Low-value Wood Research Articles

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.

Production and technical performance of scrimber composite manufactured from industrial low-value wood for structural applications

Development of scrimber composites and other engineered wood products from low-value wood and wood waste provides an effective opportunity to preserve natural resources, minimize waste, and innovate the production of higher-performance, environment-friendly construction materials. In this study, peeler cores, which are the center of poplar logs remaining after the peeling process in the veneer production, were utilized to develop scrimber composites. This study investigated the effects of different resins, including phenol-formaldehyde (PF) and urea formaldehyde (UF), as well as hydrothermal treatments at various temperatures (60 °C and 130 °C), on the physical and mechanical properties of the scrimber composites. Chemical changes in wood components and morphological changes in wood cell walls resulting from hydrothermal treatment were analyzed using Fourier transform infrared spectroscopy and scanning electron microscopy. To clarify how resin type and hydrothermal treatment affect structural performance, several physical and mechanical properties of scrimber composites, including thickness swelling, water absorption, internal bond strength, bending modulus of elasticity, and modulus of rupture, were measured. The test results revealed that hydrothermally treated wood scrims at 130 °C, when bonded with PF resin, produced scrimber composites with superior structural performance.

The Effect of Hardwood Veneer Densification on Plywood Density, Surface Hardness, and Screw Withdrawal Capacity

Increasing environmental awareness and the carbon-storing capability of wood have amplified its relevance as a building material. The demand for high-quality wood species necessitates exploring alternative, underutilized wood sources due to limited forest areas and premium wood volume. Consequently, the veneer-based industry is considering lower-value hardwood species like grey alder (Alnus Incania), black alder (Alnus glutinosa), and aspen (Populus tremula) as substitutes for high-quality birch (Betula pendula). Initially less appealing due to their lower density and mechanical properties, these species show promise through densification, which enhances their density, strength, and hardness. This study aims to enhance plywood screw withdrawal capacity and surface hardness by densifying low-density wood species and using them in plywood face-veneer layers, or in all layers. The relationship between the wood density, surface hardness, and screw withdrawal capacity of plywood made of low-value species like aspen and black alder is examined. Experimental work with a pilot-scale veneer and plywood production line demonstrates improved surface hardness (65% and 93% for aspen and black alder, respectively) and screw withdrawal capacity (16% and 35% for aspen and black alder, respectively) in densified face veneer plywood. This research highlights the potential of densified low-value wood species to meet construction requirements, expanding their practical applications.

Experimental investigation on mechanical properties of Chinese fir composites as cross-laminated timber

Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) is a significant plantation species in South China. However, this plantation species is primarily utilized to produce low-value wood products. This study evaluated the feasibility of manufacturing cross-laminated timber using fast-grown small-diameter Chinese fir by investigating its bending performance and exploring the contribution of the lamination effect to the load capacity. Through bending tests and theoretical analysis, three different lay-ups with the same cross-laminated timber thickness (105 mm) but varying lamination thicknesses (35 mm, 21 mm, 15 mm) were examined. The results revealed that the 5-layer and 7-layer CLT, with the average bending strength of 37.4 MPa and 33.9 MPa, showed the significantly higher mean values than the 3-layer CLT (23.2 MPa). Moreover, the predicted ultimate loads and failure modes aligned with the experimental observations. Additionally, all mechanical criteria met the mechanical performance requirements for the 105 mm thick cross-laminated timber according to the ANSI/APA PRG 320 standard, except for bending stiffness. These findings provide valuable insights for improving the performance of Chinese fir cross-laminated timber made from small-diameter timber by optimizing lamination thickness and underscore the viability of producing cross-laminated timber using Chinese fir.

A robust, biodegradable and recyclable all-cellulose ionogel from low-value wood

For thousands of years, wood has been utilized as a natural, abundant, and sustainable material for structural construction and furniture. To enhance its value, we have developed a simple process that can directly convert low-value wood (including cracked wood, chips, shives, and other wood residues) into high-performance all-cellulose ionogels. This process involves delignification, in situ dissolution of cellulose, and self-assembly of molecular cellulose chains. The resulting ionogel exhibits excellent properties such as high ion conductivity (∼60 mS/cm), mechanical strength (∼6 MPa), and self-healing capability (∼10 min). Notably, it also demonstrates exceptional freeze tolerance, withstanding temperatures as low as −50 °C while maintaining high ion conductivity (∼6.4 mS/cm). The ionogel is a versatile substrate for flexible electronic circuits. We have developed a sensor utilizing this ionogel that is breathable, flexible, and highly responsive to temperature, humidity, and strain. Furthermore, we have used it as a gel electrolyte to create supercapacitors with exceptional performance even in low-temperature conditions. The ionic liquid can be reused, with an all-cellulose framework that breaks down naturally in moist soil within 15 days. This sustainable method of producing high-performance ionogels from low-value wood has immense potential in shaping the next generation of soft, intelligent devices.

Водопоглощение и разбухание древесины Betula pendula ROTH, модифицированной олигомерами из побочных продуктов производства полибутадиена

Currently, natural wood and products based on it are in high demand. The technology of impregnation of low-value wood species on the example of B. pendula ROTH with an oligomeric material obtained from rubber production waste has been studied. Oligomers with a styrene content of 10 and 90% were obtained. In the first case, the low molecular weight copolymer had a molecular weight of 1100-1300, and in the second - 1700-2000. Impregnation of B. pendula ROTH wood was carried out in a solution of the obtained oligomer in toluene. In order to speed up the drying process of the protective coating and increase its strength, NF-1 siccative was introduced into the impregnation composition in an amount of 4-5%. The impregnation was carried out at temperatures of 60 and 120 ˚C, followed by heat treatment at temperatures of 100 and 160 ˚C. In the work, using the theory of experimental planning, a regression model was created that made it possible to describe the effects of a number of technological indicators on increasing the water and moisture resistance of modified wood. Verification of the coefficients of the models for significance was carried out using the Student's criterion. The obtained regression models make it possible to predict the characteristics of water resistance of birch wood modified due to its impregnation with a low-molecular copolymer containing styrene at specified values of technological parameters - the styrene content in the impregnating composition, the values of the impregnation temperature and heat treatment. It is shown that in order to increase the efficiency of the impregnation and heat treatment process, it is necessary to adhere to the minimum values of the considered temperature intervals, and the styrene content in the applied oligomeric product should be ~ 90% by weight. Modifying treatment of wood with an oligomer from by-products of polybutadiene production makes it possible to improve its water resistance. The use of the proposed impregnating compounds contributes to the disposal of waste and by-products of polybutadiene production.

Scalable production of wood carbon microspheres for high-efficiency carbon dioxide capture

Utilizing abundantly available biomass materials to prepare adsorbent substances is a simple and cost-effective method for CO2 adsorption, which, however, is often hampered by low adsorption capacity. Here, we demonstrate near-spherical active carbon (C-DWP/Zn) with high CO2 adsorption ability, employing delignification combination with ZnCl2 activation of natural wood powder. Removing lignin from wood cell walls facilitates easy absorption of Zn ions by the cellulose nanofibers (CNFs), thereby promoting micro/nano pores formation. Moreover, rapid dehydration of cellulose molecular chains alters the morphology of activated carbon, resulting in a transition from a granular to a near-spherical shape. Consequently, C-DWP/Zn with high specific surface area of 1769 m2 g−1, shows a significantly higher microporous volume than that of a control sample without delignification. The CO2 adsorption capacity of C-DWP/Zn, with values of 3.51 mmol g−1 and 5.12 mmol g−1 at 1 bar, 25 °C and 0 °C, respectively, is superior to that of commercial activated carbon. Attributable to its optimal micropore structure, C-DWP/Zn exhibits high CO2/N2 selectivity. Furthermore, the high carbon dioxide adsorption efficiency of C-DWP/Zn was maintained and the substance could be reused at least 20 times. Near-spherical active carbon adsorbents prepared from low-value wood powders, all featuring high CO2 adsorption performances, reasonable CO2/N2 selectivity, good recoverability, suitable heat of adsorption, and fast adsorption kinetics, which are promising candidates for practical CO2 adsorption.

Gloss of Varnished MDF Panels Veneered with Sanded and Thermally Compressed Veneer

The objective of this study was to investigate the gloss of different types of commercially manufactured varnish systems, including water-based (WB), polyurethane (PUR) and UV-cured (UV), applied on veneered MDF panels with sanded and thermally densified alder and birch wood veneers. The varnishes were applied at various numbers of layers on veneered panels. The gloss was measured at three angles of incident light: 20°, 60° and 85°. Statistical analysis showed that the type of varnish, the number of layers, the pre-treatment process, the wood species and direction of wood fibers significantly affect gloss of the coatings of veneered MDF panels. The type of varnish had a dominant effect on gloss. The highest gloss values were measured for the UV-varnished surface, and the lowest for WB- and PUR-varnished surfaces. Gloss was enhanced with an increase in the number of layers. Birch veneer provided higher gloss values compared to alder veneer. The gloss values measured along the wood fibers were higher than those measured across the fibers. No significant differences were found between the coatings created on sanded and thermally densified veneers for the average gloss values measured along the fibers at angles 60° and 85°. This study could have practical applications for producing value-added furniture elements using low-value wood species pre-treated by thermal compression.

Low-value wood for sustainable high-performance structural materials

Low-value wood for sustainable high-performance structural materials

Principles of obtaining light permeable conglomerate materials based on wood filler

Recently, the world has seen a demand for transparent or translucent concrete, capable of performing both, structural functions and decorative - design tasks. Such concrete use opens up new opportunities for the creative searches of designers, allows inclusion of new materials in those elements of decorating the internal and external of buildings, structures, large and small architectural forms. The research results on obtaining a new translucent material in the form of wood concrete (arbolite), which makes it possible to introduce previously unused wood processing waste of low-value wood species - birch and aspen into the technological process are presented in the article. The primary results open up new possibilities for light-conducting concretes at significantly low economic costs of their production. The results allows us to conclude about the complexity and ambiguity of wood bleaching processes and the need to strictly follow optimal formulations, modes and compositions at all stages of production.

Innovative wood use can enable carbon-beneficial forest management in California

Responsible stewardship of temperate forests can address key challenges posed by climate change through sequestering carbon, producing low-carbon products, and mitigating climate risks. Forest thinning and fuel reduction can mitigate climate-related risks like catastrophic wildfire. These treatments are often cost prohibitive, though, in part because of low demand for low-value wood "residues." Where treatment occurs, this low-value wood is often burned or left to decay, releasing carbon. In this study, we demonstrate that innovative use of low-value wood, with improved potential revenues and carbon benefits, can support economical, carbon-beneficial forest management outcomes in California. With increased demand for wood residues, forest health-oriented thinning could produce up to 7.3 million (M) oven-dry tonnes of forest residues per year, an eightfold increase over current levels. Increased management and wood use could yield net climate benefits between 6.4 and 16.9 million tonnes of carbon dioxide equivalent (M tCO2e) per year when considering impacts from management, wildfire, carbon storage in products, and displacement of fossil carbon-intensive alternatives over a 40-y period. We find that products with durable carbon storage confer the greatest benefits, as well as products that reduce emissions in hard-to-decarbonize sectors like industrial heat. Concurrently, treatment could reduce wildfire hazard on 4.9 M ha (12.1 M ac), a quarter of which could experience stand-replacing effects without treatment. Our results suggest that innovative wood use can support widespread fire hazard mitigation and reduce net CO2 emissions in California.

ПЕРСПЕКТИВА ПРИМЕНЕНИЯ ДЛЯ МОДИФИКАЦИИ ДРЕВЕСНЫХ МАТЕРИАЛОВ Α-ВИНИЛНАФТАЛИНА

Natural wood is the most common natural polymer material that is affordable, non-toxic and widely used in various fields of industry and construction. However, wood also has disadvantages, to eliminate which it is modified with the use of organic and inorganic agents, oligomers and polymers that can protect it from external factors. The paper studies the possibility of using such a vinylaromatic monomer as α-vinylnaphthalene for modification and protective treatment of natural birch wood. It is shown that during processing in the conductive elements of birch wood under the influence of elevated temperatures, the polymerization of α-vinyl naphthalene proceeds by a radical mechanism. However, 100 % conversion of α-vinylnaphthalene and polyvinylnaphthalene cannot be achieved. Thus, the conductive elements of natural wood contain a composite consisting of α-vinyl naphthalene and polyvinyl naphthalene. It is shown that with an increase in the content of the proposed modifier in birch wood, water absorption and swelling of wood-polymer-monomer composite samples significantly decreases. This will increase the service life of products based on modified wood. The introduction of the proposed technology for modifying low-value wood species will contribute to the conservation of forest resources and their rational use

СРАВНЕНИЕ ЭФФЕКТИВНОСТИ ПРИРОДНЫХ И СИНТЕТИЧЕСКИХ ПРОПИТОЧНЫХ СОСТАВОВ ДЛЯ ДРЕВЕСИНЫ БЕРЕЗЫ

The article is devoted to the study of technologies for the use of used motor and vegetable oils for hydrophobizing treatment of birch wood. In this work, synthetic and semi-synthetic engine oil is used to impregnate wood; spent corn oil, sunflower oil, organosilicon liquid GKZh-11, industrial impregnating composition of ZhTK. The effectiveness of the impregnating compositions is estimated by the indicators of water absorption and swelling in two mutually perpendicular directions (radial, tangential). Spent motor and vegetable oils saturate wood quite well and give it hydrophobic properties. At the same time, impregnation of birch wood with used engine oil (OMM) allows to improve water absorption of birch wood by 52.1% compared to natural wood and by 21% compared to water absorption. Thus, the processing of birch wood with used motor and vegetable oils makes it possible to utilize production waste and improve the properties of low-value wood species with a significant increase in its resistance to external influences.

ОБОСНОВАНИЕ ТЕХНОЛОГИЧЕСКИХВОЗМОЖНОСТЕЙСПОСОБАУПРОЧНЯЮЩЕЙ ДЕКОРАТИВНОЙ ОБРАБОТКИ НИЗКОТОВАРНОЙ ДРЕВЕСИНЫ

Hardwood is traditionally used for the production of finishing materials. Its high cost due to scarcity is a key factor holding back demand for solid wood products. Replacing hardwood with low-value and low-liquid raw materials helps to reduce the cost of production. Thanks to the technologies of modifying low-value wood based on pressing and heat treatment, it is possible to improve its natural properties and expand the areas of use. The paper discusses a multistage method of strengthening decorative processing of blanks from low-value wood based on firing, brushing, pressing and heat treatment. The introduction of the method into industry is constrained by the lack of scientifically grounded recommendations for its application. The purpose of the work is to study the possibility of using this method for the manufacture of finishing materials and facing parts. Systematization of information on combined multistage methods of processing wooden blanks has made it possible to identify their significant industrial potential. The differential method of qualimetry substantiates the expediency of a combination of four technological operations: firing, brushing, pressing and heat treatment. Multi-stage processing contributes to a comprehensive increase in aesthetic, physical-mechanical and protective properties of the blanks. The optimal sequence of operations included in the method has been determined through comparative analysis. A prototype of the facing tile was made based on the method. The results of evaluating the operational properties and manufacturing technologies of this facing tile (in comparison with analogues) have confirmed the possibility of using the method of strengthening decorative processing for the manufacture of finishing materials.

Harvesting forest biomass in the US southern Rocky Mountains: cost and production rates of five ground-based forest operations

ABSTRACTThe forests of the southern Rocky Mountains of North America have experienced substantial change since European colonization. High-grade logging, forest grazing practices, and fire suppression have altered once park-like ponderosa pine-dominated ecosystems into dense forests in need of restoration treatments, but such treatments are challenged by the low-value wood products removed during treatment. This study aims to understand and evaluate restoration harvest practices in the southern Rocky Mountains in terms of equipment used, production rates, and costs under both observed and modeled site and stand conditions across the region. During the summer of 2017 we observed five ground-based harvest operations of varying size and capacity across the region and analyzed their characteristics using detailed time study data. Observed stump-to-truck harvest rates ranged from $19.11 to $43.25 United States Dollars per tonne with an average of $29.70 per tonne, and modeled costs based on standardized variables from $19.95 to $33.39 per tonne with an average of $26.19 per tonne. Observed average productivity rates for felling, skidding, processing, loading, and biomass grinding were respectively 22.9, 16.0, 20.7, 27.8 and 49.8 tonnes per scheduled machine hour (SMH). Under modeled conditions for the same functions except grinding, productivity averaged 25.4, 18.6, 23.1, and 28.2 tonnes per SMH. Results from this study will be used as a benchmark for efficiency and costs and to model region-wide biomass production.

Technology of Creating Decorative Panels Made of Thermomodified Veneer

Development of new technologies for creating artistic products in order to improve their functional, ergonomic and aesthetic properties is an important directions of improving the design of items. The article presents the technology of production of decorative composite panels obtained by gluing coloured veneer sheets made of low-value wood. Staining is proposed to proceed by thermomodification that allows you to obtain natural colours characteristic of valuable tree species, without using chemicals. Research on determination of the basic properties of the plywood produced on the basis of the heat-treated veneer are carried out. Studies have shown that high-temperature processing of veneer when manufacturing plywood provides an increase in the dimensional stability, moisture resistance and durability of the composite, without increasing its toxicity. It is established that in the process of thermomodification wood material changes its colour to darker, the texture is revealed more clearly. Thus, as a result of alternating veneer sheets with different degrees of heat treatment, it is possible to obtain a composite material with high decorative characteristics and interesting transverse texture.

Измельчение малоценной древесины при рубках ухода

Измельчение малоценной древесины при рубках ухода

Impacts of Recent Mill Closures and Potential Biofuels Development on Maine’s Forest Products Industry

The economic contributions of a sector (i.e., employment, output, value added) are a measure of how money from that sector moves about a regional economy. Using 2014 estimates of economic contributions from the forest product industry in Maine, we estimate the 2016 contribution by considering the impacts from several recent mill closures (five pulp/paper, two bioelectric). The loss of these mills, particularly paper mills, reduces the economic contributions of the forest products industry relative to the state economy and distorts markets for low-value wood. We also explore a prospective opportunity to revive low-value wood markets by modeling the economic impacts from a hypothetical colocated biorefinery, where wood chips are turned into advanced fuels and chemical coproducts. The dollar value of economic impacts from such an investment are small relative to the total industry, but they may prove significant for some rural communities.

Получение модифицированной древесины химико-механическим способом и исследование ее свойств

The best method of hardening of low-value wood is pressing her to the extent of 40-50 %. About 2 times its volume decreases and, respectively, but the output of the modified wood. As hardener can be used on-nofibrillyarnuyu cellulose (NFP) in the form of a 2 % hydrogel magnetically activated. Completely replace the pressing NFP is impossible, since hydrogel has a very small concentration of NFP and receive content over 1 % in relation to dry wood impossible. Technology for producing modified wood involves activation of a 2 % hydrogel magnetization in STEL-49 to obtain the analyte with a potential of 600-800 mV and the pH = 2.5. In a 30 % aqueous urea solution was added 20 % activated hydrogel NFP stabilizer and 15 % the size of the particle board - UREAFORMALDEHYDE oligomer aqueous solution (UFC). The resulting mixture is impregnated with crude wood aspen or birch end under pressure to ensure through impregnation. The content of the mixture in the impregnated wood of 40-60 % by weight of the wood. The impregnated wood is dried with simultaneous compression to the extent of 20-25 %. The resulting wood has a moisture content 6-8 %, the density of 800-900 kg / m3, compressive strength parallel to the grain of 100-150 MPa. Due to the presence of urea loss on fire test is reduced 5 times. Biostability modified wood increases from baseline in 2-3 raza.Posle processing wood according to the procedure described obtained modified wood having a degree of compaction of 15 % birch and 25 % aspen, i.e. Use of the method reduces the degree of compaction is twice as compared with the known method, thus also increasing the yield of the resulting material. Reducing pressing for birch from 30 to 15 % increases the yield of modified wood by 15 %, ie 1 m3 with savings of 0.15 m3, with 1000 m3 -150 m3, When the selling price of the modified birch 30 thousand rubles. 1 m3 for savings of 150x30 = 4500 rubles. Reducing the degree of compaction of the aspen from 50 to 25 % increases the yield of modified wood by 25 %, i.e. 1 m3 with savings of 0.25 m3, with 1000 m3 -250 m3. When the selling price of the modified aspen wood 25 thousand rubles. 1 m3 for savings of 250x25 = 6250 rubles.

Approaches to Energy Pellet Cost and Quality Optimization

As the global demand for biomass-derived energy pellets continues to expand, industry focus is expected to quickly migrate from project development to ways of lowering operating costs. Process optimization and the utilization of low-cost feedstocks are expected to be of special interest. This new focus will present opportunities for targeted research that can utilize low-value wood and biomass feedstocks, increase yields, and improve product quality.