Owing to its abundant supply from renewable resources, lignin has emerged as a promising functional filler for the development of sustainable composite materials. However, achieving good interfacial compatibility between lignin and synthetic polymers, particularly poly (lactic acid) (PLA), remains a fundamental challenge. To advance the development of high-performance bio-based composites incorporating lignin and PLA, our study has scrutinized to unravel the nuances of interfacial binding interactions with the lignin and PLA composite system. Molecular level and experimental examinations were employed to decipher fundamental mechanisms governing and demonstrating the interfacial adhesion. We synthesized casted films of lignin/PLA and acetylated lignin/PLA at varying weight percentages of lignin (5%, 10%, and 20%) and comprehensively investigated their physicochemical and mechanical properties. The inclusion of acetylated lignin in the composites resulted in improved mechanical strength and Young’s modulus, while the glass transition temperature and melting point were reduced compared to neat PLA. Systematic variations in these properties revealed distinct compatibility behaviors between unmodified lignin and acetylated lignin when incorporated into PLA. Molecular dynamics (MD) simulation results elucidated that the observed changes in material properties were primarily attributed to the acetylation of lignin. Acetylated lignin exhibited lower Coulombic interaction energy and higher van der Waals forces, indicating a stronger affinity to PLA and a reduced propensity for intermolecular aggregation compared to unmodified lignin. Our findings highlight the critical role of controlling intermolecular interactions and lignin aggregation to develop PLA composites with predictable performance for new applications, such as functional packaging materials.

To manufacture and market a uniform and consistent product, the US lumber industry developed grading rules to classify their lumber. Visual grading is the most commonly applied grading system, although nondestructive evaluation (NDE) could be applied. Therefore, the objective of this research was to evaluate cross-laminated timber (CLT) panels produced from yellow-poplar ( Liriodendron tulipifera) lumber sorted by NDE and compare their bending properties in the major direction to standard published panels by the American National Standards Institutes/The Engineered Wood Association (ANSI/APA) PRG 320-2019. Ten panels were produced with dimensions of 3.75 inches thick by 18 inches wide by 120 inches long. Flatwise bending, shear block, and cyclic delamination tests were performed following ANSI/ APA PRG 320-2019. The results of the bending tests indicated that the calculated characteristic values using NDE-sorted lumber resulted in a 19 percent higher bending strength (Fb) than published values in ANSI/APA PRG 320-2019 for stress- rated lumber (E1 and E4) and 35 percent higher than visually graded yellow-poplar CLT panels reported by Azambuja et al. However, the modulus of elasticity (MOE) values (1.56 by 106 psi) were lower than those listed for E1 and E4 type panels. The adhesive evaluation showed delamination in some samples located in the outer areas of the panel, indicating that proper adhesion is possible with improvements in the panel production process used in the research. Overall, the results suggest potential opportunities to utilize yellow- poplar lumber that does not meet a visual structural grade category under Northeastern Lumber Association Manufacturers' rules by classifying and sorting the lumber according to static MOE (MOEs) values assessed using NDE.

The bioeconomy relies on cost-effective and eco-friendly products and services, which can be achieved through efficiently produced and processed bio-based feedstocks. Torrefaction, a promising technology that involves thermal treatment of biomass in the temperature range of 200-300 & DEG;C in oxygen-limited conditions, producing torrefied biomass for materials, energy, specialty products, and carbon sequestration. This biomass outperforms raw biomass or biochar in various applications, such as combustion, gasification, and co-firing with coal in power plants, and can serve as a platform for non-energetic bio-based products. Though torrefaction faces technical and practical challenges, its future outlook remains positive. Efficient use of torrefied biomass addresses limitations of raw biomass, such as transportation, storage, and densification. It contributes to sustainable supply chains, improved economic returns, energy self-sustenance, and reduced carbon footprints. When used for energy production, it can enhance process efficiency and cut greenhouse gas emissions. Torrefaction's adoption can boost growth in sectors like composites, soil amendment, carbon storage, and green chemicals. However, further research is needed to understand torrefied biomass's benefits, barriers, and opportunities and determine optimal production and utilization strategies.

Growing concerns about indoor air pollution heighten the need to develop depolluting materials to achieve a healthy built environment. This study developed functional coatings for wooden surfaces using 20 wt% photocatalytic biocarbon particles doped with manganese oxide (BC-MnO2) and two different coating materials (linseed oil and waterborne acrylic). The samples’ surface hydrophobicity and color properties were tested before and after accelerated aging. The depolluting potential of the samples was evaluated by formaldehyde removal efficiency test in indoor conditions. Results showed that adding BC-MnO2 particles increased the hydrophobicity regardless of the coating material’s type. After accelerated aging, the hydrophobicity of all samples increased, which was attributed to the curing of the oil and acrylic polymers and the increase in surface roughness eventually caused by surface damage. The color change (ΔE) was more intense in the case of uncoated wood and samples without BC-MnO2. However, the BC-MnO2-containing coatings were effective in color preservation (ΔE < 2), which was attributed to the anti-UV property of biocarbon. The BC-MnO2-containing coatings exhibited a promising formaldehyde removal efficiency of up to 24% and 46% for oil and acrylic samples, respectively. The combination of BC-MnO2 and acrylic material was more favourable to attracting the formaldehyde molecules, likely due to the similar polarity. The developed functional coatings exhibited an acceptable ability for wood protection and formaldehyde remediation and can be potentially used to enhance indoor air quality.

Formaldehyde is a common indoor air pollutant with hazardous effects on human health. This study investigated the efficiency of biocarbon (BC) functionalized with variable contents of MnO2 for formaldehyde removal in ambient conditions via integrated adsorption-photocatalytic degradation technology. The sample with the highest formaldehyde removal potential was used to prepare a functional coating made of acrylic binder mixed with 20 wt% of the particles and applied on beech (Fagus sylvatica L) substrate. SEM images showed that MnO2 was deposited around and inside the pores of the BC. EDX spectra indicated the presence of Mn peaks and increased content of oxygen in the doped BC compared to pure BC, which indicated the successful formation of MnO2. Raman spectra revealed that the disorder in the BC's structure increased with increasing MnO2 loadings. FTIR spectra of BC-MnO2 samples displayed additional peaks compared to the BC spectrum, which were attributed to MnO vibrations. Moreover, the deposition of increased MnO2 loadings decreased the porosity of the BC due to pores blockage. The BC sample containing 8 % Mn exhibited the highest formaldehyde removal efficiency in 8 h, which was 91 %. A synergetic effect between BC and MnO2 was observed. The formaldehyde removal efficiency and capacity of the coating reached 43 % and 6.1 mg/m2, respectively, suggesting that the developed coating can be potentially used to improve air quality in the built environment.

Fungal enzymes are effective in degrading various polymeric materials. In this study, we assessed the initial degradation of composites consisting of lignin-poly(lactic acid) (PLA) with both unmodified lignin (LIG) and oxypropylated lignin (oLIG) incorporated at 10 % and 40 % weight within the PLA matrix in a fungal environment. Trametes versicolor fungi were used, and the samples were treated only for eight weeks. Although there was no significant difference in weight loss, the degradation process impacted the chemical and thermal properties of the composites, as shown by Fourier transform infrared spectroscopy (FTIR) and Differential scanning calorimetry (DSC) analyses. After the degradation process, the carbonyl index values decreased for all composites and the hydroxyl index values increased for LIG/PLA and a reverse trend was observed for oLIG/PLA composites. The first heating scan from DSC results showed that the melting peak and the cold crystallization peak disappeared after the degradation process. Microscopic analysis revealed that LIG/PLA exhibited higher roughness than oLIG/PLA. Molecular docking simulations were carried out using guaiacylglycerol-β-guaiacyl ether (GGE) and lactic acid (LA) as model compounds for lignin and PLA, respectively, with laccase (Lac) enzyme for Trametes versicolor. The docking results showed that GGE had the strongest binding interaction and affinity with Lac than lactic acid and oxypropylated GGE. The oxypropylated GGE formed a shorter hydrogen bonding with the Lac enzyme than GGE and LA. The trend associated with the degradation of composites from experimental and molecular docking findings was consistent. This combined approach provided insights into the degradation process using fungi and had the potential to be applied to different polymeric composites.

The torrefaction process is widely used in the energy field, but the characteristics of the torrefied wood also have positive effects on the production of wood plastic composites. In this study, short-rotation shrub willow was torrefied at 225 and 300 °C and incorporated into polypropylene composites filled with changing levels of weight percent (wt%) of non-torrefied and torrefied (5, 15, 25, and 40 wt%) wood. Nine different formulations were extruded for mechanical, thermal, and water absorption properties. The tensile properties of composites were not affected by any level of torrefaction, while higher flexure properties were in favor of lower wt% of torrefied wood. The slowest rate of thermal degradation was confirmed for the highest wt% of torrefied wood with a torrefaction temperature of 300 °C. In contrast, the presence of torrefied wood in composites did not show a difference in crystallization or melting temperatures. The most noticeable contribution of torrefaction temperature and wt% was found for water-absorbing properties, where the higher torrefaction temperature and largest wt% of torrefied wood in the composite resulted in decreased water uptake.

Low-grade yellow-poplar (Liriodendron tulipifera) graded No. 2 Common, and No. 3 Common (National Hardwood Lumber Association -NHLA rules) is mainly used by the industry to produce wood pallets. Cross-laminated timber (CLT) panels are options to diversify the usage and increase the value of this material. Therefore, the objective of this study was to produce CLT panels from a population of NHLA graded No. 2A, No. 2B, No. 3A, and No. 3B lumber and to evaluate whether the panel properties meet the bending criteria (major strength direction) and adhesive bond requirements listed for "V"type CLT in ANSI/APA PRG 320-2019 (2020) using Northeastern Lumber Association Manufacturers No. 2 and No. 3 in longitudinal and transverse layers, respectively. Ten panels were produced to evaluate the bond quality and mechanical properties. The bond test results showed average delamination under 5 percent and were more frequent in the central areas of the panel than in the outer panel areas. The results from testing showed that the calculated allowable stress-design bending-strength (major direction) value for the yellow-poplar CLT panels was 1,718 psi (11.84 MPa), which corresponds to a value 90 percent higher than V1 (900 psi, 6.20 MPa) layups. Modulus of elasticity (MOE; major direction) was comparable to V2 and V3, with an average MOE of 1.39 by 106 psi (9,584 MPa). Based on these findings, the study indicated the potential for using low-grade yellow-poplar lumber to produce CLT panels. However, more research is needed to evaluate other mechanical properties in both the major and minor axis.

Almost 200 nations, including the European Union, have signed the Paris Agreement that aims to limit the temperature rise to 1.5 °C above pre-industrial levels by reducing greenhouse gas (GHG) emissions. To meet this target, a significant decrease in GHG emissions by 2030 and net zero by 2050 is necessary. To determine the role of wood products in achieving a 55% reduction in GHG emissions by 2030 compared with 1990 levels, we investigated Slovenia’s potential, which has close to 60% forested areas. Therefore, the country could use wood-based products to achieve the agreed-upon climate goals. Nevertheless, uncertainties remain regarding the extent to which increased tree harvesting, local manufacturing, and the utilization of wood products can aid in substituting fossil-derived materials and reducing GHG emissions. A new model was constructed to increase the understanding of the wood products’ (throughout the forest-based industrial ecosystem, incl. construction) potential contribution to reaching the stated emissions targets. Using this linear programming (LP) mathematical optimisation model and carbon footprint calculations based on life cycle assessment methods, a wood flow distribution, the financial investment needed to process these quantities, and the GHG emissions produced and/or saved were calculated. The findings stipulated that Slovenia has the potential to achieve 55 % less GHG emissions by 2030 by expanding logging to at least 3 million m3 and converting the timber to a larger amount of long service-life wooden items made (and utilised) within the country. Such products accumulate carbon for a long time and decrease the need for materials that cause higher GHG emissions. Concomitantly, a better appreciation of the substitution effects in official carbon accounting would be needed. Moreover, to materialize the potential decrease in emissions would require Slovenia’s construction sector to replace fossil- and mineral-based materials with lignocellulosic products, and to increase the capacity to utilize lower-quality wood in high added value applications, which would require significant investment. This paper offers a comprehensive analysis of diverse optimisation outcomes obtained from the investigation into climate action through the use of wood products in Slovenia.

To control and predict lignin properties remains very challenging due to the complexity of chemical structures and recovery methods of lignin. Recently, an acidcatalyzed one-pot liquefaction technique was developed to produce Kraft lignin with improved molecular uniformity directly from black liquor. Herein, we investigated the effects of the liquefaction parameters (pH, reaction temperature, and reaction time) on the yield, molecular weights, polydispersity, and quantities of different types of hydroxyl groups of the Kraft lignin using the Box-Behnken response surface methodology (RSM). Computational models were generated and refined to establish the relationships between the liquefaction parameters and the Kraft lignin properties. The results showed that pH was the most influential factor followed by the reaction temperature affecting the properties of the Kraft lignin. The yield, molecular weight, and polydispersity were found to be more predictable (R-(pred)(2) values of 87.5-91.5%) than the type and quantity of hydroxyl groups (R-(pred)(2) values of 0) of the Kraft lignin. Additionally, the weight average molecular weight (Mw) could be used as a reliable predictor for both the number average molecular weight (M-n) and the polydispersity of the Kraft lignin, which was confirmed by both the experimental and the computational approaches. Such tunable and predictable molecular properties of the lignin may be associated with the combination of acetic acid, subcritical methanol, and one-pot method. This study provided insights into understanding, predicting, and even customizing the properties of the lignin products.

The dataset includes information about biocarbon particles doped with different concentrations of MnO2 photocatalyst (BC-MnO2) Six different samples: MnO2, biocarbon, BC-MnO2-1, BC-MnO2-2, BC-MnO2-3, BC-MnO2-4 Characterization of the samples: * SEM images collected using scanning electron microscope (Carl Zeiss SUPRA 35 VP) * XRD data collected using Bruker D2 Phaser diffractometer * Porosity data collected using physisorption analyzer (Autosorb iQ-XR-AG-AG). The dataset contains data about isotherms and pores size distributions from tests under nitrogen gas (meso and macro porosity) and CO2 gas (microporosity). Formaldehyde removal potential of the samples: The raw data were generated from an electrochemical formaldehyde sensor (Stox-HCHO) at ambient conditions (temperature of 23 °C, relative humidity between 40% and 46%, and conventional visible light). The sensor was placed in a test chamber equipped with the sensor and 8 µl of formaldehyde (HCHO) solution was injected. Then the test chamber was hermetically closed and changes in formaldehyde levels were measured. The same sensor provided information about temperature and relative humidity in the test chamber. Data was aquired using TVOC-HCHO logger software. The formaldehyde removal efficiency (%) of the samples after 8h of experiment was determined from the raw data.

Biocarbon (BC) represents a potential material for application in air remediation. This study investigated the efficiency of BC particles in the removal of formaldehyde. BC samples were prepared from Arundo donax (AD) and olive stone (OS) feedstocks at variable pyrolysis temperatures (from 300°C to 800°C). The BC particles were characterized using proximate, Fourier transform infrared, water contact angle, particle size, and physisorption analyses. The formaldehyde removal capacity was tested using an electrochemical formaldehyde sensor in a batch experiment. The physicochemical and structural properties depended on the pyrolysis temperature at which the BC was produced. The increase in pyrolysis temperature increased the BC’s pH, hydrophobicity, and porosity. All the samples achieved a formaldehyde removal capacity ranging between 26% and 64% for BC pyrolyzed at 300°C and 800°C, respectively. In BC pyrolyzed at temperatures under 500°C, the formaldehyde capture was governed by a partitioning mechanism through diffusion in the noncarbonized organic fraction. In comparison, formaldehyde capture was controlled by a physical adsorption mechanism through pore filling for BC pyrolyzed at 500°C or above. BC pyrolyzed at 800°C was more efficient for formaldehyde adsorption due to the well-developed microporous structure for both AD and OS. AD-derived BC prepared at 800 °C (AD-BC800) was selected for the re-usability test, using thermal regeneration to remove the adsorbed components. The regenerated sample maintained a comparable formaldehyde removal capacity up to four re-use cycles. Moreover, the comparison between non-activated and activated AD-BC800 revealed that physical activation significantly enhanced BC’s adsorptive ability.

In this study, we investigated the impact on surface topography and micro-mechanical properties of polyvinyl alcohol (PVA) thin films when loaded with hardwood-derived biocarbon particles (BCP). The PVA/BCP composites were prepared with the conventional film casting method, after varying BCP concentrations of 6, 8, 10, 12, and 20 wt% were added to the PVA solution. Atomic force microscopy (AFM) investigations and nanoindentation tests were performed. The average roughness of the thin films increased with the increase in BCP content. The alternation between dark and light patterns observed in the AFM images showed an irregular surface topography with alternating high peaks and deep valleys. The skewness and kurtosis parameters showed that the different dispersion degrees of the BCP within the PVA matrix influenced the composites' surface roughness. The micro-mechanical properties of the thin film composites depended on the BCP type and concentration. Films reinforced with red oak-derived BCP had higher hardness and Young's modulus compared to films reinforced with willow SV1 and yellow-poplar BCP, which was attributed to the high carbon content and low ash content of red oak BCP. We argue that these results may be extrapolated to other types of BCP-reinforced thin films and can significantly contribute to enabling more efficient methods and protocols for reinforcing polymers with hardwood biocarbon.

With wood regaining substantial interest as a construction material due to sustainability concerns and aesthetics trends, efficient and safe protection methods are needed to prevent the discouloration and the loss of mechanical properties of this renewable and UV-sensitive material. In this study, sustainable coatings comprising 0 to 20 wt% biocarbon (BC) dispersed in tung oil were developed for wood protection. BC particles were added as ultraviolet (UV) absorbers and were produced by various carbonization routes. The BC powders were characterized in terms of particle size and surface functional groups by Fourier-Transform infrared, and the UV and visible absorbance of dispersed BC powders in water solutions were related to these characteristics. Two wooden substrates (beech and oak) were coated with the developed coatings and the samples underwent six months of onsite weathering. While the total colour change of uncoated samples and tung oil-coated substrates without BC kept increasing over time and resulted in a clear alteration of the wood surface aesthetics, an increased BC content in the coatings led to enhanced colour stability, with alteration of the colour close to 2 for both wood species after six months of weathering for 10 and 20 wt% BC. Coating with tung oil made the wooden substrates, initially hydrophilic, become hydrophobic, and the further introduction of biocarbon increased hydrophobicity. However, the increase in BC content was not correlated with an increase in water repellence, the highest water contact angle being observed for 5 % BC, and no further improvement in hydrophobicity was observed with higher BC content. The weathering negatively affected the water repellence of all the samples (i.e., reference samples and coated samples with various BC content). However, the introduction of 20 % BC best protected the decrease in water repellence induced by the onsite weathering.

This study aims to characterize and valorize hemp residual biomass by a slow pyrolysis process. The volatile by-products of hemp carbonization were characterized by several methods (TGA, UV-VIS, TLC, Flash Prep-LC, UHPLC, QTOF-MS) to understand the pyrolysis reaction mechanisms and to identify the chemical products produced during the process. The obtained carbon yield was 29%, generating a gaseous stream composed of phenols and furans which was collected in four temperature ranges (F1 at 20–150 °C, F2 at 150–250 °C, F3 at 250–400 °C and F4 at 400–1000 °C). The obtained liquid fractions were separated into subfractions by flash chromatography. The total phenolic content (TPC) varied depending on the fraction but did not correlate with an increase in temperature or with a decrease in pH value. Compounds present in fractions F1, F3 and F4, being mainly phenolic molecules such as guaiacyl or syringyl derivatives issued from the lignin degradation, exhibit antioxidant capacity. The temperature of the pyrolysis process was positively correlated with detectable phenolic content, which can be explained by the decomposition order of the hemp chemical constituents. A detailed understanding of the chemical composition of pyrolysis products of hemp residuals allows for an assessment of their potential valorization routes and the future economic potential of underutilized biomass.

The presented research aimed at finding new ways to value hemp by-products (stalks) from the cannabidiol industry through thermochemical conversion. Chemical and elemental composition of hemp biomass was investigated by successive chemical extractions and Scanning Electron Microscopy along with Energy-dispersive X-ray Spectroscopy. Proximate and elemental analyses completed the chemical characterization of the hemp biomass and its biochar. Thermogravimetric analysis of the hemp biomass allowed to understand its kinetic of decomposition during thermal conversion. The carbon structure and porosity of the biochar were assessed by Raman spectroscopy and CO 2 gas adsorption. Properties of interest were the energy production measured through calorific values, and the electrical conductivity. Two ways of valorisation of the hemp biomass were clearly identified, depending mainly on the chosen pyrolysis temperature. Hemp biochar carbonized at 400–600°C were classified as lignocellulosic materials with a good potential for solid biofuel applications. Specifically, the resulting carbonized biochar presented low moisture content (below 2.50%) favourable for high fuel quality, low volatile matter (27.1–10.4%) likely to show lower particle matter emissions, limited ash content (6.8–9.8%) resulting in low risk of fouling issues during the combustion, high carbon content (73.8–86.8%) suggesting strong energy density, associated with high higher heating values (28.45–30.95 MJ kg −1 ). Hemp biochar carbonized at 800–1000 °C displayed interesting electrical conductivity, opening opportunities for its use in electrical purposes. The electrical conductivity was related to the evolution of the biochar microstructure (development of graphite-like structure and changes in microporosity) in regard with the thermochemical conversion process parameters. Graphical abstract

Arborists maintain trees in landscapes where failure can cause damage to infrastructure. Codominant branch unions are considered less stable than lateral branch unions. Previous research has found that unions can be considered codominant when aspect ratio is greater than 0.70 when included bark is present, yet it remains unclear if this threshold is reasonable in the absences of included bark. We utilized digital image correlation to measure strain (deformation) and separation angle to failure to better understand how mechanical loads move through Acer rubrum L. (red maple) branch unions. Strain was found to be higher in the branch regions in limb failure and ball and socket failure modes and strain was greater in the branch protection zone regions of imbedded and flat failures. Strain at failure was found to decrease with increasing aspect ratio, plateauing beyond aspect ratios of 0.83. In the absence of included bark, red maple branch unions appear to become codominant at aspect ratio of 0.83. We recommend that arborists should proactively manage to keep aspect ratios lower than 0.60 and consider mitigation options as aspect ratios approach 0.70.

More than one hundred ninety nations, including the European Union, have signed the Paris Agreement to limit the temperature increase to 1.5 °C above pre-industrial levels. Meeting these conditions requires a steep decline in greenhouse gas (GHG) emissions by the year 2030 and zero GHG emissions by 2050. In this study, we investigated the role that wood products can play within Slovenia to reach the 2030 goal of a 55 % reduction in GHG, as compared to 1990 levels. Slovenia, with over 58 % forest cover, is well-positioned to utilize wood products to meet these climate goals. However, questions exist on how increased tree harvesting and local production, and the use of wood products contribute to replacing fossil-based materials and to lower lowering GHG emissions. To better understand the importance of wood products to GHG emission reduction, this study aimed to present a model showing how the forest-based value chain (including construction) could help reach the Paris Agreement goals. We investigated the associated environmental impacts and their related economic costs. The results indicated that Slovenia could reach the 55 % GHG emission reduction goal within 2030 through increasing tree harvesting and using these resources to increase the number of durable wood products produced within Slovenia that store carbon for long periods and substitute for other high GHG emitting materials. However, realizing these potential reductions would rely on the building industry within Slovenia to replace fossil- and mineral-based materials with wood products.

Utilization of low-grade yellow-poplar ( Liriodendron tulipifera ) lumber would provide for alternative structural lumber sources and promote the growth of cross-laminated timber (CLT) manufacturing facilities within the Appalachian Region. A significant amount of low-grade yellow-poplar lumber (i.e., National Hardwood Lumber Association [NHLA] No. 2A and Below Grade) is utilized for wood pallets. In practice, this material is not graded for structural purposes. Additionally, research on yellow-poplar for structural use has focused on grading lumber from a small population of selected logs, not by regrading NHLA lumber from manufacturing facilities. Therefore, the research's objective was to investigate the structural grades of a typical population of NHLA graded No. 2 and lower lumber and evaluate their potential to meet structural grades necessary for CLT panels. NHLA graded lumber was regraded and assigned to visual structural grades following Northeastern Lumber Manufacturers Association rules and evaluated for flatwise bending modulus of elasticity (MOE b ) by nondestructive proof loading. The results of the study indicated that 54.6 percent of the boards possessed a minimal structural visual grade required for CLT panels according to American National Standards Institutes/The Engineered Wood Association (ANSI/APA) PRG 320-2019 (2020). Splits were the most common limiting defect that downgraded boards to nonstructural grades. Also, 96.6 percent of the boards evaluated had a MOE b above the required minimal board value of 1.2 ×10 6 psi (8,274 MPa) listed in ANSI/APA PRG 320-2019 (2020). The results of the study indicated that a majority of NHLA low-grade yellow-poplar, when regraded for structural purposes, meets or exceeds minimum lumber grade values necessary for use in CLT panel production.