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Mildly delignified softwood holocellulose fibers featuring native tracheid fiber cell wall structure and high hemicellulose content are prominent building blocks for wood derived fiber-based materials. However, preserving the natural alignment of long softwood fiber is challenging since top-down structure-retaining delignified softwood is unstable as extensive removal of lignin from intercellular space induces cracking and disintegration of wood structure. Here we report the use of chemical crosslinking pretreatment to improve the intercellular bonding between softwood fibers, therefore preserving the integrity of the naturally aligned softwood fibers after delignification. The crosslinked softwood veneer was delignified with peracetic acid and further densified into transparent and high-density film by thermal compression. The obtained transparent film of naturally aligned softwood holocellulose fibers showed high optical transmittance of 71 %, high haze of 85 %, strong optical anisotropy, as well as high tensile strength of 449 ± 58 MPa and high Young's modulus of 49.9 ± 5.6 GPa. This study provides a facile approach to preserve the natural alignment of softwood fibers for the fabrication of high performance holocellulose fibers-based materials., QC 20240925

Poor condition of roofs in terms of decay of shingles and loss of tar-based surface treatments has been revealed in a number of churches at various geographical locations in mid-Sweden. The condition of tars obtained from shingles of selected churches in mid-Sweden were analysed and obtained data were compared with geographical locations of the churches. According to gas chromatography-mass spectroscopy result, dehydroabietic acid was the dominant compound found in the exposed tars from the churches except in church of Malung where similar amounts of retene was found. Oxidised resin acids were found in exposed tars from the churches but not in commercially available pit burned tar. Tar from church shingles had higher char residues than the pit burned tar which was totally consumed when heated under nitrogen gas up to 750°C using thermogravimetric analysis. Scanning electron microscopy with energy dispersive X-ray spectrometer analysis revealed higher amounts of silicates in some exposed tars; however, these compounds constituted only a minor portion of the organic matter in these specimens. Based on the data obtained in the study other factors rather than simply geographical location of churches seemed to be of importance to explain differences of the investigated properties of the church tars., Validerad;2024;Nivå 2;2024-06-27 (hanlid);Full text license: CC BY, Biobasedfire protection of wood panel for exterior conditions by using phosphorylated lignin from wheat straw

Locust bean gum, derived from the carob tree, was evaluated as a biobased adhesive in particleboard manufacturing, investigating the effect of adhesive amount, mat moisture content, and process parameters such as temperature and time. Single-layer particleboards prepared with locust bean gum showed that effective hydration of the polymer chains is necessary to achieve satisfactory interactions with wood and thus yield a sufficient particleboard strength. A mat moisture content below 30 % resulted in weak particleboards, which easily broke immediately after pressing. With increasing mat moisture content, while keeping the adhesive amount constant, the internal bond strength was increased. Moreover, with constant mat moisture contents (40 %), the internal bond strength increased when the adhesive amount was increased, even though not proportionally. With an increase from 9 % to 18 % adhesive, the internal bond strength was increased by more than 100 %. However, with a further increase in adhesive content from 18 % to 36 %, the increase in internal bond strength was statistically insignificant. Even with high mat moisture contents (35–45 %), larger lab-scale particleboards had internal bond strength that fulfilled standard requirements for P2 boards, commonly used for furniture in dry conditions (SS EN 312), when the pressing time was long enough (75 s/mm) to allow for water and vapors to be removed before releasing the pressure. Using biopolymers as adhesives, without extensive chemical modification and hazardous crosslinkers, could lead to a more benign and sustainable particleboard production. Since the chemistry and setting/curing processes of biopolymer-based adhesives differ from those of the fossil-based adhesives used today, increased understanding of how production parameters affect the properties of the particleboards prepared with biopolymers may pave the way for their better utilization in this field., QC 20231213

Birch has long suffered from a lack of active forest management, leading many researchers to use material without a detailed management history. Data collected from three birch (Betula pendula Roth, B. pubescens Ehrh.) sites in southern Sweden were analyzed using regression analysis to detect any trends or differences in wood properties that could be explained by stand history, tree age and stem form. All sites were genetics trials established in the same way. Estimates of acoustic velocity (AV) from non-destructive testing (NDT) and predicted AV had a higher correlation if data was pooled across sites and other stem form factors were considered. A subsample of stems had radial profiles of X-ray wood density and ring width by year created, and wood density was related to ring number from the pith and ring width. It seemed likely that wood density was negatively related to ring width for both birch species. Linear models had slight improvements if site and species were included, but only the youngest site with trees at age 15 had both birch species. This paper indicated that NDT values need to be considered separately, and any predictive models will likely be improved if they are specific to the site and birch species measured.

En enkel byggnad utan laster på sig, är en stabil byggnad. Om byggnaden saknarhorisontalstabilisering och en horisontell last läggs på byggnaden blir den omedelbartinstabil och man behöver därför införa horisontalstabilisering. I Sverige är denvanligaste orsaken till horisontella laster vinden, men i andra delar av världen finnsäven jordbävningar som också verkar horisontellt på byggnaden. I det här arbetet hardiagonalstagning, skivverkan och momentstyva förband undersökts förkontorsbyggnader med pelar-balkstomme i trä. Syftet var att undersöka hur mycketsystemen ändrar stabiliteten på de undersökta stabiliseringsmetoderna. För att undersöka detta har en referensbyggnad använts, som är byggd helt i trä ochsom använt sig utav diagonalstagning. Byggnaden modellerades i RFEM där de trevalda stabiliseringssystemen studerades. En testmodell, som var enklare modeller förbyggnaden där resultat togs fram och beräknades, skapades för att lättare undersökade olika systemen. Även några parameterstudier gjordes för att skapa fler resultat ochatt undersöka fler intressanta varianter. Från resultaten beräknades lastfaktorer i x-, y-,och z-led, som beskriver stabilitet på byggnaden, fjäderkonstant, som beskriverstyvheten på bygganden, och mängden använt material. Lastfaktorn i samtliga tre lastriktningar var störst hos den parameterstudie somanvända sig utav stabiliserande innerväggar som tillägg. För testmodellerna med detre stabiliserande grundsystemen presterade skivverkan bäst i två av tre fall avlastfaktor. Diagonalstagning påvisade den högsta fjäderkonstanten av grundsystemenoch parameterstudien med innerväggar hade den högsta fjäderkonstanten. Genom att använda skivverkan istället för de andra två stabiliseringssystemen, kan enenkel modell göra så att en stabilare byggnad uppnås. Mer material kommer dock gååt men det kan accepteras då man får en stabilare byggnad.

The optimization of sawing processes in the wood industry is critical for maximizing efficiency and profitability. The introduction of computerized tomography scanners provides sawmill operators with three-dimensional internal models of logs, which can be used to assess value and yield more accurately. We present a methodology for solving the sawing optimization problem employing a flexible sawing scheme that allows greater flexibility in cutting logs into products while considering product quality classes influenced by wane defects. The methodology has two phases: preprocessing and optimization. In the preprocessing phase, two alternative algorithms are given that generate and evaluate the potential sawing positions of products by considering the 3D surface of the log, product size requirements, and product quality classes. In the optimization phase, a maximum set-packing problem is solved for the preprocessed data using mixed-integer programming (MIP), aiming to obtain a feasible cut pattern that maximizes value yield. This is implemented in a system named FlexSaw, which takes advantage of parallel computation during the preprocessing phase and utilizes a MIP solver during the optimization phase. The proposed sawing methods are evaluated on the Swedish Pine Stem Bank. Additionally, FlexSaw is compared with an existing tool that utilizes cant sawing. Results demonstrate the superiority of flexible sawing. While the practical feasibility of implementing a flexible way of sawing logs is constrained by the limitations of current sawmill machinery, the potential increase in yield promotes the exploration of alternative machinery in the wood industry.

Denna rapport utgör en samlad dokumentation av underlags data, med avseende på de olika industriprocesser som ingår i visualiseringsverktyget BioMapp. De skogsindustriella processerna som beskrivs i rapportens bilagor baseras på en allmänt accepterad inventeringsmetodik för att beskriva skogsbaserade produkters miljöpåverkan och andra hållbarhetsindikatorer i ett livscykelperspektiv. Det systemanalytiska verktyg som används i projektet är livscykelanalys (LCA) på så sätt som det tillämpas i miljövarudeklarationer för produkter (EPD).De inventeringsdata som redovisas har en ambition att vara representativa för den typ av processer och miljöbelastning som är relevanta för svenska förhållande. Det har dock inte varit möjligt inom ramen för projektet att göra kompletta branschsammanställningar., This report constitutes the overall documentation of the data available in the visualization tool BioMapp with regards to various industrial processes. The forest industrial processes described in the report are based on a generally accepted inventory methodology to describe the environmental impact of forest-based products and other sustainability indicators in a life cycle perspective. The system analysis tool used in the project is life cycle analysis (LCA) in the way it is applied in environmental product declarations (EPD).These inventory data are representative in the type of processes and environmental impact that are relevant to Swedish conditions. However, it has not been possible within the framework of the project to make complete industry summaries.

The differential swelling seen between softwood opposite wood (OW) and its neighbouring compression wood (CW) developed in branches prompts several engineering issues such as dimensional instability and cracking. For a more efficient use of resources, the inevitable CW and OW should not be discarded or used as fuel, but incorporated into engineered wood products. Swelling is a hygroelastic phenomenon, where both the swelling and elastic properties of CW and OW are needed in order to make proper structural predictions. In this paper, swelling coefficients and moisture dependent elastic moduli for both CW and OW in the three principal material directions are provided along with measurements of moisture content, density, and microfibril angle. The small deformations necessitate the use of precise X-ray micro-computed tomography for measurements. The results indicate that CW and OW from Norway spruce branches differ in swelling, especially in longitudinal direction at low moisture content. It is noted that CW is a wood type with less pronounced anisotropic behaviour than both OW and normal wood from the stem, with the elastic moduli less sensitive to moisture changes in both longitudinal and transverse directions.

The strength of cross laminated timber (CLT) depends on the stiffness and strength of the lamellas and on thestrength of the finger joints. A model for how stiffness and strength vary along and between lamellas is used incombination with a finite element model of CLT and Monte Carlo simulations to calculate out-of-plane bendingstrength of homogeneous and inhomogeneous CLT. Calculated and experimentally obtained results of characteristicbending strengths, coefficient of variation of bending strength and the proportion of finger joint failures,agree very well for both types of CLT. The characteristic out-of-plane bending strength and the mean bendingstiffness were 23% and 16% higher, respectively, for inhomogeneous CLT with outer layer lamellas graded in thestrength class C35, compared to homogeneous CLT with all lamellas graded in the class C24. Simulation resultsgive basis for simple equations by which bending strength of CLT can be determined as function of the layup, thestrength class of outer layer lamellas and characteristic strength of the finger joints. Furthermore, system effectsare investigated. For inhomogeneous CLT, with outer layer lamellas of high strength class, the system effects turnout to be quite different from those of ordinary, homogeneous CLT.

Humins are heterogeneous and polydisperse furanic macromolecules derived from sugar biorefinery. Improving wood properties by humination has become of interest recently. This study examined the photodegradation stability of European pine sapwood microveneers modified with humins at different concentrations of citric acid (CA) and succinic acid (SA) as reaction catalysts, e.g., 1.5 %, 3 %, and 4.5 % wt.%. The photostability of huminated wood was assessed after 48 h, 96 h, and 144 h of exposure to the accelerated weathering test by means of mass loss and finite-span tensile strength. The results were compared with unmodified and also unweathered samples. The FT-IR spectroscopy showed apparent changes in the chemical structure of wood by humination modifications. The weight percentage gains of the samples increased with increasing the concentration of the catalyst. While no differences were observed between the samples after two weeks of the water leaching. The strength losses of weathered microveneers were, however, mostly reduced by humin-based formulas containing catalysts, where the microveneers modified with 1.5 % and 3 % CA showed respectively 32 % and 41 % lower strength loss values than the unmodified samples after 144 h of weathering. Overall, the results showed a high potential for humins to protect wood against photodegradation.

Tannins are polyphenolic compounds extracted from various tree species and used in variousmapplications such as adhesives, composites, pharmaceuticals, medicines, and food and beverage production (Mubarak et al. 2023). However, tannins, especially condensed tannins, have limited reactivity with wood. Consequently, to effectively modify wood, cross-linkers and other reactive chemicals or additives must be used. In this work, we have introduced a bio-based cross-linker in a 20% tannin (Quebracho) aqueous solution. Five levels of cross-linker (0, 2, 10, 20 and 40% of total tannin solid) were used to modify Scotspine (Pinus sylvestris L.) sapwood with dimensions of 25 × 25 × 10 mm3 (radial × tangential × longitudinal). Full-cell impregnation was applied with a 60 min vacuum and pressure for 60 min. Samples were kept at room condition for 24 h, stepwise dried to avoid drying defects and cured at 140 °C for 10 h. Modified wood samples are shown in Figure 1. Weight percentage gain (WPG) and bulking coefficient (BC) after water leaching for 5 days were measured according to Donath et al. (2004).

Beech wood, renowned for its diverse applications spanning construction, flooring, furniture, veneer, and plywood, holds a paramount position among industrial wood species. Nevertheless, the myriad of beech species worldwide, coupled with the dynamic impact of climate change, have produced structural variations within beech trees. Extensive research has scrutinized the physical and mechanical attributes of beech wood species across the globe. Findings reveal distinguishable mechanical strength, yet increased density leads to notable rates of shrinkage and swelling, somewhat constraining its utility in select domains. Identifying research gaps can create new efforts aimed at exploiting the potential of these wood resources. This paper outperforms a mere exploration of beech wood properties over the past two decades; it delves into the ramifications of climatic fluctuations, temperature shifts, wind dynamics, and soil composition. Given the lack of a comprehensive compendium documenting the full range of physical, mechanical, and microscopic attributes of the Fagus genus, this paper aims to compile information that integrates this multifaceted information.

Vanligtvis används betong för grundläggningar idag, men det undersöks om korslimmat trä (KLT) kanersätta detta. KLT är ett förnyelsebart material och har miljömässiga fördelar jämfört med betong. Enplatta i KL-trä är vekare än betong och den här studien ska utreda hur de påverkas av olika storlekarpå fjäderkonstanter. Bäddmoduls-teorin är en metod som går ut på att modellera marken sommekaniska fjädrar. Studien genomfördes med en platta på mark med två olika material med olikaegenskaper där dessa jämfördes. En specifik byggnad som RISE står för användes för inspiration ochenbart kontakttryck och deformationer kommer undersökas.En litteraturstudie har genomförts för att öka förståelsen för bäddmoduls-teorin och materialen.Beräkningar av plattstyvheter utfördes och programvara för finita elementmetoden (FEM) användesför att simulera grunden. Resultaten från detta kommer sedan jämföras.Resultatet visade stora skillnader mellan materialen. KLT-plattan gav ett kontakttryck med tvåbrytpunkter, där värdena gav lokala max- och minipunkter, för det valda intervallet avfjäderkonstanter och deformationen minskade med en jämn takt. Betongplattan visade istället enjämn ökning av kontakttrycket och en jämn minskning för deformationen i samma intervall.KLT-plattan ger ett högt kontakttryck vid lägre värden på fjäderkonstanten vilket kan vara ett problemvid grundläggningar då det inte får överstiga markens dimensionerande hållfasthet. Betong-plattanvisade lägre kontakttryck vid samma intervall på fjäderkonstanten vilket beror på dess högre styvhet.Deformationen var något högre för KLT-plattan vid lägre bäddmoduler.Bäddmoduls-teorin är enbart en approximativ metod och en djupare undersökning behövs viddimensionering av grunder. Resultatet visar att det är möjligt att bygga grunder i KL-trä men man börundvika för stora koncentrerade laster så kontakttrycket inte blir för högt., Concrete is commonly used for foundations today, but research is being conducted to see if crosslaminatedtimber (CLT) can replace it. CLT is a renewable material and has environmental advantagescompared to concrete. A CLT slab is more flexible than concrete, and this study aims to investigatehow it is affected by different sizes of spring constants. The bedding modulus theory is a method thatmodels the ground as mechanical springs. The study was conducted with a slab on the ground usingtwo different materials with different properties, and these were compared. A specific buildingassociated with RISE served as inspiration, and only contact pressure and deformations wereexamined.A literature review was conducted to increase the understanding of the subgrade modulus theory andthe materials. Calculations of slab stiffness were performed, and finite element method (FEM)software was used to simulate the foundation. The results from this will then be compared.The results showed significant differences between the materials. The CLT slab exhibited contactpressure with two breakpoints, where the values resulted in local maxima and minima, within theselected range of the spring constant, and the deformation decreased at a steady rate. The concreteslab, on the other hand, showed a steady increase in contact pressure and a consistent decrease indeformation within the same range.The CLT slab generates high contact pressure at lower values of the spring constant, which can beproblematic for foundations as it must not exceed the soil’s design strength. The concrete slabshowed lower contact pressure within the same range of spring constant, which is due to its higherstiffness. The deformation was slightly higher for the CLT slab at lower bedding moduli.The bedding modulus theory is only an approximate method, and a more in-depth investigation isneeded when designing foundations. The results show that it is possible to construct foundationsusing CLT, but concentrated loads should be

Citric acid can be used as a bio-based binding agent in composites made from lignocellulosic material due to its crosslinking ability with hydroxyl groups via ester formation. Even though plenty of research has investigated diverse manufacturing conditions, with a focus on citric acid content and pressing temperature, an apparent knowledge gap persists regarding their effect on the properties of particleboards made from softwood sawdust. Furthermore, the optimal temperature for particleboards crafted from mostly non-wood lignocellulosic materials was found to be 180–200°C which is lower than that observed for softwood material in a prior study. This study aimed to systematically examine the effects of citric acid content and pressing temperature on particleboards derived from softwood sawdust. Results highlighted a positive correlation of both citric acid content and pressing temperature with mechanical and hygroscopic properties of the particleboards, the best results being achieved at 20 wt% citric acid and 220°C, exhibiting a thickness swelling of 9%, internal bonding strength of 0.77 MPa and a modulus of rupture of 4.3 MPa. This study served as a foundational framework for future investigations into the addition of other chemicals, offering a comprehensive understanding of their interactions with citric acid in particleboard manufacturing., Validerad;2024;Nivå 2;2024-08-15 (sofila);Full text license: CC BY-NC-ND 4.0

To improve the resistance of wood to biological decay the Maillard reaction between introduced amines and wood cell-wall polymers can be utilised. However, initial studies in wood modification showed almost complete leaching of bicine and tricine from treated wood and the loss of beneficial effects. The objective of this study was to assess whether possible reactions of bicine or tricine with wood could be further enhanced and reaction products stabilised through the addition of glucose and/or citric acid. Thus, Scots pine sapwood specimens were impregnated with tricine or bicine, with or without glucose and citric acid, and then heated to a temperature of 160°C. The dimensional stability, degree of chemical leaching and mechanical properties were assessed. Overall, it was concluded that neither the presence of glucose nor citric acid did appear to enhance the reactivity of tricine or bicine. Anti-swelling efficiency (ASE) of 50% was observed for combined treatments of bicine/tricine and citric acid but the leaching resistance originated mainly from citric acid and glucose, with no indication for the retention of bicine or tricine. The presence of citric acid led to a strongly reduced modulus of rupture., Validerad;2024;Nivå 2;2024-08-15 (sofila);Full text license: CC BY-NC-ND License

Increasing environmental awareness and the carbon-storing capability of wood have amplified its relevance as a building material. The demand for high-quality wood species necessitates exploring alternative, underutilized wood sources due to limited forest areas and premium wood volume. Consequently, the veneer-based industry is considering lower-value hardwood species like grey alder (Alnus Incania), black alder (Alnus glutinosa), and aspen (Populus tremula) as substitutes for high-quality birch (Betula pendula). Initially less appealing due to their lower density and mechanical properties, these species show promise through densification, which enhances their density, strength, and hardness. This study aims to enhance plywood screw withdrawal capacity and surface hardness by densifying low-density wood species and using them in plywood face-veneer layers, or in all layers. The relationship between the wood density, surface hardness, and screw withdrawal capacity of plywood made of low-value species like aspen and black alder is examined. Experimental work with a pilot-scale veneer and plywood production line demonstrates improved surface hardness (65% and 93% for aspen and black alder, respectively) and screw withdrawal capacity (16% and 35% for aspen and black alder, respectively) in densified face veneer plywood. This research highlights the potential of densified low-value wood species to meet construction requirements, expanding their practical applications., Validerad;2024;Nivå 2;2024-07-24 (signyg);Funder: Estonian Research Council (PRG2213); Environmental Investment Center (RE.4.08.22-0012);Fulltext license: CC BY

Recently developed technology in sawmills such as advanced log scanning and traceability concepts enable new ways of grading logs and boards. When it comes to strength grading, this is often done on sawn boards using automatic scanning systems. However, if board scanners were to be augmented with data from log scanners by using traceability, more information on the wood propertiesis available. In this study, the main objective was to compare the strength prediction capability of board scanning alone, to board scanning augmented with X-ray and 3D data from log scanning, for Norway spruce (Picea abies L. Karst.) and Scots pine (Pinus sylvestris L.). In that case, data from three different scanning systems was combined, two for logs and one for boards. A further objective was to investigate whether pre-sorting logs for strength grading can be done using either 3D log data alone, or 3D log data augmented with X-ray data. The results show an improved strength prediction when adding log data to board data, and that 3D log data alone is not enough to pre-sort logs for strength, while adding X-ray log data makes it possible. Strength prediction on Scots pine performed somewhat better than prediction on Norway spruce., Validerad;2024;Nivå 2;2024-02-05 (signyg);Funder: ForestValue Research Programme;Full text license: The general policies of BioResources are as follows: Authors retain rights to their material, which, upon acceptance by the journal, is uploaded and made public on the Internet. The journal retains no copyright. Users have the right to read, download, copy, distribute, print, search, or link to the full texts of articles in the journal, and users can use, reuse, and build upon the material in the journal for non-commercial purposes as long as attribution is given when appropriate or necessary.

This review systematically examines the multitude of factors influencing bonding strength in bamboo-based composite materials, given the rising prominence of bamboo as a green building material. With bamboo's inherent variability in mechanical properties and structure, engineered bamboo products have emerged to address challenges related to connections and joints. Such advancements have necessitated a detailed exploration of adhesive systems, a significant cost determinant in bamboo production. The adhesive bonding mechanism in bamboo, akin to wood, involves intricate processes including adhesive spreading, penetration, and solidification, influenced by the unique chemical composition of bamboo. The interfacial bond quality plays a pivotal role in determining the durability and performance of the final products, with numerous factors such as bamboo species, layered structure, adhesive type, and treatment types impacting the mechanical properties. Particular attention is given to the disparities in physical and mechanical properties between the bamboo culm's core and shell layers, attributing complexities to the gluing process. Examining shear failure strength reveals its criticality in mechanical investigations, with variations in bonding strength affecting the outcome. The review underscores the need for consistent quality control and adept manipulation of these influential factors for the successful manufacture of bamboo-based products. A comprehensive discussion ensues on the variables controlling the bonding properties of the developed bamboo products, aiming to evaluate and highlight the optimal parameters and procedures essential for enhancing the quality and reliability of bamboo-based composite materials for sustainable construction applications., Validerad;2024;Nivå 2;2024-07-03 (hanlid);Funder: Prince Sattam bin Abdulaziz University (PSAU/2024/R/1445);Full text license: CC BY

The rise in energy consumption and the increase in the use of bio-based materials in the building sector, has led to the need to investigate the possibilities to use wood as a porous support material for phase change materials (PCMs), and thereby creating a thermal regulative wood-based product. This study investigated the influence of Kraft lignin-glyoxal prepolymer on the thermal-energy storage properties of wood modified with paraffin-type of PCM. The implementation of the modified wood involves preparing PCM emulsions, synthesising lignin-glyoxal prepolymer, and modifying wood with the PCM-Kraft lignin-glyoxal emulsion through vacuum-pressure impregnation. The infrared imaging suggested the ability of PCM-modified wood to delay the temperature changes, even with the introduction of Kraft lignin-glyoxal prepolymer. In conclusion, it is feasible to introduce thermal-energy storage property into wood with the addition of Kraft lignin-glyoxal prepolymer. Further studies will focus on the long-term thermal storage performance properties when this PCM system is subjected to repeated heating/cooling cycles., Validerad;2024;Nivå 2;2024-07-02 (hanlid);Funder: Swedish Wood Industry;Full text license: CC BY-NC-ND

The purpose of this research study was to investigate the properties of polyurethane coatings based on ligninnano-particles. For this purpose, the prepared coatings were applied to pine wood surfaces and weathered artificially.Subsequently, color and gloss of the coatings were measured before and after the weathering test. Fieldemission scanning electron microscopy (FE-SEM) micrographs prepared from the coatings showed that the averagesize of nano-particles in the polyurethane substrate was approximately 500 nm. Nuclear magnetic resonance(13C-NMR) spectroscopy showed that strong urethane bonds were formed in the nano-lignin-based polyurethane.Differential calorimetric analysis (DSC) test revealed that the glass-transition temperature (Tg) of lignin nanoparticlesmodified with diethylenetriamine (DETA) was 112.8°C and Tg of lignin nano-particles modified withethylenediamine (EDA) was 102.5°C, which is lower than the Tg of un-modified lignin (114.6°C) and lignin modifiedwith DETA (126.8°C) and lignin modified with EDA (131.3°C). The coatings modified with lignin nano-particleshad a greater change in gloss. The lignin nano-particles in the modified coating are trapping hydroxylradicals which reduces photoactivity and yellowing of the polyurethane by about 3 times compared to unmodifiedpolyurethane coatings. After weathering test, the nano-lignin-based coating had a rougher surface with a lowercontact angle (0.78°) compared to the unmodified polyurethane coating (0.85°)., Godkänd;2024;Nivå 0;2024-04-08 (marisr);Full text license: CC BY;Funder: Tarbiat Modares University of Tehran

Purpose: Wood comprises different cell types, such as fibers, tracheids and vessels, defining its properties. Studying cells’ shape, size, and arrangement in microscopy images is crucial for understanding wood characteristics. Typically, this involves macerating (soaking) samples in a solution to separate cells, then spreading them on slides for imaging with a microscope that covers a wide area, capturing thousands of cells. However, these cells often cluster and overlap in images, making the segmentation difficult and time-consuming using standard image-processing methods. Results: In this work, we developed an automatic deep learning segmentation approach that utilizes the one-stage YOLOv8 model for fast and accurate segmentation and characterization of macerated fiber and vessel form aspen trees in microscopy images. The model can analyze 32,640 x 25,920 pixels images and demonstrate effective cell detection and segmentation, achieving a mAP0.5-0.95 of 78 %. To assess the model’s robustness, we examined fibers from a genetically modified tree line known for longer fibers. The outcomes were comparable to previous manual measurements. Additionally, we created a user-friendly web application for image analysis and provided the code for use on Google Colab. Conclusion: By leveraging YOLOv8’s advances, this work provides a deep learning solution to enable efficient quantification and analysis of wood cells suitable for practical applications., QC 20240903

Metallic wood combines the unique structural benefits of wood and the properties of metals and is thus promising for applications ranging from heat transfer to electromagnetic shielding to energy conversion. However, achieving metallic wood with full use of wood structural benefits such as anisotropy and multiscale porosity is challenging. A key reason is the limited mass transfer in bulk wood where fibers have closed ends. In this work, programmed removal of cell-wall components (delignification and hemicellulose extraction) was introduced to improve the accessibility of cell walls and mass diffusion in wood. Subsequent low-temperature electroless Cu plating resulted in a uniform continuous Cu coating on the cell wall, and, furthermore, Cu nanoparticles (NPs) insertion into the wood cell wall. A novel Cu NPs-embedded multilayered cell-wall structure was created. The unique structure benefits compressible metal-composite foam, appealing for stress sensors, where the multilayered cell wall contributes to the compressibility and stability. The technology developed for wood metallization here could be transferred to other functionalizations aimed at reaching fine structure in bulk wood., QC 20240626

\par Inom trävetenskapen är noggrann segmentering av icke-cellulära element i mikroskopibilder avgörande för applikationer som bedömning av träkvalitet och förståelse av tillväxtmönster, men utmanande på grund av den komplexa morfologin hos träkomponenter. Denna avhandling utforskar utvecklingen av en djupinlärningsbaserad, semisuperviserad modell för segmentering av icke-cellulära element i mikroskopibilder av gran, en viktig källa för byggmaterial i Europa, vilket adresserar utmaningen med den arbetsintensiva och expertisberoende manuella annoteringen. Segmenteringsmodellen använder effektivt avancerade djupinlärningsarkitekturer, inklusive konvolutionella neurala nätverk och Vision Transformer, för att fånga de inre mönstren inbäddade i trästrukturen. Genom att använda både märkta och omärkta data föreslår denna avhandling en Pixel-level Guided Mean-Teacher (PG-MT) ramverk som en förbättring av Mean-Teacher, vilket möjliggör pixel-nivå guidad korrigering för att förbättra segmenteringsnoggrannhet och modellens robusthet med begränsade märkta dataset. Experimentella utvärderingar visar att det föreslagna PG-MT-ramverket förbättrade Dice-poängen för märgstrålesegmentering med 0,95% och IoU-poängen med 1,14% jämfört med den Uncertainty-Aware Mean-Teacher (UA-MT). Dessutom betonar integrationen med laboratorieinstrument modellens effektivitet i att exakt uppskatta tvärsnittsväggtjocklek, vilket visar en stark korrelation med röntgenmätningar. Detta bekräftar modellens praktiska användbarhet i laboratoriemiljöer, vilket förbättrar analysen av träegenskaper. Studien står dock inför begränsningar, inklusive en datamängd av begränsat omfång vilket påverkar generaliserbarheten, och potentiella bias i manuella annoteringar som kan påverka noggrannheten. Trots dessa utmaningar tillhandahåller detta arbete en robust ramverk för trä mikroskopifältet, vilket avsevärt minskar annoteringsbördan och banar väg för mer automatiserad och exakt analys av träegenskaper., Inom trävetenskapen är noggrann segmentering av icke-cellulära element i mikroskopibilder avgörande för applikationer som bedömning av träkvalitet och förståelse av tillväxtmönster, men utmanande på grund av den komplexa morfologin hos träkomponenter. Denna avhandling utforskar utvecklingen av en djupinlärningsbaserad, semisuperviserad modell för segmentering av icke-cellulära element i mikroskopibilder av gran, en viktig källa för byggmaterial i Europa, vilket adresserar utmaningen med den arbetsintensiva och expertisberoende manuella annoteringen. Segmenteringsmodellen använder effektivt avancerade djupinlärningsarkitekturer, inklusive konvolutionella neurala nätverk och Vision Transformer, för att fånga de inre mönstren inbäddade i trästrukturen. Genom att använda både märkta och omärkta data föreslår denna avhandling en Pixel-level Guided Mean-Teacher (PG-MT) ramverk som en förbättring av Mean-Teacher, vilket möjliggör pixel-nivå guidad korrigering för att förbättra segmenteringsnoggrannhet och modellens robusthet med begränsade märkta dataset. Experimentella utvärderingar visar att det föreslagna PG-MT-ramverket förbättrade Dice-poängen för märgstrålesegmentering med 0,95% och IoU-poängen med 1,14% jämfört med den Uncertainty-Aware Mean-Teacher (UA-MT). Dessutom betonar integrationen med laboratorieinstrument modellens effektivitet i att exakt uppskatta tvärsnittsväggtjocklek, vilket visar en stark korrelation med röntgenmätningar. Detta bekräftar modellens praktiska användbarhet i laboratoriemiljöer, vilket förbättrar analysen av träegenskaper. Studien står dock inför begränsningar, inklusive en datamängd av begränsat omfång vilket påverkar generaliserbarheten, och potentiella bias i manuella annoteringar som kan påverka noggrannheten. Trots dessa utmaningar tillhandahåller detta arbete en robust ramverk för trä mikroskopifältet, vilket avsevärt minskar annoteringsbördan och banar väg för mer automatiserad och exakt analys av träegenskaper.

With the evolution of GPU performance, the interest of using AI for all kinds of purposes has risen. Companies today put a great amount of resources to find new ways of using AI to increase the value of their products or automating processes. An area in the wood industry where AI is widely used and studied is in defect detection. In this thesis, the combination of using AI and hyperspectral images is studied and evaluated in the case of segmenting defects in hardwood with a U- Net network structure. The performance is compared to another known method usually used when dealing with high-dimensional data: PLS-DA. This thesis also compares the use of RGB image data in combination with AI, to further analyze the usefulness that the hyperspectral data provide. The results showed signs of improvement when using hyperspectral images com- pared to RGB images when detecting blue stain and red heartwood defects. De- tection of the defects rot and knots did however show no sign of improvements. Due to the annotations being more accurate in the RGB data, the results from the hyperspectral data-fed networks would suggest that blue stain and red heartwood could be of interest regarding further investigation. Computational performance is shown to vary across the different reduction meth- ods, and the results from this thesis provides some insight that might aid in the reasoning regarding how to choose an appropriate reduction method.

Porous cellular foams, combining lightweight, high strength, and compressibility, hold great promise in a wide range of advanced applications. Here, the native structure of pine wood was modified by in-situ lignin sulfonation and unidirectional freezing, resulting in an alveolate structure inside the wood cell wall with arrays of sub-100 nm channels. The obtained wood foam exhibited highly enhanced permeability while retaining the native cellular arrangement and high lignin and hemicellulose content. Such engineered cellular foam contributed to superior mechanical performance with compressive strength of 9 MPa and Young's modulus of 344 MPa in the longitudinal direction. The high porosity allowed homogeneous infiltration of conductive polymer PEDOT: PSS inside the wood cell wall. The resulting composite exhibited high conductivity, sponge-like compressibility and the ability to modulate electrical resistance in a reversible manner in the radial direction. This rationally designed conductive wood demonstrated potential in durable and ultrasensitive pressure-responsive devices and strain sensors., Funding Agencies|Knut and Alice Wallenberg Foundation (KAW) through the Wallenberg Wood Science Center [WWSC 2.0: KAW 2018.0452]

A reliable determination of the embedment strength and foundation modulus of timber elements is critical for the design and safety assessment of joints in timber structures. However, the existence of various test configurations for characterising the embedding properties of large diameter steel fasteners in timber elements poses challenges in directly comparing and utilising available test data. This paper aims to provide an insight into the influence of embedment property test methods, comparing experimental results from different test setups within the guidelines of the EN 383 and ASTM D 5764-97a standards for European softwood species, Scots pine wood (Pinus sylvestris) and Norway spruce (Picea abies). In addition to the test guidelines, the thickness of the specimen and the application of the load was evaluated within the protocols. A comprehensive statistical analysis was performed to identify statistically significant differences between the groups evaluated. The results of the analysis revealed disagreement between the standards in the evaluation of the strength of the embedding, highlighting the potential bias inserted by the experimental setup and protocol. Furthermore, it was proven that the thickness of the specimens influences both the embedding strength and the foundation modulus of the wood species tested. Finally, no distinctions were observed between tensile and compressive loading within the guidelines of the EN 383 standard., Bibliografiskt granskad

Reducing the time for drying sawn timber to a certain moisture level without deteriorating its quality is increasingly important for an economic and energy-efficient industrial timber-drying process and to support the transition to a sustainable society. It is, however, crucial to ensure that the quality of the timber, i.e. the degree of distortion, cracking, discolouration, and moisture variation within and between the pieces in a drying batch, is not compromised. Drying-simulation software tend to be too conservative in drying-rate recommendations, which has been observed in practise particularly for large cross-section timber of Norway spruce. This study investigated the drying rate and checking occurrence of centre-yielded Norway spruce planks when dried with more aggressive schedules than normally used in practise, i.e. using higher dry-bulb temperatures and/or lower relative humidities than recommended in the conventional optimisation programmes used in the sawmill industry in Sweden. The objective was to investigate the possibility to considerably reduce the total drying time without compromising the quality of the dried timber. The quality of the planks was indirectly assessed by estimating their moisture-content distributions, calculating the moisture gradients and monitoring checking. This was achieved with 4D (3D + time) X-ray computed tomography and a recently developed image processing algorithm based on elastic image registration. The key findings in this study suggest that Norway spruce timber can be dried with significantly higher temperatures and lower relative humidities than suggested by simulations, leading to reduced total drying time without inducing checking. This methodology can help to improve the design of drying schedules to reduce drying time and energy consumption while maintaining timber quality at a level accepted by the customers., Validerad;2024;Nivå 2;2024-03-25 (hanlid);Full text license: CC BY 4.0This article has previously appeared as a manuscript in a thesis.