The effect of biofilm formation on passive stainless steel in seawater environments is of primary importance since it leads to potential ennoblement of surfaces and subsequently to localized corrosion such as pitting and crevice corrosion. This study aims at developing an ecofriendly alginate biopolymer containing both non-toxic calcium and a limited amount of biocidal zinc ions which inhibits this effect. For this purpose, calcium alginate containing less than 1 % of zinc ions localized in the vicinity of the steel surface in natural and renewed seawater is demonstrated to reduce significantly the ennoblement process of steel. After 1 month of immersion, a mass loss of only 4 % of the active material is observed authorizing thereby long-term protection of steel in real environment. 

Mitigating the climate impact from aviation remains one of the tougher challenges in adapting society to fulfill stated climate targets. Long-range aviation cannot be electrified for the foreseeable future and the effects of combusting fuel at high altitude increase the climate impact compared to emissions of green-house gasses only, which further limits the range of sustainable fuel alternatives. We investigate seven different pathways for producing aviation biofuels coupled with either bio-energy carbon capture and storage (BECCS), or bio-energy carbon capture and utilization (BECCU). Both options allow for increased efficiency regarding utilization of feedstock carbon. Our analysis uses process-level carbon- and energy balances, with carbon efficiency, climate impact and levelized cost of production (LCOP) as primary performance indicators. The results show that CCS can achieve a negative carbon footprint for four out of the seven pathways, at a lower cost of GHG reduction than the base process option. Conversely, as a consequence of the electricity-intensive CO2 upgrading process, the CCU option shows less encouraging results with higher production costs, carbon footprints and costs of GHG reduction. Overall, pathways with large amounts of vented CO2, e.g., gasification of black liquor or bark, as well as fermentation of forest residues, reach a low GHG reduction cost for the CCS option. These are also pathways with a larger feedstock and corresponding production potential. Our results enable a differentiated comparison of the suitability of various alternatives for BECCS or BECCU in combination with aviation biofuel production. By quantifying the relative strengths and weaknesses of BECCS and BECCU and by highlighting cost, climate and carbon-efficient pathways, these results can be a source of support for both policymakers and the industry. © 2023 The Author(s)

Manganese-rich deposits in the lower member of the Datangpo Formation (DTP) (ca. 663–654 Ma) in South China formed in the aftermath of the Cryogenian Sturtian glaciation. The Mn in the DTP occurs dominantly as rhodochrosite and Ca-rhodochrosite. A hydrothermal origin of the Mn2+ is shown by the rare earth element distribution and significantly high Mn/Fe ratios (3–19, average = 10.1). Previous studies suggested a microbially-mediated process for controlling the DTP black-shale hosted Mn carbonate deposits. However, detailed reports on the formation mechanisms of micro-scale (<2–5 μm) ooid-like Mn carbonates in the DTP have rarely been published. Systematic petrography and geochemical analyses in this study demonstrate the coexistence of two types of micro-scale ooidal-like Mn carbonates formed through two distinct mechanisms, either dominated by microbially-mediated or physiochemically-forced pathways. The Type I Mn carbonate has relatively larger grain size of 2–5 μm and exhibits a radial-concentric microfabric that shows signs of growth banding in the form of alternating light and dark laminae, which mainly express variation in Ca and Mn concentrations. The initial precipitation phase of the Type I Mn carbonate is interpreted to be Mn oxide/hydroxide, based on positive Ce anomalies and selective enrichments of particular trace elements. Novel evidence indicates that the capture of Mn as a carbonate phase directly from the water column by primarily precipitated calcite, which is referred to as the Type II Mn carbonate, has also contributed to the DTP Mn-rich deposits. Multiple roles of organic matter in Mn carbonate formation have been established: (1) catalysed Mn-redox cycling; (2) trapping and transportation of initial mineral precipitates to sediments; (3) serving as a carbon source; (4) regulating the morphology of the Mn carbonate. As a key link for understanding Cryogenian carbon and Mn cycling, specific formation pathways for the DTP Mn-carbonates are likely to have been controlled by given atmospheric-oceanic compositions (including oxygen level, pCO2, and redox conditions) in response to major geological and biological events during the interglacial period. In turn, massive storage of inorganic carbon and phosphorous in Mn carbonate phases would have had a substantial influence on biogeochemical carbon cycling during the Cryogenian. 

Residual stresses created during the packaging process can adversely affect the reliability of electronics components. We used incremental hole-drilling method, following the ASTM E 837-20 standard, to measure packaging induced residual stresses in discrete packages of power electronics components. For this purpose, we bonded a strain gauge on the surface of a Gallium Nitride (GaN) power component, drilled a hole through the thickness of the component in several incremental steps, recorded the relaxed strain data on the sample surface using the strain gauge, and finally calculated the residual stresses from the measured strain data. The recorded strains and the residual stresses are related by the compliance coefficients. For the hole drilling method in the isotropic materials, the compliance coefficients are calculated from the analytical solutions, and available in the ASTM standard. But for the orthotropic multilayered components typically found in microelectronics assemblies, numerical solutions are necessary. We developed a subroutine in ANSYS APDL to calculate the compliance coefficients of the hole drilling test in the molded and embedded power electronics components. This can extend the capability of the hole drilling method to determine residual stresses in more complex layered structures found in electronics. 

Residual stresses created during the packaging process can adversely affect the reliability of electronics components. We used incremental hole-drilling method, following the ASTM E 837-20 standard, to measure packaging induced residual stresses in discrete packages of power electronics components. For this purpose, we bonded a strain gauge on the surface of a Gallium Nitride (GaN) power component, drilled a hole through the thickness of the component in several incremental steps, recorded the relaxed strain data on the sample surface using the strain gauge, and finally calculated the residual stresses from the measured strain data. The recorded strains and the residual stresses are related by the compliance coefficients. For the hole drilling method in the isotropic materials, the compliance coefficients are calculated from the analytical solutions, and available in the ASTM standard. But for the orthotropic multilayered components typically found in microelectronics assemblies, numerical solutions are necessary. We developed a subroutine in ANSYS APDL to calculate the compliance coefficients of the hole drilling test in the molded and embedded power electronics components. This can extend the capability of the hole drilling method to determine residual stresses in more complex layered structures found in electronics. 

Additive manufacturing (AM) of large-scale polymer and composite parts using robotic arms integrated with extruders has received significant attention in recent years. Despite the contributions of great technical progress and material development towards optimizing this manufacturing method, different failure modes observed in the final printed products have hindered its application in producing large engineering structures used in aerospace and automotive industries. We report failure modes in a variety of printed polymer and composite parts, including fuel tanks and car bumpers. Delamination and warpage observed in these parts originate mostly from thermal gradients and residual stresses accumulated during material deposition and cooling. Because printing large structures requires expensive resources, process simulation to recognize the possible failure modes can significantly lower the manufacturing cost. In this regard, accurate prediction of temperature distribution using thermal simulations is the first step. Finite element analysis (FEA) was used for process simulation of large-scale robotic AM. The important steps of the simulation are presented, and the challenges related to the modeling are recognized and discussed in detail. The numerical results showed reasonable agreement with the temperature data measured by an infrared camera. While in small-scale extrusion AM, the cooling time to the glassy state is less than 1 s, in large-scale AM, the cooling time is around two orders of magnitudes longer. © 2022 by the authors

Compared with silicon-based power devices, wide band gap (WBG) semiconductor devices operate at significantly higher power densities required in applications such as electric vehicles and more electric airplanes. This necessitates development of power electronics packages with enhanced thermal characteristics that fulfil the electrical insulation requirements. The present research investigates the feasibility of using ceramic additive manufacturing (AM), also known as three-dimensional (3D) printing, to address thermal and electrical requirements in packaging gallium nitride (GaN) based high-electron-mobility transistors (HEMTs). The goal is to exploit design freedom and manufacturing flexibility provided by ceramic AM to fabricate power device packages with a lower junction-to-ambient thermal resistance (<italic>R</italic>&#x03B8;JA). Ceramic AM also enables incorporation of intricate 3D features into the package structure in order to control the isolation distance between the package source and drain contact pads. Moreover, AM allows to fabricate different parts of the packaging assembly as a single structure to avoid high thermal resistance interfaces. For example, the ceramic package and the ceramic heatsink can be printed as a single part without any bonding layer. Thermal simulations under different thermal loading and cooling conditions show the improvement of thermal performance of the package fabricated by ceramic AM. If assisted by an efficient cooling strategy, the proposed package has the potential to reduce <italic>R</italic>&#x03B8;JA by up to 48%. The results of the preliminary efforts to fabricate the ceramic package by AM are presented, and the challenges that have to be overcome for further development of this manufacturing method are recognized and discussed. 

Product design and development are essential for a circular transition. Circularity decisions, such as those concerning the type of material, assembly method, and expected lifespan, made during the early design stages will significantly influence a product’s quality, cost, esthetics, sustainability, and circularity performance over the product lifecycle. However, circularity is not often considered in the early stages of product design and development. This paper presents the development of the concept circularity evaluation tool (CCET), which aims to support the evaluation of alternative product concepts in terms of their circularity potential in the early stages of product design and development. The CCET was iteratively developed based on an extensive literature review of the success criteria for tool development, guidelines, and existing tools for circular product design and development and strong collaboration with manufacturing companies. The tool was tested and verified at four manufacturing companies in Nordic countries. The tool has been proven useful for evaluating the circularity of products and supportive in the decision-making process in the early stages of product design and development. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.

For the solar energy industry to increase its competitiveness, there is a global drive to lower the cost of solar-generated electricity. Photovoltaic (PV) module assembly is material-demanding, and the cover glass constitutes a significant proportion of the cost. Currently, 3-mm-thick glass is the predominant cover material for PV modules, accounting for 10%–25% of the total cost. Here, we review the state-of-the-art of cover glasses for PV modules and present our recent results for improvement of the glass. These improvements were demonstrated in terms of mechanical, chemical and optical properties by optimizing the glass composition, including addition of novel dopants, to produce cover glasses that can provide (i) enhanced UV protection of polymeric PV module components, potentially increasing module service lifetimes; (ii) re-emission of a proportion of the absorbed UV photon energy as visible photons capable of being absorbed by the solar cells, thereby increasing PV module efficiencies and (iii) successful laboratory-scale demonstration of proof of concept, with increases of 1%–6% in Isc and 1%–8% in Ipm. Improvements in both chemical and crack resistance of the cover glass were also achieved through modest chemical reformulation, highlighting what may be achievable within existing manufacturing technology constraints. © 2020 The Authors.

This paper investigates the utilization of commercial masterbatches of graphene nanoplatelets to improve the properties of neat polymer and wood fiber composites manufactured by conventional processing methods. The effect of aspect ratio of the graphene platelets (represented by the different number of layers in the nanoplatelet) on the properties of high-density polyethylene (HDPE) is discussed. The composites were characterized for their mechanical properties (tensile, flexural, impact) and physical characteristics (morphology, crystallization, and thermal stability). The effect of the addition of nanoplatelets on the thermal conductivity and diffusivity of the reinforced polymer with different contents of reinforcement was also investigated. In general, the mechanical performance of the polymer was enhanced at the presence of either of the reinforcements (graphene or wood fiber). The improvement in mechanical properties of the nanocomposite was notable considering that no compatibilizer was used in the manufacturing. The use of a masterbatch can promote utilization of nano-modified polymer composites on an industrial scale without modification of the currently employed processing methods and facilities.

The deformation of polymers at constant applied stress is one of their major drawbacks, limiting their use in advanced applications. The study of this property using classical techniques requires extensive testing over long periods of time. It is well known that reinforced polymers show improved behavior over time compared to their neat counterparts. In this study, the effect of adding different amounts of graphene nanoplatelets (GNPs) on the time-dependent properties of high-density polyethylene (HDPE) is investigated using short-term creep tests and load/unload recovery tests. The results are discussed in terms of the test profile and the influence of loading history. Viscoplasticity/viscoelasticity analysis is performed using Zapas model and by comparing creep, creep compliance and pure viscoelasticity curves. The results show that the reinforcement of 15 wt% GNP have the most significant effect on the time-dependent behavior, reducing the strain by more than 50%. The creep compliance curves show that nano-reinforced HDPE behaves nonlinearly viscoelastically even at very low stresses. In addition to demonstrating the effect of nano-reinforcement, the discussion of the results concludes that the influence of loading history can be quite significant and should not be neglected in the design and evaluation of material behavior. © 2021 The Authors.

Additive manufacturing (AM), or 3D printing, is a growing industry involving a wide range of different techniques and materials. The potential toxicological effects of emissions produced in the process, involving both ultrafine particles and volatile organic compounds (VOCs), are unclear, and there are concerns regarding possible health implications among AM operators. The objective of this study was to screen the presence of respiratory health effects among people working with liquid, powdered, or filament plastic materials in AM. Methods: In total, 18 subjects working with different additive manufacturing techniques and production of filament with polymer feedstock and 20 controls participated in the study. Study subjects filled out a questionnaire and underwent blood and urine sampling, spirometry, impulse oscillometry (IOS), exhaled NO test (FeNO), and collection of particles in exhaled air (PEx), and the exposure was assessed. Analysis of exhaled particles included lung surfactant components such as surfactant protein A (SP-A) and phosphatidylcholines. SP-A and albumin were determined using ELISA. Using reversed-phase liquid chromatography and targeted mass spectrometry, the relative abundance of 15 species of phosphatidylcholine (PC) was determined in exhaled particles. The results were evaluated by univariate and multivariate statistical analyses (principal component analysis). Results: Exposure and emission measurements in AM settings revealed a large variation in particle and VOC concentrations as well as the composition of VOCs, depending on the AM technique and feedstock. Levels of FeNO, IOS, and spirometry parameters were within clinical reference values for all AM operators. There was a difference in the relative abundance of saturated, notably dipalmitoylphosphatidylcholine (PC16:0_16:0), and unsaturated lung surfactant lipids in exhaled particles between controls and AM operators. Conclusion: There were no statistically significant differences between AM operators and controls for the different health examinations, which may be due to the low number of participants. However, the observed difference in the PC lipid profile in exhaled particles indicates a possible impact of the exposure and could be used as possible early biomarkers of adverse effects in the airways. 

This paper reports experimental and finite element investigations conducted to assess the shear strength of corrugated web girders in stainless steel. The steel under consideration is LDX 2101. Four trapezoidal corrugated web girders were tested under shear. All tested girders reached the shear yield strength followed by strain hardening. An imperfection sensitivity study was done with the aid of finite element modelling. It was observed that an initial geometric imperfection based on the first eigen buckling mode with a maximum amplitude of the minimum dimension of the critical corrugation sub panel divided by 200, 𝑎max200⁄, leads to an ultimate shear strength greater than the shear yield strength and close to the test findings. It is concluded that EN 1993-1-5 shear design model for corrugated webs is conservative for stainless steel girders tested in the current study.

In this paper, the shear strength of corrugated web girders made of EN 1.4162/LDX 2101 stainless steel is investigated. Four full-scale trapezoidal corrugated web girders were tested under shear. Before conducting the tests, DIC was used to measure the real geometric imperfections in the web panels. Complementary finite element analysis studies were conducted to assess the sensitivity of the shear strength to initial imperfections. The experimental results indicated that all the tested girders with a local slenderness ratio of λ = 0.7 attained the shear yield strength, which was then followed by strain hardening in the material at a level that was 8–18% higher than the yield strength. This implies that the Eurocode's limit of λ = 0.25 to attain the plastic shear strength in corrugated webs can be quite conservative for stainless steel. According to the findings of the imperfection sensitivity studies, an initial geometric imperfection based on the first eigen buckling mode and with a maximum amplitude of amax/200, where amax is the maximum corrugation fold length, yielded ultimate strength within 3% of the test results. When the amplitude was increased to hw/200, where hw is the web height, the ultimate strength was estimated to be 25% lower on average than in the experiments. In three of the studied girders, initial imperfections with other forms than the first buckling mode were found to be more critical. Further, it was found that regardless of mode number, mode shapes that are more extended over the web panel result in a higher degradation of the ultimate shear strength. © 2023 The Authors

The use of Policy Lab processes has been growing in Sweden and other countries to accelerate the adaptation of regulations to emerging technologies. Policy Lab facilitates active collaboration between relevant authorities, companies, and stakeholders through interactive and iterative methods based on Design Thinking principles. This approach bridges the gap between the legislative domain responsible for developing regulatory frameworks and the innovative companies that create solutions for emerging markets using new technologies and opportunities. In our study, we applied Policy Lab processes to the EU Taxonomy Regulation to identify challenges and opportunities related to chemical safety and usage for manufacturers of complex products. The EU Taxonomy Regulation, along with its delegated acts, represent a serious effort to establish standardized sustainability reporting within EU. However, it is still in its early stages and lacks maturity. Moreover, certain ambiguities within the regulation currently prevent a comprehensive comparison of companies due to the development of other legislations. Addressing these gaps depends on the future development of, for example, REACH. Our conclusion is that the EU Taxonomy Regulation is part of a larger “movement” that reflects the policymakers’ intentions. This intention also includes increased data sharing at a significantly different level compared to current practices. In the long run, the shift will enable authorities to access the data and develop new legislations. Our specific focus was on the objective of pollution prevention and control regarding the use and presence of hazardous substances listed in Appendix C of the EU Taxonomy Regulation. According to Appendix C, activities must not lead to the manufacture, placing on the market or use of listed substances, whether on their own, in mixture or in articles. Regarding listed substances, reference is made to existing EU legislation that regulates hazardous substances within the EU. The most challenging aspect in Appendix C is point (g), which aims to identify substances, whether alone, in mixtures, or in articles, that meet the criteria set out in Article 57 of REACH but are not yet included in the Candidate list. Our workshops, interviews, and literature review confirmed that the main challenge in meeting the criteria of Appendix C, specifically point (g) is the need to enhance transparency and traceability throughout supply chains. Overcoming these challenges requires addressing barriers, such as the lack of a harmonized regulatory framework across the value chain, the need for faster identification and restriction of hazardous substances, and the reinforcement of stronger enforcement measures. The enabling of full declaration of the hazardous properties and functions of the substances, while considering the balance between information disclosure and protecting trade secrets, would reduce the need for extensive tracking of substance of very high concern along the value chain. To improve communication along the value chain and identify data gaps while protecting trade secrets, workshop participants have proposed the use of a user-friendly interface based on traffic light scenario. This interface would serve as a filter mechanism, allowing product manufacturers to establish specific criteria for material suppliers to respond to. The objective is to enhance communication, establish criteria, and effectively identify data gaps. While the SCIP database ensures accessibility of information on articles containing substances from the Candidate List above 0.1 w/w%, it is limited to hazardous substances on that list. This means that hazardous substances not listed in the Candidate List may not be covered by the database. The EU Commission has proposed the implementation of a digital product passport to enhance information sharing about products and their supply chain, including substances of concern. Our study is conducted under the Mistra SafeChem program, where screening tools for hazard and exposure assessment of substances are currently being developed. These tools aim to provide screening data for direct decision-making based on the Defined Approach (DA). These screening tools have the potential to contribute to filling data gaps during the early design phases of complex products, particularly when screening for multiple material alternatives.

Purpose. To investigate the response of the CC13 ionization chamber under non-reference photon beam conditions, focusing on penumbra and build-up regions of static fields and on dynamic intensity-modulated beams. Methods. Measurements were performed in 6 MV 100 × 100, 20 × 100, and 20 × 20 mm2 static fields. Monte Carlo calculations were performed for the static fields and for 6 and 15 MV dynamic beam sequences using a Varian multi-leaf collimator. The chamber was modelled using EGSnrc egs_chamber software. Conversion factors were calculated by relating the absorbed dose to air in the chamber air cavity to the absorbed dose to water. Correction and point-dose correction factors were calculated to quantify the conversion factor variations. Results. The correction factors for positions on the beam central axis and at the penumbra centre were 0.98-1.02 for all static fields and depths investigated. The largest corrections were obtained for chamber positions beyond penumbra centre in the off-axis direction. Point-dose correction factors were 0.54-0.71 at 100 mm depth and their magnitude increased with decreasing field size and measurement depth. Factors of 0.99-1.03 were obtained inside and near the integrated penumbra of the dynamic field at 100 mm depth, and of 0.92-0.94 beyond the integrated penumbra centre. The variations in the ionization chamber response across the integrated dynamic penumbra qualitatively followed the behaviour across penumbra of static fields. Conclusions. Without corrections, the CC13 chamber was of limited usefulness for profile measurements in 20-mm-wide fields. However, measurements in dynamic small irregular beam openings resembling the conditions of pre-treatment patient quality assurance were feasible. Uncorrected ionization chamber response could be applied for dose verification at 100 mm depth inside and close to large gradients of dynamically accumulating high- and low-dose regions assuming 3% tolerance between measured and calculated doses. © 2023 The Author(s).

The formation of strongly elastic physical gels based on poly(alkylene oxide)-grafted hyaluronan or carboxymethylcellulose, exhibiting both shear-thickening and strain-hardening have been studied using rheometry and explained using a slightly different interpretation of the transient network theory. The graft copolymers were prepared by a quantitative coupling reaction. Their aqueous solutions displayed a thermoreversible continuous transition from Newtonian fluid to viscoelastic solid which could be controlled by the reaction conditions. The evolution of all material properties of the gel could be categorized into two distinct temperature regimes with a fast evolution at low temperatures followed by a slow evolution at high temperatures. The activation energy of the zero shear viscosity and the relaxation time of the graft inside the interconnecting microdomains were almost identical to each other in both temperature regimes. This suggests that the number of microdomains remained approximately constant whereas the aggregation number inside the microdomains increased according to the binodal curve of the thermosensitive graft.

The Rekovind2 project, financed by the Swedish Energy Agency, focuses on digitizing wind turbine blade streams for reuse and recycling. This is of the utmost importance to enable new, more circular technical solutions that can replace today’s non-sustainable recycling, i.e. landfill and incineration of wind turbine blades. In this report, the work carried out to map the wind turbine blades in service in Sweden is presented. The digital platform intended to make possible the re-use of blades reaching end-of-life is build around key features that will be required for re-use: blade database with all needed informations on the blade (age, damages, material, model, ...), map with blades geolocation, digital tool to help blade processing such as cutting, and information on what can be done with EoL blades.

In order to achieve a more resource-efficient society and a future with reduced carbon dioxide emissions, new technological challenges must be dealt. One way to reach a more sustainable world is to start re-using end-of-life structures and waste and give them a “Second Life” with new functions in the society. As fiber reinforced polymer (FRP) composites are lightweight, strong, stiff and durable materials, there is great potential to re-use decommissioned FRP structures for new resource-efficient solutions in the building and infrastructure sectors. The present paper investigates innovative solutions in re-using wind turbine blades and glass fibre reinforced polymer (GFRP) pipes as structural elements in new bicycle and pedestrian bridges. Specifically, a concept design for decking system made of GFRP pipes is developed and discussed. The main design requirements for pedestrian bridges are considered and assumptions regarding end-of-life GFRP quality and their mechanical properties have been addressed. The aim of this paper is to contribute to a sustainable use of GFRP waste and at the same time provide a more cost-effective solution for short span pedestrian bridges. In a larger perspective, the authors would like to highlight the economically profitable potential of recovering and reusing/re-manufacturing end-of-life GFRP composites. © 2022, The Author(s)

To achieve a more resource-efficient society with a future with reduced carbon dioxide emissions, new technological challenges must be dealt. One way to reach a more sustainable world is to start re-using end-of-life structures and waste and give them a Second Life"with a new function in the society. As composite structures are lightweight, strong, stiff and durable materials, there is great potential to re-use decommissioned composite for new resource-efficient solutions in the building and infrastructure sector. The present paper investigates innovative solutions in re-using wind turbine blades as elements in new bicycle and pedestrian bridge designs. Several conceptual bridge designs where wind blades utilized as load bearing elements were developed and studied. The main design requirements for pedestrian bridges were considered and assumptions regarding wind blades quality and their mechanical properties addressed based on interviews with industries working with wind turbine blades repair and recycling. The aim of this paper is to contribute to a sustainable use of fibre reinforced polymer (FRP) waste and at the same time provide a more cost-effective FRP bridges. In a larger perspective, the authors would like to highlight the economically profitable potential of recovering and reusing / re-manufacturing end-of-life glass FRP composites.

Functional testing of waterproofing systems for use behind ceramic tiling based on flexible sheets 2022 This research project is a repetition of previously completed projects. These projects span a long period of time, 12 years. The projects were completed during the period 2010 to 2022. Functional testing The result is better than before. 2022 2019 (1) 2016 (2) 2014 (3) 2010 (4) Result Result Result Result Result Result No leakage 9 (47 %) 6 (32 %) 8 (40 %) 3 (15 %) 0 (0 %) Leakage 10 (53 %) 13 (68 %) 12 (60 %) 17 (85 %) 5 (100 %) In this investigation, most of the leaks are located to penetrations of large and small sewer pipes. In this investigation, we have on several occasions seen that the pipe sleeves have had substandard quality. This has manifested itself in the fact that the polymeric material which is to seal around the pipe during the test has lost its sealing ability. It is probable that the material has developed a residual deformation (settling) which means that the material has lost its ability to seal around the pipe. We have also noticed that pipe cuffs have delaminated, the layers in the cuff during the test have been divided into their components. Leakage has also occurred at inner corners, outer corners and at chafing. Only a few, two, leaks at connections to floor drains have been noted. Better yet, none of the examined waterproofing systems showed leaks that were so extensive that one can speak of a total damage. Water vapour resistance and mass per unit area The vast majority of investigated waterproofing foils have a water vapour resistance of between 2.5 and 4.5 million s m, which is a high or very high value. Results for five waterproofing foils fall below 2.5 million s / m. Based on the determinations of water vapor resistance and basis weight, it can be concluded that probably six of the waterproofing suppliers have developed new or changed foils since the last survey. The trend of wanting to make thinner foils seems to have been broken. Most of the waterproofing foils have a higher vapor passage resistance now than in the previous survey. It is also noteworthy that the PVC sealing layer has a low water vapor passage resistance. The waterproofing foil has basically the same basis weight now compared to the previous survey. Indication of long-term properties To obtain an indication of the amount of added antioxidants that improve the long-term properties of the materials, DSC analyses of the waterproofing foils have been performed. Compared with the previous study, the induction temperatures are at about the same level as before, only small differences occur. The average induction temperature for all polyethylene films is 216 ° C and, in summary, the materials appear to be stabilized at the same level as the previous study. In the same way as in the survey, 2016, most materials seem to be more stabilized for long-term use compared with the previous study, 2014. However, for all analysed materials, to make a reliable service life prediction of the material, a more comprehensive aging study is recommended

This work meets Metal Additive Manufacturing and Time Series Processing. It presents a four-step analytical procedure addressed to support the discovery of defect causes in 3D metal printing. The method has a phase of data space transformation, where the features space is firstly reduced and secondly exploited in a higher dimensional space. Later, a procedure for knowledge discovery is applied. Finally, by analyzing the results, it is concluded the most probable causes of the high rate of defects in the production phase. This procedure is proved with data obtained from a SLM machine, and the results are convincing.

The pan-European “European Plate Observing System (EPOS)” is focussed on Europe and adjacent regions and includes geophysical monitoring networks, local observations (including permanent in-situ and volcano observatories), topographic/surface dynamics information, surface and subsurface geological information, experimental and laboratory data and functions, and satellite data. In 2021 the Swedish Research Council (VR) approved an application for Sweden to join EPOS-ERIC, formally establishing existing collaborations between EPOS and Swedish research infrastructures.

Kraft lignin, a by-product from the production of pulp, is currently incinerated in the recovery boiler during the chemical recovery cycle, generating valuable bioenergy and recycling inorganic chemicals to the pulping process operation. Removing lignin from the black liquor or its gasification lowers the recovery boiler load enabling increased pulp production. During the past ten years, lignin separation technologies have emerged and the interest of the research community to valorize this underutilized resource has been invigorated. The aim of this review is to give (1) a dedicated overview of the kraft process with a focus on the lignin, (2) an overview of applications that are being developed, and (3) a techno-economic and life cycle asseeements of value chains from black liquor to different products. Overall, it is anticipated that this effort will inspire further work for developing and using kraft lignin as a commodity raw material for new applications undeniably promoting pivotal global sustainability concerns.

Hydrogen delivered at hydrogen refuelling station must be compliant with requirements stated in different standards which require specialized sampling device and personnel to operate it. Currently, different strategies are implemented in different parts of the world and these strategies have already been used to perform 100s of hydrogen fuel sampling in USA, EU and Japan. However, these strategies have never been compared on a large systematic study. The purpose of this paper is to describe and compare the different strategies for sampling hydrogen at the nozzle and summarize the key aspects of all the existing hydrogen fuel sampling including discussion on material compatibility with the impurities that must be assessed. This review highlights the fact it is currently difficult to evaluate the impact or the difference these strategies would have on the hydrogen fuel quality assessment. Therefore, comparative sampling studies are required to evaluate the equivalence between the different sampling strategies. This is the first step to support the standardization of hydrogen fuel sampling and to identify future research and development area for hydrogen fuel sampling. © 2021 The Authors

Europe’s low-carbon energy policy favors a greater use of fuel cells and technologies based on hydrogen used as a fuel. Hydrogen delivered at the hydrogen refueling station must be compliant with requirements stated in different standards. Currently, the quality control process is performed by offline analysis of the hydrogen fuel. It is, however, beneficial to continuously monitor at least some of the contaminants onsite using chemical sensors. For hydrogen quality control with regard to contaminants, high sensitivity, integration parameters, and low cost are the most important requirements. In this study, we have reviewed the existing sensor technologies to detect contaminants in hydrogen, then discussed the implementation of sensors at a hydrogen refueling stations, described the state-of-art in protocols to perform assessment of these sensor technologies, and, finally, identified the gaps and needs in these areas. It was clear that sensors are not yet commercially available for all gaseous contaminants mentioned in ISO14687:2019. The development of standardized testing protocols is required to go hand in hand with the development of chemical sensors for this application following a similar approach to the one undertaken for air sensors. © 2021 by the authors. 

The ISO 14687-2 standard sets requirements for the purity of the hydrogen that is delivered at refuelling stations. These specifications cover a wide range of impurities and include challenging measurements, mainly due to the very low levels of the required detection limits and the need for "total" measurements (total hydrocarbons, total sulphur compounds, halogenated compounds). Most of the compounds belonging to the species are organic. Thermal desorption often coupled with gas chromatography is a common speciation method used to determine the content of organic impurities. However, no existing sorbent tubes are sufficiently universal to trap all possible impurities; depending on the sorbents and the sampling volume, some compounds may irreversibly adsorb or may break through. It is therefore necessary to evaluate sorbents for the compounds targeted at the level required. In this study, the suitability of sorbent tubes for trapping organic impurities in hydrogen was investigated. Suitable sorbents were selected based on a literature review of suitable sorbent materials. Short-term stability studies for compounds among hydrocarbons, halogenated compounds and sulphurcompounds on the selected sorbents have then been performed for storage periods of two weeks since this is the period typically required to complete the collection, transport and analysis of hydrogen samples. The study clearly shows that the method is promising for total species, even through the results show that not all of the compounds belonging to the three total species to be analysed when performing hydrogen purity analysis can be quantified on one unique sorbent. A multibed sorbent consisting of Tenax TA (weak), Carboxen 1003 (medium), Carbograph 1 (strong) is shown to be a versatile sorbent suitable for the three "total species"; only a few compounds from each family would need to be analysed using other analytical methods. This method proposed here for total species will not only provide a sum of concentrations, but also an identification of which compound(s) is/are actually present in the hydrogen.

The study presents an optimised method to correct flow rates measured with a LFE flowmeter pre-set on methane while used for gas mixtures of unknown composition at the time of the measurement. The method requires the correction of the flow rate using a factor based on the viscosity of the gas mixtures once the composition is accurately known. The method has several different possible applications inclusive for the sampling of biogas and biomethane onto sorbent tubes for conformity assessment for the determination of siloxanes, terpenes and VOC in general. Five models for the calculation of the viscosity of the gas mixtures were compared and the models were used for ten binary mixtures and four multi-component mixtures. The results of the evaluation of the different models showed that the correction method using the viscosity of the mixtures calculated with the model of Reichenberg and Carr showed the smallest biases for binary mixtures. For multi-component mixtures, the best results were obtained when using the models of Lucas and Carr. 

Standards ISO14687 and EN17124 set stringent limits for numerous gaseous impurities and particulates that may damage the fuel cell system in a hydrogen vehicle, as it is highly sensitive to the presence of even very low levels of impurities. However, performing the whole set of analyses is both technically challenging and time-consuming for any laboratory and will require a combination of several analytical techniques or instruments. In this study, we discussed the selection of analytical techniques for hydrogen purity testing in order to optimize the CAPEX (capital expenditure) and OPEX (operational expenditure), while ensuring the quality of the results and the compliance of the analytical methods with ISO21087. Among the individual impurities to be analysed in ISO14687, spectroscopy techniques are suitable for ammonia, carbon dioxide, carbon monoxide, formaldehyde, formic acid, oxygen and water. Spectroscopy techniques are even suitable for some impurities belonging to the three total species such as hydrogen sulphide, hydrogen chloride and methane. However, helium and argon, which are monoatomic, do not exhibit response in the infrared region. Therefore, any spectroscopic analysis method must be completed by another method in order to simultaneously analyse all individual gaseous impurities from ISO14687. In this study, we constructed and demonstrated the feasibility of an instrument composed of a gas chromatograph having three columns (two packed columns and a PLOT (Porous Layer Open Tubular) column and two detectors (FID and TCD) coupled in parallel to two OFCEAS instruments using reference gas mixtures. Finally, we also proposed an extended configuration that will allow performing the whole set of analyses for gaseous species from ISO14687

Vehicle gas is often compressed to about 200 bar at the refueling station prior to charging to the vehicle's tank. If a high amount of oil is carried over to the gas, it may cause damage to the vehicles; it is therefore necessary to accurately measure oil carryover. In this paper, three analytical methods for accurate quantification of the oil content are presented whereby two methods are based on gas chromatography and one on FTIR. To better evaluate the level of complexity of the matrix, 10 different compressor oils in use at different refueling stations were initially collected and analysed with GC and FTIR to identify their analytical traces. The GC traces could be divided into three different profiles: oils exhibiting some well resolved peaks, oils exhibiting globally unresolved peaks with some dominant peaks on top of the hump and oils exhibiting globally unresolved peaks. After selection of three oils; one oil from each type, the three methods were evaluated with regards to the detection and quantification limits, the working range, precision, trueness and robustness. The evaluation of the three measurement methods demonstrated that any of these three methods presented were suitable for the quantification of compressor oil for samples. The FTIR method and the GC/MS method both resulted in measurement uncertainties close to 20% rel. while the GC/FID method resulted in a higher measurement uncertainty (U = 30% rel.).

Renewable gases, hydrogen and biomethane can be used for the same applications as natural gas: to heat homes, power vehicles and generate electricity. They have the potential to contribute to the decarbonisation of the gas grid. Hydrogen blending with existing natural gas pipelines is also proposed as a means to increase the performance of renewable energy systems. Carbon capture and storage (CCS) and carbon capture and utilisation (CCU) technologies can be an answer to the global challenge of significantly reducing greenhouse gas emissions. Due to production methods, these gases typically contain species in trace amounts that can negatively impact the equipment they come into contact with or pipelines when injected into the gas grid. It is therefore necessary to ensure proper (and stable) gas quality that meets the requirements set out in the relevant standards. The gas quality standards require the collection and transport of a representative gas sample from the point of use to the analytical laboratory; i.e., no compounds may be added to or removed from the gas during sampling and transport. To obtain a representative sample, many challenges must be overcome. The biggest challenge is material compatibility and managing adsorption risks in the sampling systems (sampling line and sampling vessels). However, other challenges arise from the need for flow measurement with non-pure gases or from the nature of the matrix. Currently, there are no conclusive results of short-term stability measurements carried out under gas purity conditions (suitable pressure, matrix, appropriate concentrations, simultaneous presence of several species). © 2022, The Author(s).

In this study, we evaluated the performances of a custom-built optical feedback cavity enhanced absorption spectroscopy (OFCEAS) instrument for the determination of the composition of energy gases, focusing on methane and carbon dioxide as main components, and carbon monoxide as impurities, in comparison with the well-established, validated, and traceable gas chromatographic method. A total of 115 real sample gases collected in biogas plants or landfills were analyzed using with both techniques over a period of 12 months. The comparison of the techniques showed that the virtual model which allows the measurement, needs to be optimized using real samples of varied compositions. The OFCEAS measurement technique was found to be capable of measuring both the main components and a trace component in different matrices; to within a 2% measurement uncertainty (higher than the gas chromatograph/thermal conductivity detector (GC/TCD) method). The OFCEAS method exhibits a very fast response, does not require daily calibration, and can be implemented online. The agreements between the OFCEAS technique and the GC/TCD method show that the drift of the OFCEAS instruments remains acceptable in the long term as long as no change is made to the virtual model. Matrix effects were observed, and those need to be taken into consideration when analyzing different types of samples. © 2023 The Author(s). Published by IOP Publishing Ltd.

Background: Aortic valve stenosis (AVS), which is the most common valvular heart disease, causes a progressive narrowing of the aortic valve as a consequence of thickening and calcification of the aortic valve leaflets. The beneficial effects of omega-3 polyunsaturated fatty acids (n-3 PUFA) in cardiovascular prevention have been recently demonstrated in a large randomized controlled trial. In addition, n-3 PUFA serve as the substrate for the synthesis of specialized pro-resolving mediators (SPMs), which are known by their potent beneficial anti-inflammatory, pro-resolving and tissue-modifying properties in cardiovascular disease. However, the effects of n-3 PUFA and SPMs on AVS have not yet been determined. The aim of this study was to identify the role of n-3 PUFA-derived SPMs in relation to the development of AVS. Methods: Lipidomic and transcriptomic analyses were performed in human tricuspid aortic valves. Apoe-/- mice and wire injury in C57BL/6J mice were used as models for mechanistic studies. Results: We found that n-3 PUFA incorporation into human stenotic aortic valves was higher in non-calcified regions compared with calcified regions. LC-MS-MS based lipid mediator lipidomics identified that the n-3 PUFA-derived SPM resolvin E1 (RvE1) was dysregulated in calcified regions and acted as a calcification inhibitor. Apoe-/- mice expressing the Caenorhabditis elegans Fat-1 transgene (Fat-1tgxApoe-/-), which enables the endogenous synthesis of n-3 PUFA, increased valvular n-3 PUFA content, exhibited reduced valve calcification, lower aortic valve leaflet area, increased M2 macrophage polarization and improved echocardiographic parameters. Finally, abrogation of the RvE1 receptor ChemR23 enhanced disease progression, and the beneficial effects of Fat-1tg were abolished in the absence of ChemR23. Conclusions: n-3 PUFA-derived RvE1 and its receptor ChemR23 emerge as a key axis in the inhibition of AVS progression, and may represent a novel potential therapeutic opportunity to be evaluated in patients with AVS.

Agriculture technology is moving toward automation, placing operators in a supervisory role. This change in operator workload may lead to increased stress and higher mental load, resulting in reduced attention and hence greater risk of illness or injury to humans and damage to equipment. This study investigated the use of easily applicable equipment to measure mental load. Three methods were used to measure the mental load on machine operators: heart rate monitoring, two types of electroencephalograph (EEG) evaluation, and an assessment protocol. Three driving exercises (general driving, slalom driving, and loading) and a counting exercise were used in a driving simulator to create different levels of mental load. Due to the number of exercises, a singlescale assessment protocol was used to save time. We found that only the assessment protocol gave clear results and would work well as an evaluation tool. The heart rate and EEG measurements did not provide clear data for mental load assessment. 

The rising industrial demand for environmentally friendly and sustainable materials has shifted the attention from synthetic to natural fibers. Natural fibers provide advantages like affordability, lightweight nature, and renewability. Jute fibers’ substantial production potential and cost-efficiency have propelled current research in this field. In this study, the mechanical behavior (tensile, flexural, and interlaminar shear properties) of plasma-treated jute composite laminates and the flexural behavior of jute fabric-reinforced sandwich composites were investigated. Non-woven mat fiber (MFC), jute fiber (JFC), dried jute fiber (DJFC), and plasma-treated jute fiber (TJFC) composite laminates, as well as sandwich composites consisting of jute fabric bio-based unsaturated polyester (UPE) composite as facing material and polyethylene terephthalate (PET70 and PET100) and polyvinyl chloride (PVC) as core materials were fabricated to compare their functional properties. Plasma treatment of jute composite laminate had a positive effect on some of the mechanical properties, which led to an improvement in Young’s modulus (7.17 GPa) and tensile strength (53.61 MPa) of 14% and 8.5%, respectively, as well as, in flexural strength (93.71 MPa) and flexural modulus (5.20 GPa) of 24% and 35%, respectively, compared to those of JFC. In addition, the results demonstrated that the flexural properties of jute sandwich composites can be significantly enhanced by incorporating PET100 foams as core materials. © 2023 by the authors.

Halogen-free flame-retardants (HFFRs) have a pronounced effect on the impact performance of ABS. The addition of flame-retardant (FR) particles may interfere with the morphology of ABS or introduce weak spots into the plastic. The present work studies the morphology of ABS with phosphorus-based flame-retardant systems and sets it in relation to their respective impact performance with the aim of identifying mechanisms influencing the impact performance and revealing possibilities to overcome this issue.

The present report addresses the Deliverables 2.1 and 2.2 of the project ‘Green cement based on blast-furnace slag’. Deliverable 2.1 aims at the evaluation of the mechanical and thermal performance of commercial reinforcements. Deliverable 2.2 describes the modification of those commercial reinforcements and evaluation.Two different commercial textile reinforcement grids for concrete were evaluated: (i) a basalt-fibre grid from US Basalt impregnated with epoxy resin and (ii) a carbon fibre grid from V. Fraas that is impregnated with Styrene-butadiene rubber (SBR). The grids were exposed to plasma oxidation to increase their hydrophilicity and create functional groups that can react with the uncured cement. The adhesion to the green cement matrix was then measured of both, the untreated and the plasma treated grids by pull-out testing of fibre bundles.

The present report addresses the Deliverable 2.3 of the project ‘Green cement based on blast-furnace slag’. Deliverable 2.3 aims at the development of new textile reinforcements with improved adhesion and thermal stability for green cements.Two different approaches for impregnation of textile reinforcements with materials that exhibit good adhesion to cementitious matrices as well as good thermal stability were studied: (i) impregnation with cementitious materials, (ii) impregnation with molecular precursors. Moreover, a nano-CSH impregnation system developed at Chalmers was characterized and compared to the systems developed at RISE.

A systematic investigation of phosphorus-based flame-retardant (PFR) systems in acrylonitrile-butadiene-styrene (ABS) is presented. The effect of various PFRs, combinations thereof and influence of different synergists is studied in terms of fire and mechanical performance, as well as toxicity of resulting ABS. Sustainable flame-retardant systems with a promising effect on the fire-retardant properties of ABS are identified: A combination of aluminum diethylphosphinate and ammonium polyphosphate is shown to exhibit superior flame-retardant properties in ABS compared to other studied PFRs and PFR combinations. Among a variety of studied potential synergists for this system, a grade of expandable graphite with a high-initiation temperature and a molybdenum-based smoke suppressant show the most promising effect, leading to a significant reduction of the peak heat release rate as well as the smoke production rate. Compared to current state-of-the-art brominated flame-retardant for ABS, the identified flame-retardant systems reduce the maximum smoke production rate by 70% and the peak heat release rate by 40%. However, a significant reduction of the impact performance of the resulting ABS is identified, which requires further investigation.

Hydrogen fuel cells are an alternative power supply for electric drive trains and could represent 32 % of fuel demand by 2050. To deploy fuel cell electrical vehicles, there is current regulatory barriers (ISO 14687, OIML recommendations) that requires accurate measurements. The European funded project MetroHyVe has provided solutions and improvements in the four measurements challenges (flow metering, quality control, quality assurance and sampling). New challenges arised due to increase of hydrogen economy, therefore a new European project MetroHyVe 2 started in 2020 and its objectives will provide perspectives for the hydrogen economy to solve all regulatory barriers (ISO 14687, ISO 19880-8, ISO 19880-1, ISO 21087, OIML R139-1) and new measurement challenges (flow metering, quality control, sampling and fuel cell stack testing). The presentation will provide a comprehensive overview of the project achievements. The achievements around primary standard for flow metering (light and heavy duty), worldwide inter-laboratory comparison for hydrogen fuel quality, hydrogen sampling intercomparison and fuel cell stack testing recommendations will be highlighted.

With the increased focus on reducing carbon emissions in the automotive industry, more advanced materials are introduced to reduce the vehicle weight, and more complex component geometries are designed to both satisfy customer demands and to optimize the vehicle aerodynamically. With the increase in component complexity, the strain paths produced during the forming operation of car body components often display a highly non-linear behavior which makes the task of failure prediction during the manufacturing feasibility studies more difficult. Therefore, CAE engineers need better capabilities to predict failure induced by strain path nonlinearity. This study proposes a new tool designed for creating bi-linear strain paths, by performing a pre-strain of a sheet large enough to cut out Nakajima specimens to perform the post-straining in any direction. From five pre-straining tests the tool present a stable pre-straining operation with a uniform strain field in a radius of 100 [mm] from the centre, corresponding to the region of interest of a Nakajima specimen. From the five pre-strained samples, different Nakajima specimens are cut transverse and longitudinal to the rolling direction and a failure prediction approach in an alternative, path independent evaluation space was used to predict the onset of necking with promising results.

As new and more advanced sheet metal materials are introduced to the market, more accurate techniques for determination of failure limits are needed. One area that needs attention is edge formability, where the ISO-16630 standardized Hole Expansion Test currently is used to express this through the Hole Expansion Ratio. Over the years, this standard has been criticized for producing a large scatter in repeated tests. This paper investigates a new setup for the Hole Expansion Test which introduces draw beads into the setup to ensure sufficient restraining of the specimen during the test in an effort to reduced the scatter. In total 62 tests of a DP800 steel alloy were executed, but a large scatter in the results were still seen. It was therefore concluded that a lack of restraining force in the Hole Expansion Test was not the primary cause of the reported scatter seen in other tests.

Anisotropy can influence surface function and can be an indication of processing. These influences and indications include friction, wetting, and microwear. This article studies two methods for multiscale quantification and visualization of anisotropy. One uses multiscale curvature tensor analysis and shows anisotropy in horizontal coordinates i.e., topocentric. The other uses multiple bandpass filters (also known as sliding bandpass filters) applied prior to calculating anisotropy parameters, texture aspect ratios (Str) and texture directions (Std), showing anisotropy in horizontal directions only. Topographies were studied on two milled steel surfaces, one convex with an evident large scale, cylindrical form anisotropy, the other nominally flat with smaller scale anisotropies; a EDMed surface, an example of an isotropic surface; and an additively manufactured surface with pillar-like features. Curvature tensors contain the two principal curvatures, i.e., maximum and minimum curvatures, which are orthogonal, and their directions, at each location. Principal directions are plotted for each calculated location on each surface, at each scale considered. Histograms in horizontal coordinates show altitude and azimuth angles of principal curvatures, elucidating dominant texture directions at each scale. Str and Std do not show vertical components, i.e., altitudes, of anisotropy. Changes of anisotropy with scale categorically failed to be detected by traditional characterization methods used conventionally. These multiscale methods show clearly in several representations that anisotropy changes with scale on actual surface measurements with markedly different anisotropies.

The effect of two concentrations of H2S (0.5 and 2.5 ppm), in controlled laboratory conditions (20 °C, 75%RH), on the atmospheric corrosion of pure Ag, Cu and Ni was investigated in this study. The corrosion product morphology and composition were analysed through a multi-technique approach including SEM/EDX, Raman spectroscopy, XPS and XRD. Different corrosion products were identified depending on the type of characterisations providing a better overview of the effect of H2S on the atmospheric corrosion of pure Ag, Cu and Ni. Possible mechanisms involved in the formation of these corrosion products are also discussed in this work. © 2022 The Authors

A global transition towards more sustainable, affordable and reliable energy systems is being stimulated by the Paris Agreement and the United Nation's 2030 Agenda for Sustainable Development. This poses a challenge for the corrosion industry, as building climate-resilient energy systems and infrastructures brings with it a long-term direction, so as a result the long-term behaviour of structural materials (mainly metals and alloys) becomes a major prospect. With this in mind “Corrosion Challenges Towards a Sustainable Society” presents a series of cases showing the importance of corrosion protection of metals and alloys in the development of energy production to further understand the science of corrosion, and bring the need for research and the consequences of corrosion into public and political focus. This includes emphasis on the limitation of greenhouse gas emissions, on the lifetime of infrastructures, implants, cultural heritage artefacts, and a variety of other topics. © 2022 The Authors. 

The demand for carbon fibers (CFs) based on renewable raw materials as the reinforcing fiber in composites for lightweight applications is growing. Lignin-cellulose precursor fibers (PFs) are a promising alternative, but so far, there is limited knowledge of how to continuously convert these PFs under industrial-like conditions into CFs. Continuous conversion is vital for the industrial production of CFs. In this work, we have compared the continuous conversion of lignin-cellulose PFs (50 wt % softwood kraft lignin and 50 wt % dissolving-grade kraft pulp) with batchwise conversion. The PFs were successfully stabilized and carbonized continuously over a total time of 1.0-1.5 h, comparable to the industrial production of CFs from polyacrylonitrile. CFs derived continuously at 1000 °C with a relative stretch of-10% (fiber contraction) had a conversion yield of 29 wt %, a diameter of 12-15 μm, a Young's modulus of 46-51 GPa, and a tensile strength of 710-920 MPa. In comparison, CFs obtained at 1000 °C via batchwise conversion (12-15 μm diameter) with a relative stretch of 0% and a conversion time of 7 h (due to the low heating and cooling rates) had a higher conversion yield of 34 wt %, a higher Young's modulus (63-67 GPa) but a similar tensile strength (800-920 MPa). This suggests that the Young's modulus can be improved by the optimization of the fiber tension, residence time, and temperature profile during continuous conversion, while a higher tensile strength can be achieved by reducing the fiber diameter as it minimizes the risk of critical defects. © 2022 The Authors. 

Adhesion of fibers within a spun tow, including carbon fibers and precursors, is undesirable as it may interrupt the manufacturing process and entail inferior fiber properties. In this work, softwood kraft lignin was used together with a dissolving pulp to spin carbon fiber precursors. Lignin-cellulose precursors have previously been found to be prone to fiber fusion, both post-spinning and during carbon fiber conversion. In this study, the efficiency of applying different kinds of spin finishes, with respect to rendering separable precursors and carbon fibers, has been investigated. It was found that applying a cationic surfactant, and to a similar extent a nonionic surfactant, resulted in well separated lignin-cellulose precursor tows. Furthermore, the fiber separability after carbon fiber conversion was evaluated, and notably, precursors treated with a silicone-based spin finish generated the most well-separated carbon fibers. The underlying mechanism of fiber fusion post-spinning and converted carbon fibers is discussed. 

In this study, the underlying mechanism for improved spinnability when mixing lignin and cellulose in solution was investigated. Co-processing of lignin and cellulose has previously been identified as a potential route for production of inexpensive and bio-based carbon fibers. The molecular order of cellulose contributes to the strength of the fibers and the high carbon content of lignin improves the yield during conversion to carbon fibers. The current work presents an additional benefit of combining lignin and cellulose; solutions that contain both lignin and cellulose could be air-gap spun at substantially higher draw ratios than pure cellulose solutions, that is, lignin improved the spinnability. Fibers were spun from solutions containing different ratios of lignin, from 0 to 70 wt%, and the critical draw ratio was determined at various temperatures of solution. The observations were followed by characterization of the solutions with shear and elongational viscosity and surface tension, but none of these methods could explain the beneficial effect of lignin on the spinnability. However, by measuring the take-up force it was found that lignin seems to stabilize against diameter fluctuations during spinning, and plausible explanations are discussed

Chemical recycling of textiles holds the potential to yield materials of equal quality and value as products from virgin feedstock. Selective depolymerization of textile polyester (PET) from regenerated cellulose/PET blends, by means of alkaline hydrolysis, renders the monomers of PET while cellulose remains in fiber form. Here, we present the mechanism and reactivity of textile PET during alkaline hydrolysis. Part I of this article series focuses on the cellulose part and a possible industrialization of such a process. The kinetics and reaction mechanism for alkaline hydrolysis of polyester packaging materials or virgin bulk polyester are well described in the scientific literature; however, information on depolymerization of PET from textiles is sparse. We find that the reaction rate of hydrolysis is not affected by disintegrating the fabric to increase its surface area. We ascribe this to the yarn structure, where texturing and a low density assures a high accessibility even without disintegration. The reaction, similar to bulk polyester, is shown to be surface specific and proceeds via endwise peeling. Finally, we show that the reaction product terephthalic acid is pure and obtained in high yields. © 2022 by the authors. 

Metal additive manufacturing surface topographies are complex and challenging to characterise due to e.g. steep local slopes, re-entrant features, varying reflectivity and features of interest in vastly different scale ranges. Nevertheless, average height parameters such as Ra or Sa are commonly used as sole parameters for characterisation. In this paper, a novel method for selecting relevant parameters for evaluation is proposed and demonstrated using a case study where the smoothing effects after three processing steps of the electro chemical post-process Hirtisation of a metal AM surface are quantified. The method uses a combination of conventional areal texture parameters, multiscale analysis and statistics and can be used to efficiently achieve a detailed and more relevant surface topography characterisation. It was found that the three process steps have different effects on the surface topography regarding the types and sizes of features that were affected. In total, Sdq was reduced by 97 %, S5v was reduced by 81 % and Sa was reduced by 78 %. A surface texture with much lower average roughness, less deep pits and less steep slopes was produced, which is expected to be beneficial for improved fatigue properties.