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The demand for high-grammage paper, 150 g/m2 or more, is increasing for product protection and aesthetic value. Fold cracking, resulting from high mechanical pressure during folding, considerably decreases the economic feasibility of such products for papermaking companies. Fold cracking can be reduced through creasing, but defects possibly occur as fiber bonds are broken. In this study, the fold cracking of high-grammage paper that was not treated through creasing was explored. The mechanical and folding properties of six types of pulp fibers were evaluated based on their beating degree. The fines content of the fiber differed according to the beating condition. Using pulp with low fines content improved the folding properties. The mechanical properties of hardwood pulp were enhanced with increased beating degree. The mechanical properties of softwood pulp were considerably increased, and fold cracking occurred with increasing beating degree. Therefore, to improve the fold cracking, beating should be applied appropriately, following the type and mixing ratio of pulp fibers. Finally, softwood pulp mixing is proposed as a strategy to control fold cracking while maintaining the unique characteristics of high-grammage paper. [ABSTRACT FROM AUTHOR]

Cellulose fibers' complex and compact structure hinders the quantitative extraction of residual hemicelluloses from the fiber wall. In this study, hardwood kraft paper pulp was subjected to refining with a Hollander beater at different refining loads (3, 4.5, and 5.5 kg) in order to assess the impact of refining load on xylan removal by cold caustic extraction. The refined pulp showed high water retention values and specific surface area, which increased accessibility and a correspondingly high degree of xylan removal. Coupling refining and cold caustic extraction (100 g/L soda) achieved over 50% more xylan removal than the unrefined pulp (3% against 7%, respectively). Furthermore, an improvement in xylan removal (79%) was achieved by implementing a one-pot simultaneous refining and cold caustic extraction treatment at half the time required for the sequential treatment and low soda concentration (60 g/L). Finally, the benefit of beating was also observed for xylanase treatment. Overall, the combined extractions made it possible to remove 85% of xylan from a conventional hardwood paper pulp giving rise to a high purity cellulose pulp with unimodal and narrow molecular mass distribution. [ABSTRACT FROM AUTHOR]

The transient dimensional changes during hygro-expansion and hydro-expansion of freely and restrained dried, softwood and hardwood sheets and fibers is monitored, to unravel the governing micro-mechanisms occurring during gradual water saturation. The response of individual fibers is measured using a full-field global digital height correlation method, which has been extended to monitor the transient hydro-expansion of fibers from dry to fully saturated. The hygro- and hydro-expansion is larger for freely versus restrained dried and softwood versus hardwood handsheets. The transient sheet-scale hydro-expansion reveals a sudden strain and moisture content step. It is postulated that the driving mechanism is the moisture-induced softening of the so-called "dislocated regions" in the fiber's cellulose micro-fibrils, unlocking further fiber swelling. The strain step is negligible for restrained dried handsheets, which is attributed to the "dislocated cellulose regions" being locked in their stretched configuration during restrained drying, which is supported by the single fiber hydro-expansion measurements. Finally, an inter-fiber bond model is exploited and adapted to predict the sheet-scale hygro-expansion from the fiber level characteristics. The model correctly predicts the qualitative differences between freely versus restrained dried and softwood versus hardwood handsheets, yet, its simplified geometry does not allow for more quantitative predictions of the sheet-scale hydro-expansion. [ABSTRACT FROM AUTHOR]

Copyright of China Forest Products Industry is the property of China Forest Products Industry Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Earlier work on the hygro-expansion of paper states that the larger hygro-expansivity of freely compared to restrained dried handsheets is due to structural differences between the fibers inside the handsheet. To study this hypothesis, first, the hygro-expansion of freely and restrained dried, hardwood and softwood handsheets has been characterized. Subsequently, the transient full-field hygro-expansion (longitudinal, transverse, and shear strain) of fibers extracted from these handsheets was measured using global digital height correlation, from which the micro-fibril angle was deduced. The hygro-expansivity of each individual fiber was tested before and after a wetting period, during which the fiber's moisture content is maximized, to analyze if a restrained dried fiber can "transform" into a freely dried fiber. It was found that the longitudinal hygro-expansion of the freely dried fibers is significantly larger than the restrained dried fibers, consistent with the sheet-scale differences. The difference in micro-fibril angle between the freely and restrained dried fibers is a possible explanation for this difference, but merely for the hardwood fibers, which are able to "transform" to freely dried fibers after being soaked in water. In contrast, this "transformation" does not happen in softwood fibers, even after full immersion in water for a day. Various mechanisms have been studied to explain the observations on freely and restrained dried hardwood and softwood, fiber and handsheets including analysis of the fibers' lumen and cross-sectional shape. The presented results and discussion deepens the understanding of the differences between freely and restrained dried handsheets. [ABSTRACT FROM AUTHOR]

With the increasing importance of wood as a sustainable material and addressing challenges facing the wood products industry, there is an emerging need for innovation and collaboration across all industry sectors. The mapping of the wood products industry has become crucial for gaining an overview and overall understanding of material flow. It also proved beneficial for educational and research purposes. The outcome of this study should help seek new economic opportunities and promote sustainable resource management. A Generic Map was developed to navigate the entire wood products industry as well as Dive-in Chain Maps will guide the four major production chains: sawmill (I), veneer mill (II), reconstituted wood manufacturing (III), and pulp and paper mills (IV). In addition, a By-products Management Wheel Diagram was introduced to clarify waste management practices within these chains. Our approach sheds light on efficient material flow and utilization, revealing opportunities for innovation and the development of high-value products. It also offers strategies for minimizing waste and making informed end-of-life decisions. Ultimately, this study enhances the understanding and potential for circularity and sustainability in the wood products industry. [ABSTRACT FROM AUTHOR]

Copyright of China Pulp & Paper is the property of China Pulp & Paper Magazines Publisher and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

With rising concern for environmental protection, the use of ozone has been increasingly studied in the pulp and paper industry. Feasible models for efficient quality prediction and process control are in high industrial demand. In this study, the reaction kinetics of delignification and viscosity during the ozone bleaching process (OBP) of low-consistency hardwood pulp (LCHP) are explored using exponential and zero-order response models, respectively. The effects of ozone dose, reaction temperature, reaction time, and pH on the changes in residual lignin content and pulp viscosity were analyzed. The corresponding kinetic parameters, such as the reaction order, rate constant (k), and activation energy (E), were also obtained. The models suggest that temperature should be one of the most significant factors affecting the effectiveness of the OBP system. The strategy to improve the OBP selectivity is based on reducing the reaction temperature while increasing the ozone concentration and pH in the reaction system. [ABSTRACT FROM AUTHOR]

Studies on the durability of European beech (Fagus sylvatica), alder (Alnus glutinosa), paper birch (Betula papyrifera), and Norway maple wood (Acer pseudoplatanus) after hydrothermal treatment in saturated water were carried out. Treatment of hardwoods was performed at two temperatures of 105 and 135°C for 6 hours. Fungal resistance was tested in the laboratory conditions with brown rot fungi Serpula lacrymans, Gloeophyllum trabeum and white-rot fungus Trametes versicolor. Half-specimens from each species were leached in accordance with STN EN 84 prior to the test. The results of decay resistance tests showed strong susceptibility of hydrothermally treated hardwood species to brown and white rot caused by basidiomycete fungi. In all cases, the mass loss was greater than 20%, and the moisture content significantly exceeded the fibre saturation point, above the level required for a fungal attack. Leaching had an insignificant effect on fungal resistance. All hardwoods were classified as non-durable species. [ABSTRACT FROM AUTHOR]

Wood has always been an indispensable material in human society throughout history. Its efficient utilization is even more crucial today in achieving the Sustainable Development Goals (SDGs). However, its production, trade, use, and recycling are seldom systematically assessed, with Germany being an exception due to the extensive work conducted by the University of Hamburg and the Thünen Institute over the years. To provide a more precise account of wood use, this study employs oven-dry metric tonne as the reference unit to construct a static wood flow based on the material flow analysis and wood resource balance in Germany in 2020. The Sankey diagrams comprehensively visualize the flow and stock of wood in various sectors, including forests, sawmills, pulp mills, buildings, energy, and waste. Results showed that forest felling volume exceeded growth due to significant wood demand and export, while forest carbon sinks increased because more hardwood was retained in German forests. The building and construction sector was the largest consumer of primary wood products, accounting for 52.1 % of the total, followed by furniture (29.5 %) and packaging (14.0 %). All waste paper was used to produce recycled fiber pulp, whereas only 14 % of waste wood was employed in particle board production. The woody biomass energy, amounting to 142.4 TWh, provided approximately 4.4 % of Germany's primary energy consumption, with around half of it used in private households. In addition to apparent data, this study also uses resource allocation, carbon storage, and cascade potential as examples to demonstrate that wood flow is applicable for further in-depth analysis, supporting wood efficient utilization. It can even be applied to any country and period with sufficient data and conversion factors, but here, they also prevented this study from comprehensively describing past and future wood flows. [Display omitted] [ABSTRACT FROM AUTHOR]

Background: Pulp refining is an energy consuming, but integral part of paper production with the aim to increase tensile strength and smoothness of paper sheets. Commercial enzyme formulations are used to lower the energy requirements by pre-treatment of pulp before refining. However, a high number of different commercial enzyme products are available on the market containing enzymes of varying origin and composition, which complicates the prediction of their behavior, especially using different pulp types. Results: Endoglucanase-rich enzyme formulations were characterized regarding enzyme activity at different temperatures, resulting in a significant decrease of activity above 70 °C. Some enzyme preparations additionally contained arabinosidase, xylanase and β-glucosidase activity consequently resulting in a release of xylose and glucose from pulp as determined by high-performance liquid chromatography. Interestingly, one enzyme formulation even showed lytic polysaccharide monooxygenase (LPMO) activity of 3.05 nkat mg−1. A correlation between enzyme activity using the endoglucanase specific derivatized cellopentaose (CellG5) substrate and enzyme performance in laboratory PFI (Papirindustriens forskningsinstitut) refining trials was observed on softwood pulp resulting in a maximum increase in the degree of refining values from 27.7°SR to 32.7°SR. When added to a purified endoglucanase enzyme (31.6°SR), synergistic effects were found for cellobiohydrolase II (34.7°SR) or β-glucosidase enzymes (35.7°SR) in laboratory refining. Comparison with previously obtained laboratory refining results on hardwood pulp allowed differences in enzyme performance based on varying pulp types to be elucidated. Conclusions: Interestingly, the individual enzymes indeed showed different refining effects on softwood and hardwood pulp. This difference could be predicted after development of an adapted enzyme activity assay by combination of the derivatized cellopentaose CellG5 substrate with either softwood or hardwood sulfate pulp. [ABSTRACT FROM AUTHOR]

Alpha-cellulose, a unique, natural, and essential polymer for the fiber industry, was isolated in an ecofriendly manner using eleven novel systems comprising recycling, defibrillation, and delignification of prosenchyma cells (vessels and fibers) of ten lignocellulosic resources. Seven hardwood species were selected, namely Conocorpus erectus, Leucaena leucocephala, Simmondsia chinensis, Azadirachta indica, Moringa perigrina, Calotropis procera, and Ceiba pentandra. Moreover, three recycled cellulosic wastes were chosen due to their high levels of accumulation annually in the fibrous wastes of Saudi Arabia, namely recycled writing papers (RWPs), recycled newspapers (RNPs), and recycled cardboard (RC). Each of the parent samples and the resultant alpha-cellulose was characterized physically, chemically, and anatomically. The properties examined differed significantly among the ten resources studied, and their mean values lies within the cited ranges. Among the seven tree species, L. leucocephala was the best cellulosic precursor due to its higher fiber yield (55.46%) and holocellulose content (70.82%) with the lowest content of Klasson lignin (18.86%). Moreover, RWP was the best α-cellulose precursor, exhibiting the highest holocellulose (87%) and the lowest lignin (2%) content. Despite the high content of ash and other additives accompanied with the three lignocellulosic wastes that were added upon fabrication to enhance their quality (10%, 11%, and 14.52% for RWP, RNP, and RC, respectively), they can be considered as an inexhaustible treasure source for cellulose production due to the ease and efficiency of discarding their ash minerals using the novel CaCO3-elimination process along with the other innovative techniques. Besides its main role for adjusting the pH of the delignification process, citric acid serves as an effective and environmentally friendly additive enhancing lignin breakdown while preserving cellulose integrity. Comparing the thermal behavior of the ten cellulosic resources, C. procera and C. pentandra exhibited the highest moisture content and void volume as well as having the lowest specific gravity, crystallinity index, and holocellulose content and were found to yield the highest mass loss during their thermal degradation based on thermogravimetric and differential thermal analysis in an inert atmosphere. However, the other resources used were found to yield lower mass losses. The obtained results indicate that using the innovative procedures of recycling, defibrillation, and delignification did not alter or distort either the yield or structure of the isolated α-cellulose. This is a clear indicator of their high efficiency for isolating cellulose from lignocellulosic precursors. [ABSTRACT FROM AUTHOR]

The possibility of producing fluffed pulp from hardwood raw material by an alternative technology comprising milling of pulp cloth in a stream of air (aerodynamic method) and of creating ecologically safe alternative technologies for manufacturing pulp intermediate was studied. [ABSTRACT FROM AUTHOR]

Lignin, a complex and heterogeneous biopolymer derived from wood, holds immense potential as a sustainable feedstock for various industrial applications. Kraft pulping, a widely employed process in the paper industry, generates black liquor containing lignin along with other organic and inorganic compounds. The precipitation of lignin from black liquor offers an opportunity for valorization, contributing to the circular economy and reducing the environmental impact. Although the precipitation process of softwood lignin is extensively documented and outlined in the existing literature, the identical process originating from hardwood-derived black liquor poses challenges attributed to the distinct composition of hardwood. This study systematically investigates the individual and combined influences of temperature and pH on the precipitation of hardwood lignin from kraft black liquor, utilizing a factorial design to evaluate lignin functional characteristics. The characterization of the precipitated lignin was performed using various analytical techniques, mainly NIR, elemental composition, UV-VIS, and calorimetry. The results reveal remarkable interactions between temperature and pH, indicating their synergistic effects on lignin precipitation. The optimal conditions for hardwood lignin precipitation were identified and successfully upscaled during piloting experiments conducted under industrial conditions. This research provides valuable insights into the fundamental factors governing hardwood lignin precipitation from kraft black liquor and offers a basis for the development of efficient and sustainable lignin recovery processes in the pulp and paper industry. [ABSTRACT FROM AUTHOR]

Hardwood vessel elements generate problems in industrial uncoated wood-free printing paper operation, causing vessel picking and ink refusal. These problems are mitigated using mechanical refining at the cost of paper quality. Vessel enzymatic passivation, altering its adhesion to the fiber network and reducing its hydrophobicity is a way of improving paper quality. The object of this paper is to study how the enzymatic treatment by xylanase and by an enzymatic cocktail containing cellulases and laccases affect elemental chlorine free bleached Eucalyptus globulus vessel and fiber porosities, bulk, and surface chemical compositions. Thermoporosimetry revealed the vessel structure to be more porous, surface analysis showed its lower O/C ratio and bulk chemistry analysis its higher hemicellulose content. Enzymes had different effects on porosity, bulk and surface composition of fibers and vessels, affecting vessel adhesion and hydrophobicity. Vessel picking count decreased 76% for papers containing vessels treated with xylanase and 94% for the papers with vessels treated with the enzymatic cocktail. Fiber sheet samples had lower water contact angle (54.1º) than vessels rich sheets (63.7º), that reduced with xylanase (62.1º) and cocktail (58.4º). It is proposed that differences in vessel and fiber porosity structures affect the enzymatic attacks, eventually causing vessel passivation. [ABSTRACT FROM AUTHOR]

This paper deals with the bonding characteristics of cross-laminated timber (CLT) panels made of Silver birch (Betula pendula Roth.), European aspen (Populus tremula L.), and Norway spruce (Picea abies (L.) H. Karst.) wood. Three-layered single-species CLT panels were manufactured using birch, aspen, and spruce lamellae bonded with a one-component polyurethane (PUR) adhesive. Spruce CLT panels were used as reference. The bonding characteristics of CLT were assessed based on bond shear strength, total and maximum delamination, and wood failure percentage. The reference spruce CLT met both criteria (Delamtot ≤ 10%, Delammax ≤ 40%) for passing the delamination test, where up to 80% of the test samples passed. The aspen and birch CLTs met the criterion for maximum delamination (26.5% and 33.2%, respectively), but exceeded the maximum allowed value for total delamination (12.7% and 13.2%, respectively). However, the minimum requirement of 70% wood failure percentage (WFP) was met for all CLT types, with aspen CLTs achieving 83.7% and birch CLTs 76.9%. The spruce CLTs achieved an average bond shear strength of 1.9 N/mm2, while both hardwood CLTs had significantly higher values, with the aspen CLT at 3.3 N/mm2 and the birch CLT at up to 3.9 N/mm2. Based on the results obtained, it can be concluded that cross-laminated timber (CLT) made from hardwoods like aspen and birch is suitable for environments with low humidity fluctuations. [ABSTRACT FROM AUTHOR]

This paper tests using two-regime Markov-switching models with asymmetric, time-varying exponential generalized autoregressive conditional heteroskedasticity (MS-EGARCH) variances in random-length lumber futures trading. By assuming a two-regime context (a low s = 1 and high s = 2 volatility), a trading algorithm was simulated with the following trading rule: invest in lumber futures if the probability of being in the high-volatility regime s = 2 is lower or equal to 50%, or invest in the 3-month U.S. Treasury bills (TBills) otherwise. The rationale tested in this paper was that using a two-regime Markov-switching (MS) algorithm leads to an overperformance against a buy-and-hold strategy in lumber futures. To extend the current literature in MS trading algorithms, two location parameter scenarios were simulated. The first uses an unconditional mean or expected value (no factors), and the second incorporates market and behavioral factors. With weekly simulations form 2 January 1994 to 28 July 2023, the results suggest that using MS-EGARCH models in a no-factors scenario is appropriate for active lumber futures trading with an accumulated return of 158.33%. Also, the results suggest that it is not useful to add market and behavioral factors in the MS-GARCH estimation because it leads to a lower performance. [ABSTRACT FROM AUTHOR]

Understanding cellulose hornification provides crucial information regarding drying of pulp, paper, and other cellulosic materials as well as recycling them. By measuring drainage, fiber width, and water retention value of hardwood and softwood pulps before and after sheet forming and after different drying procedures at different achieved levels of solids, the hornification was evaluated. The water retention value was also measured for the pulps when dried from acetone to observe what happens when hydrogen bonds are not available in the liquid phase. The drainage and fiber width decreased with increasing solids content; the fibers became increasingly stiff with increased water removal. Water retention measurements indicated that hornification is a stepwise process with large drops in fiber flexibility as soon as the fibers are being processed and later after a certain amount of water has been removed. In sum, the fibers must achieve a certain solids content to show hornification, and hydrogen bonds in water draw the cellulose surfaces together to create hornification. The mechanism of hornification is believed to be driven by hydrogen bonds and related to the distance between cellulose chains inside the fiber wall. Other types of bonds are probably also present and help with the irreversibility of hornification. [ABSTRACT FROM AUTHOR]

Precommercial thinning could be a valuable tool for climate change adaptation, as it can promote stand diversity while increasing productivity. Softwood and hardwood stands are usually thinned following different methods, and we lack recommendations for application in mixedwood stands. We evaluated the effects of precommercial thinning on the growth and composition of balsam fir (Abies balsameaL.)–birch stands dominated by paper and yellow birch (Betula papyrifera Marsh. and Betula alleghaniensis Britt.), comparing methods and production objectives (systematic release-softwood, systematic release-mixedwood, crop-tree release-mixedwood, and crop-tree release-hardwood) in Québec (Canada). Precommercial thinning increased tree-level and stand-level growth, especially for both birches. Compared to the non-thinned control, thinning increased tree diameter at breast height annual increments by 60%–107%, with similar results among modalities. Thinning changed initial stand composition, but mixedwood production plots composition was similar to that of the control 15 years after treatment. Promoting diversity is often perceived to be made at the expense of wood production. Our results suggest that we can obtain both increased growth and maintain diversity. Precommercial thinning is currently suggested as an adaptation tool that can foster drought resistance. Based on our study, we suggest it could serve another purpose in climate-adapted forest management, that is, maintaining diversity and thus increasing resilience to disturbances. [ABSTRACT FROM AUTHOR]

Trembling aspen (Populus tremuloides) is one of the major species within Populus, a predominant genus of hardwoods in North America. However, its utilization has been limited to pulp and paper or wood-based composite boards. This study aimed at evaluating the major physical and mechanical properties of trembling aspen lumber, with an ultimate objective of using this species to produce engineered wood products (EWPs). The testing materials consisted of 2 × 4 (38 mm × 89 mm) trembling aspen lumber pieces in lengths of 8, 10, and 12 feet (2.44, 3.05, and 3.66 m) with two visual grades, select structural (SS) and No. 2. Machine Stress-Rated (MSR), and longitudinal stress wave (LSW), edgewise third-point bending (EWB), and axial tension tests were conducted on the lumber. It was found that, (1) by increasing the maximum knot size by a half-inch from one-quarter inch, the minimum modulus of elasticity (MOE) measured using the MSR, the mean, and the fifth-percentile ultimate tensile strength (UTS) decreased by about 8.8%, 20.1%, and 29.8%, respectively. (2) Approximately 44% of the trembling aspen lumber met the 1450f-1.3E grade for MSR lumber, and 62% qualified for the 1200f-1.2E grade. (3) There was a great potential for manufacturing cross-laminated timber (CLT) of grade E3, with a rejection rate of about 29%. (4) The mean UTS and MOE values of the SS-grade trembling aspen lumber were 22.88 MPa and 9519 MPa, respectively, being 25.5% and 11.3% lower than that of Spruce–Pine–Fir (S-P-F) lumber. The fifth-percentile UTS and MOE values were 11.57 MPa and 7404 MPa, respectively, marking a decrease of 13.3% and 1.5% compared to the S-P-F lumber. (5) The oven-dried specific gravity (SG) of the trembling aspen wood was 0.40, which was about 3.5% larger than the value provided in the Wood Handbook. [ABSTRACT FROM AUTHOR]

Data fusion plays a crucial part in performance evaluation processes in multisensor systems; thus, it is important to use an effective technique to cut down on errors. By improving the sensors' location and their capacity to adjust to the deployment geometry, the paper's technique for reducing data fusion errors is proposed. The preprocessing stage of data is also included in the suggested technique, which starts with the design of the data‐collecting device and ends with a hybrid model algorithm. Particle swarm optimization and artificial neural network methods are combined in the hybrid algorithm. Preprocessing is based on the compensation and adjustment factors to ensure data gathering synergy. A true experimental apparatus was designed under three different deployment geometries, comprising five ultrasonic sensors constituting a multisensor system and a hardwood target (Triplochiton scleroxylon and Milicia excelsa). The results obtained show that the suggested deployment geometry has mean absolute percentage errors of 3.97, mean square errors of 0.182, and mean absolute errors of 0.045 which are lower than those associated with the deployment configurations found in the literature. The results of the proposed method show an overall detection accuracy in linear deployment geometry of 97.308%. Then, the circular deployment geometry obtained a detection accuracy of 97.005%. Finally, elliptical deployment geometry obtained a detection accuracy of 98.745%. These results show that the proposed method better predicts the range of a target with a lower error rate than conventional methods. [ABSTRACT FROM AUTHOR]

Softwood is widely employed in construction and faces high demand. Australia is grappling with substantial timber scarcity, specifically related to radiata pine, which is the dominant structural timber in the construction sector. However, Australia has a significant hardwood population, which can be utilized to reduce the high demand for radiata pine. This paper aims to investigate the bond properties of both Australian softwood (radiata pine) and hardwood (shining gum). It also discusses the potential to combine softwood and hardwood in glue or cross-laminated timber by evaluating the bond properties of the radiata pine–shining gum interface. For hardwood, the effect of primer is also investigated to determine its efficacy in improving failure mode, bond strength, and stiffness. Lastly, both glulam and cross-laminated timber bonding scenarios are simulated for bond testing by examining the effect of relative fibre orientation on the bond properties of the aforementioned species individually and in combination. Instead of conventional block shear testing, which is predominantly used for same-species bond testing, push-out testing is adopted in this study. However, a comparison with block shear testing is also made in this article. The results indicated that the use of primer on hardwood reduced the inconsistencies in the bond properties and improved wood-side failure rates. It was also concluded that the effect of fibre orientation in a CLT scenario with combined hardwood and softwood failure modes can vary significantly, which leads to a higher standard deviation in the results. Nevertheless, this study outlines the challenges and opportunities for producing hardwood–softwood hybrid glue or cross-laminated timber. [ABSTRACT FROM AUTHOR]

Cellulose nanocrystals (CNCs) are renewable, biodegradable and biocompatible nanomaterials that exhibit unique mechanical, optical, rheological and barrier properties useful for a variety of applications. Since CNCs remain an expensive product, coupling its production to pulp and paper products could reduce the production costs. However, pulp and paper mills do not always use a single wood species and so, differences in CNC properties based on the feedstock must be delineated. This work reports on the production and characterization of CNCs from three hardwoods, i.e. white oak, sweetgum and cottonwood, and one softwood, i.e. loblolly pine. Stable aqueous CNC dispersions were obtained from pre-extracted and fully bleached kraft wood pulps. CNC yield (with respect to pulp) ranged between 60 and 80% w/w, and a linear regression model explaining the relationship between CNC yield and pulp cellulose to lignin ratio was found significant (R2 = 0.99 and p value = 0.0044). Sweetgum CNCs had the highest yield and purity, indicating the usefulness of this unconventional raw material for scalable production of high-quality CNCs. Pine CNCs were characterized by the largest length (150–200 nm vs 100–150 nm for the rest), whereas cottonwood CNCs displayed the lowest width (6 nm vs 14–17 nm for the rest) and consequently the highest aspect ratio (~ 20 vs ~8–13 for the rest) as well as the highest Young's modulus (1780 GPa vs 100–300 GPa for the rest). A linear regression model explaining the relationship between Young's modulus and CNC aspect ratio was found significant (R2 = 0.92 and p value = 0.0387). Other physicochemical properties, such as crystallinity index, surface charge, polydispersity index and surface roughness, were similar for CNCs derived from all four species; however, thermal degradation behavior of oak CNCs was slightly different from that of the remaining CNCs (lower Thalf and residual weight). Findings in this study indicate the potential to tune the quantity (yield) and quality (purity and properties) of CNCs based on the type of wood species chosen as the feedstock, thus having a direct impact on production economics and end use in different applications. [ABSTRACT FROM AUTHOR]

This paper investigates experimentally and numerically the buckling behavior of three-layered cross-laminated timber (CLT) panels under in-plane axial compression. The main aim is to assess the panels' ultimate limit load and their typical failure mechanisms. A total of 14 specimens were tested. Seven of them were homogeneous (HO series), entirely made of beech, whereas the others were hybrid (HB series), made of beech (outer layers) and Corsican pine (inner layer). The tests gave evidence of a rather stable column buckling capacity for CLT panels, with evidence of major failure mode due to bending. In some cases, rolling shear and delamination were highlighted as additional failure mechanisms. Finally, further assessment of experimental evidence is provided by extended analytical calculations (based on existing formulations, including the Eurocode 5 approach) and even finite-element (FE) numerical analyses for the examined three-layer CLT compositions. Comparative results are discussed in terms of structural performance, capacity, and weakness of analytical models for CLT solutions. [ABSTRACT FROM AUTHOR]

To maintain or adjust posture under the challenges of gravity and increased self-weight, or the effects of light, snow, and slope, plants have the ability to develop a special type of tissue called reaction tissue. The formation of reaction tissue is a result of plant evolution and adaptation. The identification and study of plant reaction tissue are of great significance for understanding the systematics and evolution of plants, the processing and utilization of plant-based materials, and the exploration of new biomimetic materials and biological templates. Trees' reaction tissues have been studied for many years, and recently, many new findings regarding these tissues have been reported. However, reaction tissue requires further detailed exploration, particularly due to their complex and diverse nature. Moreover, the reaction tissues in gymnosperms, vines, herbs, etc., which display unique biomechanical behavior, have also garnered the attention of research. After summarizing the existing literature, this paper provides an outline of the reaction tissues in woody plants and non-woody plants, and lays emphasis on alternations in the cell wall structure of the xylem in softwood and hardwood. The purpose of this paper is to provide a reference for the further exploration and study of reaction tissues with great diversity. [ABSTRACT FROM AUTHOR]

Cross-laminated timber (CLT) panels are an innovative wooden product that has gained popularity in recent years because it has a high strength-to-weight ratio, improves construction efficiency, and it is a natural and renewable material. Therefore, the recently released 2021 International Building Code (IBC) include guidelines for CLT panels for the construction of buildings of up to 18 stories. The construction applications of CLT panels as well as the research initiatives have largely centered on softwood tree species such as laminates, and the application of hardwood species has yet to be investigated. This paper documents the structural behavior of several hardwood species abundant in the Appalachian region and demonstrates the promising feasibility of using these species in the construction industry with CLT panels considering the architectural and structural behavior and economic aspects. The hardwood tree species selected are abundant in the Appalachian region and this paper highlights their potential as a construction material and provides an insight for future development. Three hardwood species including red maple, sweetgum, and sycamore are considered for this study, and three- and five-ply panels are fabricated to evaluate their behavior. The samples are tested in three directions for compression to understand the orthotropic behavior. Considering the softwood species including southern yellow pine and Douglas fir as a baseline for comparison, a total of 120 samples are tested and evaluated based on ASTM standards. The results show an average higher compressive strength from sweetgum panels followed by red maple, sycamore, Douglas fir, and southern yellow pine in the main directions used for structural walls. The findings imply a potential market for the underutilized hardwood species in Appalachia, which may lead to future economic development in the region. [ABSTRACT FROM AUTHOR]

We encountered a number of cases in the published archaeological studies where ashes and charcoal were used as aggregates in ancient lime mixtures. These mixtures were tested in a small number of experiments, and this paper presents the results. Our tests confirmed that charcoal retains moisture and can be used to help mortars retain water. It does not, however, increase a mortar's ability to retain moisture to the same degree that crushed ceramic does. Charcoal should be an additive to a mortar and not its sole aggregate, as it is brittle and the mortar produced would be weak. Mixtures of ash with lime seem to work best when spread on a single layer. When the ash is a small part of a mortar, it does not affect its behaviour significantly. The addition of ash does not increase the ability of lime mortars to retain water. Powdered ceramics also limit the effect of ash on lime. The paper concludes with suggestions for future research into these materials and mixtures. [ABSTRACT FROM AUTHOR]

Stabilising the natural colour of wood species exposed to light in indoor conditions is a challenge that could be better addressed based on a deeper understanding of the occurring phenomena and influencing factors. This paper investigates comparatively the light-induced colour changes for three hardwood species, namely, European maple (Acer pseudoplatanus L.), European ash (Fraxinus excelsior L.) and European walnut (Juglans regia L.), as well as the influence of finishing with three types of clear, colourless waterborne lacquers: acrylic-polyurethane (F1), acrylic (F2) and polyurethane (F3) on their colour stability. Colour measurements in the CIELab system in conjunction with an artificial accelerated ageing test under the action of UV-VIS radiation, simulating natural light passing through window glass, and two types of test samples were employed to highlight the influence and contributions of the wood substrate and of the coating films to the global colour modifications. Coating films applied on 1 mm clear glass slides were employed as a sort of "detachable" finish for this purpose. Direct exposure to UV-VIS light caused visible colour changes for both uncoated and coated wood surfaces, the values of the calculated colour differences (ΔE) after a 72 h exposure being dependant on both the wood species and the coating material. Excepting two situations for walnut, statistically significantly higher colour differences were obtained for the uncoated samples: maple (9.36 units), ash (8.39 units), walnut (6.20 units), compared to the coated ones: maple (4.92–5.71 units), ash (2.25–3.94 units), walnut (4.74–7.70 units). The wood substrates underlying the coating films were found to bring the maximum contribution to the overall colour changes in the clear coated surfaces, while the coating films employed in this research demonstrated a fairly good colour stability to UV-VIS light exposure, with maximum colour changes (∆E) up to only 1.30 units. Overall, the wood species and the type of coating were found as influencing factors in interaction with the light-induced colour changes in wood surfaces in indoor conditions. [ABSTRACT FROM AUTHOR]

Wood is a preferred material for constructing staircases due to its appealing aesthetic features. The use of wood, especially hardwoods such as red oak (Quercus rubra), white oak (Quercus alba), yellow poplar (Liriodendron tulipifera), and hard maple (Acer saccharum), has been the main construction material for staircases over the years. Staircase designs have evolved because of the flexibility of wood and working with specialized manufacturing machinery. A stair guard system connection must be designed to resist rotational and translational movements whenever a force is applied to the handrail. The demand for structural design values in wooden stair guards has been steadily increasing, driven by the needs of engineers, designers, builders, and end-users alike. This paper presents experimental data for four stair guard connections (post-to-rail, infill-to-footing, infill-to-rail, and rail-to-rail) encountered in a hardwood stairway handrail guard system. The data generated from this research could be useful for modeling the structural behavior of the connections. [ABSTRACT FROM AUTHOR]

Water is a universal solvent and swelling agent that is widely used in wood industry in association with organic solvents and salts, whether for the fractionation of biomass and the production of bio-based synthons for the chemical industry, the application of sizing agents and painting for the paper industry or the incorporation of preservatives to enhance wood durability for the timber industry. The relevance of solvents and technical treatments used for wood-based products requires a proper identification of the specific role of each solvent on wood biopolymers to better understand and predict their influence on wood properties. In particular, wood impregnated with aqueous solutions of organic solvents has shown to give rise to greater swelling than that observed in pure water, described as "hyperswelling". To understand this phenomenon, the first step is to examine the existing interactions between wood microstructure and the different solvents present in these mixtures. This study is an attempt to bring to light the sorption behaviour of four different hardwoods in water–ethanol vapour mixtures containing increasing molar fractions of ethanol from 0 to 100%. Contrasted sorption behaviour in pure solvents was observed according to wood species having different biochemical compositions. This behaviour highlights the different affinities of ethanol and water for the macromolecules present in the wood microstructure. With mixed solvents, peculiar effects were confirmed in sorption behaviour of woods with lower mixed solvent uptake at high partial pressures compared to pure solvents. It is also shown that part of the sorbed ethanol molecules remains chemisorbed in the wood structures at the end of the desorption process. [ABSTRACT FROM AUTHOR]

There are no systematic approaches available in current specialist literature when it comes to the optimization of the process of drying out hardwood species of wood, such as birch, aspen, or black alder, all of which find industrial uses in Estonia. In order to investigate the drying of these three hardwood species, this paper has made use of an experimental and theoretical drying optimization methodology which was developed previously for pine sapwood within the framework of the EIC Grant No. 16200 project. The same methodology was used to determine the critical diffusion coefficient and corresponding critical relative humidity levels (RH) in relation to the surrounding air, with those levels being important from the point of view of drying optimization, and calculating those levels separately for each species of hardwood. For alder it was found that the critical diffusion coefficient is Dcr = 36.57 * (10−4 mm2 s−1), while for aspen the figure was Dcr = 30.71 * (10−4 mm2 s−1), and for birch it was Dcr = 16.35 * (10−4 mm2 s−1). It was found that the time dependencies for the total deformation of different tree species tend to differ considerably, although the same drying regime was used for all of those tree species which were incorporated into the experiments. [ABSTRACT FROM AUTHOR]

We analyzed over 8 decades of change in forest composition (represented by species proportion of basal area) and size class from more than 400 permanent plots located on the Bartlett Experimental Forest in the White Mountains of New Hampshire. These data represent one of the longest-term landscape-scale records of forest change based on permanent plots in North America. We analyzed the plots based on elevation class, land type indicating assumed successional direction (grouped into coniferous and deciduous), and inventory period within managed and unmanaged portions of the forest. An ongoing shift from small- to large-diameter stems is clear across all species, in response to the overall aging of the forest following exploitative harvesting in the 19th century. Major compositional changes include a continuing decline in shade-intolerant species (paper birch and aspen), along with the mid-tolerant yellow birch. An increase in red maple abundance through the early 1990s has leveled off or reversed. Among shade-tolerant species, increases in beech and red spruce were largely consistent with assumed land type on unmanaged plots, but heavy marking against diseased beech on managed plots restricted increase of that species. Sugar maple declined in abundance except where silvicultural intervention helped maintain it. By contrast, eastern hemlock showed a continuing expansion at all elevations below 600 m. The data continue to show little or no evidence of upward migration of species, despite evidence of recent regional change in climate. However, the BEF is poised for substantial changes when emerald ash borer and hemlock woolly adelgid, both of which are known to infest nearby areas, do arrive. [ABSTRACT FROM AUTHOR]

The differences of physical and mechanical properties of different laminations, such as softwood, hardwood or other structural composite lumber, in hybrid cross-laminated timber (HCLT), lead to their dimensional stability and bonding performance more complex than generic cross-laminated timber (CLT). In this paper, the spruce-pine-fir (SPF) dimension lumber and construction oriented strand board (COSB) were employed to fabricate HCLT. The effects of four configurations and three adhesives on the dimensional stability and bonding performance of CLT and HCLT were evaluated in term of the water absorption (WA), thickness swelling (TS), block shear strength (BSS), wood failure percentage (WFP) and rate of delamination (RD). The results showed that with the increase of the COSB laminations, the WA of HCLT specimens decreased, and the values of TS, BBS and WFP increased. The configuration had a significant influence on the dimensional stability, BBS and WFP of the specimen. The adhesive had a significant influence on the dimensional stability and some bonding performances of the specimen. The phenol resorcinol formaldehyde (PRF) specimens had the lowest average RD value compared with the one-component polyurethane (PUR) and emulsion polymer isocyanate (EPI) specimens. Failures were prone to occur in the middle of the thickness of COSB lamination during block shear and delamination tests. The outcome of this paper could help the engineering application of HLCT. [ABSTRACT FROM AUTHOR]

Terrestrial laser scanners, unmanned aerial LiDAR, and unmanned aerial photogrammetry are increasingly becoming the go-to methods for forest analysis and mapping. The three-dimensionality of the point clouds generated by these technologies is ideal for capturing the structural features of trees such as trunk diameter, canopy volume, and biomass. A prerequisite for extracting these features from point clouds is tree segmentation. This paper introduces an unsupervised method for segmenting individual trees from point clouds. Our novel, canopy-to-root, least-cost routing method segments trees in a single routine, accomplishing stem location and tree segmentation simultaneously without needing prior knowledge of tree stem locations. Testing on benchmark terrestrial-laser-scanned datasets shows that we achieve state-of-the-art performances in individual tree segmentation and stem-mapping accuracy on boreal and temperate hardwood forests regardless of forest complexity. To support mapping at scale, we test on unmanned aerial photogrammetric and LiDAR point clouds and achieve similar results. The proposed algorithm's independence from a specific data modality, along with its robust performance in simple and complex forest environments and accurate segmentation results, make it a promising step towards achieving reliable stem-mapping capabilities and, ultimately, towards building automatic forest inventory procedures. [ABSTRACT FROM AUTHOR]

In this paper, photochromic and thermochromic microcapsules were selected. There are three different coating processes: "the primer with the photochromic microcapsules, the topcoat with the thermochromic microcapsules", "the primer with the thermochromic microcapsules, the topcoat with the photochromic microcapsules", and "the photochromic and thermochromic microcapsules added into the primer and topcoats" to explore the color-changing effect of the coating on the surface of basswood (Tilia) and the comprehensive properties of the paint film. The optical properties, mechanical properties, cold liquid resistance, and aging resistance of the coating were mainly analyzed. It was concluded that the comprehensive performance of the coating was the best when thermochromic and photochromic microcapsules were mixed on the surface of basswood (Tilia). At a temperature of 80 °C, the color difference reached a maximum of 20.2, and the coating was completely discolored. The color difference of the coating after discoloration under visible light illumination was 56.9. The gloss under the angle of incidence at 60° was 37.4, hardness was 3H, adhesion grade was 1, impact resistance was 10.0 kg·cm, and cold liquid resistance grade was 1. The method of mixing the two microcapsules had better aging resistance. In this paper, the photochromic and thermochromic properties of the coating were studied, and the optimal discoloration of the surface coating of the basswood substrate was solved by different coating processes. This study provided a method for a coating to achieve both photochromic and thermochromic discoloration, broadening the application of discoloration coatings. [ABSTRACT FROM AUTHOR]

Nanofibrillated cellulose (NFC) consists of ultrafine cellulose structures in which the fibrils can have widths in the range from about 5 to 100 nm. NFC has been studied and developed in the paper industry, using bleached pulp from wood as the raw material. One of the issues in the application of NFC is their heat resistance to thermal degradation. The production process of NFC results in a decrease in their pyrolysis temperature during the nanofibrillation of bleached pulp; however, the details behind the reason and mechanisms are still unclear. In this study, NFC was prepared from bleached hardwood and softwood pulp by mechanical nanofibrillation using a grinder, and the pyrolysis behavior was investigated. For both bleached pulps, a decrease in the pyrolysis temperature was observed after nanofibrillation. The results suggest that the decrease in the pyrolysis temperature from nanofibrillation is not due to damage of the crystalline cellulose by nano fibrillation, but the damage of the hemicellulose components in the surface of the cellulose microfibrils or the interface between the crystalline cellulose and hemicellulose. If the hemicellulose on the surface of crystalline cellulose could be removed from the NFC, then the decrease in the pyrolysis temperature could be suppressed. [ABSTRACT FROM AUTHOR]

Timber is one of the fundamental materials of human civilization, it is very useful and ecologically acceptable in its natural environment, and it fits very well with modern trends in green construction. The paper presents innovative hollow glued laminated (GL) timber elements intended for log-house construction. Due to the lack of data on the behavior of the hollow timber section in compression perpendicular to the grain, the paper presented involves testing the compression strength of elliptical hollow cross-section glue-laminated timber specimens made of softwood and hardwood, as well as full cross-section glue-laminated softwood timber specimens. The experimental research was carried out on a total of 120 specimens. With the maximal reduction of 26% compared to the full cross-section, regardless of the type of wood and direction of load, the compression strength perpendicular to the grain of hollow specimens decreases by about 55% compared to the full cross-section, with the coefficient kc,90 equal to 1.0. For load actions at the edge and the middle of the element, kc,90 factors were obtained with a value closer to those obtained for full cross-section, which indicates the same phenomenology, regardless of cross-sectional weakening. At the same time, the factors in the stronger axis are lower by about 10%, and in the weaker axis by about 30% compared to those prescribed by the Eurocode. Experimental research was confirmed by FEM analysis. Comparative finite element analysis was performed in order to provide recommendations for future research and, consequently, to determine the optimal cross-section form of the hollow GL timber element. By removing the holes in the central part of the cross-section, the stress is reduced. The distance of the holes from the edges defines the local cracking. Finally, if the holes are present only in the central part of the element, the behavior of the element is more favorable. [ABSTRACT FROM AUTHOR]

Thermal modification processes are environmentally friendly methods used to improve certain properties of wood. Currently, wood from thinning of young plantations of Nothofagus alpina (raulí) in Chile is being evaluated to obtain value before the plantation has reached maturity. The objective of this paper was to assess selected properties of thermally modified wood of young (14- to 25-years-old) N. alpina wood that comes from thinning of two sites with intensive silviculture and one similar to a secondary growth forest. To achieve this, non-destructive tests were carried out to measure some chemical-crystalline characteristics, as well as physical and mechanical properties; the differences between the 25%, 50%, and 75% distance from pith to the bark in each site was studied. The modification temperatures used were 170, 190, and 210 ℃. The results show that thinning wood from N. alpina can be thermally modified with favorable results, thus presenting an option to obtain value while the plantation reaches maturity, particularly the thinning wood from the intensive forestry regimes, which presented most homogeneous results, especially at the modification temperature of 190 ℃. [ABSTRACT FROM AUTHOR]

Hardwoods commonly have high mechanical properties, which makes them interesting for structural use, but softwoods dominate the structural timber market in Europe. Tensile strength classes are recommended for engineered wood products. However, current European standards do not provide tensile strength classes for hardwoods and the declaration of tensile properties from machine grading in the industry is not yet possible. The present paper aims to contribute to the revision of European standards through the technical group CEN/TC124/WG2/TG2: Tensile strength classes for hardwoods, of the European Standardisation Committee. An experimental campaign which involved machine grading and tensile testing of over 569 boards of Southern blue gum (Eucalyptus globulus Labill.) from Spain and Portugal was made. Six new tensile strength classes were defined, from ET24 (ft,0,k = 24 N/mm2, Et,0,m = 18 kN/mm2 and ρk = 590 kg/m3) to ET42 (ft,0,k = 42 N/mm2, Et,0,m = 23 kN/mm2 and ρk = 640 kg/m3). Machine grading made possible the definition of six strength class combinations. Four combinations resulted in 40% of the sample being assigned to the higher strength class, with low percentages of rejection (varying between 1% and 14%). This demonstrates the high mechanical properties of the species and the performance improvement of machine grading with respect to current visual grading. [ABSTRACT FROM AUTHOR]

Recent research in Europe is bringing a wider range of wood species to the construction market as structural timber and glue laminated products. This option would also open markets for currently underused UK species, foremost hardwoods, but testing efforts when developing strength grading assignments for any minor UK species are prohibitive, as the resource is small and scattered. Grading approaches that require less material for destructive testing could be employed to open routes to market for structural hardwood products. In addition, the European hardwood research has been revealing some gaps and uncertainties in grading standards. In particular, data are lacking to support adjustment equations for size, moisture content, and testing arrangement for hardwoods. This paper outlines a new PhD project that will focus on these problems and aims to develop an easier route for strength grading hardwoods. [ABSTRACT FROM AUTHOR]

This paper reviews of the recent progress in the acarological researches and knowledge on mites occurring in the canopy of ornamental trees and shrubs. The inventory of Acari includes 444 mite species belonging to 33 families which were recorded from 283 hardwood tree and shrub species of 45 plant families. The highest number of mite families and species were reported from the families Rosaceae (21 mite families), Salicaceae (20) and Oleaceae (17), and Salicaceae (99 mite species), Rosaceae (98) and Fagaceae (63), respectively. The most diverse acarine fauna was found on Acer campestre (37 mite species), Prunus spinosa (37), Acer pseudoplatanus (33), Tilia cordata (33) and Salix alba (31). The most frequently occurring mite species were Euseius finlandicus (on 78 host species), Tydeus californicus (64) and Zetzellia mali (60). [ABSTRACT FROM AUTHOR]

The cement industry is one of the primary sources producing anthropogenic CO2 emissions. The significant increase in the demand for cement in years has significantly contributed to the increase in carbon emissions. Among numerous CO2 treatment technologies, calcium looping (CaL) is a practical approach to mitigating CO2 emissions. This paper used calcium looping (CaL) to capture CO2 from flue gas in a cement pre-calciner kiln system. The raw material exiting the lowest stage of the preheater is used as a calcium-based adsorbent, and the carbonation reactor is built between the tertiary and secondary preheaters, using the high-temperature flue gas exiting the tertiary preheater to provide heat for the reaction. The CFD (Computational Fluid Dynamics) simulation technology was used to evaluate the rationality of the carbonation reactor and the key factors affecting the carbon removal efficiency of the carbonation reactor. The results indicate that the velocity and pressure fields of the carbonation reactor conform to the general operating rules and are reasonable. The optimal operating speed of particles in the carbonation reactor is 15 m/s, with a separation efficiency of particles of 92.5%, ensuring the smooth discharge of reaction products. The factor analysis of the carbonation reactor shows that when the temperature is 911 K, the mass flow rate of CaO is 2.07 kg/s, and the volume fraction of CO2 is 0.28, the carbonation reaction reaches a chemical equilibrium state, and the carbon removal efficiency is 90%. It should be noted that this carbon removal efficiency is the optimal carbon removal efficiency based on a combination of economic factors. In addition, the influencing factors show a precise sequence: CO2 volume fraction > CaO addition amount > temperature. Finally, we investigated the impact of the addition of the carbonation reactor on the preheater system. The results show that adding the carbonation reactor causes an increase in the flue gas velocity at the outlet of the preheater and a decrease in pressure, reducing the separation efficiency. Although the separation efficiency decreases slightly, the impact on the pre-calciner system is minimal. [ABSTRACT FROM AUTHOR]

Finger jointing has long been a method of extending the longitudinal span of short-length timber pieces through a tooth-like profile of a nominated length and bonded with adhesive. With the high-density hardwood resource in the sub-tropics, local industries have found it difficult to obtain adequate bond integrity for high moisture areas and outdoor applications, where a good bond is governed by the dry modulus of rupture (MOR) and the percentage of wood fibre present in the separated joint after exposure to water impregnation. This paper presents the finger joint performance in terms of MOR, stiffness (MOE), and wood fiber amount (WFA) under different variables, joint profile (10 and 20 mm long fingers) using two structurally rated adhesives (a single-component polyurethane (1C-PUR) and resorcinol formaldehyde (RF)) on spotted gum (Corymbia citriodora) and Darwin stringybark (Eucalyptus tetrodonta) jointed boards. Dry bending strength or MOR testing indicated the 20 mm joints with the PUR adhesive had the best performance across both tested species compared to the RF adhesive. The measured MOE of the joints showed the RF samples to have higher MOE (7% to 13%) than the PUR samples for both joint sizes and species. Testing of joint durability through water impregnation resulted in MOR and MOE values decreasing by up to 50% for the RF and PUR joints. Conversely, the performance of water-impregnated joints after being allowed to re-condition to a 12% equilibrium moisture content produced a regain of MOR for the PUR joints across both species of 30% to 40%. Furthermore, it was found that the WFA increased for the PUR samples between the water-impregnated samples and the re-conditioned samples. [ABSTRACT FROM AUTHOR]

Increasing concerns regarding carbon emissions and climate change are prompting a shift toward the use of sustainable materials in the construction industry. Engineered timber products are gaining attention in the construction industry due to advancements in lamination techniques and adhesives as well as the renewable characteristics of wood. Bond properties play a significant role in engineered timber products. In Australia, Radiata Pine (RP, softwood) and Shining Gum (SG, hardwood) share a large proportion of local and native plantation forest resources. The present paper investigates the bond behaviours of Australian softwoods (RP–RP), hardwoods (SG–SG) and hybrid-wood (RP–SG) combinations in both parallel (PAL) and perpendicular (PER) bonding directions using one-component polyurethane adhesives. The results indicate that most of the softwood samples were subjected to wood-side (timber) failure, whereas hardwood samples failed due to delamination but exhibited higher strength and stiffness regardless of bond direction. In contrast, bond direction had a significant effect on the bond characteristics of hybrid configurations. Improved bond properties were observed when bonded in PAL directions; however, negative effects were seen when bonded in PER directions. Obtained characteristic (5th percentile) shear bond strengths for RP–RP–PAL, RP–SG–PAL and SG–SG–PAL samples were 3.88 MPa, 6.19 MPa and 8.34 MPa, whilst those for RP–RP–PER, RP–SG–PER and SG–SG–PER samples were 3.45 MPa, 2.96 MPa and 7.83 MPa, respectively. [ABSTRACT FROM AUTHOR]

This paper investigated the specific compressive strength (specific strength) of fly ash-based geopolymer composites with four hardwood extractives and two softwood extractives, as well as specific wood extractives. Additionally, the effect of the portion of pine wood (i.e., sapwood and heartwood) and wood pretreatment with NaOH were considered. Geopolymer paste (with extractives) and geopolymer wood composites (GWCs) were cured at 60 °C for 24 h. The samples were stored in a climate chamber (20 °C, 65% RH) for 7 days before finally testing under compression. From the results, the specific strengths of geopolymers with hardwood extractives were not significantly affected. However, geopolymers containing pine extractives showed the most significant reduction in specific strength. There were no significant differences in the specific strengths of geopolymers containing polyphenols and resin acid. Generally, geopolymers containing fatty acids recorded the lowest specific strengths. There was no difference between the GWCs with untreated sapwood and heartwood. However, the wood pretreatment led to a 21% and 10% increase in the specific strengths of GWCs with sapwood and heartwood, respectively. The findings of this study form the basis for improved GWCs production and a wide range of applications for green composite materials. [ABSTRACT FROM AUTHOR]

Boomerangs are among the most recognisable elements of Australian Aboriginal technology. In the popular mindset, the prevailing image of these wooden artefacts is that of thrown implements that return to the thrower, principally used for hunting animals. However, boomerangs have a deep multipurpose role in Indigenous societies, with just a few examples of their known functions, including fighting, digging, and making music (i.e., "clap sticks"). Recently, yet another function for boomerangs has been proposed (Martellotta et al., 2021): the functional modification of lithic tools (i.e., retouching)—a form of use that is almost unknown among non-Aboriginal researchers. Here, we provide the first comprehensive review of evidence for the use of boomerangs as lithic retouching tools (percussors). A detailed lexical analysis demonstrates similarities between Palaeolithic bone retouchers used for the same purposes as the Australian hardwood boomerangs, thus confirming our traceological hypothesis and the power of using a multidisciplinary approach in investigating Australia's deep past. This paper provides the foundation for discussions surrounding the multipurpose concept behind many Aboriginal tools by focusing on the most iconic item. We propose that, in future studies, the complex technological and functional features of boomerangs should take precedence over their famous "returning effect". [ABSTRACT FROM AUTHOR]

Glued laminated timber made from hardwood is a sustainable structural product that is currently gaining momentum due to climatic changes and afforestation policy. Diversities in hardwood species have led to a lack of a complete standard for the production of glued laminated timber from hardwood in Europe. This paper addresses hardwood species available in Croatian forests, namely Carpinus Betulus L. (European hornbeam), Quercus Cerris L. (Turkey oak), and Acer Campestre L. (Maple), in terms of their suitability for the production of glued laminated timber. The suitability is assessed by a multi‐criteria analysis with seven criteria. Visual and physical properties include density, the occurrence of knots, and grain deviation in lamellas. Mechanical properties include the bending strength, modulus of elasticity, and shear strength of glue lines. In order to obtain physical and mechanical properties, corresponding experimental research has been carried out. Production costs have been evaluated in collaboration with the manufacturer. Results indicate a very high potential of European hornbeam and Turkey oak for the production of glued laminated timber. [ABSTRACT FROM AUTHOR]

Renewable hemicellulose with a unique structure exhibits a wide range of potential applications. However, it has been a formidable challenge to isolate hemicellulose with an intact structure from lignocellulosic materials. In this study, LiBr·3H2O (LBTH) was used as a green solvent for the effective fractionation of hemicellulose from bleached hardwood kraft pulp (BHKP) under mild conditions (25–85 °C). It was found that hemicellulose in BHKP can be dissolved in LBTH with ease and high selectivity owing to the breaking of hydrogen bonds between hemicellulose and cellulose, and the dissolved hemicellulose can be regenerated with a high degree of polymerization (DP) in the range of 240–264 using ethanol precipitation. The highest removal rate of hemicellulose from BHKP was as high as 95.2%, and the corresponding yield of pure hemicellulose reached 84.3%. Moreover, simultaneously obtained undissolved cellulose pulp through LBTH treatment had a high content of α-cellulose (96.7%), high DP (880), and trace levels of Fe (2 ppm), which met the standard requirement for dissolving pulp for the production of lyocell. In addition, LBTH can be easily recycled to guarantee a green and sustainable process. This work provides a new approach for highly selective fractionation of hemicellulose and cellulose from commercial BHKP based on an efficient and environmentally friendly LBTH treatment, which could be very promising for better valorization of hemicellulose and cellulose in many advanced applications. [ABSTRACT FROM AUTHOR]