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  • 1.
    Aarstad, Olav
    et al.
    NTNU Norwegian University of Science and Technology, Norway.
    Heggset, Ellinor B
    RISE - Research Institutes of Sweden (2017-2019), Bioekonomi, PFI.
    Pedersen, Ina Sander
    NTNU Norwegian University of Science and Technology, Norway.
    Björnöy, Sindre H.
    NTNU Norwegian University of Science and Technology, Norway.
    Syverud, Kristin
    RISE - Research Institutes of Sweden (2017-2019), Bioekonomi, PFI.
    Strand, Berit L.
    NTNU Norwegian University of Science and Technology, Norway.
    Mechanical properties of composite hydrogels of alginate and cellulose nanofibrils2017Inngår i: Polymers, E-ISSN 2073-4360, Vol. 9, nr 8, artikkel-id 378Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Alginate and cellulose nanofibrils (CNF) are attractive materials for tissue engineering and regenerative medicine. CNF gels are generally weaker and more brittle than alginate gels, while alginate gels are elastic and have high rupture strength. Alginate properties depend on their guluronan and mannuronan content and their sequence pattern and molecular weight. Likewise, CNF exists in various qualities with properties depending on, e.g., morphology and charge density. In this study combinations of three types of alginate with different composition and two types of CNF with different charge and degree of fibrillation have been studied. Assessments of the composite gels revealed that attractive properties like high rupture strength, high compressibility, high gel rigidity at small deformations (Young’s modulus), and low syneresis was obtained compared to the pure gels. The effects varied with relative amounts of CNF and alginate, alginate type, and CNF quality. The largest effects were obtained by combining oxidized CNF with the alginates. Hence, by combining the two biopolymers in composite gels, it is possible to tune the rupture strength, Young’s modulus, syneresis, as well as stability in physiological saline solution, which are all important properties for the use as scaffolds in tissue engineering.

    Fulltekst (pdf)
    fulltext
  • 2.
    Akbari, Saeed
    et al.
    RISE Research Institutes of Sweden, Digitala system, Smart hårdvara.
    Johansson, Jan
    RISE Research Institutes of Sweden, Material och produktion, Tillverkningsprocesser.
    Johansson, Emil
    Adaxis, France.
    Tönnäng, Lenny
    RISE Research Institutes of Sweden, Material och produktion, Tillverkningsprocesser.
    Hosseini, Seyed
    RISE Research Institutes of Sweden, Material och produktion, Tillverkningsprocesser.
    Large-Scale Robot-Based Polymer and Composite Additive Manufacturing: Failure Modes and Thermal Simulation2022Inngår i: Polymers, E-ISSN 2073-4360, Vol. 14, nr 9, artikkel-id 1731Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

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

  • 3.
    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, Material och produktion, Polymera material och kompositer.
    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 Boxes2023Inngår i: Polymers, E-ISSN 2073-4360, Vol. 15, nr 18, artikkel-id 3842Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 4.
    Brooke, Robert
    et al.
    RISE - Research Institutes of Sweden (2017-2019), ICT, Acreo. Linkoping University, Sweden.
    Edberg, Jesper
    RISE - Research Institutes of Sweden (2017-2019), ICT, Acreo. Linkoping University, Sweden.
    Crispin, Xavier
    Linkoping University, Sweden.
    Berggren, Magnus
    Linköping University, Sweden.
    Engquist, Isak
    Linkoping University, Sweden.
    Jonsson, Magnus
    Linkoping University, Sweden.
    Greyscale and paper electrochromic polymer displays by UV patterning2019Inngår i: Polymers, E-ISSN 2073-4360, Vol. 11, nr 2, artikkel-id 267Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Electrochromic devices have important implications as smart windows for energy efficient buildings, internet of things devices, and in low-cost advertising applications. While inorganics have so far dominated the market, organic conductive polymers possess certain advantages such as high throughput and low temperature processing, faster switching, and superior optical memory. Here, we present organic electrochromic devices that can switch between two high-resolution images, based on UV-patterning and vapor phase polymerization of poly(3,4- ethylenedioxythiophene) films. We demonstrate that this technique can provide switchable greyscale images through the spatial control of a UV-light dose. The color space was able to be further altered via optimization of the oxidant concentration. Finally, we utilized a UV-patterning technique to produce functional paper with electrochromic patterns deposited on porous paper, allowing for environmentally friendly electrochromic displays.

  • 5.
    Chen, Genqiang
    et al.
    Donghua University, China; Umeå University, Sweden.
    Wu, Guochao
    Umeå University, Sweden.
    Alriksson, Björn
    RISE - Research Institutes of Sweden (2017-2019), Bioekonomi, Processum.
    Wang, Wei
    Donghua University, China.
    Hong, Feng F.
    Donghua University, China.
    Jönsson, Leif J.
    Umeå University, Sweden.
    Bioconversion of waste fiber sludge to bacterial nanocellulose and use for reinforcement of CTMP paper sheets2017Inngår i: Polymers, E-ISSN 2073-4360, Vol. 9, nr 9, artikkel-id 458Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Utilization of bacterial nanocellulose (BNC) for large-scale applications is restricted by low productivity in static cultures and by the high cost of the medium. Fiber sludge, a waste stream from pulp and paper mills, was enzymatically hydrolyzed to sugar, which was used for the production of BNC by the submerged cultivation of Komagataeibacter xylinus. Compared with a synthetic glucose-based medium, the productivity of purified BNC from the fiber sludge hydrolysate using shake-flasks was enhanced from 0.11 to 0.17 g/(L × d), although the average viscometric degree of polymerization (DPv) decreased from 6760 to 6050. The cultivation conditions used in stirred-tank reactors (STRs), including the stirring speed, the airflow, and the pH, were also investigated. Using STRs, the BNC productivity in fiber-sludge medium was increased to 0.32 g/(L × d) and the DPv was increased to 6650. BNC produced from the fiber sludge hydrolysate was used as an additive in papermaking based on the chemithermomechanical pulp (CTMP) of birch. The introduction of BNC resulted in a significant enhancement of the mechanical strength of the paper sheets. With 10% (w/w) BNC in the CTMP/BNC mixture, the tear resistance was enhanced by 140%. SEM images showed that the BNC cross-linked and covered the surface of the CTMP fibers, resulting in enhanced mechanical strength.

  • 6.
    Costa, Carolina
    et al.
    Mid Sweden University, Sweden.
    Medronho, Bruno
    Mid Sweden University, Sweden; University of Algarve, Portugal.
    Filipe, Alexandra
    University of Algarve, Portugal.
    Mira, Isabel
    RISE - Research Institutes of Sweden (2017-2019), Biovetenskap och material, Yta, process och formulering.
    Lindman, Björn
    Mid Sweden University, Sweden.
    Edlund, Håkan
    Mid Sweden University, Sweden.
    Norgren, Magnus
    Mid Sweden University, Sweden.
    Emulsion Formation and Stabilization by Biomolecules: The Leading Role of Cellulose.2019Inngår i: Polymers, E-ISSN 2073-4360, Vol. 11, nr 10, artikkel-id E1570Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Emulsion stabilization by native cellulose has been mainly hampered because of its insolubility in water. Chemical modification is normally needed to obtain water-soluble cellulose derivatives. These modified celluloses have been widely used for a range of applications by the food, cosmetic, pharmaceutic, paint and construction industries. In most cases, the modified celluloses are used as rheology modifiers (thickeners) or as emulsifying agents. In the last decade, the structural features of cellulose have been revisited, with particular focus on its structural anisotropy (amphiphilicity) and the molecular interactions leading to its resistance to dissolution. The amphiphilic behavior of native cellulose is evidenced by its capacity to adsorb at the interface between oil and aqueous solvent solutions, thus being capable of stabilizing emulsions. In this overview, the fundamentals of emulsion formation and stabilization by biomolecules are briefly revisited before different aspects around the emerging role of cellulose as emulsion stabilizer are addressed in detail. Particular focus is given to systems stabilized by native cellulose, either molecularly-dissolved or not (Pickering-like effect).

  • 7.
    El Seoud, Omar A
    et al.
    University of São Paulo, Brazil.
    Kostag, Marc
    University of São Paulo, Brazil.
    Jedvert, Kerstin
    RISE - Research Institutes of Sweden, Material och produktion, IVF.
    Malek, Naved I
    Sardar Vallabhbhai National Institute of Technology, India.
    Cellulose in Ionic Liquids and Alkaline Solutions: Advances in the Mechanisms of Biopolymer Dissolution and Regeneration.2019Inngår i: Polymers, E-ISSN 2073-4360, Vol. 11, nr 12, artikkel-id E1917Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This review is focused on assessment of solvents for cellulose dissolution and the mechanism of regeneration of the dissolved biopolymer. The solvents of interest are imidazole-based ionic liquids, quaternary ammonium electrolytes, salts of super-bases, and their binary mixtures with molecular solvents. We briefly discuss the mechanism of cellulose dissolution and address the strategies for assessing solvent efficiency, as inferred from its physico-chemical properties. In addition to the favorable effect of lower cellulose solution rheology, microscopic solvent/solution properties, including empirical polarity, Lewis acidity, Lewis basicity, and dipolarity/polarizability are determinants of cellulose dissolution. We discuss how these microscopic properties are calculated from the UV-Vis spectra of solvatochromic probes, and their use to explain the observed solvent efficiency order. We dwell briefly on use of other techniques, in particular NMR and theoretical calculations for the same purpose. Once dissolved, cellulose is either regenerated in different physical shapes, or derivatized under homogeneous conditions. We discuss the mechanism of, and the steps involved in cellulose regeneration, via formation of mini-sheets, association into "mini-crystals", and convergence into larger crystalline and amorphous regions. We discuss the use of different techniques, including FTIR, X-ray diffraction, and theoretical calculations to probe the forces involved in cellulose regeneration.

  • 8.
    Filgueira, Daniel
    et al.
    University of Vigo, Spain.
    Holmen, Solveig
    NTNU, Norway.
    Melbø, Johnny K
    RISE - Research Institutes of Sweden (2017-2019), Bioekonomi, PFI. RISE Research Institutes of Sweden, Bioekonomi och hälsa, Material- och ytdesign.
    Moldes, Diego
    University of Vigo, Spain.
    Echtermeyer, Andreas T.
    NTNU, Norway.
    Chinga-Carrasco, Gary
    RISE - Research Institutes of Sweden (2017-2019), Bioekonomi, PFI.
    3D printable filaments made of biobased polyethylene biocomposites2018Inngår i: Polymers, E-ISSN 2073-4360, Vol. 10, nr 3, artikkel-id 314Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Two different series of biobased polyethylene (BioPE) were used for the manufacturing of biocomposites, complemented with thermomechanical pulp (TMP) fibers. The intrinsic hydrophilic character of the TMP fibers was previously modified by grafting hydrophobic compounds (octyl gallate and lauryl gallate) by means of an enzymatic-assisted treatment. BioPE with low melt flow index (MFI) yielded filaments with low void fraction and relatively low thickness variation. The water absorption of the biocomposites was remarkably improved when the enzymatically-hydrophobized TMP fibers were used. Importantly, the 3D printing of BioPE was improved by adding 10% and 20% TMP fibers to the composition. Thus, 3D printable biocomposites with low water uptake can be manufactured by using fully biobased materials and environmentally-friendly processes.

    Fulltekst (pdf)
    fulltext
  • 9.
    Heen Blindheim, Fredrik
    et al.
    RISE Research Institutes of Sweden, Bioekonomi och hälsa, Material- och ytdesign.
    Ruwoldt, Jost
    RISE Research Institutes of Sweden, Bioekonomi och hälsa, Material- och ytdesign.
    The Effect of Sample Preparation Techniques on Lignin Fourier Transform Infrared Spectroscopy2023Inngår i: Polymers, E-ISSN 2073-4360, Vol. 15, nr 13, artikkel-id 2901Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The characterization and quantification of functional groups in technical lignins are among the chief obstacles of the utilization of this highly abundant biopolymer. Although several techniques were developed for this purpose, there is still a need for quick, cost-efficient, and reliable quantification methods for lignin. In this paper, three sampling techniques for fourier transform infrared (FTIR) spectroscopy were assessed both qualitatively and quantitatively, delineating how these affected the resultant spectra. The attenuated total reflectance (ATR) of neat powders and DMSO-d6 solutions, as well as transmission FTIR using the KBr pelleting method (0.5 wt%), were investigated and compared for eight lignin samples. The ATR of neat lignins provided a quick and easy method, but the signal-to-noise ratios in the afforded spectra were limited. The ATR of the DMSO-d6 solutions was highly concentration dependent, but at a 30 wt%, acceptable signal-to-noise ratios were obtained, allowing for the lignins to be studied in the dissolved state. The KBr pelleting method gave a significant improvement in the smoothness and resolution of the resultant spectra compared to the ATR techniques. Subsequently, the content of phenolic OH groups was calculated from each FTIR mode, and the best correlation was seen between the transmission mode using KBr pellets and the ATR of the neat samples (R2 = 0.9995). Using the titration measurements, the total OH and the phenolic OH group content of the lignin samples were determined as well. These results were then compared to the FTIR results, which revealed an under-estimation of the phenolic OH groups from the non-aqueous potentiometric titration, which was likely due to the differences in the pKa between the lignin and the calibration standard 4-hydroxybenzoic acid. Further, a clear correlation was found between the lower (Formula presented.) and the increased phenolic OH group content via SEC analyses. The work outlined in this paper give complementary views on the characterization and quantification of technical lignin samples via FTIR. © 2023 by the authors.

  • 10.
    Jakubowicz, Ignacy
    et al.
    RISE Research Institutes of Sweden, Samhällsbyggnad, Infrastruktur och betongbyggande.
    Yarahmadi, Nazdaneh
    RISE Research Institutes of Sweden, Samhällsbyggnad, Infrastruktur och betongbyggande.
    Review and Assessment of Existing and Future Techniques for Traceability with Particular Focus on Applicability to ABS Plastics2024Inngår i: Polymers, E-ISSN 2073-4360, Vol. 16, nr 10, artikkel-id 1343Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    It is generally recognized that the use of physical and digital information-based solutions for tracking plastic materials along a value chain can favour the transition to a circular economy and help to overcome obstacles. In the near future, traceability and information exchange between all actors in the value chain of the plastics industry will be crucial to establishing more effective recycling systems. Recycling plastics is a complex process that is particularly complicated in the case of acrylonitrile butadiene styrene (ABS) plastic because of its versatility and use in many applications. This literature study is part of a larger EU-funded project with the acronym ABSolEU (Paving the way for an ABS recycling revolution in the EU). One of its goals is to propose a suitable traceability system for ABS products through physical marking with a digital connection to a suitable data-management system to facilitate the circular use of ABS. The aim of this paper is therefore to review and assess the current and future techniques for traceability with a particular focus on their use for ABS plastics as a basis for this proposal. The scientific literature and initiatives are discussed within three technological areas, viz., labelling and traceability systems currently in use, digital data sharing systems and physical marking. The first section includes some examples of systems used commonly today. For data sharing, three digital technologies are discussed, viz., Digital Product Passports, blockchain solutions and certification systems, which identify a product through information that is attached to it and store, share and analyse data throughout the product’s life cycle. Finally, several different methods for physical marking are described and evaluated, including different labels on a product’s surface and the addition of a specific material to a polymer matrix that can be identified at any point in time with the use of a special light source or device. The conclusion from this study is that the most promising data management technology for the near future is blockchain technology, which could be shared by all ABS products. Regarding physical marking, producers must evaluate different options for individual products, using the most appropriate and economical technology for each specific product. It is also important to evaluate what information should be attached to a specific product to meet the needs of all actors in the value chain.

    Fulltekst (pdf)
    fulltext
  • 11.
    Javed, Asif
    et al.
    Karlstad University, Sweden.
    Rättö, Peter
    RISE Research Institutes of Sweden, Bioekonomi och hälsa, Bioraffinaderi och energi. Karlstad University, Sweden.
    Järnström, Lars
    Karlstad University, Sweden.
    Ullsten, Henrik
    Calamo AB, Sweden.
    Lignin-containing coatings for packaging materials—pilot trials2021Inngår i: Polymers, E-ISSN 2073-4360, Vol. 13, nr 10, artikkel-id 1595Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    One severe weakness of most biopolymers, in terms of their use as packaging materials, is their relatively high solubility in water. The addition of kraft lignin to starch coating formulations has been shown to reduce the water solubility of starch in dry coatings. However, lignin may also migrate into aqueous solutions. For this paper, kraft lignin isolated using the LignoBoost process was used in order to examine the effect of pH level on the solubility of lignin with and without ammonium zirconium carbonate (AZC). Machine-glazed (MG) paper was coated in a pilot coating machine, with the moving substrate at high speed, and laboratory-coated samples were used as a reference when measuring defects (number of pinholes). Kraft lignin became soluble in water at lower pH levels when starch was added to the solution, due to the interactions between starch and lignin. This made it possible to lower the pH of the coating solutions, resulting in increased water stability of the dry samples; that is, the migration of lignin to the model liquids decreased when the pH of the coating solutions was reduced. No significant difference was observed in the water vapor transmission rate (WVTR) between high and low pH for the pilot-coated samples. The addition of AZC to the formulation reduced the migration of lignin from the coatings to the model liquids and led to an increase in the water contact angle, but also increased the number of pinholes in the pilot-coated samples. © 2021 by the authors

  • 12.
    Lainioti, Georgis
    et al.
    Institute of Chemical Engineering Sciences, Greece; University of Patras, Greece.
    Koukoumtzis, Vasilis
    Institute of Chemical Engineering Sciences, Greece; University of Patras, Greece.
    Andrikopoulos, Konstantinos
    Institute of Chemical Engineering Sciences, Greece; University of Patras, Greece.
    Tsantaridis, Lazaros
    RISE Research Institutes of Sweden, Samhällsbyggnad, Bygg och fastighet.
    Östman, Birgit
    Linnaeus University, Sweden.
    Voyiatzis, George
    Institute of Chemical Engineering Sciences, Greece.
    Kallitsis, Joannis
    Institute of Chemical Engineering Sciences, Greece; University of Patras, Greece.
    Environmentally Friendly Hybrid Organic–Inorganic Halogen-Free Coatings for Wood Fire-Retardant Applications2022Inngår i: Polymers, E-ISSN 2073-4360, Vol. 14, nr 22, artikkel-id 4959Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Wood and wood-based products are extensively used in the building sector due to their interesting combination of properties. Fire safety and fire spread, however, are of utmost concern for the protection of buildings. Therefore, in timber structures, wood must be treated with fire-retardant materials in order to improve its reaction to fire. This article highlights the flame retardancy of novel hybrid organic–inorganic halogen-free coatings applied on plywood substrates. For this purpose, either a huntite-rich mineral (H5) or its modified nano-Mg (OH)2 type form (H5-m), acting as an inorganic (nano) filler, was functionalized with reactive oligomers (ROs) and incorporated into a waterborne polymeric matrix. A water-soluble polymer (P (SSNa-co-GMAx)), combining its hydrophilic nature with functional epoxide groups, was used as the reactive oligomer in order to enhance the compatibility between the filler and the matrix. Among various coating compositions, the system composed of 13% polymeric matrix, 73% H5 and 14% ROs, which provided the best coating quality and flame retardancy, was selected for the coating of plywood on a larger scale in one or two layers. The results indicated that the novel plywood coating systems with the addition of ecological coating formulations (WF-13, WF-14 and WF-15), prepared at two layers, reached Euroclass B according to EN13501-1, which is the best possible for fire systems applied to wood. © 2022 by the authors.

  • 13.
    Martin-Bertelsen, Birte
    et al.
    Lund University, Sweden.
    Andersson, Erika
    Lund University, Sweden.
    Köhnke, Tobias
    RISE Research Institutes of Sweden, Material och produktion, Kemi, biomaterial och textil.
    Hedlund, Artur
    RISE Research Institutes of Sweden, Material och produktion, Kemi, biomaterial och textil.
    Stigsson, Lars
    KIRAM AB, Sweden.
    Olsson, Ulf
    Lund University, Sweden.
    Revisiting the dissolution of cellulose in NaOH as "Seen" by X-rays2020Inngår i: Polymers, E-ISSN 2073-4360, Vol. 12, nr 2, artikkel-id 342Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Cotton production is reaching a global limit, leading to a growing demand for bio-based textile fibers produced by other means. Textile fibers based on regenerated cellulose from wood holds great potential, but in order to produce fibers, the components need to be dissolved in suitable solvents. Furthermore, the dissolution process of cellulose is not yet fully understood. In this study, we investigated the dissolution state of microcrystalline cellulose in aqueous NaOH by using primarily scattering methods. Contrary to previous findings, this study indicated that cellulose concentrations of up to 2 wt % are completely molecularly dissolved in 8 wt % NaOH. Scattering data furthermore revealed the presence of semi-flexible cylinders with stiff segments. In order to improve the dissolution capability of NaOH, the effects of different additives have been of interest. In this study, scattering data indicated that the addition of ZnO decreased the formation of aggregates, while the addition of PEG did not improve the dissolution properties significantly, although preliminary NMR data did suggest a weak attraction between PEG and cellulose. Overall, this study sheds further light on the dissolution of cellulose in NaOH and highlights the use of scattering methods to assess solvent quality. © 2020 by the authors.

  • 14.
    McDonagh, Birgitte
    et al.
    SINTEF, Norway.
    Chinga-Carrasco, Gary
    RISE Research Institutes of Sweden, Bioekonomi och hälsa, Material- och ytdesign.
    Characterization of porous structures of cellulose nanofibrils loaded with salicylic acid2020Inngår i: Polymers, E-ISSN 2073-4360, Vol. 12, nr 11, artikkel-id 2538Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Bleached and unbleached pulp fibers were treated with 2,2,6,6-tetramethylpyperidine-1-oxyl (TEMPO) mediated oxidation to obtain cellulose nanofibrils (CNFs). The resulting bleached and unbleached CNFs were mixed with salicylic acid (0, 5, 10, 20 wt%) before casting and freeze-drying or 3D-printing. A series of methods were tested and implemented to characterize the CNF materials and the porous structures loaded with salicylic acid. The CNFs were characterized with atomic force microscopy and laser profilometry, and release of salicylic acid was quantified with UV-visible absorbance spectroscopy, conductivity measurements, and inductive coupled plasma mass spectrometry (ICP-MS). Fourier-transform infrared spectroscopy (FTIR) complemented the analyses. Herein, we show that aerogels of bleached CNFs yield a greater release of salicylic acid, compared to CNF obtained from unbleached pulp. The results suggest that biodegradable constructs of CNFs can be loaded with a plant hormone that is released slowly over time, which may find uses in small scale agricultural applications and for the private home market. © 2020 by the authors. 

  • 15.
    Oliaei, Erfan
    et al.
    RISE Research Institutes of Sweden, Bioekonomi och hälsa, Material- och ytdesign. KTH Royal Institute of Technology, Sweden.
    Lindström, Tom
    Stony Brook University, USA.
    Berglund, Lars A.
    KTH Royal Institute of Technology, Sweden.
    Sustainable Development of Hot-Pressed All-Lignocellulose Composites—Comparing Wood Fibers and Nanofibers2021Inngår i: Polymers, E-ISSN 2073-4360, Vol. 13, nr 16, artikkel-id 2747Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Low-porosity materials based on hot-pressed wood fibers or nanocellulose fibrils (no polymer matrix) represent a new concept for eco-friendly materials with interesting mechanical properties. For the replacement of fossil-based materials, physical properties of wood fiber materials need to be improved. In addition, the carbon footprint and cumulative energy required to produce the material also needs to be reduced compared with fossil-based composites, e.g., glass fiber composites. Lignin-containing fibers and nanofibers are of high yield and special interest for development of more sustainable materials technologies. The present mini-review provides a short analysis of the potential. Different extraction routes of lignin-containing wood fibers are discussed, different processing methods, and the properties of resulting fiber materials. Comparisons are made with analogous lignin-containing nanofiber materials, where mechanical properties and eco-indicators are emphasized. Higher lignin content may promote eco-friendly attributes and improve interfiber or interfibril bonding in fiber materials, for improved mechanical performance.

  • 16.
    Petrakli, Fotini
    et al.
    IRES Innovation in Research & Engineering Solutions, Belgium.
    Gkika, Anastasia
    IRES Innovation in Research & Engineering Solutions, Belgium.
    Bonou, Aexandra
    IRES Innovation in Research & Engineering Solutions, Belgium.
    Karayannis, Panagiotis
    IRES Innovation in Research & Engineering Solutions, Belgium.
    Koumoulos, Elias
    IRES Innovation in Research & Engineering Solutions, Belgium; National Technical University of Athens, Greece.
    Semitekolos, Dionisas
    National Technical University of Athens, Greece.
    Trompeta, Aikaterini
    National Technical University of Athens, Greece.
    Rocha, Nuno
    INEGI—Institute of Mechanical Engineering and Industrial Management, Portugal: LAETA Associated Laboratory for Energy, Transports and Aeronautics, Portugal.
    Santos, Raquel
    INEGI—Institute of Mechanical Engineering and Industrial Management, Portugal: LAETA Associated Laboratory for Energy, Transports and Aeronautics, Portugal.
    Simmonds, Guy
    AP&M Anthony, Patrick and Murta Exportacao, Portutgal.
    Monaghan, Glen
    GSG Global Safe Guard Ltd, UK.
    Valota, Giorgio
    Brembo S.p.A, Italy.
    Gong, Guan
    RISE Research Institutes of Sweden, Material och produktion, Polymera material och kompositer.
    Charitidis, Costas
    National Technical University of Athens, Greece.
    End-of-life recycling options of (nano)enhanced CFRP composite prototypes waste-a life cycle perspective2020Inngår i: Polymers, E-ISSN 2073-4360, Vol. 12, nr 9, artikkel-id 2129Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Life cycle assessment is a methodology to assess environmental impacts associated with a product or system/process by accounting resource requirements and emissions over its life cycle. The life cycle consists of four stages: material production, manufacturing, use, and end-of-life. This study highlights the need to conduct life cycle assessment (LCA) early in the new product development process, as a means to assess and evaluate the environmental impacts of (nano)enhanced carbon fibre-reinforced polymer (CFRP) prototypes over their entire life cycle. These prototypes, namely SleekFast sailing boat and handbrake lever, were manufactured by functionalized carbon fibre fabric and modified epoxy resin with multi-walled carbon nanotubes (MWCNTs). The environmental impacts of both have been assessed via LCA with a functional unit of '1 product piece'. Climate change has been selected as the key impact indicator for hotspot identification (kg CO2 eq). Significant focus has been given to the end-of-life phase by assessing different recycling scenarios. In addition, the respective life cycle inventories (LCIs) are provided, enabling the identification of resource hot spots and quantifying the environmental benefits of end-of-life options. © 2020 by the authors.

  • 17.
    Ruwoldt, Jost
    et al.
    RISE Research Institutes of Sweden, Bioekonomi och hälsa, Material- och ytdesign.
    Chinga Carrasco, Gary
    RISE Research Institutes of Sweden, Bioekonomi och hälsa, Material- och ytdesign.
    Opedal, Mihaela Tanase
    RISE Research Institutes of Sweden, Bioekonomi och hälsa, Material- och ytdesign.
    Sustainable Materials from Organosolv Fibers and Lignin, Kraft Fibers, and Their Blends2024Inngår i: Polymers, E-ISSN 2073-4360, Vol. 16, nr 3, artikkel-id 377Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The aim of this study was to investigate new materials from organosolv fibers, organosolv lignin, kraft fibers, and their blends. The organosolv fibers showed reprecipitated lignin on the surface, a comparably low fiber length of 0.565 mm on average, and a high fines content of 82.3%. Handsheets were formed and thermopressed at 175 °C and 50 MPa, yielding dense materials (1050–1100 kg/m3) with properties different to that of regular paper products. The thermopressing of organosolv fibers alone produced materials with similar or better tensile strength (σb = 18.6 MPa) and stiffness (E* = 2.8 GPa) to the softwood Kraft reference pulp (σb = 14.8 MPa, E* = 1.8 GPa). The surface morphology was also smoother with fewer cavities. As a result, the thermopressed organosolv fibers exhibited higher hydrophobicity (contact angle > 95°) and had the lowest overall water uptake. Combinations of Kraft fibers with organosolv fibers or organosolv lignin showed reduced wetting and a higher density than the Kraft fibers alone. Furthermore, the addition of organosolv lignin to Kraft fibers greatly improved tensile stiffness and strength (σb = 23.8 MPa, E* = 10.5 GPa), likely due to the lignin acting as a binder to the fiber network. In conclusion, new thermopressed materials were developed and tested, which show promising potential for sustainable fiber materials with improved water resistance.

    Fulltekst (pdf)
    fulltext
  • 18.
    Shen, Zhiqiang
    et al.
    University of Connecticut, USA.
    Röding, Magnus
    RISE - Research Institutes of Sweden, Biovetenskap och material, Jordbruk och livsmedel. University College London, Australia.
    Kröger, Martin
    ETH Zürich, Switzerland.
    Li, Ying
    University of Connecticut, USA .
    Carbon nanotube length governs the viscoelasticity and permeability of buckypaper2017Inngår i: Polymers, E-ISSN 2073-4360, Vol. 9, nr 4, artikkel-id 115Artikkel i tidsskrift (Fagfellevurdert)
  • 19.
    Stenlund, Patrik
    et al.
    RISE Research Institutes of Sweden, Material och produktion, Metodik för produktframtagning.
    Enstedt, Linnea
    RISE Research Institutes of Sweden, Bioekonomi och hälsa, Kemiska processer och läkemedel.
    Gilljam, Karin
    Regenics AS, Norway.
    Standoft, Simon
    RISE Research Institutes of Sweden, Material och produktion, Kemi, biomaterial och textil.
    Ahlinder, Astrid
    RISE Research Institutes of Sweden, Bioekonomi och hälsa, Jordbruk och livsmedel.
    Lundin Johnson, Maria
    RISE Research Institutes of Sweden.
    Lund, Henrik
    Regenics AS, Norway.
    Millqvist-Fureby, Anna
    RISE Research Institutes of Sweden, Bioekonomi och hälsa, Kemiska processer och läkemedel.
    Berglin, Mattias
    RISE Research Institutes of Sweden, Material och produktion, Metodik för produktframtagning. University of Gothenburg, Sweden.
    Development of an All-Marine 3D Printed Bioactive Hydrogel Dressing for Treatment of Hard-to-Heal Wounds2023Inngår i: Polymers, E-ISSN 2073-4360, Vol. 15, nr 12, artikkel-id 2627Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Current standard wound care involves dressings that provide moisture and protection; however, dressings providing active healing are still scarce and expensive. We aimed to develop an ecologically sustainable 3D printed bioactive hydrogel-based topical wound dressing targeting healing of hard-to-heal wounds, such as chronic or burn wounds, which are low on exudate. To this end, we developed a formulation composed of renewable marine components; purified extract from unfertilized salmon roe (heat-treated X, HTX), alginate from brown seaweed, and nanocellulose from tunicates. HTX is believed to facilitate the wound healing process. The components were successfully formulated into a 3D printable ink that was used to create a hydrogel lattice structure. The 3D printed hydrogel showed a HTX release profile enhancing pro-collagen I alpha 1 production in cell culture with potential of promoting wound closure rates. The dressing has recently been tested on burn wounds in Göttingen minipigs and shows accelerated wound closure and reduced inflammation. This paper describes the dressings development, mechanical properties, bioactivity, and safety. 

  • 20.
    Torres, Elena
    et al.
    AITEX Textile Industry Research Association, Spain.
    Gaona, Aide
    AITEX Textile Industry Research Association, Spain.
    García-Bosch, Nadia
    AITEX Textile Industry Research Association, Spain.
    Muñoz, Miguel
    AITEX Textile Industry Research Association, Spain.
    Fombuena, Vicent
    Universitat Politècnica de València, Spain.
    Moriana Torro, Rosana
    RISE Research Institutes of Sweden, Bioekonomi och hälsa, Material- och ytdesign.
    Vallés-Lluch, Ana
    Universitat Politècnica de València, Spain.
    Improved Mechanical, Thermal, and Hydrophobic Properties of PLA Modified with Alkoxysilanes by Reactive Extrusion Process2021Inngår i: Polymers, E-ISSN 2073-4360, Vol. 13, nr 15, artikkel-id 2475Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An eco-friendly strategy for the modification of polylactic acid (PLA) surface properties, using a solvent-free process, is reported. Reactive extrusion (REX) allowed the formation of new covalent bonds between functional molecules and the PLA polymeric matrix, enhancing its mechanical properties and modifying surface hydrophobicity. To this end, the PLA backbone was modified using two alkoxysilanes, phenyltriethoxysilane and N-octyltriethoxysilane. The reactive extrusion process was carried out under mild conditions, using melting temperatures between 150 and 180 °C, 300 rpm as screw speed, and a feeding rate of 3 kg·h−1. To complete the study, flat tapes of neat and functionalized PLA were obtained through monofilament melt extrusion to quantify the enhancement of mechanical properties and hydrophobicity. The results verified that PLA modified with 3 wt% of N-octyltriethoxysilane improves mechanical and thermal properties, reaching Young’s modulus values of 4.8 GPa, and PLA hydrophobic behavior, with values of water contact angle shifting from 68.6° to 82.2°.

  • 21.
    Vadillo, Julen
    et al.
    BRTA Basque Research and Technology Alliance, Spain.
    Montes, Sarah
    BRTA Basque Research and Technology Alliance, Spain.
    Grande, Hans-JÃŒrgen
    BRTA Basque Research and Technology Alliance, Spain; University of the Basque Country, Spain.
    Verstichel, Steven
    Normec OWS, Belgium.
    Almqvist, Jonna
    RISE Research Institutes of Sweden, Bioekonomi och hälsa, Bioraffinaderi och energi.
    Wrześniewska-Tosik, Krystyna
    Łodz Institute of Technology, Poland.
    Enhanced Biodegradability in Soil of Chicken Feather by Steam Explosion for Potential Application in Agricultural Biodegradable Plastics2023Inngår i: Polymers, E-ISSN 2073-4360, Vol. 15, nr 18, artikkel-id 3701Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Feather waste is a major issue from an economic and environmental point of view. Even though there are already routes for the valorisation of feathers into fertilisers and feather meal, these are considered to have low added value. For more attractive applications, for example in agricultural biodegradable plastics, higher and faster degradability in soil is required. To face this challenge alternative approaches to accelerate biodegradation and disintegration processes are needed. In this context, steam explosion appears as an effective technology to modify the structure of feather and improve its soil degradability. In this work, chicken feathers were treated by steam explosion and the effect of treatment on their structure and physico-chemical and thermal properties were evaluated. Finally, the effect of the process conditions on the disintegration and biodegradation in soil of feathers was also investigated, finding an increased degradation in soil of steam explosion treated feathers. These results open up the possibilities of using feather waste as a component for environmentally friendly agricultural bioplastics that can be degraded in-situ in soil.

  • 22.
    Vita, Silvia
    et al.
    University of Genoa, Italy; Boero Bartolomeo S.p.A., Italy.
    Ricotti, Rico
    Boero Bartolomeo S.p.A., Italy.
    Dodero, Andrea
    University of Genoa, Italy.
    Vicini, Silvia
    University of Genoa, Italy.
    Borchardt, Per
    RISE Research Institutes of Sweden, Material och produktion, Kemi, biomaterial och textil.
    Pinori, Emiliano
    RISE Research Institutes of Sweden, Material och produktion, Kemi, biomaterial och textil.
    Castellano, Maila
    University of Genoa, Italy.
    Rheological, mechanical and morphological characterization of fillers in the nautical field: The role of dispersing agents on composite materials2020Inngår i: Polymers, E-ISSN 2073-4360, Vol. 12, nr 6, artikkel-id 1339Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Coatings have a fundamental role in covering the external surface of yachts by acting both as protective and aesthetic layers. In particular, fillers represent the essential layer from the point of view of mechanical properties and consist of a polymeric matrix, different extenders and additives, and dispersing agents, with the latter having the role to provide good extender-matrix compatibility. In the present work, the effects of dispersing agents with an ionic or steric action on the interactions between hollow glass microspheres and an epoxy-polyamide resin are evaluated. Un-crosslinked filler materials are studied via rheological tests, whereas the mechanical and morphological properties of the crosslinked samples are assessed. The results clearly indicate that steric dispersing agents provide a much greater compatibility effect compared to ionic ones, owing to their steric hindrance capability, thus leading to better-performing filler materials with a less-marked Payne effect, which is here proved to be an efficient tool to provide information concerning the extent of component interactions in nautical fillers. To the best of our knowledge, this work represents the first attempt to deeply understand the role of dispersing agents, which are until now empirically used in the preparation of fillers. © 2020 by the authors.

  • 23.
    Wolter, Nick
    et al.
    University of Bremen, Germany; Fraunhofer, Germany.
    Beber, Vinicius
    Fraunhofer, Germany.
    Sandinge, Anna
    RISE Research Institutes of Sweden, Säkerhet och transport, Brandteknik. DTU Technical University of Denmark, Denmark.
    Blomqvist, Per
    RISE Research Institutes of Sweden, Säkerhet och transport, Brandteknik.
    Goethals, Frederik
    CENTEXBEL, Belgium.
    Van Hove, Marc
    CENTEXBEL, Belgium.
    Jubete, Elena
    CIDETEC, Spain.
    Mayer, Bernd
    University of Bremen, Germany; Fraunhofer, Germany.
    Koschek, Katharina
    University of Bremen, Germany; Fraunhofer, Germany.
    Carbon, glass and basalt fiber reinforced polybenzoxazine: The effects of fiber reinforcement on mechanical, fire, smoke and toxicity properties2020Inngår i: Polymers, E-ISSN 2073-4360, Vol. 12, nr 10, artikkel-id 2379Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Bisphenol F and aniline-based benzoxazine monomers were selected to fabricate basalt, glass and carbon fiber reinforced polybenzoxazine via vacuum infusion, respectively. The impacts of the type of fiber reinforcement on the resulting material properties of the fiber reinforced polymers (FRPs) were studied. FRPs exhibited a homogenous morphology with completely impregnated fibers and near-zero porosity. Carbon fiber reinforced polybenzoxazine showed the highest specific mechanical properties because of its low density and high modulus and strength. However, regarding the flammability, fire, smoke and toxicity properties, glass and basalt reinforced polybenzoxazine outperformed carbon fiber reinforced polybenzoxazine. This work offers a deeper understanding of how different types of fiber reinforcement affect polybenzoxazinebased FRPs and provides access to FRPs with inherently good fire, smoke and toxicity performance without the need for further flame retardant additives. © 2020 by the authors.

  • 24.
    Wu, Da
    et al.
    Chalmers University of Technology, SWeden.
    Larsson, Ragnar
    Chalmers University of Technology, SWeden.
    Rouhi, Mohammad
    RISE - Research Institutes of Sweden, Material och produktion, SICOMP.
    Modeling and Experimental Validation of the VARTM Process for Thin-Walled Preforms.2019Inngår i: Polymers, E-ISSN 2073-4360, Vol. 11, nr 12, artikkel-id E2003Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this paper, recent shell model is advanced towards the calibration and validation of the Vacuum-assisted Resin Transfer Molding (VARTM) process in a novel way. The model solves the nonlinear and strongly coupled resin flow and preform deformation when the 3-D flow and stress problem is simplified to a corresponding 2-D problem. In this way, the computational efficiency is enhanced dramatically, which allows for simulations of the VARTM process of large scale thin-walled structures. The main novelty is that the assumptions of the neglected through-thickness flow and the restricted preform deformation along the normal of preform surface suffice well for the thin-walled VARTM process. The model shows excellent agreement with the VARTM process experiment. With good accuracy and high computational efficiency, the shell model provides an insight into the simulation-based optimization of the VARTM process. It can be applied to either determine locations of the gate and vents or optimize process parameters to reduce the deformation.

  • 25.
    Zarna, Chiara
    et al.
    NTNU, Norway.
    Rodriguez Fabia, Sandra
    RISE Research Institutes of Sweden, Bioekonomi och hälsa, Material- och ytdesign.
    Echtermeyer, Andreas
    NTNU, Norway.
    Chinga-Carrasco, Gary
    RISE Research Institutes of Sweden, Bioekonomi och hälsa, Material- och ytdesign.
    Influence of Compounding Parameters on the Tensile Properties and Fibre Dispersion of Injection-Moulded Polylactic Acid and Thermomechanical Pulp Fibre Biocomposites2022Inngår i: Polymers, E-ISSN 2073-4360, Vol. 14, nr 20, artikkel-id 4432Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Thermomechanical pulp (TMP) fibres can serve as renewable, cost-efficient and lightweight reinforcement for thermoplastic polymers such as poly(lactic acid) (PLA). The reinforcing ability of TMP fibres can be reduced due to various factors, e.g., insufficient dispersion of the fibres in the matrix material, fibre shortening under processing and poor surface interaction between fibres and matrix. A two-level factorial design was created and PLA together with TMP fibres and an industrial and recyclable side stream were processed in a twin-screw microcompounder accordingly. From the obtained biocomposites, dogbone specimens were injection-moulded. These specimens were tensile tested, and the compounding parameters statistically evaluated. Additionally, the analysis included the melt flow index (MFI), a dynamic mechanical analysis (DMA), scanning electron microscopy (SEM) and three-dimensional X-ray micro tomography (X- (Formula presented.) CT). The assessment provided insight into the microstructure that could affect the mechanical performance of the biocomposites. The temperature turned out to be the major influence factor on tensile strength and elongation, while no significant difference was quantified for the tensile modulus. A temperature of 180 °C, screw speed of 50 rpm and compounding time of 1 min turned out to be the optimal settings. © 2022 by the authors.

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