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  • 1.
    Al-Maqdasi, Zainab
    et al.
    Luleå University of Technology, Sweden.
    Gong, Guan
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Nyström, Birgitha
    Podcomp AB, Sweden.
    Emami, Nazanin
    Luleå University of Technology, Sweden.
    Joffe, Roberts
    Luleå University of Technology, Sweden.
    Characterization of Wood and Graphene Nanoplatelets (GNPs) Reinforced Polymer Composites.2020In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 13, no 9, article id E2089Article in journal (Refereed)
    Abstract [en]

    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.

  • 2.
    Al-Maqdasi, Zainab
    et al.
    Luleå University of Technology, Sweden.
    Pupure, Liva
    Luleå University of Technology, Sweden; Riga Technical University, Latvia.
    Gong, Guan
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Emami, Nazanin
    Luleå University of Technology, Sweden.
    Joffe, Roberts
    Luleå University of Technology, Sweden.
    Time-dependent properties of graphene nanoplatelets reinforced high-density polyethylene2021In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 138, no 30, article id 50783Article in journal (Refereed)
    Abstract [en]

    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.

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  • 3.
    André, Alann
    et al.
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Bru, Thomas
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Ghafoor, Abdul
    RISE Research Institutes of Sweden, Digital Systems, Industrial Systems.
    Sinha, Sugandh
    RISE Research Institutes of Sweden, Digital Systems, Industrial Systems.
    Mattsson, Cecilia
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Digital platform for managementof EoL windturbine blades: Rekovind 2 - WP22023Report (Other academic)
    Abstract [en]

    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.

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  • 4.
    André, Alann
    et al.
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Juntikka, Magdalena
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Mattsson, Cecilia
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Nedev, Georgi
    SWECO, Sweden.
    Reza, Haghani
    Chalmers University of Technology, Sweden.
    The Re-use of End-of-Life Fiber Reinforced Polymer Composites in Construction2022In: CICE 2021: 10th International Conference on FRP Composites in Civil Engineering pp 1183-1195|, Springer Science and Business Media Deutschland GmbH , 2022, p. 1183-1195Conference paper (Refereed)
    Abstract [en]

    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)

  • 5.
    André, Alann
    et al.
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Kullberg, J.
    RISE Research Institutes of Sweden.
    Nygren, D.
    RISE Research Institutes of Sweden.
    Mattsson, Cecilia
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Nedev, G.
    RISE Research Institutes of Sweden.
    Haghani, Reza
    RISE Research Institutes of Sweden.
    Re-use of wind turbine blade for construction and infrastructure applications2020In: IOP Conference Series: Materials Science and Engineering, IOP Publishing Ltd , 2020, Vol. 942, no 1, article id 012015Conference paper (Refereed)
    Abstract [en]

    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.

  • 6.
    Antonsson, Ulf
    et al.
    RISE Research Institutes of Sweden, Built Environment, Building and Real Estate.
    Berntsson, Ulf
    RISE Research Institutes of Sweden, Built Environment, Infrastructure and concrete technology.
    Nordling, Bengt
    RISE Research Institutes of Sweden, Built Environment, Infrastructure and concrete technology.
    Demker, Ingvar
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Sjöqvist, Mia
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Funktionsprovning av tätskiktsystem för våtutrymmen 20222022Report (Other academic)
    Abstract [en]

    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

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  • 7.
    Argyropoulos, Dimitris
    et al.
    North Carolina State University, USA.
    Crestini, Claudia
    Ca’ Foscari University of Venice, Italy.
    Dahlstrand, Christian
    Ren FuelK2B AB, Sweden.
    Furusjö, Erik
    RISE Research Institutes of Sweden, Bioeconomy and Health, Biorefinery and Energy. Luleå University of Technology, Sweden.
    Gioia, Claudio
    Universityof Trento, Italy.
    Jedvert, Kerstin
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Henriksson, Gunnar
    KTH Royal Institute of Technology, Sweden.
    Hulteberg, Christian
    Lund University, Sweden.
    Lawoko, Martin
    KTH Royal Institute of Technology, Sweden.
    Pierrou, Clara
    RenFuel Materials AB, Sweden.
    Samec, Joseph
    RenFuel Materials AB, Sweden; Stockholm University, Sweden; Chulalongkorn University, Thailand; Ren FuelK2B AB, Sweden.
    Subbotina, Elena
    Yale University, USA.
    Wallmo, Henrik
    Valmet AB, Sweden.
    Wimby, Martin
    Valmet AB, Sweden.
    Kraft Lignin: A Valuable, Sustainable Resource, Opportunities and Challenges.2023In: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, article id e202300492Article in journal (Refereed)
    Abstract [en]

    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.

  • 8.
    Arya, Mina
    et al.
    University of Borås, Sweden.
    Malmek, Else-Marie
    Juteborg AB, Sweden.
    Ecoist, Thomas Koch
    Ecoist AB, Sweden.
    Pettersson, Jocke
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Skrifvars, Mikael
    University of Borås, Sweden.
    Khalili, Pooria
    University of Borås, Sweden.
    Enhancing Sustainability: Jute Fiber-Reinforced Bio-Based Sandwich Composites for Use in Battery Boxes2023In: Polymers, E-ISSN 2073-4360, Vol. 15, no 18, article id 3842Article in journal (Refereed)
    Abstract [en]

    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.

  • 9.
    Bachinger, Angelika
    et al.
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Bengtsson, Jenny
    RISE Research Institutes of Sweden, Materials and Production, Chemistry, Biomaterials and Textiles.
    Lindkvist, K
    RISE Research Institutes of Sweden.
    The morphology of ABS with phosphorus-based flame-retardants and its influence on the impact performance2021In: Abstract Book of FRPM21, 2021, p. 86-87Conference paper (Refereed)
    Abstract [en]

    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.

  • 10.
    Bachinger, Angelika
    et al.
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Hellström, Peter
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    de Muinck, Derk
    RISE Research Institutes of Sweden.
    Commercial textile reinforcements – performance in green cement and surface treatment2021Report (Other academic)
    Abstract [en]

    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.

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  • 11.
    Bachinger, Angelika
    et al.
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Hellström, Peter
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Domergue, Anaïs
    Gaüzere, Laurie
    de Muinck, Derk
    RISE Research Institutes of Sweden.
    Development of textile reinforcements with improved adhesion and thermal stability for green cement2021Report (Other academic)
    Abstract [en]

    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.

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  • 12.
    Bachinger, Angelika
    et al.
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Sandinge, Anna
    RISE Research Institutes of Sweden, Safety and Transport, Fire and Safety.
    Lindqvist, Karin
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Strid, Anna
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Gong, Guan
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Systematic evaluation of bromine-free flame-retardant systems in acrylonitrile-butadiene-styrene2022In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 139, no 13, article id 51861Article in journal (Refereed)
    Abstract [en]

    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.

  • 13.
    Bengtsson, Andreas
    et al.
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Bengtsson, Jenny
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Jedvert, Kerstin
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Kakkonen, Markus
    Fibrobotics Oy, Finland.
    Tanhuanpää, Olli
    Fibrobotics Oy, Finland.
    Brännvall, Elisabet
    RISE Research Institutes of Sweden, Bioeconomy and Health.
    Sedin, Maria
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Continuous Stabilization and Carbonization of a Lignin-Cellulose Precursor to Carbon Fiber2022In: ACS Omega, E-ISSN 2470-1343, Vol. 7, no 19, p. 16793-16802Article in journal (Refereed)
    Abstract [en]

    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. 

  • 14.
    Bengtsson, Jenny
    et al.
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Bengtsson, Andreas
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Ulmefors, Hanna
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Sedin, Maria
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Jedvert, Kerstin
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Preventing fiber-fiber adhesion of lignin-cellulose precursors and carbon fibers with spin finish application2023In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434XArticle in journal (Refereed)
    Abstract [en]

    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. 

  • 15.
    Bengtsson, Jenny
    et al.
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Peterson, Anna
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Idström, Alexander
    Chalmers University of Technology, Sweden.
    de la Motte, Hanna
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Jedvert, Kerstin
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Chemical Recycling of a Textile Blend from Polyester and Viscose, Part II: Mechanism and Reactivity during Alkaline Hydrolysis of Textile Polyester2022In: Sustainability, E-ISSN 2071-1050, Vol. 14, no 11, article id 6911Article in journal (Refereed)
    Abstract [en]

    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. 

  • 16.
    Boss, Annika
    et al.
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Jansson, Anna
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Emanuelsson, Viktor
    RISE Research Institutes of Sweden.
    Venkatesh, Abhijit
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Brunklaus, Birgit
    RISE Research Institutes of Sweden, Built Environment, System Transition and Service Innovation.
    Sustainable Vehicles with Recycled Plastics2023Report (Other academic)
    Abstract [en]

    The production of vehicles is one of the most resource-intensive industries. 10 % of the overall consumption of plastics, 6 million tonnes/year is used by the European vehicle industry1. Increase the use of recycled plastics in vehicles is one of the key challenges for sustainable transformation of the vehicle industry as it plays an important role in saving resources and reducing greenhouse emissions. The main goal of this project was to contribute to increased use of recycled plastic in the Swedish vehicle industry. Volvo Cars goal is that 25 % of the plastic used in cars should be recycled or biobased by 2025. The goal will most probably be reached according to Volvo Cars. Volvo group has the goal to be fossil neutral, which requires recycled material in the truck components. The recycled plastics evaluated in the project came from both post industrial waste (PIR) and post consumer waste (PCR). Rondo Plast, Polykemi, Albis, Mocom, Biesterfield, Borealis, Sabic, Total and LG Chem have supplied recycled and virgin plastics tested in the project. The plastics we have focusing on in this project were polypropylene (PP) plastics (homo- and copolymer) and PC/ABS plastic compounds. Thus, these plastics are most used in vehicle components and recycled PP plastics are more accessible than the other plastics that can be used in vehicles. Analysis and evaluation of recycled plastics have been performed by RISE. Also, long term ageing and recyclability studies have been performed. A study to upgrade PP plastic recycled from packaging (PCR) with additives from DOW and Rondo Plast were performed.

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  • 17.
    Boss, Annika
    et al.
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Strid, Anna
    RISE Research Institutes of Sweden, Materials and Production, Product Realisation Methodology.
    Olsson, Elisabeth
    RISE Research Institutes of Sweden.
    Andersson, Emelie
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Brodin, Malin
    RISE Research Institutes of Sweden, Materials and Production, Product Realisation Methodology.
    Andersson, Mattias
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Ämnen som hindrar eller försvårar återvinning av plast i prioriterade produktgrupper inom byggsektorn2023Report (Other academic)
    Abstract [sv]

    I detta uppdrag undersöker vi kemiska tillsatser i plaster som försvårar eller utgör hinder för återvinning av materialet. I denna rapport avser kemiska tillsatser additiv som medvetet introducerats i produkten eller materialet, och det är dessa kemiska ämnens natur som avgör problematiken ur återvinningssynpunkt. Vi fokuserar på byggsektorn eftersom denna sektor använder stora mängder plast av hög kvalité. Trots detta är återvinningsgraden för plast låg och potentialen att öka återvinningsgraden är därmed stor. Ett materials potential för återvinning bestäms av flera faktorer, varav kemikalieinnehåll är en. Det är viktigt att tänka på vilken eller vilka produkter plasten är lämplig att återvinnas till, och hänsyn måste alltid tas till gällande kemikalielagstiftning för just de produkttyperna. Kemiska ämnen som kan vara skadliga för människan och/eller miljön är särskilt viktiga att utreda, men det finns också andra tillsatser i material och produkter som försvårar återvinningsprocessen eller påverkar kvalitén på den återvunna plasten negativt så att marknaden för det återvunna materialet blir begränsad. Ytterligare en faktor att ta i beaktande är hur exponeringen för kemikalierna ser ut, om de är bundna i plasten eller kan emitteras och utsätta människor och miljön för direkta risker. De stora kategorierna i denna kartläggning har varit golv, rör och rördelar, kablar, profiler och lister, isoleringsmaterial, samt tätningsskikt. För dessa produktgrupper dominerar polymertyperna PVC, PE av olika densitetsgrad och comonomer-innehåll, PP (homo- och copolymer), PS och PUR. Då härdplaster, där även PUR ingår, förekommer i form av lacker, adhesiv och ytbeläggningar i byggprodukter behandlas dessa också övergripande. Många materialströmmar finns tillgängliga för återvinning inom kategorin byggplast generellt sett, men möjligheterna och incitamenten att sortera ut dessa i sina ursprungliga fraktioner är låg. Detta beror antingen på att efterfrågan på mekaniskt återvunnet material i dessa produktkategorier inte är stor nog, som för PEX och vissa typer av rör, eller på att volymerna är för låga för lönsamhet. Ett exempel på det sistnämnda är profiler och lister av PVC där etablerad cirkulär återvinning finns ute i Europa, men produktkategorin är för liten i Sverige för att drivkraften ska uppstå. Eftersom flera av de polymermaterial och produkter vi kartlagt i denna rapport har en historisk användning av idag reglerade, eller till och med förbjudna kemiska ämnen, kompliceras återvinningen av byggplast i att de inkommande avfallsströmmarna är av mycket varierande ålder. För att möjliggöra en högre återvinningsgrad och bättre kvalitet krävs därför utökad och mer noggrann sortering så att problematiska, och i vissa fall hälso- och miljöfarliga, innehållsämnen inte följer med i den mekaniska återvinningen, men inte heller så att kvalitativa fraktioner av en viss produkt- och polymertyp avvisas från återvinning av säkerhetsskäl. Ett axplock av problematiska tillsatser är tungmetallstabilisatorer och mjukgörare i produkter av PVC, flamskyddsmedel i isolering av EPS och XPS, samt silanförnätad PEX som innehåller tennkatalysator. Kontaminering i form av härdplastrester, felsorterad PEX i PE-recyklat, samt tejper och fogar på tätskikt utgör de mer oavsiktliga, fysiska hindren för kvalitetsmässig återvinning tillsammans med faktumet att en stor del av kablar och rör helt enkelt inte utvinns ur marken efter sin användningstid. Sammanfattningsvis skulle fler fraktioner av byggplast kunna återvinnas mekaniskt genom att stärka infrastrukturen kring insamling och sortering, men för detta krävs ökad efterfrågan och långsiktig lönsamhet. Kemiska återvinningsmetoder seglar upp som en möjlig lösning för flera av de hinder som identifieras i denna studie, till exempel tvärbundna material, material med hög andel fyllmedel, eller för avskiljning av oönskade tillsatser likt tungmetaller och ftalater. Kartläggningen av detta område får därför ses som en intressant frågeställning för ytterligare arbete.

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  • 18.
    Boz Noyan, E. C.
    et al.
    Chalmers University of Technology, Sweden.
    Venkatesh, Abhijit
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Boldizar, A.
    Chalmers University of Technology, Sweden.
    Washing Post-Consumer Flexible Polyethylene Packaging Waste2022In: Recycling, E-ISSN 2313-4321, Vol. 7, no 6, article id 90Article in journal (Refereed)
    Abstract [en]

    The mechanical and thermal properties of injection-molded recycled polyethylene were studied, specifically with respect to the influence of large-scale washing and melt-compounding of polyethylene from post-consumer packaging waste. Three types of materials were studied: those taken after sorting, after sorting and washing, and after sorting, washing, and melt-compounding, including melt-filtration, all from a large-scale material flow. The materials were further processed on a laboratory scale and compared. The results showed that large-scale washing significantly reduced thermo-oxidative stability, as well as molar mass and melt viscosity. The degradation during large-scale washing made the material susceptible to further degradation in the subsequent extrusion compounding, as shown by the differences in compounding at 240 and 200 °C using a high-shear screw configuration. The compounding parameters, screw configuration, and compounding temperature did not influence the stiffness and strength of the unwashed and large-scale-washed materials, but the elongation-at-break varied, specifically, with the increased temperature. Washing had an influence on the mechanical properties as well, and the unwashed material provided molded samples with stiffness measurements of approximately 550 MPa, whereas the large-scale-washed material provided stiffness of approximately 400 MPa. The strength measurements were approximately 15 MPa for samples made of both unwashed and large-scale-washed material, and the elongation-at-break measurements were between 50 and 150%. The large-scale-washed and compounded materials had very different mechanical properties, with stiffness measurements of approximately 320 MPa, strength of approximately 20 MPA, and elongation-at-break of approximately 350%. The significantly different mechanical properties of the large-scale-washed and compounded materials were likely due to the melt-filtration included in the compounding through the removal of metal and rubber particles, and they may also have been due to the compatibilizing and stabilizing additive used in the compounding. © 2022 by the authors.

  • 19.
    Cameron, Christopher
    et al.
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Hozić, Dženan
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Stig, Fredrik
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    van der Veen, Sjord
    Airbus Operations SAS, France.
    A method for optimization against cure-induced distortion in composite parts2023In: Structural and multidisciplinary optimization (Print), ISSN 1615-147X, E-ISSN 1615-1488, Vol. 66, no 3, article id 51Article in journal (Refereed)
    Abstract [en]

    This paper describes a novel method developed for the optimization of composite components against distortion caused by cure-induced residual stresses. A novel ply stack alteration algorithm is described, which is coupled to a parametrized CAD/FE model used for optimization. Elastic strain energy in 1D spring elements, used to constrain the structure during analysis, serves as an objective function incorporating aspects of global/local part stiffness in predicted distortion. Design variables such as the number and stacking sequence of plies, and geometric parameters of the part are used. The optimization problem is solved using commercial software combined with Python scripts. The method is exemplified with a case study of a stiffened panel subjected to buckling loads. Results are presented, and the effectiveness of the method to reduce the effects of cure-induced distortion is discussed. © 2023, The Author(s).

  • 20.
    Cameron, Christopher
    et al.
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Larsson, Johan
    KTH Royal Institute of Technology, Sweden.
    Loukil, Mohamed
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites. Linköping University, Sweden.
    Murtagh, Timothy
    RUAG Space, Sweden.
    Wennhage, Per
    KTH Royal Institute of Technology, Sweden.
    Bearing strength performance of mixed thin/thick-ply, quasi-isotropic composite laminates2021In: Composite structures, ISSN 0263-8223, E-ISSN 1879-1085, Vol. 261, article id 113312Article in journal (Refereed)
    Abstract [en]

    The effect of using thin plies to increase the bearing strength of composite laminates has been investigated. A series of 5 laminates of theoretically identical stiffness with varying proportions of thin plies were manufactured using a single material system. Four specimens from each plate were tested for bearing strength and damage was subsequently characterized using an optical microscope. The results show that performance in terms of bearing stiffness, strength at onset of damage, and ultimate bearing stress increase proportionally with the increasing amount of thin plies within the stack. Shifting from a 100% conventional ply laminate to a 100% thin-ply laminate gave an increase of 47% in the strength at onset of damage. Placement of the thin plies within the stack was also shown to be important for strength at initial onset of damage. Microscopic examination of the failure modes for all samples showed fiber kinking, localized to the center of the hole, to be the dominant failure mode regardless of the stacking sequence. © 2020 The Authors

  • 21.
    Cameron, Christopher
    et al.
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Saseendran, Sibin
    RISE Research Institutes of Sweden.
    Stig, Fredrik
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Rouhi, Mohammad
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites. National University of Singapore, Singapore.
    A rapid method for simulating residual stress to enable optimization against cure induced distortion2021In: Journal of composite materials, ISSN 0021-9983, E-ISSN 1530-793X, Vol. 55, no 26, p. 3799-Article in journal (Refereed)
    Abstract [en]

    In this paper a rapid method for residual cure stress analysis from composite manufacturing is presented. The method uses a high-fidelity path-dependent cure kinetics subroutine implemented in ABAQUS to calibrate a linear elastic model. The path-dependent model accounts for the tool-part interaction, forming pressure, and the changing composite modulus during the rubbery phase of matrix curing. Results are used to calculate equivalent lamina-wise coefficients of thermal expansion (CTE) in 3 directions for a linear temperature analysis. The goal is to accurately predict distortions for large complex geometries as rapidly as possible for use in an optimization framework. A carbon-epoxy system is studied. Simple coupons and complex parts are manufactured and measured with a 3 D scanner to compare the manufactured and simulated distortion. Results are presented and the accuracy and limitations of the rapid simulation method are discussed with particular focus on implementation in a numerical optimization framework. © The Author(s) 2021.

  • 22.
    Costa, Sergio
    et al.
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites. Chalmers University of Technology, Sweden.
    Bru, Thomas
    Chalmers University of Technology, Sweden.
    Portugal, Andre
    Olsson, Robin
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Numerical validation of an improved model for the shearing and transverse crushingof orthotropic compositesManuscript (preprint) (Other academic)
    Abstract [en]

    This paper details a complete crush model for composite materials with focus on shear dominated crushing under a3D stress state. The damage evolution laws and nal failure strain conditions are based on data extracted from shearexperiments. The main advantages of the current model are: no need to measure the fracture toughness in shear andtransverse compression, mesh objectivity without the need for a regular mesh and nite element characteristic length, apressure dependency of the shear response, account for load reversal and for some orthotropic eects (making the modelsuitable for Non-Crimp Fabric composites). The model is validated against a range of relevant experiments, namely athrough-the-thickness compression specimen and a at crush coupon with the bres oriented at 45 and 90 degrees to theload. Damage growth mechanisms, orientation of the fracture plane, nonlinear evolution of Poisson's ratio and energyabsorption are accurately predicted.

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  • 23.
    Costa, Sergio
    et al.
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Fagerström, Martin
    Chalmers University of Technology, Sweden.
    Olsson, Robin
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Development and validation of a finite deformation fibre kinking model for crushing of composites2020In: Composites Science And Technology, ISSN 0266-3538, E-ISSN 1879-1050, Vol. 197, article id 108236Article in journal (Refereed)
    Abstract [en]

    A mesoscale model for fibre kinking onset and growth in a three-dimensional framework is developed and validated against experimental results obtained in-house as well as from the literature. The model formulation is based on fibre kinking theory i.e. the initially misaligned fibres rotate due to compressive loading and nonlinear shear behaviour. Furthermore, the physically-based response is computed in a novel and efficient way using finite deformation theory. The model validation starts by correlating the numerical results against compression tests of specimens with a known misalignment. The results show good agreement of stiffness and strength for two specimens with low and high misalignment. Fibre kinking growth is validated by simulating the crushing of a flat coupon with the fibres oriented to the load direction. The numerical results show very good agreement with experiments in terms of crash morphology and load response.

  • 24.
    Costa, Sergio
    et al.
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Zrida, Hana
    Gestamp Hardtech AB, Sweden.
    Olsson, Robin
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Herráez, Miguel
    University Rey Juan Carlos, Spain.
    Östlund, Rickard
    Gestamp Hardtech AB, Sweden.
    A unified physically-based finite deformation model for damage growth in composites2022In: Composites. Part A, Applied science and manufacturing, ISSN 1359-835X, E-ISSN 1878-5840, Vol. 161, article id 107103Article in journal (Refereed)
    Abstract [en]

    Two 3D homogenized models for damage growth in a unidirectional (UD) composite ply are simplified and merged into a unified model. The fibre kinking behaviour is based on fibre kinking theory handled in a finite deformation framework. The nonlinear shear behaviour is pressure dependent and is modelled by combining damage and friction on the fracture plane. Fibre kinking growth and transverse behaviour are modelled with a single damage variable. This allows both modes to occur simultaneously and mutually influence each other in an efficient and physically-based way. For validation the model is tested against micro-mechanical Finite Element (FE) simulations under pure longitudinal compression and influenced by shear. The results show nearly perfect agreement for stiffness, strength and crushing stress. The model validation is performed against two different components under three-point bending and a quasi-static crash scenario. Both simulation show good correlation with experiments, validating thus the present unified model. © 2022 The Author(s)

  • 25.
    El Seoud, Omar
    et al.
    University of São Paulo, Brazil.
    Jedvert, Kerstin
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Kostag, Marc
    University of São Paulo, Brazil.
    Possidonio, Shirley
    UNIFESP, Brazil.
    Cellulose, chitin and silk: the cornerstones of green composites2022In: Emergent Materials, ISSN 2522-5731, Vol. 5, no 3, p. 785-Article in journal (Refereed)
    Abstract [en]

    This overview article is concerned with fabrication and applications of the composites of three major biopolymers, cellulose (Cel), chitin (Chn)/chitosan (Chs), and silk fibroin (SF). A brief discussion of their molecular structures shows that they carry functional groups (-OH, -NH-COCH3, -NH2, -CONH-) whose hydrogen-bonding, and der Waals interactions lead to semi-crystalline structures in the solid phase. There are several classes of solvents that disrupt these interactions, hence dissolve the above-mentioned biopolymers. These include solutions of inorganic and organic electrolytes in dipolar aprotic solvents (DASs), ionic liquids (ILs), and their solutions in DASs. Mixing of biopolymer solutions leads to efficient mutual interactions, hence formation of relatively homogeneous composites. These are then regenerated in non-solvents (water, ethanol, acetone) in different physical forms, e.g., fibers, nanoparticles and films. We discuss the fabrication of these products that have enormous potential use in the textile industry, in medicine, in the food industry, and decontamination of fluids. These applications will most certainly expand due to the attractive characteristics of these composites (renewability, sustainability, biodegradation) and the increased public concern about the adverse environmental impact of petroleum-based polymers, as recently shown by the presence of microplastics in air, water, land, and food (Akdogan & Guven in Environ Pollut. 254:113011 (2019)).

  • 26.
    Eliasson, Sara
    et al.
    Scania CV AB, Sweden; Centre for ECO2 Vehicle Design, Sweden; KTH Royal Institute of Technology, Sweden.
    Karlsson Hagnell, Mathilda
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Wennhage, Per
    Centre for ECO2 Vehicle Design, Sweden; KTH Royal Institute of Technology, Sweden.
    Barsoum, Zuheir
    Centre for ECO2 Vehicle Design, Sweden; KTH Royal Institute of Technology, Sweden.
    A Statistical Porosity Characterization Approach of Carbon-Fiber-Reinforced Polymer Material Using Optical Microscopy and Neural Network2022In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 15, no 19, article id 6540Article in journal (Refereed)
    Abstract [en]

    The intensified pursuit for lightweight solutions in the commercial vehicle industry increases the demand for method development of more advanced lightweight materials such as Carbon-Fiber-Reinforced Composites (CFRP). The behavior of these anisotropic materials is challenging to understand and manufacturing defects could dramatically change the mechanical properties. Voids are one of the most common manufacturing defects; they can affect mechanical properties and work as initiation sites for damage. It is essential to know the micromechanical composition of the material to understand the material behavior. Void characterization is commonly conducted using optical microscopy, which is a reliable technique. In the current study, an approach based on optical microscopy, statistically characterizing a CFRP laminate with regard to porosity, is proposed. A neural network is implemented to efficiently segment micrographs and label the constituents: void, matrix, and fiber. A neural network minimizes the manual labor automating the process and shows great potential to be implemented in repetitive tasks in a design process to save time. The constituent fractions are determined and they show that constituent characterization can be performed with high accuracy for a very low number of training images. The extracted data are statistically analyzed. If significant differences are found, they can reveal and explain differences in the material behavior. The global and local void fraction show significant differences for the material used in this study and are good candidates to explain differences in material behavior. © 2022 by the authors.

  • 27.
    Eliasson, Sara
    et al.
    Scania, Sweden; Centre for ECO2 Vehicle Design, Sweden; KTH Royal Institute of Technology, Sweden.
    Karlsson Hagnell, Mathilda
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Wennhage, Per
    Centre for ECO2 Vehicle Design, Sweden; KTH Royal Institute of Technology, Sweden.
    Barsoum, Zuheir
    Centre for ECO2 Vehicle Design, Sweden; KTH Royal Institute of Technology, Sweden.
    An Experimentally Based Micromechanical Framework Exploring Effects of Void Shape on Macromechanical Properties2022In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 15, no 12, article id 4361Article in journal (Refereed)
    Abstract [en]

    A micromechanical simulation approach in a Multi-Scale Modeling (MSM) framework with the ability to consider manufacturing defects is proposed. The study includes a case study where the framework is implemented exploring a cross-ply laminate. The proposed framework highlights the importance of correct input regarding micromechanical geometry and void characteristics. A Representative Volume Element (RVE) model is developed utilizing true micromechanical geometry extracted from micrographs. Voids, based on statistical experimental data, are implemented in the RVE model, and the effects on the fiber distribution and effective macromechanical properties are evaluated. The RVE algorithm is robust and maintains a good surrounding fiber distribution around the implemented void. The local void fraction, void size, and void shape affect the effective micromechanical properties, and it is important to consider the phenomena of the effective mechanical properties with regard to the overall void fraction of an RVE and the actual laminate. The proposed framework has a good prediction of the macromechanical properties and shows great potential to be used in an industrial implementation. For an industrial implementation, weak spots and critical areas for a laminate on a macro-level are found through combining local RVEs. © 2022 by the authors. 

  • 28.
    Eriksson, Viktor
    et al.
    Chalmers university of Technology, Sweden.
    Beckerman, Leyla
    Chalmers university of Technology, Sweden.
    Aerts, Erik
    Chalmers university of Technology, Sweden.
    Andersson Trojer, Markus
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Evenäs, Lars
    Chalmers university of Technology, Sweden.
    Polyanhydride Microcapsules Exhibiting a Sharp pH Transition at Physiological Conditions for Instantaneous Triggered Release2023In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 39, no 49, p. 18003-18010Article in journal (Refereed)
    Abstract [en]

    Stimulus-responsive microcapsules pose an opportunity to achieve controlled release of the entire load instantaneously upon exposure to an external stimulus. Core-shell microcapsules based on the polyanhydride poly(bis(2-carboxyphenyl)adipate) as a shell were formulated in this work to encapsulate the model active substance pyrene and enable a pH-controlled triggered release. A remarkably narrow triggering pH interval was found where a change in pH from 6.4 to 6.9 allowed for release of the entire core content within seconds. The degradation kinetics of the shell were measured by both spectrophotometric detection of degradation products and mass changes by quartz crystal microbalance with dissipation monitoring and were found to correlate excellently with diffusion coefficients fitted to release measurements at varying pH values. The microcapsules presented in this work allow for an almost instantaneous triggered release even under mild conditions, thanks to the designed core-shell morphology. 

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  • 29.
    Eriksson, Viktor
    et al.
    Chalmers University of Technology, Sweden.
    Mistral, Jules
    Chalmers University of Technology, Sweden; Université Lyon, France.
    Yang Nilsson, Ting
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Andersson Trojer, Markus
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Evenäs, Lars
    Chalmers University of Technology, Sweden.
    Microcapsule functionalization enables rate-determining release from cellulose nonwovens for long-term performance2023In: Journal of materials chemistry. B, ISSN 2050-750X, E-ISSN 2050-7518Article in journal (Refereed)
    Abstract [en]

    Functional textiles is a rapidly growing product segment in which sustained release of actives often plays a key role. Failure to sustain the release results in costs due to premature loss of functionality and resource inefficiency. Conventional application methods such as impregnation lead to an excessive and uncontrolled release, which - for biocidal actives - results in environmental pollution. In this study, microcapsules are presented as a means of extending the release from textile materials. The hydrophobic model substance pyrene is encapsulated in poly(d,l-lactide-co-glycolide) microcapsules which subsequently are loaded into cellulose nonwovens using a solution blowing technique. The release of encapsulated pyrene is compared to that of two conventional functionalization methods: surface and bulk impregnation. The apparent diffusion coefficient is 100 times lower for encapsulated pyrene compared to impregnated pyrene. This clearly demonstrates the rate-limiting barrier properties added by the microcapsules, extending the potential functionality from hours to weeks. 

  • 30.
    Francis, Sachin
    et al.
    RISE Research Institutes of Sweden. Chalmers University of Technology, Sweden.
    Bru, Thomas
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Asp, Leif
    Chalmers University of Technology, Sweden.
    Wysocki, Maciej
    RISE Research Institutes of Sweden, Materials and Production.
    Cameron, Christopher
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Characterisation of tape-based carbon fibre thermoplastic discontinuous composites for energy absorption2021In: Plastics, rubber and composites, ISSN 1465-8011, E-ISSN 1743-2898, Vol. 50, no 7, p. 351-Article in journal (Refereed)
    Abstract [en]

    Tape-based discontinuous composite is a relatively new type of composite material that offers improved mechanical properties for similar process-ability compared to Sheet Moulding Compound or Bulk Moulding Compound. This makes it potentially attractive for the automotive industry. In this paper, a thin-ply carbon fibre reinforced polypropylene-based discontinuous composite is studied. Mechanical tests are performed to obtain the tensile, compression and shear behaviour of the material. The energy absorption via tearing is also studied to assess the suitability of the material for energy absorption applications, such as crash-boxes. The tearing test results show a large degree of plastic deformation and an advancing damage front leading to higher specific energy absorption via tearing compared to conventional composite materials. © 2021 The Author(s). 

  • 31.
    Grammatikos, Sotirios A.
    et al.
    NTNU Norwegian University of Science and Technology, Norway.
    Tsampas, Spyros Anastasios
    GKN Aerospace Engine Systems, Sweden.
    Papatzani, Styliani
    Hellenic Army Academy, Greece; Hellenic Ministry of Culture, Greece.
    Luping, Tang
    Chalmers University of Technology, Sweden.
    Löfgren, Ingemar
    Thomas Concrete Group AB, Sweden.
    Pettersson, Jocke
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    On the Mechanical Recycling of Decommisioned Insulation Polymer Composite Components2020In: IOP Conference Series: Materials Science and Engineering, Institute of Physics Publishing , 2020, no 1Conference paper (Refereed)
    Abstract [en]

    Fibre reinforced polymer composites (FRPs) are being increasingly used in aerospace and automotive applications due to their high specific mechanical properties. The construction industry has also started taking advantage of the potential of FRPs for both structural and non-structural purposes. The result of this remarkable absorption of FRPs within the worldwide production market, has led to an immense increase of decommissioned thermoset-matrix components. Nowadays, the majority of the decommissioned FRP components are recovered energy-wise through incineration or simply discarded in landfills around the globe. Within the framework of this paper, we present a solution for the extension of the service life of decommissioned FRP components. Decommissioned electrical insulation FRP pipes were granulated and incorporated as fillers within both cementitious and polymer matrix composites. The effect of FRP granulates on the mechanical performance of cementitious and polymer matrix composites is examined to determine the maximum granulate-filler fraction that can be recycled without compromising the mechanical performance and manufacturing process. © 2020 IOP Publishing Ltd. All rights reserved.

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  • 32.
    Grammatikos, Sotirios A.
    et al.
    Norwegian University of Science and Technology, Norway.
    Tsampas, Spyros Anastasios
    GKN Aerospace Engine Systems, Sweden.
    Pettersson, Jocke
    RISE - Research Institutes of Sweden (2017-2019), Materials and Production, SICOMP. RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Luping, Tang
    Chalmers University of Technology, Sweden.
    Löfgren, Ingemar
    Thomas Concrete Group AB, Sweden.
    Recycling and re-purposing decommisioned construction polymer composites for construction applications2018In: ECCM 2018 - 18th European Conference on Composite Materials, Applied Mechanics Laboratory , 2018Conference paper (Refereed)
    Abstract [en]

    Fibre reinforced polymer composites (FRPs) are being increasingly used in aerospace and automotive applications due to their high specific mechanical properties. The construction industry has also started taking advantage of the potential of FRPs for both structural and non-structural purposes. The result of this remarkable absorption of FRPs within the worldwide production market, has led to an immense increase of decommissioned thermoset-matrix components. Nowadays, the majority of the decommissioned FRP components are recovered energy-wise through incineration or simply discarded in landfills around the globe. Within the framework of this paper, we present a solution for the extension of the service life of decommissioned FRP components. Decommissioned electrical insulation FRP pipes were granulated and incorporated as fillers within both cementitious and polymer matrix composites. The effect of FRP granulates on the mechanical performance of cementitious and polymer matrix composites is examined to determine the maximum granulate-filler fraction that can be recycled without compromising the mechanical performance and manufacturing process.

  • 33.
    Guo, Zengwei
    et al.
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Warlin, Niklas
    Lund University, Sweden.
    Mankar, Smita
    Lund University, Sweden.
    Sidqi, Mohamed
    Clariant International AG, Switzerland.
    Andersson, Mattias
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Zhang, Baozhong
    Lund University, Sweden.
    Nilsson, Erik
    Plasman, Sweden.
    Development of Circularly Recyclable Low Melting Temperature Bicomponent Fibers toward a Sustainable Nonwoven Application2021In: ACS Sustainable Chemistry and Engineering, E-ISSN 2168-0485, Vol. 9, no 49, p. 16778-16785Article in journal (Refereed)
    Abstract [en]

    Sustainable low melting temperature bicomponent polyester fibers that can be circularly recycled were developed. The potentially biobased poly(hexamethylene terephthalate) (PHT), acting as the low melting temperature sheath material in the designed bicomponent fibers, was synthesized in a pilot scale. The obtained PHT with an intrinsic viscosity of 0.47 dL/g showed suitable processability when it was processed together with a poly(butylene terephthalate) (PBT) core in a melt-spinning process of bicomponent fibers. Compared with the commercial low melting temperature terephthalate-isophthalate copolyester LMP-160, PHT showed superior mechanical properties according to DMA analysis. The low melting temperature bicomponent fibers with a ratio of the PBT core and PHT sheath at 70:30 were produced smoothly at 290 °C in a pilot melt-spinning line. Preliminary chemical recycling investigations by methanolysis revealed that PHT/PBT bicomponent fibers were completely depolymerized within 2 h at 200 °C, yielding pure terephthalate, which could be conveniently separated and recycled. This indicated the feasibility of circular recycling, which will greatly improve the sustainability of nonwovens thermally bonded by these new bicomponent fibers. © 2021 The Authors. 

  • 34.
    Holmberg, Jonas
    et al.
    RISE Research Institutes of Sweden, Materials and Production, Manufacturing Processes.
    Berglund, Johan
    RISE Research Institutes of Sweden, Materials and Production, Manufacturing Processes.
    Stormvinter, Albin
    RISE Research Institutes of Sweden, Materials and Production, Manufacturing Processes.
    Andersson, Pär
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites. RISE Research Institutes of Sweden, Materials and Production, Manufacturing Processes.
    Lundin, Per
    Ludin Stress Service AB, Sweden.
    Influence of Local Electropolishing Conditions on Ferritic–Pearlitic Steel on X-Ray Diffraction Residual Stress Profiling2023In: Journal of materials engineering and performance (Print), ISSN 1059-9495, E-ISSN 1544-1024Article in journal (Refereed)
    Abstract [en]

    Layer removal with electropolishing is a well-established method when measuring residual stress profiles with lab-XRD. This is done to measure the depth impact from processes such as shot peening, heat treatment, or machining. Electropolishing is used to minimize the influence on the inherent residual stresses of the material during layer removal, performed successively in incremental steps to specific depths followed by measurement. Great control of the material removal is critical for the measured stresses at each depth. Therefore, the selection of size of the measurement spot and electropolishing parameters is essential. The main objective in this work is to investigate how different electrolytes and electropolishing equipment affect the resulting surface roughness, geometry, microstructure, and consequently the measured residual stress. A second objective has been to establish a methodology of assessing the acquired electropolished depth. The aim has been to get a better understanding of the influence of the layer removal method on the accuracy of the acquired depth. Evaluation has been done by electropolishing one ground and one shot peened sample of a low-alloy carbon steel, grade 1.1730, with different methods. The results showed a difference in stresses depending on the electrolyte used where the perchloric acid had better ability to retain the stresses compared to the saturated salt. Electropolishing with saturated salt is fast and results in evenly distributed material removal but has high surface roughness, which is due to a difference in electropolishing of the two phases, ferrite, and pearlite. Perchloric acid electropolishing is slower but generates a smooth surface as both ferrite and pearlite have the same material removal rates but may cause an increased material removal for the center of the electropolished area. In this work, it is suggested to use perchloric acid electropolishing for the final layer removal step. © 2023, The Author(s).

  • 35.
    Hozić, Dzenan
    et al.
    RISE Research Institutes of Sweden. Linköping University, Sweden.
    Thore, Carl-Johan
    Linköping University, Sweden.
    Cameron, Christopher
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Loukil, Mohamed
    RISE Research Institutes of Sweden. Linköping University, Sweden.
    A new method for simultaneous material and topology optimization of composite laminate structures using Hyperbolic Function Parametrization2021In: Composite structures, ISSN 0263-8223, E-ISSN 1879-1085, Vol. 276, article id 114374Article in journal (Refereed)
    Abstract [en]

    This paper presents a new discrete parametrization method for simultaneous topology and material optimization of composite laminate structures, referred to as Hyperbolic Function Parametrization (HFP). The novelty of HFP is the way the candidate materials are parametrized in the optimization problem. In HFP, a filtering technique based on hyperbolic functions is used, such that only one design variable is used for any given number of material candidates. Compared to state-of-the-art methods such Discrete Material and Topology Optimization (DMTO) and Shape Function with Penalization (SFP), HFP has much fewer optimization variables and constraints but introduces additional non-linearity in the optimization problems. A comparative analysis of HFP, DMTO and SFP are performed based on the problem of maximizing the stiffness of composite plates under a total volume constraint and multiple manufacturing constraints using various loads, boundary conditions and input parameters. The comparison shows that all three methods are highly sensitive to the choice of input parameters for the optimization problem, although the performance of HFP is overall more consistent. HFP method performs similarly to DMTO and SFP in terms of the designs obtained and computational cost. However, HFP obtains similar or better objective function values compared to the DMTO and SFP methods. © 2021 The Author(s)

  • 36.
    Hozić, Dzenan
    et al.
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites. Linköping University, Sweden.
    Thore, Carl-Johan
    Linköping University, Sweden.
    Cameron, Christopher
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Loukil, Mohamed
    Linköping University, Sweden.
    Deterministic-based robust design optimization of composite structures under material uncertainty2023In: Composite structures, ISSN 0263-8223, E-ISSN 1879-1085, Vol. 322, article id 117336Article in journal (Refereed)
    Abstract [en]

    We propose a new deterministic robust design optimization method for composite laminate structures under worst-case material uncertainty. The method is based on a simultaneous parametrization of topology and material and combines a design problem and a material uncertainty problem into a single min–max optimization problem which provides an efficient approach to handle variation of material properties in stiffness driven design optimization problems. An analysis is performed using a design problem based on a failure criterion formulation to evaluate the ability of the proposed method to generate robust composite designs. The design problem is solved using various loads, boundary conditions and manufacturing constraints. The designs generated with the proposed method have improved objective responses compared to the worst-case response of designs generated with nominal material properties and are less sensitive to the variation of material properties. The analysis indicates that the proposed method can be efficiently applied in a robust structural optimization framework. © 2023 The Author(s)

  • 37.
    Hozić, Dzenan
    et al.
    Linköping University, Sweden.
    Thore, Carl-Johan
    Linköping University, Sweden.
    Cameron, Christopher
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Loukil, Mohamed
    RISE Research Institutes of Sweden. Linköping University, Sweden.
    Material uncertainty quantification for optimized composite structures with failure criteria2023In: Composite structures, ISSN 0263-8223, E-ISSN 1879-1085, Vol. 305, article id 116409Article in journal (Refereed)
    Abstract [en]

    We propose a method to analyze effects of material uncertainty in composite laminate structures optimized using a simultaneous topology and material optimization approach. The method is based on computing worst-case values for the material properties and provides an efficient way of handling variation in material properties of composites for stiffness driven optimization problems. An analysis is performed to evaluate the impact of material uncertainty on designs from two design problems: Maximization of stiffness and minimization of a failure criteria index, respectively. The design problems are solved using different loads, boundary conditions and manufacturing constraints. The analysis indicates that the influence of material uncertainty is dependent on the type of optimization problem. For compliance problems the impact on the objective value is proportional to the changes of the constitutive properties and the effect of material uncertainty is consistent and predictable for the generated designs. The strength-based problem shows that material uncertainty has a significant impact on the response, and the effects of material uncertainty is not consistent and changes for different design requirements. In addition, the results show an increase of up to 25% of the maximum failure index when considering the worst-case deviation of the constitutive properties from their nominal values. © 2022 The Author(s)

  • 38.
    Huang, Liming
    et al.
    Chalmers University of Technology, Sweden; Tongji University, China.
    Tang, Luping
    Chalmers University of Technology, Sweden.
    Bachinger, Angelika
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Li, Y.
    Shenzhen University, China.
    Yang, Z.
    Tongji University, China.
    Improving the performance of alkali-activated slag mortar with electro/chemically treated carbon fiber textile2023In: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 418, article id 138214Article in journal (Refereed)
    Abstract [en]

    Alkali-activated slag is a widely used low-carbon binder. Incorporation of textile can mitigate the brittle weakness of alkali-activated composites. The bonding between fibers and matrix is critical for the performance of textile reinforced mortar. This paper is focused on the effect of different treatment methods on the bonding properties of carbon fiber in alkali-activated slag. The interfacial shear strength of fiber bundles in matrix was determined by the pull-out test. The flexural strength of the reinforced mortar was evaluated by a repeated bending. A scanning electron microscopy test was performed to characterize the interfacial properties of the fiber bundles. The results show that the interfacial shear strength of carbon fibers in matrix is improved by the electroplating with calcium silica slurry (CSS), impregnation in different solutions, and plasma treatments. An electroplating in CSS has the best improvement in the bonding strength with an increase by 620%. The CSS treatment increases the maximum flexural strength of CFT reinforced mortar with 22.5% and 30% at 7 and 28 d respectively, and it significantly inhibits the crack growth under the cyclic loading. This effect becomes more significant after a longer curing age. The electroplating treatment eliminates the cracks in the interface of fiber yarns. Slag reacts with the plated portlandite to strengthen the bonding between mortar and fiber bundles, so it has a better inhibiting effect on the crack growth after a longer curing. © 2023 The Authors

  • 39.
    Jafari, Mohammad Javad
    et al.
    Linköping University, Sweden.
    Bäcklund, Fredrik
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites. Karolinska Institute, Sweden.
    Arndt, Tina
    Karolinska Institute, Sweden.
    Schmuck, Benjamin
    Karolinska Institute, Sweden; SLU Swedish University of Agricultural Sciences, Sweden.
    Greco, Gabriele
    SLU Swedish University of Agricultural Sciences, Sweden.
    Rising, Anna
    Karolinska Institute, Sweden; SLU Swedish University of Agricultural Sciences, Sweden.
    Barth, Andreas
    Stockholm University, Sweden.
    Ederth, Thomas
    Linköping University, Sweden.
    Force-Induced Structural Changes in Spider Silk Fibers Introduced by ATR-FTIR Spectroscopy2023In: ACS Applied Polymer Materials, ISSN 2637-6105, Vol. 5, no 11, p. 9433-9444Article in journal (Refereed)
    Abstract [en]

    Silk fibers have unique mechanical properties, and many studies of silk aim at understanding how these properties are related to secondary structure content, which often is determined by infrared spectroscopy. We report significant method-induced irreversible structural changes to both natural and synthetic spider silk fibers, derived from the widely used attenuated total reflection Fourier-transform infrared (ATR-FTIR) technique. By varying the force used to bring fibers into contact with the internal reflection elements of ATR-FTIR accessories, we observed correlated and largely irreversible changes in the secondary structure, with shape relaxation under pressure occurring within minutes. Fitting of spectral components shows that these changes agree with transformations from the α-helix to the β-sheet secondary structure with possible contributions from other secondary structure elements. We further confirm the findings with IR microspectroscopy, where similar differences were seen between the pressed and unaffected regions of spider silk fibers. Our findings show that ATR-FTIR spectroscopy requires care in its use and in the interpretation of the results. 

  • 40.
    Johansson, Ann-Christine
    et al.
    RISE Research Institutes of Sweden, Bioeconomy and Health, Biorefinery and Energy.
    Sott, Richard
    RISE Research Institutes of Sweden, Materials and Production, Applied Mechanics.
    Mattsson, Cecilia
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Comparative study of thermochemical recycling with solvolysis and pyrolysis of End-of-Life wind turbine blades: Rekovind2 - WP32023Report (Other academic)
    Abstract [en]

    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.

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  • 41.
    Jónsdóttir, Hafdís
    et al.
    Chalmers Industriteknik, Sweden.
    Bekken Björkman, Max
    Chalmers Industriteknik, Sweden.
    Boss, Annika
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Lindqvist, Karin
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Ett cirkulärt system för emballageplastfrån byggindustrin steg 2 (CirEm steg 2)2023Report (Other academic)
    Abstract [en]

    Construction products are the second largest area of use for plastic after packaging. The construction industry also uses a large amount of plastic packaging, but only a small part of the plastic waste from this industry is recycled. From 2020, according to law, all plastic from construction and demolition must be sorted out separately into at least one fraction, but in order to achieve a more sustainable use of plastic as well as increased and qualitative material recycling, the plastic needs to be sorted into several fractions and collected so that the material can be recycled and used in new products. The project CirEm stage 2 ("A circular system for packaging plastic from the construction industry stage 2") is financed by the Swedish Energy Agency within the framework of the innovation program RE:Source and carried out by Chalmers Industriteknik and RISE together with 14 project participants in the form of construction companies, sellers of construction products, waste contractors, recyclers, plastic producers, property owners, architects, branch organizations and IT companies. The goal of the project is to develop and test an efficient collection and recycling system for plastic packaging from the construction industry. The project has investigated and identified opportunities and challenges with collecting and recycling plastic packaging waste and other soft plastics from construction sites and sellers of construction products. Through various collection trials, the project has shown how the waste should be sorted at the source in order to improve the quality of the secondary plastic raw material. Experiments where secondary plastic raw material has been produced and then used in product manufacturing have shown how such collected plastic can find different areas of use. The transparent plastic could, for example, be used for plastic hoods and the colored one for wood cover film and sacks. The project has shown that it works well to produce high-quality plastic products based on secondary plastic raw material from plastic packaging, but that the quality aspect is closely related to how the plastic waste is collected and handled. There are therefore good opportunities to achieve high value retention, but in order to create an effective collection and recycling system for plastic packaging and other soft plastics from the construction industry, it is still necessary to work on improving sorting at the source and to increase awareness of the possibilities for recycling. A challenge in this context is that waste generators do not currently see sufficient financial incentives to sort plastic packaging and other soft plastics into more than one fraction. The cost picture for those who are responsible for the waste therefore needs to change in order to create greater driving forces for increased sorting and thus higher value retention.

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  • 42.
    Jönsson, Christina
    et al.
    RISE Research Institutes of Sweden, Materials and Production, Product Realisation Methodology.
    Wei, Ren
    University of Greifswald, Germany.
    Biundo, Antonino
    KTH Royal Institute of Technology, Sweden; REWOW srl, Italy.
    Landberg, Johan
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Schwarz Bour, Lisa
    RISE Research Institutes of Sweden, Materials and Production, Product Realisation Methodology.
    Pezzotti, Fabio
    RISE Research Institutes of Sweden, Materials and Production, Manufacturing Processes.
    Toca, Andreea
    Swedish Stockings, Sweden; Hyper Island, Sweden.
    Jacques, Les
    LYCRA Company, UK.
    Bornscheuer, Uwe
    University of Greifswald, Germany.
    Syrén, Per-Olof
    KTH Royal Institute of Technology, Sweden.
    Biocatalysis in the Recycling Landscape for Synthetic Polymers and Plastics towards Circular Textiles2021In: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 14, no 19, p. 4028-Article in journal (Refereed)
    Abstract [en]

    Although recovery of fibers from used textiles with retained material quality is desired, separation of individual components from polymer blends used in today's complex textile materials is currently not available at viable scale. Biotechnology could provide a solution to this pressing problem by enabling selective depolymerization of recyclable fibers of natural and synthetic origin, to isolate constituents or even recover monomers. We compiled experimental data for biocatalytic polymer degradation with a focus on synthetic polymers with hydrolysable links and calculated conversion rates to explore this path The analysis emphasizes that we urgently need major research efforts: beyond cellulose-based fibers, biotechnological-assisted depolymerization of plastics so far only works for polyethylene terephthalate, with degradation of a few other relevant synthetic polymer chains being reported. In contrast, by analyzing market data and emerging trends for synthetic fibers in the textile industry, in combination with numbers from used garment collection and sorting plants, it was shown that the use of difficult-to-recycle blended materials is rapidly growing. If the lack of recycling technology and production trend for fiber blends remains, a volume of more than 3400 Mt of waste will have been accumulated by 2030. This work highlights the urgent need to transform the textile industry from a biocatalytic perspective.

  • 43.
    Kohne, Thomas
    et al.
    KTH Royal Institute of Technology, Sweden.
    Fahlkrans, Johan
    Scania CV AB, Sweden.
    Stormvinter, Albin
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Maawad, Emad
    Helmholtz-Zentrum Hereon, Germany.
    Winkelmann, Aimo
    AGH University of Science and Technology, Poland.
    Hedström, Peter
    KTH Royal Institute of Technology, Sweden.
    Borgenstam, Annika
    KTH Royal Institute of Technology, Sweden.
    Evolution of Martensite Tetragonality in High-Carbon Steels Revealed by In Situ High-Energy X-Ray Diffraction2023In: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940, Vol. 54, no 4, p. 1083-1100Article in journal (Refereed)
    Abstract [en]

    The martensitic transformation was studied by in situ and ex situ experiments in two high-carbon, 0.54 and 0.74 wt pct C, steels applying three different cooling rates, 15 °C/s, 5 °C/s, and 0.5 °C/s, in the temperature range around Ms, to improve the understanding of the evolution of martensite tetragonality c/a and phase fraction formed during the transformation. The combination of in situ high-energy X-ray diffraction during controlled cooling and spatially resolved tetragonality c/a determination by electron backscatter diffraction pattern matching was used to study the transformation behavior. The cooling rate and the different Ms for the steels had a clear impact on the martensitic transformation with a decrease in average tetragonality due to stronger autotempering for a decreasing cooling rate and higher Ms. A slower cooling rate also resulted in a lower fraction of martensite at room temperature, but with an increase in fraction of autotempered martensite. Additionally, a heterogeneous distribution of martensite tetragonality was observed for all cooling rates. © 2023, The Author(s).

  • 44.
    Larsson, R.
    et al.
    Chalmers University of Technology, Sweden.
    Singh, Vivekendra
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites. Chalmers University of Technology, Sweden.
    Olsson, Robin
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites. Chalmers University of Technology, Sweden.
    Marklund, Erik
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    A micromechanically based model for dynamic damage evolution in unidirectional composites2022In: International Journal of Solids and Structures, ISSN 0020-7683, E-ISSN 1879-2146, Vol. 238, article id 111368Article in journal (Refereed)
    Abstract [en]

    This article addresses the micromechanically motivated, quasistatic to dynamic, failure response of fibre reinforced unidirectional composites at finite deformation. The model draws from computational homogenization, with a subscale represented by matrix and fibre constituents. Undamaged matrix response assumes isotropic viscoelasticity–viscoplasticity, whereas the fibre is transversely isotropic hyperelastic. Major novelties involve damage degradation of the matrix response, due to shear in compression based on a rate dependent damage evolution model, and the large deformation homogenization approach. The homogenized quasi-brittle damage induced failure is described by elastically stored isochoric energy and plastic work of the undamaged polymer, driving the evolution of damage. The developed model is implemented in ABAQUS/Explicit. Finite element validation is carried out for a set of off-axis experimental compression tests in the literature. Considering the unidirectional carbon–epoxy (IM7/8552) composite at different strain rates, it appears that the homogenized damage degraded response can represent the expected ductile failure of the composite at compressive loading with different off-axes. Favourable comparisons are made for the strain and fibre rotation distribution involving localized shear and fibre kinking. © 2021 The Authors

  • 45.
    Larsson, R.
    et al.
    Chalmers University of Technology, Sweden.
    Singh, Vivekendra
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites. Chalmers University of Technology, Sweden.
    Olsson, Robin
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites. Chalmers University of Technology, Sweden.
    Marklund, Erik
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    A micromechanically based model for strain rate effects in unidirectional composites2020In: Mechanics of materials, ISSN 0167-6636, E-ISSN 1872-7743, Vol. 148, article id 103491Article in journal (Refereed)
    Abstract [en]

    This article addresses dynamic behaviour of fibre reinforced polymer composites in terms of a transversely isotropic viscoelastic-viscoplastic constitutive model established at the unidirectional ply level. The model captures the prelocalized response of the ply in terms of rate dependent elasticity and strength without damage. A major novelty is that the model draws from computational homogenization, with matrix and fibre materials as subscale constituents for a representative volume element of the ply. The micromechanics of the strain rate dependent polymer matrix is represented by an isotropic pressure sensitive viscoelastic-viscoplastic prototype model. For the fibre material, transverse elasticity is assumed. The constituents are homogenized via the fluctuating strain of the subscale, where a simple ansatz is applied to allow for constant stress in the plane transverse to the fibre orientation. Despite the relatively simple modelling assumptions for the constituents, the homogenized model compares favourably to experimental data for an epoxy/carbon fibre based composite, subjected to a variety of challenging uniaxial off-axis tests. The model response clearly reflects observed strain rate dependencies under both tensile and compressive loadings. 

  • 46.
    Lauenstein, Åsa
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Hållbara gjutna produkter. Slutrapport från projektet GRETA2023Report (Other academic)
    Abstract [en]

    Sustainable cast products. Final report from the GRETA project There is a high awareness within Swedish foundry industry that a sustainable transition is both necessary and desirable and that it to a high extent will affect energy consumption and carbon footprint as well as the handling of raw materials and residues. This project provided Swedish foundry industry with the means to achieve a sustainable transition with maintained competitiveness through more efficient use of resources. The project was divided into three parts. The first examined how a higher resource efficiency can be achieved for the energy consumption for a given cast component and production process. Starting with a given cast product, the second part investigated means to achieve a higher resource efficiency in the production process itself. In the third part, the perspective was further broadened as the use phase of the cast component was included in the discussion. The work included twelve case studies and pilot projects following specific investments in knowledge and equipment at a number of foundries. The member companies of the Swedish Foundry Association were involved in interviews and discussions in order to prioritize actions and solutions in each case. A large number of open reports were published and six new research projects were started.

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  • 47.
    Lindqvist, Karin
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Materials and Production, IVF.
    Andersson, Mattias
    RISE - Research Institutes of Sweden (2017-2019), Materials and Production, IVF.
    Boss, Annika
    RISE - Research Institutes of Sweden (2017-2019), Materials and Production, IVF. RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Oxfall, Henrik
    RISE - Research Institutes of Sweden (2017-2019), Materials and Production, IVF.
    Thermal and mechanical properties of blends containing PP and recycled XLPE cable waste2019In: Journal of Polymers and the Environment, ISSN 1566-2543, E-ISSN 1572-8919, Vol. 27, no 2, p. 386-394Article in journal (Refereed)
    Abstract [en]

    Recycled XLPE from cable manufacturing waste and end-of-life cables were mixed with virgin polypropylene (PP) in order to evaluate the potential to be used in new injection molded products. The influence of metal contaminations on the mechanical and thermal properties and how the blends could be stabilized in order to be recycled and give reliable properties over time were studied. The results show that blends of 25–50% XLPE in PP give good mechanical properties with retained or improved impact strength independent of the source of XLPE. Ageing at 105 °C for 6 months showed a more severe material degradation and loss of mechanical properties for blends that contained XLPE with end-of-life cable. Addition of metal deactivator proved to retain the mechanical properties for more than 8 months of ageing at 105 °C. Simulated recycling of 50% XLPE in PP stabilized with a metal deactivator, showed that mechanical properties were preserved.

  • 48.
    Liu, Jiliang
    et al.
    ESRF European Synchrotron Radiation Facility, France.
    Bengtsson, Jenny
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Yu, Shun
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Burghammer, Manfred
    ESRF European Synchrotron Radiation Facility, France.
    Jedvert, Kerstin
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Variation in the hierarchical structure of lignin-blended cellulose precursor fibers2023In: International Journal of Biological Macromolecules, ISSN 0141-8130, E-ISSN 1879-0003, Vol. 225, p. 1555-Article in journal (Refereed)
    Abstract [en]

    Regenerated cellulose fibers have been considered as potential precursor fibers for carbon fibers because of their balanced cost and performance. Increased attention has been paid to blending lignin with the regenerated cellulose to generate precursor fibers which render good mechanical properties and higher carbon yield. The mechanical properties of carbon fibers have been found closely correlated to the structure of precursor fibers. However, the effects of lignin blending on molecular- and morphological structure of the precursor are still unclear. This study aims at clarifying the structural information of lignin–cellulose precursor fibers from molecular level to mesoscale by scanning X-ray microdiffraction. We present the existence of a skin–core morphology for all the precursor fibers. Increase of lignin content in precursor fiber could reduce the portion of skin and cause obvious disorder of the meso- and molecular structure. By correlating structural variations with lignin blending, 30% lignin blending has been found as a potential balance point to obtain precursor fibers maintaining structural order together with high yield rate. 

  • 49.
    Liu, X.
    et al.
    University of Texas at Arlington, USA.
    Costa, Sergio
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Liu, B.
    University of Texas at Arlington, USA.
    Trehan, S.
    DTU Technical University of Denmark, Denmark.
    Convolutional Neural Network for Predicting Mechanical Behavior of Composites with Fiber Waviness2022In: Proceedings of the American Society for Composites - 37th Technical Conference, ASC 2022, DEStech Publications Inc. , 2022Conference paper (Refereed)
    Abstract [en]

    The fiber waviness is inevitable in non-crimp fabric (NCF) reinforced composites. It is very challenging to accurately and efficiently predict the material behavior with fiber waviness. This work presents a machine learning approach to the prediction of material behavior of NCF composites under a compressive load. The out-of-plane fiber orientations are first extracted from micrographs of NCF laminates. A digital twinning process is followed to create finite element (FE) models with elementwise fiber orientations. Based on the FE models, a physics-based damage model is employed to generate high-fidelity simulation datasets, capturing the kink-band due to the fiber waviness. With the simulation datasets, convolutional neural network (CNN) models are developed to take the images of the fiber orientations and predict the corresponding stiffness, strength, and stress-strain curves of the NCF composites. The results show that the CNN models can capture spatial information of the fiber orientation and efficiently predict the corresponding material behavior with a high accuracy. In addition, the correlations of the fiber orientations and the final material behaviors are investigated based on the developed CNN models. 

  • 50.
    Lu, Zhonghai
    et al.
    KTH Royal Institute of Technology, Sweden.
    Zhu, W
    KTH Royal Institute of Technology, Sweden.
    Chen, Y
    KTH Royal Institute of Technology, Sweden.
    Charnley, J
    Lusstech, UK.
    Dejke, Valter
    RISE Research Institutes of Sweden, Materials and Production, Polymeric Materials and Composites.
    Pomazanskyi, A
    Nuromedia GmbH, Germany.
    Ko, ST
    Össur, Iceland.
    Zeybek, B
    Teesside University, UK.
    Mehryar, P
    Teesside University, UK.
    Ali, Z
    Teesside University, UK.
    Karamousadakis, M
    Twi Hellas, Greece.
    Chen, D
    KTH Royal Institute of Technology, Sweden.
    Wearable pressure sensing for lower limb amputees2022In: BioCAS 2022 - IEEE Biomedical Circuits and Systems Conference: Intelligent Biomedical Systems for a Better Future, Proceedings, Institute of Electrical and Electronics Engineers Inc. , 2022, p. 105-109Conference paper (Refereed)
    Abstract [en]

    Pressure sensing in prosthetic sockets is valuable as it provides quantified data to assist prosthetists in designing comfortable sockets for amputees. We present a wearable pressure sensing system for lower limb amputees. The full system consists of three essential elements from sensing scheme (wearable sensors, sensor calibration and deployment), electronic measurement system (embedded hardware and software), to time-series database and visualization. The full system has been successfully applied in clinical trials to effectively collect pressure data in real-time.

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