing machine that uses an Arduino, a motor driver, a stepper motor, and a servo motor. The machine is meant to create 2D designs and write in numerous input languages using 3-axis simultaneous interpolated operations. The suggested machine is low-cost, simple to build, and can be operated with merely G codes. The performance of the CNC writing machine was assessed by testing it on a range of solid surfaces, including paper, cardboard, and wood. The results reveal that the machine can generate high-quality text and images with great accuracy and consistency. The proposed machine's ability to write in several input languages makes it appropriate for various applications, including art, design, and engineering.

Bilateral Defect Cutting Strategy for Sawn Timber Based on Artificial Intelligence Defect Detection Model.

Solid wood is renowned as a superior material for construction and furniture applications. However, characteristics such as dead knots, live knots, piths, and cracks are easily formed during timber's growth and processing stages. These features and defects significantly undermine the mechanical characteristics of sawn timber, rendering it unsuitable for specific applications. This study introduces BDCS-YOLO (Bilateral Defect Cutting Strategy based on You Only Look Once), an artificial intelligence bilateral sawing strategy to advance the automation of timber processing. Grounded on a dual-sided image acquisition platform, BDCS-YOLO achieves a commendable mean average feature detection precision of 0.94 when evaluated on a meticulously curated dataset comprising 450 images. Furthermore, a dual-side processing optimization module is deployed to enhance the accuracy of defect detection bounding boxes and establish refined processing coordinates. This innovative approach yields a notable 12.3% increase in the volume yield of sawn timber compared to present production, signifying a substantial leap toward efficiently utilizing solid wood resources in the lumber processing industry.

Enhancing the bending strength, load-carrying capacity and material efficiency of aspen and black alder plywood through thermo-mechanical densification of face veneers

Many research papers highlight the positive impact of wood densification on mechanical properties of solid wood as well as wood veneers. Previous experimental studies comparing densified to non-densified wood materials of the same thickness consistently demonstrated higher strength properties in bending for densified materials. However, these studies often overlooked an important comparison: the strength and load-carrying capacity of non-densified wood material to its densified state, in which the thickness is reduced and thus the material’s moment of inertia. The current study, aims to address this gap for plywood made from low-quality, underutilized hardwood species, encompassing both non-densified and densified veneers. Additionally, these plywood panels are compared with high-quality birch plywood. Plywood samples made from common aspen (Populus tremula L.) and black alder (Alnus glutinosa L.) species, incorporating densified veneers, are compared to conventional silver birch (Betula pendula Roth.) plywood. The study also considers material utilization efficiency. Results showed that plywood made from non-densified aspen and black alder veneers exhibited comparable strength to standard birch plywood, positioning them as competitive alternatives to high-quality wood species. While densified black alder veneers increased strength in average from 83.6 MPa to 126.3 MPa, a loss in load-carrying capacity was observed from 1930 N to 1637 N due to reduced thickness and moment of inertia.

Study on Innovative Laminated Flooring with Resin-Impregnated Paper

A new type of laminated flooring decorated by resin impregnated paper (LWFWRIP) was designed, with the advantages of low formaldehyde emission, improved flame retardant, and high wear resistance. The structure of this new type of wood flooring is based on the ordinary laminated flooring, followed by a decorative layer of thin wood pieces, and then the transparent improved flame retardant, wear-resistant paper is added to the top. It is found that the hot-pressing temperature is the most significant factor affecting the adhesion of resin impregnated paper. The optimal hot-pressing parameters are selected as the hot-pressing pressure of 3.5 MPa, hot-pressing temperature of 180 °C, and hot-pressing time of 40 s. The new laminated flooring was improved with high flame retardant, high wear-resistant, combined with the conventional advantages of both solid wood composite flooring and reinforced wood flooring. The new laminated flooring decorated by resin impregnated paper has broad application prospects.

Mechanical Properties of Full-Scale Wooden Beams Strengthened with Carbon-Fibre-Reinforced Polymer Sheets

The strengthening, rehabilitation and repair of wooden beams and beams made of wood-based materials are still important scientific and technical issues. This is reflected, among other things, in the number of scientific articles appearing and the involvement of research centres around the world. This is also related to society’s growing belief in the importance of ecological and sustainable development. This article presents an overview of the latest work in this field and the results of our own research on strengthening solid wooden beams with carbon-fibre-reinforced polymer (CFRP) sheets. The tests were carried out on full-size solid beams with nominal dimensions of 70 × 170 × 3300 mm. A 0.333 mm thick CFRP sheet was used for reinforcement. The research analysed various reinforcement configurations and different reinforcement ratios. For the most effective solution, a 46% increase in load capacity, 35% stiffness and 249% ductility were achieved with a reinforcement ratio of 1.7%. Generally, the higher the reinforcement ratio and coverage of the surface of the wood, the higher the strengthening effectiveness. The brittle fracture of wood in the tensile zone for unreinforced beams and the ductile crushing of wood in the compressive zone for reinforced beams were obtained. The most important achievement of this work is the description of the static work of beams in previously unanalysed configurations of strengthening and the confirmation of their effectiveness. The described solutions should extend the life of existing wooden buildings and structures and increase the competitiveness of wooden-based structures. The results indicate that, from the point of view of optimizing the cost of reinforcement, it is crucial to develop cheaper ways of combining wood and composite than to verify different types of fibres.

Approach to Validate ISPM-15 Compliance for Commercial Treatment Certification of Dielectric Standard Heating of Bulk Solid Wood Packing Materials using Radio Frequency

Abstract To substantially reduce the risk of alien invasive species moving to new geographic areas, phytosanitary treatment of wood packaging materials (WPM) in compliance with the International Standard of Phytosanitary Measures No. 15 (ISPM-15) is required by trading partners. Approved treatments include conventional heating, methyl bromide and sulfuryl fluoride fumigation, and dielectric heating (DH). The DH standard was officially adopted in 2013 but has not been practiced commercially due primarily to insufficient operational validation at commercial scale. In 2022, we converted our 50-kW radio frequency (RF) unit with a 1,200-board foot capacity from an oscillator electromagnetic field power generator to a solid-state power supply, which allows for selective power input adjustments during treatment; we also switched from a five-plate to a three-plate winged electrode system to improve heating uniformity. Each loading cycle can treat sufficient material to build ∼94 standard Grocery Manufacturers Association pallets. Our research team characterized the dielectric heating pattern and options for monitoring wood temperatures over a wide-ranging test matrix of WPM that varied by wood species, dimension, moisture content, and loading configuration. We found that this upgraded RF system markedly reduced treatment times and improved heating uniformity, allowing us to develop methods that can be used to verify compliance with ISPM-15 for improved technology transfer to industry. We also discuss the operational cost of RF treatment and make general cost comparisons to conventional heat treatment for WPM.

Chemical Bonds Formed in Solid Wood by Reaction with Maleic Anhydride and Sodium Hypophosphite

The reaction of wood with maleic anhydride (MA) and sodium hypophosphite (SHP) has been identified as a viable modification method, with macroscopical properties indicating formation of cross-linking to explain the results. However, the chemical reaction between wood and the modification reagents has not been studied yet. To resolve this, the reaction was studied with solid-state 13C cross-polarization magic-angle-spinning (CP-MAS) and 31P MAS nuclear magnetic resonance (NMR) and X-ray photoelectron spectroscopy (XPS) to reveal the formation of bonds between wood components, MA and SHP during the treatments to explain the formation of cross-linking and the possible fixation of phosphorus in wood. XPS, solid state 13C and 31P MAS NMR revealed the maleation of wood in the absence of SHP, whilst its presence led to forming a succinic adduct observed through the C-P bond formation, as evidenced by the loss of the maleate C=C bonds at around 130 ppm and the upfield shift of the peak at 165–175 ppm, which was also significantly smoothed, as well as the increase in a peak at 26 ppm due to the reaction between the maleate group and SHP; however, the C-P-C bond could not be unambiguously rationalized from the obtained data. On the other hand, a resonance line at 16 ppm in 31P MAS NMR and the peaks in the XPS P 2p spectrum suggested the formation of a cross-linked structure at low concentrations of SHP, which was more likely to be phosphonate (C-P-O) than organophosphinic acid (C-P-C). The results herein provide a greater fundamental understanding of the mechanisms involved in the reaction of wood, MA and SHP, providing further scope for improved treatment systems in the future.