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This article explores wood-fiber-based fabrics containing Lyocell yarn in the warp and Spinnova–Lyocell (60%/40%) yarn in the weft, which are used to form unidirectional all-cellulose composites (ACC) through partial dilution in a NaOH–urea solution. The aim is to investigate the role of the yarn orientation in composites, which was conducted by measuring the tensile properties in both the 0° and 90° directions. As a reference, thermoplastic biocomposites were prepared from the same fabrics, with biobased polypropylene (PP) as the matrix. We also compared the mechanical and thermal properties of the ACC and PP biocomposites. The following experiments were carried out: tensile test, TGA, DSC, DMA, water absorption test and SEM. The study found no significant difference in tensile strength regarding the Spinnova–Lyocell orientation between ACC and PP biocomposites, while the composite tensile strength was clearly higher in the warp (Lyocell) direction for both composite variants. Elongation at break doubled in ACC in the Lyocell direction compared with the other samples. Thermal analysis showed that mass reduction started at a lower temperature for ACC, but the thermal stability was higher compared with the PP biocomposites. Maximum thermal degradation temperature was measured as being 352 °C for ACC and 466 °C for neat PP, and the PP biocomposites had two peaks in the same temperature range (340–474 °C) as ACC and neat PP combined. ACCs absorbed 93% of their own dry weight in water in just one hour, whereas the PP biocomposites BC2 and BC4 absorbed only 10% and 6%, respectively. The study highlights the different properties of ACC and PP reference biocomposites that could lead to further development and research of commercial applications for ACC.

As long-term investigations are often too time- and cost-consuming, short-term experimentsare introduced for investigating the behaviour of connections in timber-concrete-compositeelements. The paper presents a proposal for short-term double shear tests with adhesive andmechanical connections for investigating their time-dependent behaviour. The proposedevaluation method determines the elastic and visco-elastic parts of the slip modulus of theconnection. The validity of the identified parameters needs to be verified by long-term tests.

There is an urgent need for the development of viable recycling solutions for the increasing waste streams of glass fiber composites (GFRPs) from all sectors i.e. leisure boats, windmills and building constructions. Two potential recycling methods that can separate and recover both the polymers and the high-quality fibers from these kinds of materials are pyrolysis and solvolysis. In this project recycling of an epoxy-based Endof-Life wind turbine blade was evaluated in lab scale using the two methods. In previous literature the main focus has been on the quality of the fibers but in this project the main focus was to compare the chemical composition of the oil products. The produced oils from solvolysis and pyrolysis have been compared with a multianalysis approach by using elemental analysis, GC-MS, pyro-GC-MS/FID, 2D NMR (HSQC) for gaining more information about the chemical structure of the produced monomers (phenols), oligomers and polymers. Almost all the volatile matter in the End-of-Life wind turbine blade was recovered as pyrolysis oil, 36 wt.% yield. The solvolysis oil yield was lower, 17 wt.%, mainly due to a major part of the solvolysis oil ended up in the aqueous solvent. The composition of the oils from both technologies was analyzed based on both their volatile i.e. monomeric and polymeric content. The result point to that both methods produced oils with similar polymeric parts according to NMR and pyro-GC-MS/FID, based on an oxygenated aliphatic network connected with aromatic phenolic structures. Increased information of chemical oil composition will be useful for further processing as raw material in refineries/chemical industries. The monomeric part of the oil produced from pyrolysis was found in relatively large amounts, ~57 wt.%, and can be a future high-value product from recycling of wind turbine blades. The total recovery of phenolics from the pyrolysis was 18 wt.% of the wind turbine blade weight., Project name ” Rekovind2 - Digitalization of wind blade streams before reuse and recycling”, Swedish Energy Agency project number 47044-2, Dnr 2021-029795, RISE Project P113615-1

A structural battery is a multifunctional battery that can carry a load while storing energy. Structural batteries have been a cutting-edge research focus in the last decade and are mainly based on polyacrylonitrile (PAN)-carbon fibers (CFs). In this work, positive electrodes based on PAN-carbon fibers were manufactured with powder impregnation (siphon impregnation) technique using a water-based slurry containing lithium iron phosphate (LFP) as the active electrode material and the water-soluble binder polyethylene glycol (PEG). Different coating compositions, electrode-drying temperatures, and coating parameters were investigated to optimize the coating uniformity and the electrochemical performances. Scanning electron microscopy results showed that the electrode materials coat the CFs uniformly, conformably, and individually. Electrochemical characterization of pouch cells shows that the electrodes containing 6 wt% PEG dried at 140 degrees C have the best battery performance, delivering a first discharge capacity of 151 mAh g-1 and capacity retention higher than 80% after 100 cycles. Moreover, excellent capacity reversibility was achieved when the electrodes were cycled at multiple C-rates attesting to their stability. The results demonstrate that CFs perform excellently as current collectors in positive electrodes., QC 20230824

To address the rising need of sustainable solutions in electronic devices, the development of electronically conductive composites based on lightweight but mechanically strong wood structures is highly desirable. Here, a facile approach for the fabrication of highly conductive wood/polypyrrole composites through top-down modification of native lignin followed by polymerization of pyrrole in wood cell wall. By sodium sulfite treatment under neutral condition, sulfonated wood veneers with increased porosity but well-preserved cell wall structure containing native lignin and lignosulfonates are obtained. The wood structure has a content of sulfonic groups up to 343 µmol g−1 owing to in situ sulfonated lignin which facilitates subsequent oxidative polymerization of pyrrole, achieving a weight gain of polypyrrole as high as 35 wt%. The lignosulfonates in the wood structure act as dopant and stabilizer for the synthesized polypyrrole. The composite reaches a high conductivity of 186 S m−1 and a specific pseudocapacitance of 1.71 F cm−2 at the current density of 8.0 mA cm−2. These results indicate that tailoring the wood/polymer interface in the cell wall and activating the redox activity of native lignin by sulfonation are important strategies for the fabrication of porous and lightweight wood/conductive polymer composites with potential for sustainable energy applications., QC 20230602

Optically transparent wood has been fabricated by structure-retaining delignification of wood and subsequent infiltration of thermo- or photocurable polymer resins but still limited by the intrinsic low mesopore volume of the delignified wood. Here we report a facile approach to fabricate strong transparent wood composites using the wood xerogel which allows solvent-free infiltration of resin monomers into the wood cell wall under ambient conditions. The wood xerogel with high specific surface area (260 m2 g–1) and high mesopore volume (0.37 cm3 g–1) is prepared by evaporative drying of delignified wood comprising fibrillated cell walls at ambient pressure. The mesoporous wood xerogel is compressible in the transverse direction and provides precise control of the microstructure, wood volume fraction, and mechanical properties for the transparent wood composites without compromising the optical transmittance. Transparent wood composites of large size and high wood volume fraction (50%) are successfully prepared, demonstrating potential scalability of the method., QC 20230711

Silk fibroin, a widely used natural biopolymer, presents remarkable flexibility and biodegradability, making it of great interest as a polymer matrix for functional composite materials. Herein, composites of silk nanofibrils and metal-organic framework (MOF) nanosheets were successfully fabricated by a coincubation and coassembly process. Under heat incubation, silk fibroin self-assembled into one-dimensional nanofibrils, while MOF nanosheets simultaneously covered or wrapped on the silk nanofibrils in a water suspension. Transparent composite membranes were obtained from their water suspensions by the solution casting method. The regenerated silk nanofibrils formed a network structure, and the integrated MOF nanosheets (0.1 to 3.0 wt %) endowed the composites with aggregation-induced emission luminogen (AIEgen)-based fluorescence. The fluorescence intensity of the composites was significantly enhanced owing to the interfacial interactions between silk nanofibrils and MOF nanosheets. The composite membranes also offer excellent UV shielding while maintaining optical transparency in the visible spectrum. This work provides an efficient pathway to fabricate luminescent silk protein-based composites for functional materials such as fluorescence sensing and anticounterfeiting., QC 20230704

Nature has evolved elegant ways to alter the wood cell wall structure through carbohydrate-active enzymes, offering environmentally friendly solutions to tailor the microstructure of wood for high-performance materials. In this work, the cell wall structure of delignified wood is modified under mild reaction conditions using an oxidative enzyme, lytic polysaccharide monooxygenase (LPMO). LPMO oxidation results in nanofibrillation of cellulose microfibril bundles inside the wood cell wall, allowing densification of delignified wood under ambient conditions and low pressure into transparent anisotropic films. The enzymatic nanofibrillation facilitates microfibril fusion and enhances the adhesion between the adjacent wood fiber cells during densification process, thereby significantly improving the mechanical performance of the films in both longitudinal and transverse directions. These results improve the understanding of LPMO-induced microstructural changes in wood and offer an environmentally friendly alternative for harsh chemical treatments and energy-intensive densification processes thus representing a significant advance in sustainable production of high-performance wood-derived materials., QC 20230627

In the context of processing, utilization and disposal of polylactic acid composites, pyrolysis is a promising technique that addresses this complex synergy. In this work, pyrolysis kinetics and thermodynamic parameters of rice husks/clay fiber-reinforced PLA composites were investigated using Kissinger–Akahira–Sunose (KAS) and Ozawa–Flynn–Wall (OFW) at multiple heating rates (16, 25 and 34 °C min−1). PLA composites’ pyrolysis followed a single-step degradation process. The flammability indices, combustion characteristic indices and mean reactivities obtained for the PLA composites are much lower than those for neat PLA (2.00 × 10−5–2.44 × 10−5% min−1 °C−2, 0.87 × 10−8–1.79 × 10−8% min−2 °C−3 and 6.97 × 10−3–8.04 × 10−3% min−1 °C−1, respectively) which signals that rice husks and clay improved flame retardancy of accruing PLA composites. The average activation energy values obtained from the KAS method were found to be in ranges 137.83–143.99 kJ mol−1 and 124.51–133.95 kJ mol−1 for raw and modified rice husks/clay fiber-reinforced PLA composites, respectively. Corresponding activation energies for raw and modified rice husks/clay fiber-reinforced PLA composites from the OFW method were 141.24–146.92 kJ mol−1 and 128.17–137.50 kJ mol−1, respectively. By comparing activation energy and enthalpy, it was found that the composites were favored to format activated complex due to the low energy barrier., QC 20230626

This study investigates the viability of implementing multifunctional structural power composites in a four-seater air taxi, the CityAirbus. For a given specific energy of the power source, the cruise endurance can be approximately doubled by using structural power composites as opposed to conventional batteries. Replacing all the eligible composite mass and batteries with structural power composites can reduce the CityAirbus weight by 25%. To achieve the current design performance, the minimum required elastic modulus, strength, specific energy and power for the structural power composite are 54 GPa, 203 MPa, 74 Wh/kg and 376 W/kg, respectively: current state-of-the-art structural power composites are now approaching this level of performance. Hence, structural power composites are considered feasible for adoption in the urban air mobility sector and have the potential to improve endurance and facilitate commercialization. This paper also discusses several key challenges that must be addressed to realize the adoption of structural power composites in future electric air taxis., QC 20230602

To impart epoxy resin (EP) with excellent flame retardancy and smoke suppression, we prepared a novel inorgianic-organic nanocomposite flame retardant, zinc ferrite@polyphosphazene (ZF@PZS). The inorganic zinc ferrite plays a role in catalytic carbonization, improving char yields. The organic polyphosphazene helps zinc ferrite improve its compatibility and flame retardancy. Through synergistic effects, ZF@PZS exhibited excellent flame-retardant and smoke-suppression properties in the EP matrix. Compared to neat EP, the limiting oxygen index of the epoxy with 5 phr ZF@PZS increased from 24.6 % to 32.1 % and reached UL94 V-0 rating; the peak heat release rate, peak smoke production rate, and carbon monoxide production of EP composites also decreased by 37 %, 50 %, and 39 %, respectively. Condensed and gas phase analysis indicated that ZF@PZS helps epoxy generate more dense, stable, rigid residues and less pyrolysis volatile products, improving flame retardancy compared to ZF and PZS alone. Besides, the storage modulus of the composite was increased., QC 20230613

The sustainable development of functional energy-saving building materials is important for reducing thermal energy consumption and promoting natural indoor lighting. Phase-change materials embedded in wood-based materials are candidates for thermal energy storage. However, the renewable resource content is usually insufficient, the energy storage and mechanical properties are poor, and the sustainability aspect is unexplored. Here a novel fully bio-based transparent wood (TW) biocomposite for thermal energy storage, combining excellent heat storage properties, tunable optical transmittance, and mechanical performance is introduced. A bio-based matrix based on a synthesized limonene acrylate monomer and renewable 1-dodecanol is impregnated and in situ polymerized within mesoporous wood substrates. The TW demonstrates high latent heat (89 J g?1) exceeding commercial gypsum panels, combined with thermo-responsive optical transmittance (up to 86%) and mechanical strength up to 86 MPa. The life cycle assessment shows that the bio-based TW has a 39% lower environmental impact than transparent polycarbonate panels. The bio-based TW holds great potential as scalable and sustainable transparent heat storage solution., QC 20230420

The aim of the current work is to investigate the effect of SiC particle weight percent and rolling passes on Al/Cu/SiC laminated composites, fabricated by accumulative roll-bonding (ARB) and cross-accumulative roll-bonding (CARB) processes. The optical microscopy (OM) images of composites revealed that despite the good bonding of the layers, they underwent plastic instabilities as a consequence of strain hardening of the layers. However, these instabilities occurred more in ARBed composites than in composites fabricated by the CARB process. This is because in the latter process, the composites are rolled in two directions, which leads to better strain distribution. Furthermore, with an increase in passes, SiC particles were well distributed in the matrix and interfaces. The mechanical findings showed that, by increasing passes, there was a growth in the values of strengths and elongation. This behavior is believed to be related to increased work-hardening of layers, better distribution of reinforcing particles, and an enhanced bonding of interfaces at higher rolling passes. In addition, the results of thermal conductivities showed a downward trend with an increase in passes; in fact, the increased number of Al/Cu interfaces declined the heat conduction of composites., QC 20230322

Ultraviolet cured-in-place-pipe (UV-CIPP) materials are commonly used in trenchless pipeline rehabilitation. Their bending strength is a crucial indicator to evaluate the curing quality. Studies show that this indicator is affected by multiple factors, including the curing time, UV lamp curing power, curing distance, and material thickness. Laboratory experiments have limitations in analyzing the effect of multiple factors on the bending strength of UV-CIPP materials and quantitatively predicting the optimum curing parameters. Aiming at resolving these shortcomings, resolve machine learning techniques were applied to predict the bending strength. In this regard, the surface curing reaction temperature monitoring data and three-point bending data of 30 groups of UV-CIPP material under the influence of different curing parameters were used as a dataset to predict the bending strength of UV-CIPP material. The results show that the influence degree of each factor on the bending strength of the UV-CIPP material, from high to low, is as follows: UV lamp power (−0.439), the temperature at the illuminated side (−0.392), curing time (−0.323), the temperature at the back side (−0.233), curing distance (0.143) and material thickness (−0.140). The best penalty parameter c (44.435) and width g (0.072) of the kernel function in the support vector machine (SVM) model were obtained using the genetic algorithm (GA) optimization, and the results were compared with the grey wolf optimizer (GWO) and particle swarm optimization (PSO). The performed analyses revealed that the developed GA-SVM model exhibits the best prediction results compared to other machine learning algorithms. The optimum bending strength of the UV-CIPP material used in this test is 294.77 MPa, which corresponds to the curing time, UV lamp power, curing distance, material thickness, light side temperature, and back side temperature of 7.59 min, 157.33 mW/cm2, 189.99 mm, 4.38 mm, 79.49 °C, and 76.59 °C, respectively.

The lifespan and the performance of flexible electronic devices and components are affected by the large accumulation of heat, and this problem must be addressed by thermally conductive polymer composite films. Therefore, the need for the development of high thermal conductivity nanocomposites has a strong role in various applications. In this article, the effect of different particle reinforcements such as single and hybrid form, coated and uncoated particles, and chemically treated particles on the thermal conductivity of various polymers are reviewed and the mechanism behind the improvement of the required properties are discussed. Furthermore, the role of manufacturing processes such as injection molding, compression molding, and 3D printing techniques in the production of high thermal conductivity polymer composites is detailed. Finally, the potential for future research is discussed, which can help researchers to work on the thermal properties enhancement for polymeric materials., Validerad;2023;Nivå 2;2023-08-15 (marisr);License fulltext: CC-BY. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

During the pressing of powder mixtures to make cemented carbide tools, the degree to which the powder spreads to fill the die and to which it compacts is uncertain. This leads to inconsistent dimensions and densities in the finished product. This performance changes with the composition of the powder, including the amount of pressing agent in the mixture, the particle size distribution and particle shape. One way to quantify the degree to which powder will spread to fill the mold evenly is using the property called 'flowability'. There are several techniques by which flowability can be measured, and each technique does not always give results that are consistent with other techniques. It is, therefore, important to know what technique(s) predict(s) the final behavior of the powder in this application before it is used in quality assurance or to design a process. Additionally, powder size distribution and shape metrics are measured using dynamic image analysis to investigate if there is any relationship between key values of these properties and compaction behavior. In this study, static Angle of repose, Tap Density, Hall flow time and Powder rheometry were benchmarked against each other and against the dimensions of presses and liquid phase sintered tool inserts to understand which technique had the strongest dependence on the compactability, which was defined as the ratio of the tallest dimension in the insert to the smallest. After the study, the results showed that a more extensive particle size distribution improves the compaction properties and that the powders with a higher resistance to a rotating blade tend to have better compaction properties. On the other hand, a clear pattern for the results of all measurement methods and the correlation between the compaction behavior of the carbide tools could not be discerned. In conclusion, the study showed that it is possible to determine a relationship between the results of measurement methods and the compaction be, Vid pressning av pulverblandningar för tillverkning av hårdmetallverktyg är det osäkert i vilken grad pulvret sprider sig för att fylla matrisen och i vilken grad det komprimeras. Detta leder till inkonsekventa dimensioner och densitet i den färdiga produkten. Denna prestanda förändras med pulvrets sammansättning, inklusive mängden bindemedel som finns i blandningen, partikelstorleksfördelningen och partikelformen. Ett sätt att kvantifiera i vilken grad pulvret sprids för att fylla formen jämnt är att använda den egenskap som kallas "flytbarhet". Det finns flera tekniker för att mäta flytbarhet, och varje teknik ger inte alltid resultat som överensstämmer med andra tekniker. Det är därför viktigt att veta vilken eller vilka tekniker som förutsäger pulvrets slutliga beteende i denna tillämpning innan den används i kvalitetssäkring eller för att utforma en process. Vidare mäts pulvrets partikelstorleksfördelning och form med dynamisk bildanalys för att undersöka om det finns något samband mellan nyckelvärden för dessa egenskaper och komprimeringsbeteendet. I den här studien jämfördes statisk rasvinkel, tappdensitet, hallflödestid och pulverreometri samt med dimensionerna på pressar och sintrade verktygsinsatser i vätskefas för att förstå vilken teknik som hade det starkaste beroendet på kompatibiliteten, vilket definieras som förhållandet mellan den högsta dimensionen i insatsen och den minsta. Efter studien visade resultaten att en mer omfattande partikelstorleksfördelning förbättrar komprimeringsegenskaperna och att pulver med högre motståndskraft mot ett roterande blad tenderar att ha bättre komprimeringsegenskaper. Vidare kunde inte ett tydligt mönster för resultaten för alla mätmetoder och sambandet på komprimeringbeteendet för hårmetallverktygen urskiljas. Sammanfattningsvis visade studien på att det går att använda sig av mätmetoder för att kunna urskilja ett samband mellan resultaten på mätmetoderna och pulvers kompaktibillitetsegenskaper. Genom att använda si

Underhåll av tandimplantat är tidskrävande och kan vara smärtsamt för patienten. Av denna anledning är det önskvärt att maximera tiden mellan återbesök. En faktor som påverkar återbesökstiden är hur mycket distansskruven i ett tandimplantat har lossnat med tiden. För att forska vidare på detta så behövs en momentnyckel som kan mäta det maximala momentet som krävs för att lossa distansskruven. För att uppnå detta har en systematisk produktutvecklingsprocess genomförts. Hållfasthetsberäkningar och FEM-analyser har genomförts för att se till att prototypens mekaniska egenskaper uppfyller de krav som ställs. För att framställa prototypen har 3D-skrivning använts, där mätningar, kalibrering och programmering gjorts för att säkerställa så momentnyckeln kan mäta det maximala momentet. Arbetet resulterade i en prototyp av kolfiberkomposit och titan för att mäta det maximala momentet som krävs för att lossa en distansskruv., Maintenance of dental implants is time-consuming and can be painful for thepatient. For this reason, it is desirable to maximize the time between return visits. One factor that affects the revisit time is how much the abutment screw in a dental implant has loosened over time. In order to further research on this, a torque wrench is needed that can measure the maximum torque required to loosen the abutment screw. To achieve this, a systematic product development process has been carried out. Strength theory calculations and FEM analyses have been carried out to ensure that the prototype's mechanical properties meet the requirements. To produce the prototype, 3D printing has been used, measurements, calibration and programming has been done to ensure that the torque wrench can measure the maximum torque. The work resulted in a prototype made of carbon fiber composite and titanium for measuring the maximum torque required to loosen a abutment screw.

During machining operation, cemented carbide tools are exposed to high loads and temperatures, which eventually leads to plastic deformation of the tool material. The aim of this work was to investigate if the microstructures of creep deformed micro grain cemented carbides can be linked to alloying elements and mechanical properties. Eleven different fine-grained Tungsten carbide (WC) and Cobalt (Co) based materials have been exposed to compressive creep tests at application relevant temperature. The WC grain size, Sigma 2 (∑2) boundary fraction, and crystallographic structure of the creep deformed materials were investigated with scanning electron microscopy equipped with an electron backscatter diffraction detector. Furthermore, the microstructure of some materials was analysed before and after creep deformation using scanning electron microscopy. A screening of alloying elements that have the potential to increase creep resistance was performed. Growth perpendicular to the load axis was observed in several creep deformed materials, and it could be linked to lower creep resistance. Transition metals from group 4 and 6 limited grain growth, and therefore, improved creep resistance. It was found that a high ∑2 boundary fraction is related to higher creep resistance. The ∑2 boundary fraction was observed to be affected by grain size and alloyingelements., Under skärande bearbetning utsätts hårdmetallsverktyg för höga tryck och temperaturer. Över tid leder det till att materialet plastiskt deformeras. Syftet med det här arbetet var att undersöka om mikrostrukturen i krypdeformerade hårdmetallsmaterial kan kopplas till legeringsämnen och mekaniska egenskaper. Elva olika finkorniga Volframkarbid (WC) och Kobolt (Co) baserade material har utsatts för tryckbelastade kryptest vid applikationsrelevant temperatur. WC kornstorleken, andelen Sigma 2 (∑2) korngränser samt kristallstrukturen i de krypdeformerade materialen undersöktes med hjälp av bakåtspridd elektrondiffraktion (EBSD). Några av materialen analyserades också med hjälp av elektronmikroskopi före och efter deformation. En screening av vilka legeringselement som har potential att förbättra krypmotståndet utfördes. Korntillväxt vinkelrätt mot lastriktningen observerades i ett flertal av de krypdeformerade materialen, och denna korntillväxt kunde kopplas till lägre krypmotstånd. Övergångsmetaller från grupp 4 och 6 begränsade korntillväxten och förbättrade därav krypmotståndet. Det visade sig också att en högfraktion av ∑2 korngränser är relaterat till bättre krypmotstånd. Det observerades att fraktionen av ∑2 korngränser påverkas av kornstorlek och legeringsämnen.

The joint between different lightweight materials plays a significant role in multi-material design of structural components for the automotive industry, aiming to reduce the vehicle's weight without compromising performance or safety. Yet, conventional mechanical joining technologies between metals and Carbon Fibre Reinforced Polymers (CFRP) result in either a hole being drilled in the composite material, leading to damages which reduce the load bearing capacity, or the weight of the part being increased due to the incorporation of fasteners. At the same time, alternative mechanical joining methodologies involve complex and costly processing, hindering their industrial application. This work presents a new, simple, cost-efficient and non-weight penalizing mechanical joining technology between a metal sheet and fibre reinforced polymer prepregs consisting of a single-step punching process. In this process, the metallic sheet is completely perforated, while the prepreg is not. The punch pushes the carbon fibres through the metallic hole, with no, or minimal fibre breakage, generating a mechanical interlock. The shear strength and the absorbed energy of the co-cured joint increase with the incorporation of the mechanical interlocking joint., Licens fulltext: CC BY License

Korslimmat trä (KL-trä) tillverkas av brädor som limmas ihop korsvis i flera skikt. Skivorna som erhållsanvänds som byggelement, mestadels för väggar och bjälklagselement. Utgångsmaterialet trä tarstår i jämvikt med det omgivande klimatet och kommer därför ändra fuktkvoten. I studien undersöktesen skiva av KL-trä under varierande fuktförhållanden i en klimatkammare hos Linnéuniversitetet.Egenfrekvenser samt fuktkvoten följdes upp och sambandet med klimatet studerades. Det visade sigatt första och tredje uppmätta egenfrekvensen (böjning) visade negativ korrelation med omgivandefukten, den gick upp när fukten minskades (och tvärtom). För andra egenfrekvensen (torsion)däremot visade sig ett mer komplicerat samband. Ett flertal möjliga orsaker presenteras som förklaring. Medverkande organisationer var Linnéuniversitetet som huvudpart samt SödraSkogsägarna och Saab som bidragit som stödfunktionen och bollplank.

High-entropy Alloys (HEAs) are considered prospective materials demonstrating the new approach of alloy design creating new compositions for harsh conditions. However, searching for alloy chemical composition providing the best material properties is a costly process. Additive manufacturing (AM) can be an effective technique for adjusting the alloy composition by using several initial materials. The powder bed fusion (PBF) AM process allows the printing of solid parts using powder blends. In the present study, the CrFeCoNi(Al,Ti) HEAs were printed by the PBF technique using the blends of three powders. The structural and phase investigations revealed the chemical inhomogeneity in the materials that led to the new phase formations affecting the mechanical characteristics. The high-temperature annealing at 1200 °C can be considered a post-treatment process for the printed alloys as a homogenization process while the annealing at a lower temperature of 800 °C initiates the decomposition of the initially formed f.c.c. phase.

The research field of composite materials is particularly fascinating due to the design freedom they offer and the infinite number of constituent combinations, including those that are already explored, and many more that are yet to be tried. One composite material that holds great potential contains carbon in its fiber shape. Carbon fibers possess unique properties that excel in mechanical aspects, as well as interesting electrical and thermal properties that are yet to be fully explored. These fibers are readily available on the market and can be introduced as reinforcement in various lengths and orientations, yielding diverse results depending on the intended effect. Although carbon fiber reinforced polymer composites (CFRP) are present on the market for quite some time, specifically in high-performance applications, they are predominantly used when their performance outweighs their cost. Meanwhile, carbon fiber composite waste is starting to cumulate in noticeable amounts. This waste originates from both, production scrap and end-of-life scenarios, as components introduced in service life in the past 30 years are being decommissioned and discarded. Unfortunately, the prevalent solution for handling this waste is landfilling, due to its ease, affordability, and accessibility. Consequently, substantial amounts of composite waste are accumulating worldwide. Furthermore, it has finally come to our attention that our planet's resources are finite. Our exploitation of these resources has been largely devoid of consideration for the needs of future generations. As a result, recently, sustainability has emerged as a key enabler for a circular economy, driven by increasing environmental concerns and demands from customers and users for market transformation. The implementation of sustainable practices is now underway, albeit at a gradual pace. In summary, we find ourselves facing a trifold predicament: a splendid material being underutilized due to production costs, th

Polyurethane (PU) possesses excellent thermal properties, making it an ideal material for thermal insulation. Incorporating Phase Change Materials (PCMs) capsules into Polyurethane has proven to be an effective strategy for enhancing building envelopes. This innovative design substantially enhances indoor thermal stability and minimizes fluctuations in indoor air temperature. To investigate the thermal conductivity of the Polyurethane-Phase Change Materials foam composite, we propose a hierarchical multi-scale model utilizing Physics-Informed Neural Networks (PINNs). This model allows accurate prediction and analysis of the material’s thermal conductivity at both the meso-scale and macro-scale. By leveraging the integration of physics-based knowledge and data-driven learning offered by Physics-Informed Neural Networks, we effectively tackle inverse problems and address complex multi-scale phenomena. Furthermore, the obtained thermal conductivity data facilitates the optimization of material design. To fully consider the occupants’ thermal comfort within a building envelope, we conduct a case study evaluating the performance of this optimized material in a detached house. Simultaneously, we predict the energy consumption associated with this scenario. All outcomes demonstrate the promising nature of this design, enabling passive building energy design and significantly improving occupants’ comfort. The successful development of this Physics-Informed Neural Networks-based multi-scale model holds immense potential for advancing our understanding of Polyurethane-Phase Change Material’s thermal properties. It can contribute to the design and optimization of materials for various practical applications, including thermal energy storage systems and insulation design in advanced building envelopes.

A hybrid wing box, consisting of CFRP skins bolted to an aluminum inner structure, is tested in cyclic and quasi-static bending/twisting loading at temperatures up to 90 degrees C. Besides bolted joints, the test object contains ply drop-off regions with embedded artificial defects and impact damages in the CFRP skins. Thermally and mechanically induced strains are measured and a good correspondence is achieved in comparison to the previously computed strains. The magnitude of the thermally induced strains is significant, 10-20% of the mechanically induced strains at static design load. Fatigue failure of several titanium bolts, and fatigue cracks in the bolt holes in the aluminum plate, in the main joint are detected. No delamination growth of the artificial defects in the ply drop-off regions nor from the impact damages is observed by C-scan inspections. The final failure took place at 128% of the design load and was initiated by a combination of bearing and bolt bending failure in the main CFRP-aluminum joint. This work demonstrates and emphasizes the importance of large-scale tests for the purpose of inducing multiple interactive damage and failure mechanisms, as well as thermal effects in hybrid CFRP-aluminum structures., Funding Agencies|Sweden?s Innovation Agency; [2020-00187]

Sensing cement-based composites refer to composites that have sensing functionality that can measure several physical and chemical parameters. Sensing cement-based composites are fabricated by incorporating some functional fillers, such as conductive fibers (CFs), carbon nanofibers (CNFs), carbon nanotubes (CNTs), and graphene, into conventional concrete. The self-sensing phenomenon in a material is based on the property of an electrically conductive material to show a change in its electrical resistivity. Several factors affect the electrical resistivity of cement-based composites. These include, for example, the type of added conductive phases, their concentration, the microstructure of the surrounding binder matrix, and its composition or moisture content. Variable stress, strains, relative humidity, temperature, or crack development can all affect conductivity. A novel material, so-called "nanomodified Portland cement," is an in situ synthesis of carbon-based materials on untreated Portland cement particles. The synthesized method is based on the application of a chemical vapor deposition process (CVD). The nanomodified Portland cement was produced and used as a conductive filler in a sensing cement-based composite to improve the dispersion issue of the carbon-based materials, which have a hydrophobic nature and the tendency to agglomerate in the cement-based composites. The sensing capability of the nanomodified Portland cement composites was studied and compared with other conductive materials, revealing the percolation threshold and tunneling phenomena as possible explanations for the sensing mechanism with and without mechanical deformation. The achieved results of this study suggest that nanomodified Portland cement is a promising material for use in sensing cement-based composites as it exhibits high sensitivity to compressive stress and strain, humidity, and temperature. Furthermore, it has the potential to be utilized in the development of integrated mon

Lithium-ion batteries are one of the key technologies to address the global climate challenge. Higher battery capacity could also be seen as indirectly influencing the entire value chain. One way to increase capacity is to add silicon to the graphite anode, since silicon can store much more lithium ions than graphite. Several high-performance schemes utilizing silicon nano solutions have been demonstrated. However, industrial-scale implementation of these solutions still poses a challenge. In this thesis I present a novel scalable furnace technique to create silicon nanoparticles attached to the nanographite flakes. The novel furnace technique allows compatibility with already established industrial-scale electrode manufacturing techniques, presenting itself as a promising strategy for engineering electrodes with endurable performance., Litiumjonbatterier är en av nyckelteknologierna för att möta den globala klimatutmaningen. Högre batterikapacitet kan också indirekt påverka hela värdekedjan. Ett sätt att öka kapaciteten är att tillsätta kisel till grafitanoden eftersom kisel kan lagra mycket mer litiumjoner än grafit. Flera högpresterande system som använder kiselnanolösningar har demonstrerats. Implementering i industriell skala av dessa lösningar är dock fortfarande en utmaning. I denna avhandling presenteras en ny skalbar ugnsteknik för att skapa kiselnanopartiklar på nanografitflak. Den nya ugnstekniken är kompatibel med redan etablerade industriella metoder för tillverkning av elektroder, och kan vara en lovande strategi för att konstruera långtidsstabila elektroder., Vid tidpunkten för framläggningen av avhandlingen var följande delarbete opublicerat: delarbete III (inskickat).At the time of the defence the following paper was unpublished: paper III (submitted)

Elastic strain sensor nanocomposites are emerging materials of high scientific and commercial interest. This study analyzes the major factors influencing the electrical behavior of elastic strain sensor nanocomposites. The sensor mechanisms were described for nanocomposites with conductive nanofillers, either dispersed inside the polymer matrix or coated onto the polymer surface. The purely geometrical contributions to the change in resistance were also assessed. The theoretical predictions indicated that maximum Gauge values are achieved for mixture composites with filler fractions slightly above the electrical percolation threshold, especially for nanocomposites with a very rapid conductivity increase around the threshold. PDMS/CB and PDMS/CNT mixture nanocomposites with 0-5.5 vol.% fillers were therefore manufactured and analyzed with resistivity measurements. In agreement with the predictions, the PDMS/CB with 2.0 vol.% CB gave very high Gauge values of around 20,000. The findings in this study will thus facilitate the development of highly optimized conductive polymer composites for strain sensor applications.

Particleboards are used worldwide in various industry segments, like construction and furniture production. Nevertheless, increase in wood prices and logistical challenges urge the particleboard industry to find alternative raw materials. By-products and residues from the agricultural and food industries could offer possibilities for material sourcing at a local level. This study aimed to investigate the chemical composition, particle geometry, anatomical structure, and microtensile characteristics of such material, specifically barley husks (BH), oat husks (OH), and wheat bran (WB). Barley and oat husks were found to have comparable hemicelluloses and lignin contents to industrial wood chips but contained more ash. Wheat bran was rich in extractives and showed high buffering capacity. Light microscopy and microcomputed tomography revealed details of leaf structure for BH and OH as well as the multi-layer structure of WB. The ultimate microtensile strength of BH, various OH samples, and WB were respectively 2.77 GPa, 0.84-2.42 GPa, and 1.45 GPa. The results indicated that the studied materials could have potential uses as furnish materials in non-load bearing particleboards, where thermal or acoustic insulation properties are desirable.

This pre-study “Composites for sustainable shipping” was carried out as a response to the lightweight industry's desire to map the remaining barriers that still prevent more and larger applications of composite materials in shipping. Ever since the first-generation Visby corvettes were launched in the early 2000s, the industry has shown that it is possible to manufacture large composite ships with good strength and seaworthiness with low maintenance requirements. Despite this, the potential of modern lightweight materials for shipping is underutilized. Essentially, the stumbling blocks can be divided into three areas: Fire properties, competence, and economy. To this can be added uncertainty during operation in cold climates (ice properties) and recycling issues, as obstacles to more widespread use of composites. Within the framework of this study, ice calculations were carried out to demonstrate new methods of optimising composite hulls, and the results of an earlier preliminary study were supplemented with fire tests for new fire protections at the request of the industry. Furthermore, the results of the preliminary study show that composites have a given place in future shipping in several and new ways. With the rise of electric powertrains, just as for the aviation and automotive industries, light weight is a prerequisite to be able to go from a fuel with a high energy density to one with a lower. Lightweight is an enabler for an electric fleet. Electric operation and fossilfree energy carriers also mean direct innovation opportunities linked to material selection. Structural batteries, airframe technology, thermally and electrically conductive lightweight materials are areas we see emerging in the wake of the progress of electric operation., Förstudien ”Kompositer för en hållbar sjöfart” genomfördes som ett svar på lättviktsindustrins vilja att kartlägga de stötestenar som fortfarande hindrar fler och större tillämpningar av kompositmaterial inom sjöfarten. Allt sedan den första generationens Visby-korvetter sjösattes under tidigt 2000-tal har industrin visat att det går att tillverka stora fartyg i komposit med goda hållfasthets- och sjöegenskaper med låga underhållskrav. Trots detta så är potentialen i moderna lättviktsmaterial för sjöfarten underutnyttjad. I huvudsak kan stötestenarna delas upp i tre områden: brandegenskaper, kompetens och ekonomi. Därtill kan läggas osäkerhet vid drift i kalla klimat (isegenskaper) och återvinningsfrågor, som hinder för mer utbrett nyttjande av kompositer. Inom ramen för studien genomfördes isberäkningar för att visa på nya metoder att optimera kompositskrov och en tidigare förstudies resultat kompletterades med brandprover för nya brandskydd på begäran från industrin. Samtidigt visar förstudiens resultat att kompositer har en given plats i framtidens sjöfart på flera och nya sätt. Med framväxten av elektriska drivlinor är, precis som för flyg- och bilindustri, lättvikt en förutsättning för att kunna gå från ett bränsle med hög energidensitet till ett med lägre. Lättvikt är en möjliggörare för en eldriven flotta. Eldrift och fossilfria energibärare innebär också direkta innovationsmöjligheter kopplade till materialval. Strukturella batterier, bärplansteknik, termiskt och elektriskt ledande lättviktsmaterial är områden vi ser växa fram i kölvattnet av eldriftens framfart., I samarbete med: FMV, Green City Ferries, SAAB, Kockums, Swede Ship Composite AB, Poseidon Konsult AB, BPAB samt Teknos. Detta projekt har genomförts inom Trafikverkets branschprogram Hållbar sjöfart, som drivs av Lighthouse., Branschprogrammet hållbar sjöfart

Concrete is one of the most common construction materials used worldwide. The service life of concrete structures is typically limited by deterioration due to corrosion of reinforcement. Therefore, the need for strengthening corrosion-damaged structures has increased in the last decades. Strengthening using Fibre Reinforced Polymers (FRP) is one among many methods that can restore the strength and extend the service life of sound Reinforced Concrete (RC) structures. The effect of FRP strengthening on corrosion-damaged RC structures raised increased research efforts the latest years. The effectiveness of this method on strengthening and repair of corrosion-damaged RC beams was studied in this thesis. The flexural behavior of two beam geometries with several variations of the strengthening system was investigated using non-linear finite element analyses (NLFEA). Corrosion damages were modelled along the whole tensile bars and a horizontal corrosion-induced crack was modelled at the level of the tensile bars along the whole width and the length of the beams. Three FRP components were used for strengthening: FRP plate, inclined U-jackets, and vertical U-jackets with the same FRP arrangement chosen for the studied beam geometries. It was found that the addition of FRP plate to the beam soffit was effective to increase the load-bearing capacity of the beams significantly. When the inclined U-jackets were added to the beams along with the FRP plate, the failure at the FRP plate end close to the supports was prevented, and some additional load-bearing capacity was obtained. However, the increase in load-bearing capacity varied due to factors such as the beam geometry as well as the arrangement, inclination, and dimension of the inclined U-jackets. The addition of vertical U-jackets did not improve the flexural behaviour of the beams when they were placed in the mid-span region. Although, the addition of the vertical U-jackets close to the supports at the location of the f, Finansiering från Trafikverket, TRV 2019/64827, Reparation och förstärkning av betongkonstruktioner med korroderad armering

Low weight, small footprint, and high performances are essential requisites for the implementation of energy storage devices within consumer electronics. One way to achieve these goals is to increase the thickness of the active material layer. In this work, carbonized and graphitized rayon felt, a cellulose-derived material, is used as a three-dimensional current collector scaffold to enable the incorporation of large amount of active energy storage materials and ionic liquid-based gel electrolyte in the supercapacitor devices. PEDOT:PSS, alone or in combination with active carbon, has been used as the active material. Three-dimensional supercapacitors with high per unit area capacitance (more than 1.1 F/cm(2)) have been achieved owing to the loading of large amount of active material in the felt matrix. Areal energy density of more than 101 mu Wh/cm(2) and areal power density of more than 5.9 mW/cm(2) have been achieved for 0.8 V operating voltage at a current density of 1 mA/cm(2). A nanographite material was found to be beneficial in reducing the internal serial resistance of the supercapacitor to lower than 1.7 omega. Furthermore, it was shown that even after 2000 times cycling test, the devices could still retain its performance with at least 88% coulombic efficiency for all the devices. All the materials are readily available commercially, environmentally sustainable and the process can potentially be upscaled with industrial process., Funding Agencies|Knut och Alice Wallenbergs Stiftelse; Onnesjo foundation; Stiftelsenfor Strategisk Forskning; VINNOVA

This study investigated the mechanical properties and microstructural characteristics of fiberboard composite produced by naturally-bonded Malaysian bamboo fiber (Bambusa vulgaris). The components that obtained through soda pulping of bamboo culms such as fiber and black liquor, were used for the preparation of high-density fibreboard composite at two target densities of 850 and 950 kg/m3. The bamboo fiberboard composite (BFC) were then produced at 200°C and two pressing parameters of 125 and 175 s/mm. The mechanical properties, e.g., flexural strength and internal bonding (IB) of BFC samples were evaluated according to BS EN 310: 1993 and BS EN 319: 1993, respectively. It was found that the mechanical performance of the composite with 850 kg/m3 density was significantly higher than 950 kg/m3 ones, especially for the samples with 125 s/mm pressing parameter. Microstructure characteristic of the BFC samples illustrated that the fiber linkages were cracked in the composites with higher density, e.g., the composite with the density of 950 kg/m3 and also black liquor were slightly degraded at longer pressing time, which led to the reduction in mechanical properties, especially in IB strength.

Mechanical behavior of additively manufactured lattice materials has been mainly investigated under uniaxial compression, while their performance under uniaxial and multiaxial tension are yet to be understood. To address this gap, a generic elastoplastic homogenization scheme with continuum damage model is developed, and three different lattice materials, namely cubic, modified face-center cubic and body-center cubic, are analyzed under uniaxial, biaxial and triaxial tension. The influence of micro-architecture on the material's failure behavior as well as its macroscopic mechanical performance is thoroughly discussed. For validation, a set of uniaxial tensile experiments are conducted on functionally graded cubic lattice samples that are additively manufactured using Electron Beam Melting (EBM) process. Digital image correlation technique is employed to obtain the macroscopic stress-strain curves, and manufacturing imperfections are inspected using light omitting microscopy. It turns out that the behavior of as-built samples could substantially differ from numerical predictions. Thus, a defect-informed numerical model is employed to accommodate the effect of imperfections. The outcome is in a very good agreement with experimental data, indicating that with proper input data, the developed scheme can accurately predict the mechanical and failure behavior of a given lattice material.