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  • 1.
    Bengtsson, Andreas
    et al.
    KTH Royal Institute of Technology, Sweden.
    Bengtsson, Jenny
    RISE - Research Institutes of Sweden, Material och produktion, IVF.
    Olsson, Carina
    RISE - Research Institutes of Sweden, Material och produktion, IVF.
    Sedin, Maria
    RISE - Research Institutes of Sweden, Bioekonomi, Papperstillverkning och förpackningar.
    Jedvert, Kerstin
    RISE - Research Institutes of Sweden, Material och produktion, IVF.
    Theliander, Hans
    Chalmers University of Technology, Sweden.
    Sjöholm, Elisabeth
    RISE - Research Institutes of Sweden, Bioekonomi, Biobaserade material.
    Improved yield of carbon fibres from cellulose and kraft lignin2018Inngår i: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 72, nr 12, s. 1007-1016Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    To meet the demand for carbon-fibre-reinforced composites in lightweight applications, cost-efficient processing and new raw materials are sought for. Cellulose and kraft lignin are each interesting renewables for this purpose due to their high availability. The molecular order of cellulose is an excellent property, as is the high carbon content of lignin. By co-processing cellulose and lignin, the advantages of these macromolecules are synergistic for producing carbon fibre (CF) of commercial grade in high yields. CFs were prepared from precursor fibres (PFs) made from 70:30 blends of softwood kraft lignin (SW-KL) and cellulose by dry-jet wet spinning with the ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate ([EMIm][OAc]) as a solvent. In focus was the impact of the molecular mass of lignin and the type of cellulose source on the CF yield and properties, while membrane-filtrated kraft lignin and cellulose from dissolving kraft pulp and fully bleached paper-grade SW-KP (kraft pulp) served as sources. Under the investigated conditions, the yield increased from around 22% for CF from neat cellulose to about 40% in the presence of lignin, irrespective of the type of SW-KL. The yield increment was also higher relative to the theoretical one for CF made from blends (69%) compared to those made from neat celluloses (48-51%). No difference in the mechanical properties of the produced CF was observed.

  • 2.
    Bengtsson, Andreas
    et al.
    KTH Royal Institute of Technology, Sweden.
    Bengtsson, Jenny
    RISE - Research Institutes of Sweden, Material och produktion, IVF.
    Sedin, Maria
    RISE - Research Institutes of Sweden, Bioekonomi, Papperstillverkning och förpackningar.
    Sjöholm, Elisabeth
    RISE - Research Institutes of Sweden, Bioekonomi, Biobaserade material.
    Carbon Fibers from Lignin-Cellulose Precursors: Effect of Stabilization Conditions2019Inngår i: ACS Sustainable Chemistry and Engineering, ISSN 2168-0485, Vol. 7, nr 9, s. 8440-8448Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    There is an increasing demand for lightweight composites reinforced with carbon fibers (CFs). Due to its high availability and carbon content, kraft lignin has gained attention as a potential low-cost CF precursor. CFs with promising properties can be made from flexible dry-jet wet spun precursor fibers (PFs) from blends (70:30) of softwood kraft lignin and fully bleached softwood kraft pulp. This study focused on reducing the stabilization time, which is critical in CF manufacturing. The impact of stabilization conditions on chemical structure, yield, and mechanical properties was investigated. It was possible to reduce the oxidative stabilization time of the PFs from about 16 h to less than 2 h, or even omitting the stabilization step, without fusion of fibers. The main reactions involved in the stabilization stage were dehydration and oxidation. The results suggest that the isothermal stabilization at 250 °C override the importance of having a slow heating rate. For CFs with a commercial diameter, stabilization of less than 2 h rendered in tensile modulus 76 GPa and tensile strength 1070 MPa. Impregnation with ammonium dihydrogen phosphate significantly increased the CF yield, from 31-38 to 46-50 wt %, but at the expense of the mechanical properties.

  • 3.
    Bengtsson, Jenny
    et al.
    RISE - Research Institutes of Sweden, Bioekonomi, Biobaserade material. Chalmers University of Technology, Sweden.
    Jedvert, Kerstin
    RISE - Research Institutes of Sweden, Material och produktion, IVF.
    Hedlund, Artur
    RISE - Research Institutes of Sweden, Material och produktion, IVF.
    Köhnke, Tobias
    RISE - Research Institutes of Sweden, Material och produktion, IVF.
    Theliander, Hans
    Chalmers University of Technology, Sweden.
    Mass transport and yield during spinning oflignin-cellulose carbon fiber precursors2019Inngår i: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 73, nr 5, s. 509-516Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Lignin, a substance considered as a residue in biomass and ethanol production, has been identified as a renewable resource suitable for making inexpensive carbon fibers (CFs), which would widen the range of possible applications for light-weight CFs reinforced composites. Wet spinning of lignin-cellulose ionic liquid solutions is a promising method for producing lignin-based CFs precursors. However, wet-spinning solutions containing lignin pose technical challenges that have to be solved to enable industrialization. One of these issues is that a part of the lignin leaches into the coagulation liquid, which reduces yield and might complicate solvent recovery. In this work, the mass transport during coagulation is studied in depth using a model system and trends are confirmed with spinning trials. It was discovered that during coagulation, efflux of ionic liquid is not hindered by lignin concentration in solution and the formed cellulose network will enclose soluble lignin. Consequently, a high total concentration of lignin and cellulose in solution is advantageous to maximize yield. This work provides a fundamental understanding on mass transport during coagulation of lignin-cellulose solutions, crucial information when designing new solution-based fiber forming processes.

  • 4.
    Bengtsson, Jenny
    et al.
    RISE - Research Institutes of Sweden, Material och produktion, IVF. Chalmers University of Technology, Sweden.
    Jedvert, Kerstin
    RISE - Research Institutes of Sweden, Material och produktion, IVF.
    Köhnke, Tobias
    RISE - Research Institutes of Sweden, Material och produktion, IVF.
    Theliander, Hans
    Chalmers University of Technology, Sweden.
    Identifying breach mechanism during air-gap spinning of lignin–cellulose ionic-liquid solutions2019Inngår i: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, artikkel-id 47800Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    To be able to produce highly oriented and strong fibers from polymer solutions, a high elongational rate during the fiber-forming process is necessary. In the air-gap spinning process, a high elongational rate is realized by employing a high draw ratio, the ratio between take-up and extrusion velocity. Air-gap spinning of lignin–cellulose ionic-liquid solutions renders fibers that are promising to use as carbon fiber precursors. To further improve their mechanical properties, the polymer orientation should be maximized. However, achieving high draw ratios is limited by spinning instabilities that occur at high elongational rates. The aim of this experimental study is to understand the link between solution properties and the critical draw ratio during air-gap spinning. A maximum critical draw ratio with respect to temperature is found. Two mechanisms that limit the critical draw ratio are proposed, cohesive breach and draw resonance, the latter identified from high-speed videos. The two mechanisms clearly correlate with different temperature regions. The results from this work are not only of value for future work within the studied system but also for the design of air-gap spinning processes in general. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47800.

  • 5.
    Bengtsson, Jenny
    et al.
    RISE - Research Institutes of Sweden, Material och produktion, IVF.
    Jedvert, Kerstin
    RISE - Research Institutes of Sweden, Material och produktion, IVF.
    Köhnke, Tobias
    RISE - Research Institutes of Sweden, Material och produktion, IVF.
    Theliander, T
    Coagulation of dry-jet wet-spun lignin-based carbon fibre precursors2018Inngår i: Proceedings of the 15th European workshop on lignocellulosics and pulp, 2018, s. 123-126Konferansepaper (Fagfellevurdert)
  • 6.
    Bengtsson, Jenny
    et al.
    RISE - Research Institutes of Sweden, Material och produktion, IVF.
    Olsson, Carina
    RISE - Research Institutes of Sweden, Material och produktion, IVF.
    Hedlund, Artur
    RISE - Research Institutes of Sweden, Material och produktion, IVF.
    Köhnke, Tobias
    RISE - Research Institutes of Sweden, Material och produktion, IVF.
    Bialik, Erik
    Molecules in Motion, Sweden.
    Understanding the Inhibiting Effect of Small-Molecule Hydrogen Bond Donors on the Solubility of Cellulose in Tetrabutylammonium Acetate/DMSO2017Inngår i: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 121, nr 50, s. 11241-11248Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Certain ionic liquids are powerful cellulose solvents, but tend to be less effective when small-molecule hydrogen bond donors are present. This is generally attributed to competition with cellulose for hydrogen bonding opportunities to the anion of the ionic liquid. We show that the solubility of cellulose in dimethyl sulfoxide solutions of tetrabutylammonium acetate is less strongly affected by water than by ethanol on a molar basis, contrary to what can be expected based on hydrogen bond stoichiometry. Molecular dynamics simulations indicate that the higher tolerance to water is due to water-cellulose interactions that improves solvation of cellulose and, thereby, marginally favors dissolution. Through Kirkwood-Buff theory we show that water, but not ethanol, improves the solvent quality of DMSO and partly compensates for the loss of acetate-cellulose hydrogen bonds.

  • 7.
    Bengtsson, Jenny
    et al.
    RISE - Research Institutes of Sweden, Material och produktion, IVF.
    Olsson, Carina
    RISE - Research Institutes of Sweden, Material och produktion, IVF.
    Idström, Alexander
    RISE - Research Institutes of Sweden, Material och produktion, IVF.
    Köhnke, Tobias
    RISE - Research Institutes of Sweden, Material och produktion, IVF.
    Impact of non-solvents in the tetrabutylammonium acetate: dimethyl sulfoxide-cellulose system2016Inngår i: The 7th Workshop on cellulose, regenerated cellulose and cellulose derivatives, 2016, s. 19-22Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    This work examines the potential of tetrabutylammonium acetate: dimethyl sulfoxide (TBAAc:DMSO) as a solvent used in a process for producing man-made cellulose fibers. The tolerance towards nonsolvents is an important step to evaluate the recyclability of the solvent. TBAAc:DMSO was in this work further confirmed to be an efficient solvent for cellulose. Non-solvent tolerance depended on cellulose concentration, TBAAc:DMSO ratio and type of non-solvent. There was no significant change in mechanical properties for filaments regenerated from solutions containing 2 wt% non-solvent compared to those spun from virgin solvent. With 4 wt% ethanol present in solution very brittle filaments were produced, not suitable for use as textile fibers.

  • 8.
    Bengtsson, Jenny
    et al.
    RISE - Research Institutes of Sweden, Material och produktion, IVF.
    Olsson, Carina
    RISE - Research Institutes of Sweden, Material och produktion, IVF.
    Köhnke, Tobias
    RISE - Research Institutes of Sweden, Material och produktion, IVF.
    Bialik, Erik
    Lund University, Sweden.
    Elucidating the effect of non-solvents on the TBAAc/DMSO-cellulosesolvent system2017Inngår i: Cellulosic material properties and industrial potential: Final meeting in COST FP1205, 2017Konferansepaper (Annet vitenskapelig)
  • 9.
    Hiller, Carolina
    et al.
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Energiteknik (ET).
    Dolff, Carolina
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Energiteknik (ET).
    Hasselaar, Evert
    Bengtsson, Jenny
    RISE - Research Institutes of Sweden, Material och produktion, IVF.
    LET’S TALK ABOUT ENERGY. How to communicate energy issues to tenants2014Rapport (Fagfellevurdert)
  • 10.
    Olsson, Carina
    et al.
    RISE - Research Institutes of Sweden, Material och produktion, IVF.
    Idström, Anna
    University of Helsinki, Finland.
    Bengtsson, Jenny
    RISE - Research Institutes of Sweden, Material och produktion, IVF.
    Köhnke, Tobias
    RISE - Research Institutes of Sweden, Material och produktion, IVF.
    Coagulation of cellulose solutions and its effect on material properties2016Inngår i: Proceedings of the 14th European workshop on lignocellulosics and pulp, 2016Konferansepaper (Annet vitenskapelig)
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v. 2.35.9