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• The choice of post-use wood treatment significantly affects emissions and radiative forcing. • Post-use wood treatment may lead to adverse outcomes in low carbon systems. • Recycling and reusing stand out as crucial features for low carbon and future contexts. This study investigates the climate change effects in terms of greenhouse gas emissions and radiative forcing resulting from different pathways of processing wood materials when they reach the end-of-life stage. The shares of combustion, landfill, recycling, and reuse, which vary with the pathways of post-use wood, influence the material and energy production systems. The dynamics of CO 2 and CH 4 emissions, together with the cumulative radiative forcing of each pathway, are evaluated from various regional system perspectives. The results show that the choice of a treatment pathway for post-use wood could strongly influence the profile of greenhouse gas emissions and, consequently, the global warming potential. Taking into account the situation of the reference material and energy production systems, the post-use wood can have unfavorable consequences for the climate, as in the case when the material and energy production systems are based on the low-carbon energy of natural gas. However, from the perspective where the treatment of post-use wood influences the quantity of forest biomass on the forest floor, the increased share of reuse and recycling contributes positively to the climate change mitigation, but only during the early stage. Under such a context, options relying on carbon capture and storage to handle biogenic CO 2 emissions at energy conversion facilities could cause a cooling effect on the Earth's atmosphere. [ABSTRACT FROM AUTHOR]

The high density and poor thermal insulation of traditional wood-plastic composites limited the application in the field of building materials. In this paper, wood fiber (WF) and PLA were used as raw materials and azodicarbonamide was used as the foaming agent. Lightweight WF/PLA composites were prepared by the hot-pressing foaming method, aiming to obtain renewable, low-density material with high strength-to-weight ratio and thermal insulation performance. The results showed that after adding 20 % WF into PLA, the cell morphology was excellent and the cell size was uniform. The magnification reached the minimum value of 0.36 g/cm3 and the foaming magnification was 3.42 times. The impact strength and compressive strength were 3.16 kJ/m3 and 4.12 MPa, its comprehensive mechanical properties were outstanding. The thermal conductivity of foamed materials was 0.110–0.148 (W/m·K), which was significantly lower than that of unfoamed materials and common wood. Its excellent mechanical properties and thermal insulation can be suitable for application in the construction field to replace traditional wood. [Display omitted] • Preparation of renewable and lightweight wood fiber/poly(lactic acid) composites • The composites have high mechanism strength and thermal insulation performance. • Wood flour content can affect the lightweight material properties. [ABSTRACT FROM AUTHOR]

In addressing the limitations of wood's susceptibility to water and moisture, this study explored the development of a durable, superhydrophobic surface through a novel ɛ-polylysine/polydimethylsiloxane (PDMS)/wax composite system. Leveraging the layer-by-layer (LBL) assembly, the incorporation of cationic ɛ-polylysine not only improved the adherence of PDMS and wax to the wood surface through electrostatic attraction but also facilitated a more uniform distribution, achieving optimal hydrophobicity at a ɛ-polylysine concentration of 2 g/L. The synergistic effect of the wood's natural rough structure and the deposition of these hydrophobic substances endowed the treated wood with superhydrophobic properties, showcasing exceptional self-cleaning capabilities by efficiently repelling a variety of liquid contaminants. Durability assessments through sandpaper abrasion, chemical exposure, and accelerated weathering tests confirmed the enhanced long-term stability of the treated wood surfaces. Furthermore, the incorporation of ε-polylysine provided nice antimicrobial properties, showing a substantial reduction in bacterial adhesion. The ε-polylysine/PDMS/wax composite system represents a significant advancement in the development of multifunctional wood surfaces, promising broader applications in sustainable building materials, furniture, and packaging solutions. [Display omitted] • Superhydrophobic wood surface made by the layer-by-layer assembly method • The production method is simple and requires no special equipment. • The prepared superhydrophobic wood surface exhibits excellent durability. • A good antimicrobial, antifouling, self-cleaning wood surface was found. [ABSTRACT FROM AUTHOR]

Efforts have been dedicated to developing sustainable alternatives for conventional construction materials, resulting in the development of densified wood as an innovative, environmentally friendly, and high-performance material. This study focuses on investigating the effects of treatment parameters (e.g., partial delignification boiling time, chemical concentrations, and hot-pressing pressures) on the chemical, morphological, and mechanical properties of the densified wood. Results revealed that the partial delignification process of low-density Balsa wood reduced lignin content by 50–80%, which enhanced the crystallinity of the wood by 21–54%. However, prolonged periods of partial delignification caused a degradation in the crystalline regions in wood. The modulus of rupture (MOR) and modulus of elasticity (MOE) of the densified wood samples increased by 90–680% and 10–810% compared with those of the raw wood samples, respectively. The MOR of the densified wood also showed a dependency on lignin content and porosity. An optimal lignin content of approximately 10% was associated with the highest MOR in densified wood. Moreover, the relationship between the MOR and porosity suggested that the MOR improvement occurred in two stages. The first stage of MOR improvement is controlled by the reduction in the porosity and the second stage is controlled by the improved hydrogen bonding among cellulose nanofibrils. • Partial delignification reduced lignin content and enhanced crystallinity of wood. • Strength was largely improved through chemical treatment and hot pressing. • Prolonged boiling treatment degrades wood crystalline structure. • Porosity reduction and enhanced nanofibril bonding control strength of treated wood. [ABSTRACT FROM AUTHOR]

Petroleum-based plastics are useful but they pose a great threat to the environment and human health. It is highly desirable yet challenging to develop sustainable structural materials with excellent mechanical and optical properties for plastic replacement. Here, we report a simple and efficient method to manufacture high-performance all-biobased structural materials from cellulosic wood skeleton (WS) and gelatin via oxidation and densification. Specifically, gelatin was grafted to the oxidized cellulose wood skeletons (DAWS) and then physically crosslinked via Tannic acid (TA), resulting in a significant enhancement of the material properties. Notably, only a mild pressure was applied during the drying process to form a densified TA/Gelatin/transparent wood film(TWF). The developed TA/Gelatin/TWF (thickness:100 ± 12 μm) exhibited a desirable combination of high strength (∼154.59 MPa), light transmittance (86.2 % at 600 nm), low haze (16.7 %), high water stability (wet strength: ∼130.13 MPa) and ultraviolet blocking efficacy which surpass most of the petroleum-based plastics. In addition, due to the all bio-based origins (wood and gelatin), TA/Gelatin/TWF are easily biodegradable under natural conditions, leading to less impact on the environment. These findings would hold promises for exploring high-quality all bio-based wood composites as eco-friendly alternatives to substitute plastics with wide applications, e.g. anti-counterfeiting, UV protection, and flexible electricals. [ABSTRACT FROM AUTHOR]

Petroleum-based plastics are useful but they pose a great threat to the environment and human health. It is highly desirable yet challenging to develop sustainable structural materials with excellent mechanical and optical properties for plastic replacement. Here, we report a simple and efficient method to manufacture high-performance all-biobased structural materials from cellulosic wood skeleton (WS) and gelatin via oxidation and densification. Specifically, gelatin was grafted to the oxidized cellulose wood skeletons (DAWS) and then physically crosslinked via Tannic acid (TA), resulting in a significant enhancement of the material properties. Notably, only a mild pressure was applied during the drying process to form a densified TA/Gelatin/transparent wood film(TWF). The developed TA/Gelatin/TWF (thickness:100 ± 12 μm) exhibited a desirable combination of high strength (∼154.59 MPa), light transmittance (86.2 % at 600 nm), low haze (16.7 %), high water stability (wet strength: ∼130.13 MPa) and ultraviolet blocking efficacy which surpass most of the petroleum-based plastics. In addition, due to the all bio-based origins (wood and gelatin), TA/Gelatin/TWF are easily biodegradable under natural conditions, leading to less impact on the environment. These findings would hold promises for exploring high-quality all bio-based wood composites as eco-friendly alternatives to substitute plastics with wide applications, e.g. anti-counterfeiting, UV protection, and flexible electricals. [ABSTRACT FROM AUTHOR]

Coastal and marine urbanization have caused the sprawl of a variety of marine infrastructures, primarily built with artificial materials. We conducted a systematic review and a meta-analysis of 76 studies to determine how material type affects the ecological performance of artificial structures for possible eco-engineering applications. We compared three rocky-type materials, specifically autochthonous natural rocks, allochthonous natural rocks and concrete (i.e., the most abundant novel rock type of the Anthropocene) to each other and to other non-rocky materials commonly used to build infrastructures: metal, plastic, ceramic, rubber and wood. We tested the effects on diversity, abundance, or biomass of epibiota, as well as on key functional groups of epibenthic organisms (algae, sessile and vagile invertebrates). Studies were mostly short term (<7 months duration), with variable outcomes among experiments and functional groups. Overall rocky substrates (including concrete) performed better (more diverse and abundant epibenthic communities) than other non-rocky construction materials (such as metal, plastic, or rubber), and autochthonous rocks performed better than any allochthonous (rocky and non-rocky) material. We did not detect a better ecological performance of eco-friendly concretes over traditional (gray) Portland concrete in terms of species growth, but eco-materials could still provide significant benefits by lowering raw materials demand, energy costs and/or CO 2 emissions or enhancing the structure aesthetic. We suggest that material type as well as its origin (autochthonous vs allochthonous) are important but still largely overlooked properties of marine artificial structures that should be considered in combination with other types of substrate eco-engineering manipulations to reduce the impacts on native biota. • Autochthonous rocky-type materials perform better than any extrinsic rocky or non-rocky material. • Rocky-type materials (including concrete) support more abundant and diverse epibenthic communities than metal and rubber. • Better performance of rocky-type materials increases over time, but studies were generally short-term. • Material type affects raw material demands and the carbon footprint of infrastructures. [ABSTRACT FROM AUTHOR]

With the advances in technology and the growing focus on environmental protection and sustainable development, the field of engineering materials is constantly pursuing the development of new materials. Lignocellulose-based composites have gradually become a hot research topic because they not only possess the natural advantages of wood, such as renewability and good mechanical properties, but also have other advantages that cannot be matched by other materials, such as strong structural designability and easy functional modification. The application of advanced structural materials has brought new breakthroughs and development opportunities to traditional wood, with engineering lignocellulose-based composites being an important representative of innovative materials. In this regard, this paper provides an overview of the characteristics and applications of engineered lignocellulose-based composites based on advanced structural materials. Firstly, the structure and advantages of wood are introduced, followed by a focused discussion on the structure, preparation methods, and application areas of densified wood, transparent wood, and bioinspired wood. Finally, the future research directions are outlined to propel further advancements in this field. [Display omitted] ● Reviewed characteristics and applications of engineering lignocellulose-based composites based on advanced materials. ● Discussed the structures, preparation methods, and application areas of densified, transparent, and biomimetic wood. ● Explored the prospects, trends, and research directions of engineered lignocellulosic matrix composites. [ABSTRACT FROM AUTHOR]

The aim of this work is to improve the understanding of the fire behaviour of building materials used in the wildland urban interface at a large scale. To this end, wood cladding was exposed to the heat flux from the burning of a cistus hedge ignited by a spreading fire front in a fuel bed of excelsior litter. Six experiments were performed with different configurations: hedge/cladding distance, cistus bulk density, hedge length. During the experiments, the assessment of the cladding ignition was observed by camera. Wind direction and velocity were measured continuously since the tests were conducted outdoors and wind is a significant driver of flame spread. Heat fluxes and temperatures were also measured in order to compare the intensity of the thermal aggression on the cladding coming from the burning hedge. When the distance between the hedge and the cladding was 3 m, the wood did not ignite even when the wind was in the direction of propagation towards the cladding. In these cases, the maximum heat flux was 18 kW m−2. This value did not allow the ignition of the wood cladding. When the distance was reduced, the ignition of the cladding depended on the wind direction. When the cladding was ignited, the heat fluxes from the burning hedge could exceed 100 kW m−2. • Ignitability of wood cladding at the Wildland-Urban Interface. • Fire spread from a vegetation hedge to a building material. • Comparison of the critical heat flux for ignition at material and large scale. [ABSTRACT FROM AUTHOR]

[Display omitted] • Sustainable high-performance bamboo/wood composites (SHBWC) are introduced. • The relationship between global forest area and Roundwood production is analyzed. • The mechanical properties uncertainties of SHBWC are compared with Merbau. • Suggestions for the application of SHBWC and effective reinforced methods are given. • Mechanical performance of SHBWC is analyzed from microscopic characteristics. Sustainable building materials play a vital role in achieving carbon peaking and carbon neutrality goals. Comprehensive knowledge is required to fully understand the development status of sustainable building materials, particularly those made from bamboo or wood fiber, and their advantages in terms of mechanical performance and uncertainties compared to natural wood. The development status of sustainable high-performance bamboo/wood composites (SHBWC) is summarized, and a comparative analysis is conducted on the physical and mechanical performance as well as uncertainties of typical SHBWC compared to natural Merbau, which has extreme density. The findings indicate that the high demand for roundwood is exerting pressure on forest resources, leading to a certain extent of scarcity. Among the various SHBWC, bamboo scrimber (including BSM and BSS), wood scrimber (WS), and laminate bamboo lumber (LBL) are identified as most commonly used. These materials have varying densities, with BSM, BSS, WS, LBL, and Merbau following a descending order. BSS material demonstrates superior tensile and bending strength, measuring at 255.47 MPa and 233.12 MPa, respectively, with a modulus of 25.23 GPa, surpassing other materials. SHBWC show enhanced mechanical properties, uncertainties, dense microscopic characteristics, and a shorter sustainable supply cycle than natural hardwood. However, the mechanical performance of the SHBWC tested in this study could be further improved by reducing gaps in their microstructures. Overall, SHBWC offer a viable alternative to natural high-quality wood in construction applications. [ABSTRACT FROM AUTHOR]

Interactions between geopolymer and wood cell wall was investigated to better understand the bonding mechanism of geopolymer-wood composites as sustainable building materials. Elemental distributions, topological chemistry, and micro-mechanical properties between geopolymer and spruce wood cell wall were mainly investigated by the scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), UV microspectrophotometry (UMSP), nanoindentation, and nanoscratch. It was discovered that lignin may migrate from the wood cell wall to the surface of the geopolymer and thereafter partially contribute to the production of the geopolymer without appreciably damaging the wood cell wall. Geopolymer mineralized and hardened the surfaces of wood cell walls (S3 and S2 layers) evidenced by the increasing H/E and H 3 /E 2 from spruce cell walls to geopolymer. The average width of the interaction region was around 7.65 μm according to different friction coefficients. [Display omitted] • Interactions in situ revealed by topological and micro-mechanical tests. • Organic compounds (lignin) migrated from wood cell wall to the surface of geopolymer structure. • Geopolymer mineralized and hardened the surfaces of wood cell wall. • Interaction width was 7.65 μm based on friction coefficient by sigmoidal curve fitting. [ABSTRACT FROM AUTHOR]

• The modification of the geometry of a flat thin panel into a corrugated shape is an effective mechanical strengthening mechanism. • The mechanical properties of corrugated panels in the longitudinal direction are superior to those in the transverse direction. • Corrugated panels do not individually have sufficient mechanical performance to be an alternative to plywood and OSB. • I-Joist with a corrugated web seems to be the best potential structural application for corrugated panels. Typically, wood-based structural materials and their constituents are rectangular and full shapes. It is rare to find a periodic geometry such as the corrugated shape in these wood-based materials, whereas this geometry is very common in advanced composite materials. This project aims to characterize wood based corrugated panels in order to use them as a structural composite. The corrugated panels were characterized in terms of compressive, tensile, and bending properties in the direction parallel and perpendicular to the panel corrugations. Among the structural applications that could be developed, I-joists with corrugated panel-based web seem to be the most promising option. [ABSTRACT FROM AUTHOR]

Wood is becoming a very important structural material for buildings because it is a renewable resource and has a very small carbon footprint. This paper reports an experimental study on the effect of annual rings on wood anisotropy measurements using near-field microwave scanning for Pine, Hemlock, Red Cedar, and Hardwood laminated wood beams. Transmission measurements show significant anisotropy (>10 dB) for Pine wood compared to Hemlock wood and Red Cedar wood for linear polarization. The effect of annual rings in guiding the transmitted signal through wood fibers is observed through transmission measurements. Microwave guidance in transmission disappears with increasing the moisture content (17%–138%) of the Pine wood sample. The study provides a novel, accurate, fast, low-cost structural-wood testing method based on cavity-backed slot antennas for transmission and reflection measurements. [ABSTRACT FROM AUTHOR]

At present, the popularity of timber as a structural material is booming. However, the current knowledge on disproportionate collapse prevention and extreme loading of timber buildings is scarce. To prevent disproportionate and progressive collapse, catenary action is an important mechanism, where the axial capacity of bending members is activated. Because of the brittle behavior of timber in the relevant failure modes, it can only achieve catenary action via strengthening. In this paper, analytical expressions are derived for the elastic, plastic, and catenary capacity of laterally loaded wood and timber beams with a tension-side strip reinforcement. A load-path dependent M - N interaction diagram with damage accumulation explains the ultimate catenary capacity and the transition between the bending- and catenary-dominated load-carrying mode. The analytical expressions are validated and discussed based on tests on beech clearwood specimens reinforced with carbon fibers in a polyurethane matrix. Furthermore, a case study on glued laminated timber beams is presented to demonstrate the potential of reinforcing timber beams subjected to extreme loading. [Display omitted] • Analytical models for strip-reinforced wood and timber beams are presented and validated. • A load-path-dependent M-N interaction diagram with damage accumulation is shown. • The models are validated against tests and a case-study is presented. • The strength parameters are the most important. • Strengthening led to multi-fold increases in impact resistance and flexural rigidity. [ABSTRACT FROM AUTHOR]

Highlights • UHPC and fiber reinforced polymer bonded to timber interface. • Large scale beams and panels. • FLexural behaviour. • Modeling. • High performance structures. Abstract In wood construction, some attention has to be made in strength and stiffness of the structure. The deflection of wooden elements is often a weakness and an issue for designers. Several solutions have immerged to ameliorate the mechanical behavior of timber structure like the strengthening by adding specific materials such as ultra-high performance fiber-reinforced concrete (UHPFRC). The mechanical performance of wood structures is improved by composite structures. The cross-section of timber can also be internally reinforced by rebars of carbon fiber-reinforced polymer (CFRP) or steel. The combination of concrete, wood and rebars are an interesting solution to improve and strengthen timber structures but the connection system have to be performant otherwise the composite structure does not be fully optimal. This paper presents the short-term performances of glulam-concrete-rebar composite beams with different bonding processes and in particular a new specific treatment of wood. An analytical model based on a nonlinear and iterative procedure is developed to predict the failure of the composite structure by including the characteristics of the each material. According the results, composite beams improve the structural response by increasing both the strength and stiffness of the structure. Hybrid structure can be a good alternative to the conventional wooden structure. Finally, the reliability of large-scale panels is evaluated by performing bending tests. [ABSTRACT FROM AUTHOR]

Abstract Carbonaceous materials with unique microstructure obtained by pyrolyzing renewable and environment-friendly nature plants have promising applications in areas such as battery and catalyst support. However, unexpected cracks accompanied by low oxidation resistance retard further development. In this study, a thin SiC coating for strengthening purpose was in-situ deposited on biomorphic porous carbon materials fabricated by pyrolyzing wood while maintaining low density. Continuously ordered microchannel structures from carbonized nature wood with a diameter of ca. 20 μm was completely replicated after depositing SiC coating, resulting in the good anisotropy in mechanical and thermal properties. The thin SiC coating was found to greatly increase compressive strength from 26.4 to 47.4 MPa and thermal conductivity from 0.49 to 14.94 W/m K in the axial direction with improved oxidation resistance of weight loss from 78.5% to 1.51%. In the radial direction, however, the increase of the two properties was lower due to the longitudinal microchannel structure. Feasibility of the biomorphic carbon serving as catalyst support with highly developed continuous channels was evaluated by loading typical molybdenum disulfide (MoS 2). Result shows a significant improvement in both adsorption and photodegradation efficiency against the pure MoS 2 , which is because of the enlarged specific surface area of the catalyst. Graphical abstract Image [ABSTRACT FROM AUTHOR]

Highlights • Wide area of sampling, four countries and five different companies. • A I-A III recycled wood has 6 times higher portion of non-wooden material than AI. • The most critical inorganic pollutants in recycled wood are Cl, Cr, Cu and Pb. • Concentrations of analyzed inorganic pollutants increase with smaller particle size. • Samples from sophisticated sorting systems have lower portion of other materials. Abstract Recycled wood is becoming an important material source for production of new materials and chemicals. Predominantly clean recycled wood should be used for the products with high added value. However, contamination of the recycled wood defines the potential end uses. Thus, it is of the huge commercial and environmental importance to monitor the contamination of the respective material. In the present research, we focused on concentrations of non-wooden materials in recycled wood and the presence of indicative inorganic pollutants, namely: chlorine (Cl), chromium (Cr), copper (Cu), zinc (Zn), lead (Pb), iron (Fe) and bromine (Br). Sampling of various qualities of commercially available recycled wood was performed for one year in recycling companies from Germany, Slovenia, Finland and UK. In addition to the above-mentioned long term monitoring, fraction analysis was also performed on selected batches. For nine different fractions, the water soluble part and lignin content were additionally determined. The results showed that high quality recycled wood had low shares of non-wooden materials and only a few samples exceeded the limit values for inorganic pollutants prescribed by German ordinance Altholzverordnung or EPF standard. On the other hand, mixed recycled wood, of lower quality contained a significantly higher portion of non-wooden material (up to 3%). These mixtures also had higher concentrations of inorganic pollutants. More than 85% of samples exceeded the limit concentration prescribed by the German ordinance Altholzverordnung for recovered wood for at least one of the analysed chemicals. The concentration of chemical elements in samples from nine different size fractions negatively correlated with the particle size in the fractions. The same trend was also observed for the soluble part and the lignin content. In general, it can be concluded that recycled wood deriving from larger annual process capacity volumes with sophisticated sorting systems, contains less non-wooden material and can provide clean wood. On the other hand, the mixed recycled wood contained high concentrations of inorganic elements, regardless of the origin or sorting system. [ABSTRACT FROM AUTHOR]

Bio-based plastics, such as Wood-Plastics Composites (WPC), represent a new generation of sustainable building materials. They contain up to 80% of renewable resources and comparatively less fossil-based plastics. Reportedly, WPC products preserve crude oil for upcoming generations. However, WPC suffers from a moderate consumer acceptance due to its plastics-like appearance and a lack of differentiation to low-price plastics. Obviously, WPC hardly takes advantage of its environmental opportunity. This paper examines to what extend WPC could benefit from an eco-label as a means of self-regulation and how internalization acts in favor of society. An economic impact analysis is carried out using basic knowledge from a comprehensive literature research about eco-labeling effects on market allocation and welfare. The current WPC-market was subject of further investigations to find out whether a WPC eco-label has a welfare-increasing potential. The analysis revealed that labels are currently in use for differentiation among WPC products which yields higher profits and thus reduces consumer surplus. From social perspective it would be more beneficial to employ such labels for better distinguishing between pure plastics and WPC. In such a case a WPC eco-label would perfectly reduce externalities from crude oil plastics production and this goes along with a growing demand for green-plastics and higher willingness-to-pay of eco-aware consumers which is beneficial for the development of a green building market. Finally, social welfare is most likely to be higher than without labeling even if producer profit increased as well. Nevertheless, total welfare is expected to be maximal only if a public regulator prevents the industry from profit maximization which, however, is not recommendable for the investment-intensive WPC-branch. [ABSTRACT FROM AUTHOR]

[Display omitted] • We provide a platform for biomimicry of different wood species, which have technologically interesting properties. • Critical structural and morphological elements of willow wood derived from X-ray micro-CT can be captured with a high degree of fidelity using a novel cross-correlation reconstruction algorithm. • Orthotropic symmetry of willow wood and its structural anisotropy can be captured, reconstructed and 3D printed for applications of wood biomimicry. Biomimetics -using nature to inspire innovation- has resulted in the development of many novel materials. Wood, nature's light-weight structural material, defies mimicry at multiple scales, but its design features have been abstracted and used to develop honeycomb composites of limited geometric complexity. In this paper we demonstrate how it is possible to more completely biomimic wood, capture its exquisite mesoscale features and reproduce its mechanical properties. We utilised micro computed tomography (XCT) to image willow wood and used a novel cross-correlation reconstruction algorithm to mimic its 3D microstructure using minimal information. The mechanical properties of the simulated wood were compared with those derived from parent XCT data using finite-element simulations and testing of 3D printed samples of both wood types. The porosity and connectivity of both sample types was also compared. Our reconstruction algorithm was able to capture critical structural elements of willow wood with a high degree of fidelity, while mechanical properties of both wood types were closely matched. We conclude that our image-based stochastic modelling biomimetics offers a unique approach to capturing the mesoscale complexity of wood and will lead to new opportunities for designing novel materials inspired by xylotomy and powered by fast and high-performance computation. [ABSTRACT FROM AUTHOR]

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. • Biocarbon particles are good light absorbers in the ultra-violet and visible range. • Absorbance of biocarbon particles is proportional to their concentration in solution. • An increased biocarbon content in tung oil coatings led to enhanced colour stability. • Introduction of biocarbon in tung oil-based coatings increased their hydrophobicity. • Coatings with 20 wt% biocarbon preserved most their water repellence post-weathering. [ABSTRACT FROM AUTHOR]

This study proposed an impregnation method that can dredge the internal liquid flow paths of poplar(Populus L.) wood to achieve a high degree of densification. The permeability of poplar wood was improved by opening the circulation paths from the inside-out through the decomposition and expansion of sodium bicarbonate. A high concentration of sodium silicate was achieved by a vacuum-impregnation process. An in situ reaction produced silica that filled the tiny pores of the cell walls, and some filled the larger pores, such as tube pores and cell cavities. Combined, this resulted in highly-densified modified poplar wood. Macroscopic and microscopic morphological observations showed that the filling rate of the agent inside the poplar wood was extremely high, with a WPG (weight percentage gain) of 65.2 %. Due to the densification of poplar wood, the mechanical properties were greatly improved. The FT-IR (fourier transform infrared) and XRD (X-ray diffraction) results showed that some sodium silicate was chemically bonded to the cell walls, and the penetration of the agent into the crystalline region slightly decreased the relative crystallinity of the modified poplar wood. The poplar pores were filled with a large amount of the inorganic material, and the flame retardant and smoke suppression performance was greatly enhanced. The total heat release was reduced due to a decrease in the amount of combustible components. The good heat absorption and insulation ability of the inorganic material allowed the poplar wood to more easily form a char layer, which hindered the release of smoke and the spread of fire. Densified poplar is a green high-strength flame retardant material that may be widely used in interior furniture and wood-based construction materials to realize the high-value utilization of poplar wood. [Display omitted] • Enhancement of internal permeability of poplar wood by gas expansion. • A method to fill multi-size pores inside poplar wood to achieve densification. • Improved the mechanical and flame retardant properties of poplar wood. [ABSTRACT FROM AUTHOR]

Wood is the raw material used in the production of paper and building materials. It also plays an important role in human productivity and survival. However, the regulatory mechanisms of wood formation remain unclear in woody plants. In this study, we selected two poplar clones with different growth rates from the same full-sib family and performed SMRT and Illumina sequencing. We obtained 218,439 consensus reads and 50.73 G Illumina clean reads for subsequent analysis. A total of 4032 novel genes, 6587 alternatively spliced (AS) genes, 34,895 AS events, and 3602 long noncoding RNAs (lncRNAs) were identified. Moreover, 2545 genes, 89 lncRNAs, and 554 AS events were found to be differentially expressed in the two clones. Furthermore, we found that 56 and 38 genes involved in wood formation could undergo alternative polyadenylation (APA) and AS, respectively. In addition, 377 lncRNAs have the potential to regulate wood formation. This study reveals potential factors that regulate wood formation at the transcriptional level and provides new insights into wood formation. • We explored the difference at the transcriptional level of two poplar clones from the same full-sib family. • We found some genes involved in wood formation could undergo APA and AS events. • We found long non-coding RNAs could regulate wood formation. [ABSTRACT FROM AUTHOR]

Wood is an attractive, versatile, and sustainable construction material with excellent strength to weight ratio and a lower carbon footprint than other construction materials. One of the most important requirements in manufacturing engineered wood products (EWPs) and efficiently applying timber resources is achieving durable and mechanically stable bonds. Various types of adhesives have been used to produce wood products, and recently the application of one-component polyurethane (1C PUR) adhesives has obtained an increased market share in the EWPs industry because of its advantages like being formaldehyde-free, bonding of wood at high-moisture content, curing at ambient temperatures, and invisible glue line. 1C PUR adhesives have been used in bonding softwoods, hardwoods, preservative-treated, acetylated, and heat-treated wood. However, some drawbacks exist, such as their creep, especially temperature-dependent creep, thus also their behavior in fire, this being due to the intrinsic chemical structure of most, but not all, 1C PUR adhesives. Moreover, 1C PUR adhesives show good performance in bonding wood to dissimilar materials such as fiber-reinforced polymer (FRP). In case of the need for bonding high-density woods, woods with high extractive contents, or specific characteristics requirements, applying primers can improve the bondline quality. This paper explores the characteristics of 1C PUR adhesive, examines recent studies on their application, and offers a thorough analysis of the impact of manufacturing factors, bonding options, and 1C PUR adhesives performance in the EWPs industry. [ABSTRACT FROM AUTHOR]

Wood is one of the most commonly-used and sustainable construction materials, but it is flammable in nature. Pre-charring is an ancient approach used to protect wooden construction materials against biochemical impacts, but its effectiveness in improving fire performance is still poorly understood. This work proposes a novel method to generate engineered wood with a uniform and robust surface char layer through slow pyrolysis under low thermal irradiation of 20 kW/m2. We found that the flammability of the pre-charred wood can be significantly reduced under higher irradiations up to 50 kW/m2 by increasing the ignition time by up to seven-fold and doubling the ignition temperature to about 670 °C. For the tested wood species (Merbau), we quantify a minimum char-layer thickness of 6 ± 1 mm to achieve effective fire retardancy. The fire hazards of pre-charred wood are also mitigated significantly, where observed flames become weaker, thinner, and bluer than that of the virgin wood. The peak heat release rate of burning pre-charred wood is reduced by over 50%, helping maintain the fire resilience of timber structures. This work quantifies the fire performance of pre-charred wood, highlighting a promising direction toward fire-safe timber construction materials. • Novel engineered woods (Merbau) with robust pre-charred layers are developed. • Minimum char-layer thickness to achieve effective fire retardancy is 6 ± 1 mm. • Thermal inertia (fire-retardant performance) is extraordinarily improved. • Ignition delay time, ignition temperature and ignition heat flux all increase. • Fire hazards of the pre-charred wood are reduced significantly. [ABSTRACT FROM AUTHOR]

In recent years, research articles involving molecular dynamics simulations of construction materials have grown significantly in number. The growth reflects an emerging need to understand microscopic physical and chemical processes, which are fundamental to further improve the macroscopic performance of construction materials. Nano-engineering, as a concept about manipulating material structures for creating new materials or modifying existing materials, highly depends on the understanding of materials at the nanoscale, where molecular dynamics simulation becomes an effective and powerful investigation tool. In this paper, the applications of molecular dynamics simulations in understanding the fundamental deformation mechanism of various construction materials including concrete and cement, fiber-reinforced polymers and related bonded systems upon nano-engineering approach are presented. In addition, the study on nature materials towards their structural morphology and functions at the atomistic level is illustrated so as to inspire the future development of advanced construction materials. The challenges and innovations associated with nano-engineering are also discussed. [ABSTRACT FROM AUTHOR]

Renewable building materials may partially offset the intensive use of materials from finite resources, with the advantage of biodegradability and carbon take-up. Thermally modified wood (TMW) provides an appropriate service life for easily replacing elements of façade systems, which do not require high mechanical strength. In this study, TMW underwent one year of natural weathering conditions and on the other hand, eighty accelerated aging cycles, to determine potential changes of relevant properties of TMW in service. The results showed a positive effect of TMW when exposed to outdoor conditions, with a stable MOE (values mathematically corrected), lower reduction rate of MOR and more constant color parameters than untreated wood. Furthermore, the thermal degradation analysis showed that the mass loss in TMW was not compromised by the weathering tests. These stable properties over time provide favorable perspectives for TMW as potential construction element for outdoor applications. [ABSTRACT FROM AUTHOR]

A new formulation is proposed for describing the moisture sorption hysteresis in lignocellulosic products. This model introduces the concept of gripped-box. This concept allows complex experimental pathways to be fitted with only two adjustable parameters, including the closure of scanning loops without any pumping effect. The product history is embedded in a unique internal variable, which defined the actual window of interest. The formulation proposed in the present work can be easily implemented in existing computational softwares. Based on comprehensive experiments, the model parameters were defined for five lignocellulosic materials largely used in the building construction. [ABSTRACT FROM AUTHOR]

There are characteristics unique to natural materials such as timber that must be dealt with carefully to develop successful sound insulation prediction models. Timber has low internal losses typical of low-density building materials but with material properties that vary according to growth conditions. To study these factors in cross laminated timber (CLT) products, orthotropic thin plate and isotropic thick plate models are investigated. Equivalent elastic moduli are obtained using two methods from values and limits provided in the timber standards and literature, or by the manufacturer. The equivalent moduli are used to calculate the sound insulation of three- and five-layer CLT plates. Appropriate upper and lower limits are calculated from the combined material parameters and compared with sound insulation results measured in accredited laboratories for the first time. EN ISO 10140 test standards require that surface density of the sample be documented in the laboratory; additional precision information such as the fifth percentile of the material density is not required. However, considering the limits on the internal loss factors and elastic moduli only in the thin plate sound insulation model, gives a poor overall prediction performance (23.6% within the upper and lower limits). In this paper we combine the limits on elastic moduli, internal loss factors, and density. With these combined parameters the prediction is improved; less than half of the measured sound insulation values fall within the upper and lower limits of a typical thin plate model (44.0%). The single figure sound reduction index values are underestimated in seven out of nine cases. The prediction is further improved when a thick plate model is considered. There are several layers of complexity in the measurement and modelling conditions that must be carefully considered. The contributions from these compounding factors are discussed, and additional moduli and density parameters are proposed for inclusion in the literature and standards. [ABSTRACT FROM AUTHOR]

[Display omitted] • The preparation of transparent wood was combined with a super-hydrophobic coating to give transparent wood better self-cleaning performance and promoted its application in the field of optoelectronics. • The silica particle size was controlled at 50–200 nm to ensure the transparency of the superhydrophobic coating and avoid the influence on its light transmittance. • Improved the pollution resistance of transparent lignin composite material, and ensured its resistance to UV and heat, thus promoting its application in the outdoor field. Transparent wood has broad application potential in new technology fields such as electronics, optics, and energy. The super-hydrophobic and self-cleaning properties of transparent wood are of great significance for exploring lightweight building materials or electronic devices. Herein, we reported a method of preparing super-hydrophobic transparent wood (STW) based on delignified wood template and explored its application in the next generation of smart photovoltaic panels. In this work, the obtained STW had a thickness of 2 mm and a transmittance of 93.7 %, which had a superior transmittance effect at the visible wavelength. Furthermore, the water contact angle (WCA) of it was 163.5°, and the water sliding angle of the surface of STW was 5.2°, which could realize self-cleaning by hydration induction. Meanwhile, it had outstanding pollution resistance, durability, and stability under heat treatment and UV aging test conditions. This uncomplicated and unpolluted method for the preparation of super-hydrophobic transparent wood has a broad application prospect in the fields of electronics and optical devices. [ABSTRACT FROM AUTHOR]

[Display omitted] • The composite wood-based phase change material is prepared by mimicking natural bone. • This composite is 3–39 times stronger than conventional phase change materials. • The mechanical mechanism is explored at nanocale by molecular dynamic simulation. • The composite shows a large latent heat, temperature regulation and thermal stability. Phase change material (PCM) with thermal energy storage capacity and automatic temperature regulation hold tremendous potential for construction energy conservation. However, conventional PCMs often exhibits liquid leakage, volume change and insufficient mechanical property, which are prone to load-bearing accidents, hindering their application as an engineering building material. Herein, inspired by the oriented "brick-and-mortar" structure in bone, we report a facile strategy to develop a form-stable, ultrastrong and highly energy-stored composite wood-based PCM (PWPCM) via in-situ polymerization of polyurethane-based PCM using hierarchically well-aligned wood as bio-template. PWPCM showed high tensile strength of 81.9 MPa and elastic modulus of 10.2 GPa along the longitudinal direction due to the well-aligned cellulose nanofibrils arrays and the "brick-and-mortar" structure based on strong intermolecular bonding between cellulose and PCM chains, as confirmed by molecular dynamic simulations. PWPCM was 73.4 times stronger than pure PCM, and 4–40 times as high as most conventional PCMs ever reported, representing one of the strongest composite PCMs. Benefited from the high-loading PCM, PWPCM showed wide phase transition temperature range and high enthalpy of 116.1 J/g, together with outstanding temperature regulation and shape-stability. This work provides a promising strategy for fabricating low-cost, eco-friendly, strong wood-based PCM for energy-saving construction and intelligent agriculture. [ABSTRACT FROM AUTHOR]

Bioeconomy addresses the triple balancing challenge posed by the Paris Agreement: inducing additional GHG mitigation alongside biophysical carbon dioxide removals, while keeping fossil carbon in the ground. The use of woody plants as construction materials could simultaneously address this challenge: CO 2 is absorbed through photosynthesis, while wood-based products provide mitigation by replacing either petrochemical materials such as plastic boards or energy-intensive materials like bricks. This study combines, at the scale of France, static and dynamic life cycle assessment with soil carbon simulations to investigate the long-term environmental performance of using, as input for the building sector, black locust (Robinia pseudoacacia L.) planted on "carbon vulnerable lands". These are areas specifically selected for their low soil organic carbon (SOC) levels and low potential to interfere with food security. After the consecutive cultivation of three rotations, black locust was shown to stock an additional 92000 kg ha−1 of carbon in soils as SOC. The mitigation effect from the plastic board replacement is the major contributor to the assessed environmental impacts, including climate change, leading the black locust system to generally perform better than the reference system where the carbon vulnerable areas are left as they are with their initial vegetation. Considering that cultivation starts in 2022, the dynamic evaluation of the global mean temperature change (GMTC) shows that the black locust system results in net negative emissions in the near- and mid-term, but with a GMTC overshot in the second half of the century. Even if a considerable carbon stock is created through time (e.g., 81% and 39% of the carbon captured by photosynthesis, in 2050 and 2100 respectively), the GHG emissions stemming from manufacturing and end-of-life processes were shown to offset the benefit of carbon capture. [Display omitted] • Black locust plantation and utilization in buildings induce negative emissions. • Black locust system yields greater climate benefits than the initial vegetation. • Plastic board replacement explains the superior performance for 13/16 impacts. • By 2136, the largest temperature reduction of 3.9E-09 K per ha is simulated. • 15% of the carbon captured by 3 rotations is still stocked after 260 years. [ABSTRACT FROM AUTHOR]

• Wood was reengineered into a high-strength and light-weight bio-composite material. • Wood was delignified through an efficient ultrasound-assisted organosolv process. • The composite's epoxy resin matrix was synthesized from the extracted lignin. • Wood-based composite showed specific mechanical properties in the range of metals. • Compositing improved wood's hydrophobicity, antioxidation and thermal stability. The preparation of wood composites involves long preparation steps and non-renewable matrices while generating lignin waste without high-value utilization. Here, we present a reengineering approach to developing a high-strength and lightweight bio-composite material through fractionating natural wood into highly porous delignified wood (DW) and lignin, synthesis of a lignin-based epoxy resin (LER), followed by composting the DW and the LER. The newly developed wood-based composite has drastically improved properties of hydrophobicity, antioxidation and thermal stability, and more notably extraordinary mechanical properties superior to many metal alloys. Hence the reengineered wood composite developed can be a renewable functional material for structural applications. [ABSTRACT FROM AUTHOR]

Reducing carbon emissions from building materials production and operation would have a huge impact on the global energy and environment. Wood presents great potential as an environment-friendly building material due to its relatively low carbon emission and cost. However, several issues, including the mechanical anisotropic, extremely low optical transparency, and single function, greatly hinder the further application of wood as a building material. Herein, hybrid wood-derived laminates were dedicatedly fabricated through top-down strategy using bulk wood as raw materials. The obtained hybrid laminates demonstrate low anisotropic mechanical factor of 1.14, which was only one-eighth of the corresponding value of natural wood (8.07). Besides, such wood laminates exhibit moderate light permeability (35% of transmittance), which could provide with softening of glare and uniform illumination, thereby reducing the power consumption. Also, the remaining wood cellulose and incorporated inorganic microspheres in our laminates backscatter solar radiation and emit thermal, resulting in continuous cooling with a dT of 12 °C under one solar intensity irradiation. Combined with excellent water stability and self-cleaning property, our laminates are expected to be used as the building blocks for the construction of energy-efficient buildings with low carbon emission. • Rational design and manufacture of hybrid laminates with PRC for carbon reduction. • A low anisotropic mechanical factor of 1.14 was achieved by directional stacking. • Moderate light permeability and uniform scattering contributed to indoor lighting. • The hybrid laminates remained 12 °C below the natural wood at one solar intensity. • Self-cleaning and water stability bring additional benefit to energy-saving building. [ABSTRACT FROM AUTHOR]

Forest management is an important tool for GHG mitigation by representing three carbon pools: living biomass, forest soil, and wood-based products. Additionally, increasing attention has been given to the potential for wood products to substitute fossil-intensive products as a climate mitigation strategy. The goal of this paper is to analyse the theoretical GHG effects of fully replacing four common non-wood products with wood-based products of 'low' and 'high' technology options that have a similar functionality: (1) Spruce particle board substituting polyurethane (PU) foam insulation board; (2) spruce cross-laminated timber beam (CLT) substituting steel beam; (3) birch energy wood substituting electric heating; and (4) birch plywood substituting plaster board. The analysis was based on forestry in Western Norway as a case study, where forests typically consist of naturally generated birch and expanding areas of planted Norway spruce. In this study we compare wood products derived from paired stands of Norway spruce and downy birch. The analysis showed that spruce gave a higher theoretical substitution effect relative to birch for the selected pairs of woody and non-woody products. CLT substituting steel beam gave the highest substitution effect, approximately 15% higher than particle board substituting PU foam board. The theoretical substitution effect in mass units of carbon per kg wood product for the two spruce wood products was approximately 17 times higher relative to substituting Norwegian hydro energy-based electric heating, whereas plywood substituting plaster board may in fact increase GHG emissions. As the gross emissions were relatively similar for the birch plywood and the spruce particle board, the major substitution effect was related to the avoided emission of the non-woody product rather than to the tree species per se. The paper concludes that the choice of product to be substituted was the key factor that determined the final substitution effects. Furthermore, the study showed that transportation was the single most important factor that affected the emissions between planting and delivery of the timber at production gate. The analysis enables informed decisions related to CO 2 -emissions at the various steps from tree planting to wood conversion, and underline the importance of informed decision related to the choice of substitution products. • We compared the theoretical substitution effect of four wood products (spruce particle board, spruce cross-laminated timber beam, birch energy wood, and birch plywood) for the case of Western Norway. • The spruce products gave a better substitution effect relative to birch, and cross laminated beam from spruce substituting steel beam had the highest substitution effect amongst the four selected alternatives. • Avoided emission was the major determining factor for the calculated substitution effect, thus, the estimated substitution factors were mainly related to the selected product to be substituted rather than to the tree species used as raw material. • Emissions related to transportation was the single most important emission factor of all forestry activities, amounting to approximately 48% of the estimated emissions. Export by boat suggested a potential increase in the transport emissions of 62%. [ABSTRACT FROM AUTHOR]

Wood, as a naturally-grown material, exhibits a highly anisotropic and inhomogeneous material structure, with a complex wood fibre distribution influenced by randomly occurring knots. Thus, for the prediction of effective strength properties of wood, advanced computational tools are required, which are able to predict as well as consider multidimensional strength information at different scales of observation. Within this work, three such computational methods will be presented: an extended finite element approach able to describe strong strain-softening and, thus, reproduce brittle failure modes accurately; a newly-developed limit analysis approach, exclusively describing ductile failure; and an elastic limit approach based on continuum micromechanics. All three methods are applied to earlywood and latewood unit cells and to clear wood, finally yielding effective failure surfaces for a range of multidimensional stress states. These failure surfaces are compared with each other and with experimental results from biaxial tests. Based on these comparisons, the strengths and weaknesses of the three computational methods are discussed, and their applicability to wood is evaluated. The extended finite element method is a powerful technique that allows for a very realistic description of strength-governing processes. Nevertheless, its complexity and high computational effort prevent widespread use in the engineering field. The plastic limit analysis and elastic limit approaches, however, show good predictive performance compared with the extended finite element method, coupled with excellent efficiency and stability. In this study it is found that together, the latter two approaches are able to enclose the experimentally-obtained failure regions for clear wood almost perfectly, while also delivering new insights with respect to the ductile failure potential of wood. The conclusion can be drawn that there exist promising computational methods that are capable of delivering reliable multidimensional strength information for wood and, subsequently, will enable effective strength predictions for wooden boards and wood-based products. Finally, this work is intended as a contribution to performance-based optimisation of wooden structures, a necessity for wood to become competitive with respect to other building materials. [ABSTRACT FROM AUTHOR]

Mechanical pretreatment is an effective process for chemical or biochemical conversion of woody biomass. The deconstruction features of the wood cell wall play an important role in its chemical or biochemical processing. In this work, we evaluated the wood cell wall fracture in the early stage of mechanical pretreatment process conducted with various initial moisture contents. Electronic microscopy (i.e., SEM and TEM) and confocal laser scanning microscopy (CLSM) were used to visualize the cellular structure changes due to cell wall fractures. Results reveal that the enzymatic digestibility of micronized wood produced from different initial moisture contents was improved by 2–6 folder than that of the raw material. The types of cell wall fractures after mechanical pretreatment were distinguished by the initial moisture contents of wood. In wood samples with lower moisture content, interwall fracture occurred predominantly at the middle lamella region, while intrawall fracture occurred primarily at inner cell wall layers, with sever breakage in wood fibers for high moisture content samples. Differences in the distribution of surface chemical composition also resulted from different cell wall fractures. Lignin preferentially covered the fracture surface of low-moisture content samples, while carbohydrates were more predominate in high-moisture content samples. These morphological and structural alternation contributed to improving enzymatic digestibility of micronized wood. Findings from this study demonstrate how mechanical pretreatment modifies the fracture features of wood cell wall for further chemical/biochemical reactions. [ABSTRACT FROM AUTHOR]

The use of wood and wood-based products has positive effects on environmental considerations, e.g., climate change mitigation or the reduction of waste and other emissions. With regard to climate change mitigation, the benefit of wood-based products is based on storage effects and substitution effects. Especially in the German construction sector, large quantities of wood are used. Moreover, in this sector, products often remain in use over several decades. For these reasons the main objective of this paper is to provide information on factors influencing the choice of construction materials in the German construction sector for policy makers and market participants. The chosen method for estimating the interactions between prices of wood-based products, the prices of the associated substitutes, and the use of wood in the construction sector is the calculation of elasticities of demand. The analysis focuses on two product groups: (1) buildings as a whole and (2) different construction materials, such as bricks or sawnwood. In the field of residential and non-residential construction, the current state of knowledge for Germany is for the first time supported and partly quantified by mathematical methods. Non-significant results in the field of residential construction give an indication that the choice of building materials is based on non-quantifiable and statistically non-available factors. Elasticities for non-residential buildings in Germany are estimated for the first time. The estimated values are plausible in size and sign. It is evident that the tested products are substitutes. Hence, relevant information can be derived for market participants and related policies. [ABSTRACT FROM AUTHOR]

In the area of chemical applications in construction they are new materials, which do not have equivalents in nature. Polymers can be used to successfully replace traditional materials of the wood, metal or ceramics types. Among the polymers, one of the most important groups are epoxy resins, whose popularity stems from a combination of excellent mechanical and chemical properties. At the same time, the characteristics of epoxy resins are strongly dependent on the type and quantity of curing agent. The article presents the results of research on epoxy mortar modified with PET glycolisate, hardened by using three different amine curing agents. Characteristics such as flexural and compressive strength and water absorption were determined. The results were subjected to statistical analysis and compared, indicating the curing agent that allows the obtainment of a composite that is characterized by the highest values of the tested parameters. [ABSTRACT FROM AUTHOR]

Ordered mesoporous carbon materials with diverse architectures including flakes, fibers, rods, gyroids, gyroids with nanoparticles, and spheres were successfully prepared from liquefied wood by controlling the nucleation and growth process through modulating the concentration of HCl via a facile hydrothermal/soft templating method. [Display omitted] • Well-defined gyroid-like ordered mesoporous carbon materials were synthesized through a facile hydrothermal/soft templating method. • Biomass derived liquefied wood was used as the carbon precursor. • The morphology of ordered mesoporous carbon materials can be readily designed via the nucleation and growth process by changing the concentration of HCl. A HCl concentration-controlled hydrothermal/soft-templating strategy is proposed to prepare ordered mesoporous carbons (OMCs) with diverse morphologies from flakes to gyroids then to spheres by using liquefied wood as a carbon precursor. The effect of nucleation and growth process on morphology change was systematically studied. Results showed that an accelerated nucleation rate and a transformation of self-assembly pattern from slow and weak aggregates to fast and strong assembly are achieved in accordance with increasing HCl concentration. Detailed mechanism studies reveal that a reaction solution without seed nuclei formed at the initial stage of the hydrothermal process under low HCl concentration will lead the micelles to slowly self-assemble into microscale flakes, whereas a high HCl concentration will make the micelles rapidly self-assemble into rodlike micelles and further grow along the surface of the initially formed seed nuclei to produce nanoscale products with an annular structure. The OMCs with highly ordered p6mm mesostructure synthesized at a proper HCl concentration of 1.61 M exhibit higher electrochemical performance than the less ordered OMCs. The detailed study of nucleation and growth mechanism provides new understanding of controllable design and synthesis of OMCs with desired morphology. [ABSTRACT FROM AUTHOR]

Various construction materials and interior equipment contain volatile organic compounds (VOCs). Their higher quantities in indoor air are linked to poor health consequences and are controversial regarding health risks, given that people spend so much time indoors. As a result, VOCs in indoor air cause concern regarding sick building syndrome. From a historical perspective, wood and wood-based panels have been frequently employed. Nonetheless, wood appears to be a product and a material of the future in today's world. The emission of VOCs from wood and wood products is essential when assessing the impact of different materials on the indoor environment. The emission rate is affected by both the wood species and the boundary circumstances (drying, storage, etc.). The issue of VOCs emitted from wood, and wood-based panels are addressed in this review paper. The most prevalent VOCs were listed. The advantages and limits of using VOCs for analytical determination from these composites are discussed. [Display omitted] • VOC emissions from wood-based materials are measured qualitatively and quantitatively on a large scale. • Evaluation of volatile organic compounds from wood-based composite panels. • Assessment of volatile organic compounds during interspecific interactions. • Effect of volatile organic emissions from building and furnishing materials. • Evaluation and analysis of pressed wood, cellulose-based papers, and wooden bark were also reviewed. [ABSTRACT FROM AUTHOR]

Chamaecyparis formosensis Matsumura and C. obtusa var. formosana (Hayata) Rehder are important, precious, and well-known species grown in Asia. Renowned for excellent natural durability, their wood logs are regularly used as quality building materials or furniture. However, these two species have similar appearances, e.g., leaf, twig, wood, hardly distinguishable by the naked eye. The purpose of the present study is to phytochemically differentiate these two species using volatile compounds from the woods. Wood essential oils were obtained by 6-h hydrodistillation. The chemical composition was identified by GC-MS, and semi-quantification was carried out to determine the content of each compound. Furthermore, compounds with a significantly higher content than those of the other species were screened by t -test and principal component analysis (PCA). Results from semi-quantification and t -test showed that C. formosensis contained higher content of cis -myrtanol (ratio 37.1 ± 19.8), chamaecynone (11.0 ± 6.7), and α-eudesmol (8.5 ± 7.9), while C. obtusa var. formosana comprised mainly of α-terpineol (30.2 ± 10.1) and borneol (24.0 ± 16.1). Moreover, PCA results showed that the representative compounds of C. formosensis were cis -myrtanol and chamaecynone, while those of C. obtusa var. formosana were α-terpineol, borneol, and α-cadinol. Taken together, the above-mentioned results suggested significant compositional differences between these two species. For distinguishing the two kinds of wood, C. formosensis should be easily identified by its two characteristic compounds: cis -myrtanol and chamaecynone; while C. obtusa var. formosana could also be distinguished by its characteristic compounds: α-terpineol and borneol. [Display omitted] • Chemical compositions of wood essential oils of the two species are differentiated. • C. formosensis and C. obtusa var. formosana have their own characteristic compounds. • The two species can be distinguished from each other using indicator compounds. [ABSTRACT FROM AUTHOR]

Adhesive bonding is increasingly being considered by engineers for load-bearing joints to complement, or supplement, traditional mechanical fasteners for a large variety of structural materials, including fibre-reinforced polymers, timber, and steel. However, practitioners are still largely applying analysis and design methods, including codes and standards, that rely heavily on fudge factors. This is not due to the relative novelty of the joining technique, and the complexity of the associated mechanics. This paper guides the reader through some of the most important aspects of adhesively bonded joints, and the reasons why classical mechanics can only be applied in conjunction with fudge factors. Subsequently, the principles of fracture mechanics (FM) are presented; it is shown that, despite its conceptual strengths, FM is rather difficult to implement, as it introduces mechanical concepts practitioners are not familiar with. Then probabilistic methods (PM) are introduced; it is shown that PM can be considered as an extension of classical mechanics, as they can be easily implemented as a post-processing routine of the latter. Additionally, it is shown that PM, unlike FM, neither require specific test procedures for characterisation, nor complicated numerical analyses. Lastly, the paper offers a step-by-step guide for the implementation of PM for the dimensioning of adhesively bonded joints. The second part of this paper illustrates the latter analysis and design of adhesively bonded joints on a series of examples involving FRP, timber, and steel. [ABSTRACT FROM AUTHOR]

This study investigated carbonate pre-treatment of wood followed by densification for producing advanced wood structural materials. Poplar wood blocks of 100 mm long and 20 mm wide with thickness of 10 mm were treated with sodium carbonate with and without sulfide at different carbonate loadings at 150 ºC for 30 min. Carbonate effectively removed lignin and hemicelluloses which facilitated subsequent wood densification for improving wood mechanical properties. Comparing with wood pre-treatment using sodium hydroxide, carbonate pre-treatment improved wood yield but achieved similar level of wood mechanical strength. Considering sodium carbonate is the key ingredient of commercial pulping process liquors such as spent pulping liquor (black liquor) and green liquor (an aqueous solution of the dissolved inorganic smelt from the combustion of concentrated pulping spent liquor), the present study indicated that low cost, effective, and cleaner wood pre-treatment can be achieved using spent process liquors rather than fresh and expensive sodium hydroxide (white liquor). Laboratory black liquor was used to pretreat the same poplar wood blocks, the good wood mechanical properties of the treated wood after densification confirmed this hypothesis. The practical significance of the present study is the utilization the residue alkali in spent process liquors rather than fresh NaOH for wood pre-treatment to reduce environmental impact. Furthermore, the spent liquor after wood-pretreatment can be directly feed into commercial pulp mill chemical recovery system to reduce capital and operation cost. [Display omitted] • Carbonate wood pre-treatment for subsequent wood densification. • Carbonate is effective in delignification and dissolve hemicelluloses. • Pulping spent liquor and green liquor for wood pre-treatment for densification. • Carbonate and pulping liquor pre-treatment improved wood mechanical properties after densification. [ABSTRACT FROM AUTHOR]

Agricultural fiber sources, such as wheat straw, are promising lignocellulosic feedstocks for the generation of renewable substitutes for synthetic materials (e.g., plastics, construction materials, biofuel, and other biorefinery products). The interest in the utilization of lignin has increased rapidly during the last years; the number of publications increased more than five times between 2000 and 2020. The number of publications concerning lignin from wheat straw follows the general trend with an increasing scientific interest in lignin but comprises less than 5% of the total lignin publications. The structure and morphology of lignin in straw and wood differ between the different species. The monolignol composition and spatial location in plant tissue are notably different, as well as the nature and abundance of lignin-carbohydrate linkages involving p-coumaric acid (pCA) and ferulic acid (FA) units in wheat straw lignin. To further enable the utilization of wheat straw as a resource for bio-based materials, a solid understanding of the wheat lignin structure and composition is required. This review aims to consolidate the state-of-the-art in wheat lignin and focuses on lignin and its distribution, fundamental chemical structures, and morphology in wheat straw and compares these features with lignin in wood cell walls. • The state-of-the-art in wheat lignin is consolidated. • Wheat straw lignin has primarily β-O-4 linkages and fewer C-C than wood lignin. • Wheat straw and wood differ clearly in lignin distribution, structure, and morphology. • Main units in wheat straw lignin are (H,G,S), (G) in softwood, and (G,S) in hardwood. • Lignin-carbohydrate linkages are of great significance to biomass refinement. [ABSTRACT FROM AUTHOR]

Hemicellulose plays a vital role in nature wood matrix. Here, we first demonstrate the significance of hemicellulose for improving the microstructure and macroscopic properties of transparent wood (i.e. wood/polymer composite), an emerging structural material. A delignified basswood templet with high hemicellulose content (~23 wt%) and well-preserved cellulose supramolecular structure was prepared via a peracetic acid-based process. This hemicellulose-rich delignified wood templet possesses nearly intact cell wall structure and sufficient space in the lumen and middle lamella for petroleum-based polymer space-filling. Consequently, the resultant hemicellulose-rich wood/PMMA composite exhibits high optical transmittance (~85 %), medium haze (~72 %), acceptable optical stability as well as excellent mechanical strength (tensile strength of 165.3 MPa and toughness of 1.65 MJ/m3), benefitting from the absence of microstructural defects and heterogeneity in the matrix. It is anticipated that our study would provide new insights into the fabrication of advanced transparent wood material from the point-of-view of wood chemical composition. [Display omitted] • Favorable wood cell wall structure is achieved by preserving native hemicellulose. • Hemicellulose is vital for regulating microstructural characteristics of transparent wood. • Hemicellulose-rich transparent wood has enhanced optical and mechanical performance. • A new insight into eco-friendly fabrication of advanced transparent wood is provided. [ABSTRACT FROM AUTHOR]

[Display omitted] • Thermal-responsive shape manipulatable TW is fabricated with delignification and impregnation of vitrimers. • Exchangeable dynamic thiocarbamate bonds (TCBs) are introduced into TW system. • Processable TW possesses hierarchical framework and tight interfacial interaction. • TW has ideal transparency, mechanical property, and shape manipulation ability. • Shape memory TW can conduct light management, thermal insulation and UV absorption. Transparent wood (TW) combining unique anisotropic structures with advantageous properties has many promising applications in advanced building fields. However, achieving shape manipulatable TW with high-performance remains a great challenge. Interestingly, vitrimers with dynamic covalent adaptable bonds presents a fascinating blueprint for prompting the advancement of multifunctional TW. Herein, a high-performance shape manipulatable TW with exchangeable dynamic thiocarbamate bonds (TCBs) was fabricated by the delignification and subsequent impregnation of stimuli-responsive vitrimers through solvent-free thiol-isocyanate click reaction by a low temperature solidification. The as-prepared TW exhibited impressive properties, for example, remarkable optical transparency (transverse transmittance of ≈90 % and haze of ≈90 %), attractive light management ability, low thermal conductivity (≈0.30 W·m−1·K−1), excellent mechanical properties (longitudinal tensile strength of 37.24 MPa and flexural strength of 48.88 MPa), and fascinating shape manipulation, which make our TW has promising potential applications as energy efficient and intelligent building materials. In addition, this feasible strategy provides a new avenue to design and combine multi-functional TW with high-performance to expand its applications in building construction. [ABSTRACT FROM AUTHOR]

Transparent wood (TW) is a promising light and thermal management material that has enormous potential for energy-efficient engineering applications. However, almost all the polymers currently used to fabricate TW fall under the thermosetting or thermoplastic category, exhibiting extremely monotonous performance and lack of intelligence. Herein, a smart shape-reconfigurable TW is developed through infiltration the polythiourethane covalent adaptable networks (PTU CANs) into the delignified wood (DW) scaffolds. Benefiting from the solid-state plasticity and thermadapt shape-memory behavior of PTU CANs and the highly aligned cellulose nanofibers of the DW scaffolds, the resulting TW exhibits reconfigurable shape memory behavior, excellent optical properties (transmittance of ∼90% and tunable light guiding effects), and low thermal conductivity (212.8 mW m−1K−1). In addition, the tensile strength, modulus, and toughness of TW are 60.14 MPa, 2.09 GPa, and 1.19 MJ m−3, respectively. Moreover, the reconfigurable shape-memory performance of the TW allows it to be used as a smart actuator for designing a fire alarm system. Compared with traditional TW, the TW reported in this work not only maintains high optical transmittance, but also exhibits excellent reconfigurable shape memory properties, which can promote the high-value utilization for TW. The incorporation of the shape reconfiguration, light guiding, energy saving, and fire alarm actuating properties to the TW opens a new avenue for the design and development of advanced functional and intelligent building materials. [Display omitted] • Reconfigurable shape-memory transparent wood (TW) was developed. • TW shows high transparency, low thermal conductivity, and high mechanical strength. • TW exhibits tunable light guiding effect due to its shape-reconfiguration ability. • TW can be used as a smart actuator to design a firm alarm system. • It opens a new avenue toward the design of a smart and advanced building material. [ABSTRACT FROM AUTHOR]

The use of wood-based products might contribute to the mitigation of climate change and resource depletion in the building sector. However, the increasing demand for wood-based products might generate a trade-off affecting biomass availability, forest ecosystem services, and the climate change mitigation potential of forests. Therefore, it is important to couple the use of wood-based products with the adoption of circular economy strategies. Upstream strategies can facilitate the future reuse of wood elements in new buildings, whilst downstream strategies aim at the reuse wood elements originating from demolished or disassembled buildings, in new buildings. The aim of this study was to identify patterns describing upstream and downstream strategies currently adopted in architectural practice. A sample of real-world case-study buildings was identified and the respective designers were interviewed. The interviews identified three patterns for upstream strategies, namely the reversibility of joints, independence of different building components and prefabrication, and two patterns for downstream strategies, namely the recovery of salvaged wood and adaptability of the building layout. Several challenges were also highlighted. The use of upstream and downstream strategies can increase the time (and costs) in the design and manufacturing phase. Downstream strategies can also be influenced by the quality of salvaged wood. Upstream strategies showed difficulties to comply with current building standards (e.g. acoustic standards). Finally, metrics and indicators are needed in order to measure the efficiency of wood recirculation in upstream and downstream strategies, as well as to support their implementation. • Coupling bio and circular economy can support the increased demand of bio-products. • Wood cascading, especially reuse, can increase the efficient use of wood resources. • The study focused on design strategies to facilitate the reuse of wood in buildings. • A sample of case-study buildings served to analyze strategies adopted by designers. • Strategies can focus on the future reuse (upstream) or post-use (downstream) of wood. [ABSTRACT FROM AUTHOR]

[Display omitted] • Benefits and limitations of balsa wood in sandwich structure construction are reviewed and summarised. • Engineering material properties and mechanisms responsible for the benefits and limitations of balsa core sandwich structures are discussed. • Benefits include environmental sustainability, low raw material cost, high specific mechanical properties, and thermal insulation properties. • Limitations include limited applicability of part processing techniques, impact, blast and fire performance, as well as water durability. • Topics for further research to advance balsa sandwich structures are discussed. Renewed efforts towards greater use of environmentally sustainable materials have created new opportunities for balsa wood (Ochroma pyramidale) to replace non-renewable, petroleum-based cores such as polymer foams in a broad range of sandwich structures. This paper reviews published research into the applications, manufacturing, microstructure, mechanical properties and in-service performance of sandwich structures with balsa wood cores. The benefits of balsa wood in sandwich structure construction are reviewed, including environmental sustainability, low raw material cost, excellent specific mechanical properties, and thermal insulation properties. The potential challenges of balsa cores in sandwich structures are also evaluated, including potential global supply chain issues, limited applicability of part processing techniques, impact, blast and fire performance, as well as water durability. Published research into the underlying properties and mechanisms responsible for the benefits and limitations of balsa core sandwich structures are reviewed. Topics for further research to advance the characterisation and applications of balsa structural sandwich materials are also discussed. [ABSTRACT FROM AUTHOR]

• Densified wood is obtained by delignification of NaOH/Na 2 SO 3 and hot-pressing. • Sodium silicate impregnated densified wood has good waterproof and excellent dimensional stability. • MOR, MOE and compressive strength of the modified wood increased by 5.0, 2.4 or 27.2 times, respectively. • The chemically pretreated wood exhibited superior fire-resistant performance after the impregnation with sodium silicate and densification. In terms of outdoor building materials, during the service, drawbacks of fast-growing poplar (Populus tomentosa Carrière) are susceptible to mildew, and cracking or great loss of strength due to its inherent hydrophilic and porous structure. Here we propose an effective method to prepare dimensionally stable wood with high mechanical strength and flame retardancy. This simple method consists of three main steps, i.e., chemical pretreatment to remove lignin and hemicellulose, vacuum impregnation with inorganic sodium silicate solution, and high temperature densification. The flexural strength, modulus of elasticity and compressive strength of the modified wood were increased to 322.5 MPa, 24.6 GPa and 228.5 MPa, which were counted to be the increases of 5.0, 2.4 and 27.2 times, respectively, compared with the unmodified wood. High mechanical strength of wood probably is caused by the densification and Si-O-Si bonding between cellulose nanofibers. The thickness swelling of moisture absorption at 30 days and water absorption at 72 h were measured to be 0% and 1.1%, respectively. It was shown excellent mechanical strength and dimensional stability compared to the natural wood. Moreover, the chemically pretreated wood exhibited superior fire-resistant performance after the impregnation with sodium silicate and densification. This simple, extensible, and effective approach provides huge potentials for the development of materials with high mechanical properties, excellent dimensional stability, and flame retardancy to be used as outdoor structural building components. [ABSTRACT FROM AUTHOR]