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  • 1.
    Bengtsson, Jenny
    et al.
    RISE - Research Institutes of Sweden, Bioeconomy, Biobased Materials. Chalmers University of Technology, Sweden.
    Jedvert, Kerstin
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Hedlund, Artur
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Köhnke, Tobias
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Theliander, Hans
    Chalmers University of Technology, Sweden.
    Mass transport and yield during spinning oflignin-cellulose carbon fiber precursors2019In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 73, no 5, p. 509-516Article in journal (Refereed)
    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.

  • 2.
    Bengtsson, Jenny
    et al.
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Jedvert, Kerstin
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Köhnke, Tobias
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Theliander, Hans
    Chalmers University of Technology, Sweden.
    Dry-jet wet-spun lignin-based carbon fibre precursors2018Conference paper (Other academic)
  • 3.
    Bengtsson, Jenny
    et al.
    RISE - Research Institutes of Sweden, Materials and Production, IVF. Chalmers University of Technology, Sweden.
    Jedvert, Kerstin
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Köhnke, Tobias
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Theliander, Hans
    Chalmers University of Technology, Sweden.
    Identifying breach mechanism during air-gap spinning of lignin–cellulose ionic-liquid solutions2019In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, article id 47800Article in journal (Refereed)
    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.

  • 4.
    Bengtsson, Jenny
    et al.
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Jedvert, Kerstin
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Köhnke, Tobias
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Theliander, T
    Coagulation of dry-jet wet-spun lignin-based carbon fibre precursors2018In: Proceedings of the 15th European workshop on lignocellulosics and pulp, 2018, p. 123-126Conference paper (Refereed)
  • 5.
    Bengtsson, Jenny
    et al.
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Olsson, Carina
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Hedlund, Artur
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Köhnke, Tobias
    RISE - Research Institutes of Sweden, Materials and Production, 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/DMSO2017In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 121, no 50, p. 11241-11248Article in journal (Refereed)
    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.

  • 6.
    Bengtsson, Jenny
    et al.
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Olsson, Carina
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Idström, Alexander
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Köhnke, Tobias
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Impact of non-solvents in the tetrabutylammonium acetate: dimethyl sulfoxide-cellulose system2016In: The 7th Workshop on cellulose, regenerated cellulose and cellulose derivatives, 2016, p. 19-22Conference paper (Other academic)
    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.

  • 7.
    Bengtsson, Jenny
    et al.
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Olsson, Carina
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Köhnke, Tobias
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Bialik, Erik
    Lund University, Sweden.
    Elucidating the effect of non-solvents on the TBAAc/DMSO-cellulosesolvent system2017In: Cellulosic material properties and industrial potential: Final meeting in COST FP1205, 2017Conference paper (Other academic)
  • 8.
    Dang, B.T.T.
    et al.
    Chalmers University of Technology.
    Brelid, H.
    Södra Innovation.
    Köhnke, Tobias
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Theliander, H.
    Chalmers University of Technology.
    Impact of ionic strength on delignification and hemicellulose removal during kraft cooking in a small-scale flow-through reactor2013In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 28, no 3Article in journal (Refereed)
    Abstract [en]

    The effect of ionic strength/sodium ion concentration and type of anions on the delignification rate, the retention of xylan and the reactions of hexenuronic acid during kraft cooking has been investigated. A novel, small, flow-through digester was used in the cooking experiments in order to prevent the resorption of lignin and xylan and to maintain a constant concentration of active chemicals throughout the kraft cook. An increase in ionic strength/sodium ion concentration in the cooking liquor decreases the removal rate of both lignin and xylan during kraft cooking. In general, the removal rate of xylan tends to correlate with the delignification rate. However, the present investigation finds that the retention of xylan at a given degree of delignification increases at high ionic strength/sodium ion concentration. The addition of sodium salts of carbonate or chloride to the cooking liquor was shown to increase the rate of formation/degradation reactions of hexenuronic acids and the total amount of uronic acids substituted on the xylan backbone decreases when the concentration of sodium ions increases in the cooking liquor. This promotes a decrease in the dissolution of xylan and consequently an increase in the retention of xylan in the wood residues. The obtained results demonstrate that the xylan content in the fiber wall increases at higher ionic strength/sodium ion concentration, which leads to a slight increase in pulp yield.

  • 9.
    Dang, B.T.T.
    et al.
    Chalmers University of Technology, Sweden.
    Brelid, H.
    Södra Innovation, Sweden.
    Köhnke, Tobias
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Theliander, Hans
    Chalmers University of Technology, Sweden.
    Effect of sodium ion concentration profile during softwood kraft pulping on delignification rate, xylan retention and reactions of hexenuronic acids2014In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 29, no 4, p. 604-611Article in journal (Refereed)
    Abstract [en]

    The objective of this investigation was to study how different concentration profiles of sodium ions influence the delignification rate, hexenuronic acid formation/degradation and xylan retention under kraft cooking conditions. The concentration of sodium ions was varied in time between 0.52 and 3.00 mol/kg solvent, taking two different routes by the controlled addition of sodium carbonate. The reaction rates of hexenuronic acid were found to increase when the sodium ion concentration was at the higher level. Furthermore, the results implied that the kinetics of hexenuronic acid reactions responds rapidly to changes in sodium ion concentration. Delignification and the removal rates of xylan decreased rapidly after the sodium ion concentration was increased. However, when the sodium ion concentration was decreased, the response to the change was delayed. These findings indicate that effects of ionic strength on the rate of delignification and removal of xylan arise as a consequence of changes in solubility and on mass transport phenomena rather than from the rates of chemical reaction. Furthermore, the results suggest that non-dissolved xylan located in the fibre wall matrix may also sorb on cellulose surfaces relatively early on in the cook if the concentration of sodium ions is at high level. © 2014, SPCI. All rights reserved.

  • 10.
    Hedlund, Artur
    et al.
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Hagman, Joel
    RISE, Swerea.
    Köhnke, Tobias
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Theliander, Hans
    RISE, Swerea. Chalmers University of Technology, Sweden.
    Hagström, Bengt
    RISE, Swerea.
    Cosolvent and non-solvent effects on EmimAc-cellulose solutions’ rheology investigated inoscillatory shear and elongation2016In: 6th Avancell conference, 2016Conference paper (Other academic)
  • 11.
    Hedlund, Artur
    et al.
    RISE - Research Institutes of Sweden, Materials and Production, IVF. Chalmers University of Technology, Sweden.
    Köhnke, Tobias
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Hagman, Joel
    Lund University, Sweden.
    Olsson, Ulf
    Lund University, Sweden.
    Theliander, Hans
    Chalmers University of Technology, Sweden; KTH Royal Institute of Technology, Sweden.
    Microstructures of cellulose coagulated in water and alcohols from 1-ethyl-3-methylimidazolium acetate: contrasting coagulation mechanisms2019In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 26, no 3, p. 1545-1563Article in journal (Refereed)
    Abstract [en]

    Abstract: Coagulation of cellulose solutions is a process whereby many useful materials with variable microstructures and properties can be produced. This study investigates the complexity of the phase separation that generates the structural heterogeneity of such materials. The ionic liquid, 1-ethyl-3-methylimidazolium acetate ([C2mim][OAc]), and a co-solvent, dimethylsulfoxide (DMSO), are used to dissolve microcrystalline cellulose in concentrations from 5 to 25 wt%. The solutions are coagulated in water or 2-propanol (2PrOH). The coagulated material is then washed and solvent exchanged (water → 2PrOH → butanone → cyclohexane) in order to preserve the generated microstructures upon subsequent drying before analysis. Sweep electron microscopy images of 50 k magnification reveal open-pore fibrillar structures. The crystalline constituents of those fibrils are estimated using wide-angle X-ray spectroscopy and specific surface area data. It is found that the crystalline order or crystallite size is reduced by an increase in cellulose concentration, by the use of the co-solvent DMSO, or by the use of 2PrOH instead of water as the coagulant. Because previous theories cannot explain these trends, an alternative explanation is presented here focused on solid–liquid versus liquid–liquid phase separations. Graphical abstract: [Figure not available: see fulltext.].

  • 12.
    Hedlund, Artur
    et al.
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Köhnke, Tobias
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Theliander, Hans
    Chalmers University of Technology, Sweden.
    Coagulation of cellulose solutions and controlling properties of regenerated cellulose materials2017In: Cellulosic material Properties and industrial potential: Final meeting in COST FP1205 / [ed] Monica Ek, 2017, p. 64-66Conference paper (Refereed)
  • 13.
    Hedlund, Artur
    et al.
    RISE - Research Institutes of Sweden, Materials and Production, IVF. Chalmers University of Technology, Sweden.
    Köhnke, Tobias
    RISE, Swerea, IVF.
    Theliander, Hans
    Chalmers University of Technology, Sweden.
    Coagulation of cellulose-EmimAc-DMSO solutions studied in order to control properties of wet-spun cellulose fibers2016In: The 7th Workshop on cellulose, regenerated cellulose and cellulose derivatives, 2016, p. 49-52, article id 15Conference paper (Other academic)
  • 14.
    Hedlund, Artur
    et al.
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Köhnke, Tobias
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Theliander, Hans
    Chalmers University of Technology, Sweden.
    Coagulation of EmimAc-cellulose solutions: Dissolution-precipitation disparity and effects of non-solvents and cosolvent2015In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 30, no 1, p. 32-42Article in journal (Refereed)
    Abstract [en]

    Coagulation values (CVs) of cellulose/1-ethyl-3-methylimidazolium acetate (EmimAc)/dimethyl-sulfoxide (DMSO) solutions for water, ethanol (EtOH) and 2-propanol (2-PrOH) were measured by using a light-scattering technique. Expressed in moles per mole, CVs of H2O were roughly twice as high as the CVs of EtOH and 2-PrOH at equal cellulose concentration for EmimAc solutions without the addition of a cosolvent. We explain this observation mainly in terms of alcohol alkyl chains efficiently obstructing EmimAc anions, preventing anions from simultaneously interacting with cellulose hydroxyls. DMSO was found to mitigate the coagulating effect of water and, to a lesser extent, the effect of alcohols. The explanation may be the different enthalpies of mixing for water and alcohols, with DMSO. An explanation on a more practical level, is based on how the solvatochromic α and β parameters change due to small amounts of the different non-solvents. Small additions of methanol induce disproportionately large changes from basic towards acidic properties for DMSO, meanwhile, the same stoichiometric addition of water induces only minor changes. Precipitation occurred at concentrations of non-solvent much higher than the concentrations that limit dissolution. The most likely explanation for this is a metastable region in the phase diagram. It was also seen that the typically observed inhibitive effect of high Mw on solubility during dissolution did not apply to precipitation.

  • 15.
    Hedlund, Artur
    et al.
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Köhnke, Tobias
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Theliander, Hans
    Chalmers.
    Coagulation Values of Cellulose-EmimAc-DMSO solutions and their precipitation-dissolution disparity2014In: Proceedings of the  4th Avancell conference: Creating Value from the Swedish Forest Resources, 2014, p. 15-21Conference paper (Other academic)
  • 16.
    Hedlund, Artur
    et al.
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Köhnke, Tobias
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Theliander, Hans
    RISE - Research Institutes of Sweden, Materials and Production, IVF. Chalmers University of Technology, Sweden.
    Diffusion in Ionic Liquid-Cellulose Solutions during Coagulation in Water: Mass Transport and Coagulation Rate Measurements2017In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 50, no 21, p. 8707-8719Article in journal (Refereed)
    Abstract [en]

    This article describes central features of the mass transport during the coagulation in water of cellulose-1-ethyl-3-methylimidazoium acetate ([C2mim][OAc]) solutions, namely, that the diffusivities are mainly affected by the relative concentrations of water and [C2mim][OAc], that the concentration of cellulose does not affect diffusivities and coagulation rates, that the diffusivities of low-Mw compounds are similar to those in aqueous [C2mim][OAc] solutions without macromolecules, that the polymer concentration is diluted by the large influx of coagulant causing a positive net mass gain, NMG, from diffusive fluxes, and that such NMG, although observed only as a function in time, is also a function in space that has local peaks significantly higher than the mean NMG value. The conclusion from the first three findings was that the diffusion advances through a liquid phase which possesses a continuous pore network and most of the volume. The precipitated cellulose is concentrated into fibrils whose inhibitive effect on the diffusion of small molecules through the surrounding phase is marginal. This key understanding about mass transport during coagulation also simplifies numerical modeling significantly.

  • 17.
    Hedlund, Artur
    et al.
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Köhnke, Tobias
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Theliander, Hans
    Chalmers University.
    Measurements of mass transport during coagulation of cellulose-EmimAc-DMSO solutions2015In: Proceedings of the 4th EPNOE international Polysaccharide Conference, 2015Conference paper (Other academic)
  • 18.
    Hedlund, Artur
    et al.
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Köhnke, Tobias
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Theliander, Hans
    Chalmers University of Technology, Sweden.
    Structure of cellulosematerials coagulated from different EmimAc-DMSO solutions2015Conference paper (Other academic)
  • 19.
    Hedlund, Artur
    et al.
    RISE - Research Institutes of Sweden, Materials and Production, IVF. Chalmers University of Technology, Sweden.
    Theliander, Hans
    Chalmers University of Technology, Sweden.
    Köhnke, Tobias
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Mass transport during coagulation of cellulose-ionic liquid solutions in different non-solvents2019In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882XArticle in journal (Refereed)
    Abstract [en]

    Abstract: Cellulose can be regenerated from cellulose-ionic liquid (IL) solutions by immersion in water or alcohols. These compounds are potent non-solvents due to their proton-donating ability in hydrogen bonds to IL anions. Although they share this fundamental way of reducing IL solvent quality, coagulation in water is distinctly different from coagulation in alcohols with regard to the microstructures formed and the mechanisms that generate the microstructures. In this study, the possibility of mass-transport effects on microstructures was investigated. The mass-transport of all components: non-solvent (EtOH, 2PrOH), IL ([C2mim][OAc]), and a co-solvent (DMSO), during coagulation was studied. The data was compared to previous data with water as the non-solvent. Results showed that diffusion is essentially limited to a continuous non-solvent-rich phase that is formed during phase separation in all non-solvents. There were also significant differences between non-solvents. For instance, [C2mim][OAc] diffusion coefficients were 6–9 times smaller in 2PrOH than in water, and there were apparent effects from cellulose concentration in 2PrOH that were not observed in water. The differences stem from the interactions between solvent, non-solvents, and cellulose, which can be both mutual and competitive. Weaker [C2mim][OAc]-non-solvent interactions with alcohols give more persistent [C2mim][OAc]-cellulose interactions than with water as the non-solvent, which has consequences for mass-transport. Graphic abstract: [Figure not available: see fulltext.]. © 2019, The Author(s).

  • 20.
    Idström, Alexander
    et al.
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Gentile, Luigi
    Lunds Universitet, Sweden.
    Gubitosi, Marta
    Lunds Universitet, Sweden.
    Olsson, Carina
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Stenqvist, Björn
    Lunds Universitet, Sweden.
    Lund, Mikael
    Lunds Universitet, Sweden.
    Bergquist, Karl Erik
    Lunds Universitet, Sweden.
    Olsson, Ulf
    Lunds Universitet, Sweden.
    Köhnke, Tobias
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Wernersson, E.
    Tetrabutylammonium acetate as a solvent for cellulose2017Conference paper (Other academic)
  • 21.
    Idström, Alexander
    et al.
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Gentile, Luigi
    Lund University, Sweden.
    Gubitosi, Marta
    Lund University, Sweden.
    Olsson, Carina
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Stenqvist, Björn
    Lund University, Sweden.
    Lund, Mikael
    Lund University, Sweden.
    Bergquist, Karl Erik
    Lund University, Sweden.
    Olsson, Ulf
    Lund University, Sweden.
    Köhnke, Tobias
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Wernersson, E
    Tetrabutylammonium acetate/dimethyl sulfoxide  as a solvent for cellulose2017Conference paper (Other academic)
  • 22.
    Idström, Alexander
    et al.
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Gentile, Luigi
    Lund University, Sweden.
    Gubitosi, Marta
    Lund University, Sweden.
    Olsson, Carina
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Stenqvist, Björn
    Lund University, Sweden.
    Lund, Mikael
    Lund University, Sweden.
    Bergquist, Karl Erik
    Lund University, Sweden.
    Olsson, Ulf
    Lund University, Sweden.
    Köhnke, Tobias
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Wernersson, E.
    Tetrabutylammonium acetate/dimethyl sulfoxide  as a solvent for cellulose2016Conference paper (Other academic)
  • 23.
    Idström, Alexander
    et al.
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Gentile, Luigi
    Lund University, Sweden.
    Gubitosi, Marta
    Lund University, Sweden.
    Olsson, Carina
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Stenqvist, Björn
    Lund University, Sweden.
    Lund, Mikael
    Lund University, Sweden.
    Bergquist, Karl Erik
    Lund University, Sweden.
    Olsson, Ulf
    Lund University, Sweden.
    Köhnke, Tobias
    RISE, Swerea, IVF.
    Wernersson, Erik
    Lund University, Sweden.
    Dissolution of cellulose in tetrabutylammonium acetate/dimethyl sulfoxide2016In: The 7th Workshop on cellulose, regenerated cellulose and cellulose derivatives, 2016, p. 15-18, article id 1Conference paper (Other academic)
    Abstract [en]

    The dissolution of cellulose in tetrabutylammonium acetate (TBAAc)/dimethyl sulfoxide (DMSO) was studied combining experimental and simulation techniques. It was found that the dissolution limit at 40 °C corresponded to a molar ratio close to one acetate per cellulose anhydroglucose units. MD simulations suggested that the acetate ions bind to cellulose by dual hydrogen bonds. This effectively turns cellulose into a polyelectrolyte, attracting the bulky tetrabutylammonium (TBA+ ) counter ions, which prevent close contact between chains in the dissolved state. This hypothesis was tested by 1 Hand 13C-NMR spectroscopy, which confirmed that acetate forms hydrogen bonds to cellulose, and by diffusion NMR spectroscopy, which demonstrated a strong dynamic correlation between bound acetate and tetrabutylammonium in near-quantitative agreement with simulation. The present results suggest that offering hydrogen bonding to the acetate ions is the main driving force for dissolving cellulose and that the TBA+ counter ions form a diffuse layer around the acetate-decorated cellulose chains.

  • 24.
    Idström, Alexander
    et al.
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Gentile, Luigi
    Lund University, Sweden.
    Gubitosi, Marta
    Lund University, Sweden.
    Olsson, Carina
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Stenqvist, Björn
    Lund University, Sweden.
    Lund, Mikael
    Lund University, Sweden.
    Bergquist, Karl-Erik
    Lund University, Sweden.
    Olsson, Ulf
    Lund University, Sweden.
    Köhnke, Tobias
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Bialik, Erik
    Lund University, Sweden.
    On the dissolution of cellulose in tetrabutylammonium acetate/dimethyl sulfoxide: a frustrated solvent2017In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 24, no 9, p. 3645-3657Article in journal (Refereed)
    Abstract [en]

    We have found that the dissolution of cellulose in the binary mixed solvent tetrabutylammonium acetate/dimethyl sulfoxide follows a previously overlooked near-stoichiometric relationship such that one dissolved acetate ion is able to dissolve an amount of cellulose corresponding to about one glucose residue. The structure and dynamics of the resulting cellulose solutions were investigated using small-angle X-ray scattering (SAXS) and nuclear magnetic resonance techniques as well as molecular dynamics simulation. This yielded a detailed picture of the dissolution mechanism in which acetate ions form hydrogen bonds to cellulose and causes a diffuse solvation sheath of bulky tetrabutylammonium counterions to form. In turn, this leads to a steric repulsion that helps to keep the cellulose chains apart. Structural similarities to previously investigated cellulose solutions in aqueous tetrabutylammonium hydroxide were revealed by SAXS measurement. To what extent this corresponds to similarities in dissolution mechanism is discussed.

  • 25.
    Jedvert, Kerstin
    et al.
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Idström, Alexander
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Köhnke, Tobias
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Alkhagen, Mårten
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Cellulosic nonwovens produced via efficient solution blowing technique2020In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 137, no 5, article id 48339Article in journal (Refereed)
    Abstract [en]

    The demand for nonwoven materials has increased during the last few years and is expected to increase further due to its use in a broad range of new application areas. Today, the majority of nonwovens are from petroleum-based resources but there is a desideratum to develop sustainable and competitive materials from renewable feedstock. In this work, renewable nonwovens are produced by solution blowing of dissolved cellulose using 1-ethyl-3-methylimidazolium acetate (EMIMAc) as solvent. Properties of cellulose solutions and process parameters, such as temperature, flow rate, air pressure, and distance to collector, are evaluated in respect to spinnability and material structural properties. Nonwovens with fiber diameters mainly in the micrometer range were successfully produced and it was shown that high temperature or low flow rate resulted in thinner fibers. The produced materials were stiffer (higher effective stress and lower strain) compared to commercial polypropylene nonwoven. © 2019 The Authors. Journal of Applied Polymer Science published by Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 48339. © 2019 The Authors.

  • 26.
    Jönsson, Christin
    et al.
    RISE - Research Institutes of Sweden, Materials and Production, IVF, Energi och miljö.
    Posner, Stefan
    RISE - Research Institutes of Sweden, Materials and Production, IVF, Energi och miljö.
    Olsson, Carina
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Köhnke, Tobias
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Kristinsdottir, Anna Runa
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Strååt, Martin
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Schwarz, Lisa
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Guo, Zengwei
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Återvinning av textilier: Hur säkerställer man giftfria flöden i relation till textilåtervinning2016Report (Other academic)
    Abstract [sv]

    Huvudsyftet med arbetet var att främja ökad återvinning av textilt spill utan ökad spridning av giftiga ämnen eller minskad kvalitet. Arbetet har till stor del utförts genom fallstudier men även genom myndighetsdialoger, underlag till myndigheter och företag samt initiering av nya relevanta forskningsstudier.Målet i arbetspaket 3 Textil var att ta fram ett kvalificerat underlag för ökad användning av giftfri återvunnen textilråvara genom att studera och beskriva kunskapsläget samt ta fram ny kunskap och driva en aktiv dialog med relevanta aktörer inom fyra fokusområden:1. Spårbarhet2. Minskning av spill3. Teknikutveckling för återvinning av textil4. Återvinning på den svenska marknadenMålet har väl uppfyllts och projektet har bidragit till ökad kunskap om möjligheter för ökad användning av giftfri återvunnen textilråvara. Framförallt har fallstudier genererat detaljerad förståelse för vilka specifika utmaningar som är kopplade till olika textila material och fiberslag.Arbetet har utförts i tät samverkan och dialog med parter från textilbranchen: Boob, Filippa K, Gudrun Sjöden, Fjällräven och WRSD, Swegmarks, Ragnsells, Re:Newcell, samt några av deras leverantörer och flera medlemmar i Kemikaliegruppen på Swerea IVF.Projektet visar att materialspecifik kunskap och teknik är det viktigaste steget mot ökad återvinning av industriella restprodukter. Detta är således en förutsättning för att den sekundära råvaran ska ha ett tillräckligt värde och ändamålsenlig kvalitet. Dessa specifika aspekter kommer att studeras vidare inom efterföljand

  • 27.
    Köhnke, Tobias
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Textile recycling at Swerea IVF, Cradle to Cradle Product Symposium & Innovation Celebration2015Conference paper (Other academic)
  • 28.
    Köhnke, Tobias
    et al.
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Theliander, Hans
    Chalmers University of Technology, Sweden.
    Hedlund, Artur
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Coagulation and structure formation of cellulose from EmimAc- DMSO solutions2015Conference paper (Other academic)
  • 29. Köhnke, Tobias
    et al.
    Theliander, Hans
    Chalmers University of Technology, Sweden.
    Hedlund, Artur
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Investigations into the coagulation of cellulose from EmimAc: DMSO solutions in common protic solvents2015Conference paper (Other academic)
  • 30.
    Nechyporchuk, Oleksandr
    et al.
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Bordes, Romain
    Chalmers University of Technology, Sweden.
    Köhnke, Tobias
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Wet Spinning of Flame-Retardant Cellulosic Fibers Supported by Interfacial Complexation of Cellulose Nanofibrils with Silica Nanoparticles2017In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 9, no 44, p. 39069-39077Article in journal (Refereed)
    Abstract [en]

    The inherent flammability of cellulosic fibers limits their use in some advanced applications. This work demonstrates for the first time the production of flame-retardant macroscopic fibers from wood-derived cellulose nanofibrils (CNF) and silica nanoparticles (SNP). The fibers are made by extrusion of aqueous suspensions of anionic CNF into a coagulation bath of cationic SNP at an acidic pH. As a result, the fibers with a CNF core and a SNP thin shell are produced through interfacial complexation. Silica-modified nanocellulose fibers with a diameter of ca. 15 μm, a titer of ca. 3 dtex and a tenacity of ca. 13 cN tex–1 are shown. The flame retardancy of the fibers is demonstrated, which is attributed to the capacity of SNP to promote char forming and heat insulation on the fiber surface.

  • 31.
    Nechyporchuk, Oleksandr
    et al.
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Håkansson, Karl
    RISE - Research Institutes of Sweden, Bioeconomy, Biorefinery and Energy.
    Gowda.V, Krishne
    KTH Royal Institute of Technology, Sweden.
    Lundell, Fredrik
    KTH Royal Institute of Technology, Sweden.
    Hagström, Bengt
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Köhnke, Tobias
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Continuous Assembly of Cellulose Nanofibrils and Nanocrystals into Strong Macrofibers through Microfluidic Spinning2018In: Advanced Materials Technologies, ISSN 2365-709X, article id 1800557Article in journal (Refereed)
    Abstract [en]

    Microfluidic fiber spinning is a promising technique for assembling cellulose nanomaterials into macroscopic fibers. However, its implementation requires upscalabe fabrication processes while maintaining high strength of the fibers, which could not be previously achieved. Herein, a continuous wet spinning process based on microfluidic flow focusing is developed to produce strong fibers from cellulose nanofibrils (CNFs) and nanocrystals (CNCs). Fibers with an average breaking tenacity as high as 29.5 cN tex−1 and Young's modulus of 1146 cN tex−1 are reported for the first time, produced from nonhighly purified CNF grades. Using the same developed method, wet spinning of fibers from CNCs is achieved for the first time, reaching an average Young's modulus of 1263 cN tex−1 and a breaking tenacity of 10.6 cN tex−1, thus exhibiting strength twice as high as that of common CNC films. A rather similar stiffness of CNC and CNF spun fibers may originate from similar degrees of alignment, as confirmed by wide-angle X-ray scattering (WAXS) and birefringence measurements, whereas lower strength may primarily arise from the shorter length of CNCs compared to that of CNFs. The benefit of CNCs is their higher solids content in the dopes. By combining both CNCs and CNFs, the fiber properties can be tuned.

  • 32.
    Nechyporchuk, Oleksandr
    et al.
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Köhnke, Tobias
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Regenerated Casein-Nanocellulose Composite Fibers via Wet Spinning2019In: ACS Sustainable Chemistry and Engineering, ISSN 2168-0485, Vol. 7, no 1, p. 1419-1426Article in journal (Refereed)
    Abstract [en]

    Development of sustainable biobased fibers is required to displace their fossil-based counterparts, e.g., in textile, nonwoven, or composite applications. Regenerated protein fibers have a potential in this regard if their mechanical properties are improved. Herein, we study for the first time the use of nanocellulose as reinforcement in regenerated protein fibers produced using wet spinning. The influence of cellulose nanocrystals (CNC) incorporated into regenerated casein fibers is examined in terms of mechanical and morphological properties. The influence of different conditions for fiber chemical cross-linking is also investigated. Incorporation of CNC (up to 37.5 wt %) into spin dopes results in a continuous increase of fiber Young's modulus (up to twofold) in the dry state. Both maximum and breaking tenacity of dry fibers are enhanced by CNC, with a maximum at 7.0-10.5 wt % of CNC. When testing after being wetted, both breaking tenacity and Young's modulus of the composite fibers decrease, likely due to weakening of hydrogen bonds between CNC in the presence of water. We also demonstrate that the presence of salt during chemical cross-linking is crucial to produce intact and separated fibers in the yarn.

  • 33.
    Olsson, Carina
    et al.
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Idström, Anna
    University of Helsinki, Finland.
    Bengtsson, Jenny
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Köhnke, Tobias
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Coagulation of cellulose solutions and its effect on material properties2016In: Proceedings of the 14th European workshop on lignocellulosics and pulp, 2016Conference paper (Other academic)
  • 34.
    Olsson, Carina
    et al.
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Köhnke, Tobias
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Idström, Alexander
    RISE, Swerea, IVF. Chalmers University of Technology, Sweden.
    Gentile, Luigi
    Lund University, Sweden.
    Gubitosi, Marta
    Lund University, Sweden.
    Stenqvist, Björn
    Lund University, Sweden.
    Lund, Mikael
    Lund University, Sweden.
    Bergquist, Karl-Erik
    Lund University, Sweden.
    Olsson, Urban
    Lund University, Sweden.
    Wernersson, E.
    Tetrabutylammonium acetate as a solvent for cellulose2016Conference paper (Other academic)
1 - 34 of 34
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