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  • 1.
    Andersson Trojer, Markus
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Materials and Production, IVF.
    Olsson, Carina
    RISE - Research Institutes of Sweden (2017-2019), Materials and Production, IVF.
    Bengtsson, Jenny
    Chalmers University of Technology, Sweden.
    Hedlund, Arthur
    Chalmers University of Technology, Sweden.
    Bordes, Romain
    Chalmers University of Technology, Sweden.
    Directed self-assembly of silica nanoparticles in ionic liquid-spun cellulose fibers.2019In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 553, p. 167-176, article id S0021-9797(19)30648-4Article in journal (Refereed)
    Abstract [en]

    The application range of man-made cellulosic fibers is limited by the absence of cost- and manufacturing-efficient strategies for anisotropic hierarchical functionalization. Overcoming these bottlenecks is therefore pivotal in the pursuit of a future bio-based economy. Here, we demonstrate that colloidal silica nanoparticles (NPs), which are cheap, biocompatible and easy to chemically modify, enable the control of the cross-sectional morphology and surface topography of ionic liquid-spun cellulose fibers. These properties are tailored by the silica NPs' surface chemistry and their entry point during the wet-spinning process (dope solution DSiO2 or coagulation bath CSiO2). For CSiO2-modified fibers, the coagulation mitigator dimethylsulphoxide allows for controlling the surface topography and the amalgamation of the silica NPs into the fiber matrix. For dope-modified fibers, we hypothesize that cellulose chains act as seeds for directed silica NP self-assembly. This results for DSiO2 in discrete micron-sized rods, homogeneously distributed throughout the fiber and for glycidoxy-surface modified DSiO2@GLYEO in nano-sized surface aggregates and a cross-sectional core-shell fiber morphology. Furthermore, the dope-modified fibers display outstanding strength and toughness, which are both characteristic features of biological biocomposites.

  • 2.
    Bengtsson, Andreas
    et al.
    KTH Royal Institute of Technology, Sweden.
    Bengtsson, Jenny
    RISE - Research Institutes of Sweden (2017-2019), Materials and Production, IVF.
    Olsson, Carina
    RISE - Research Institutes of Sweden (2017-2019), Materials and Production, IVF.
    Sedin, Maria
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy, Papermaking and Packaging.
    Jedvert, Kerstin
    RISE - Research Institutes of Sweden (2017-2019), Materials and Production, IVF.
    Theliander, Hans
    Chalmers University of Technology, Sweden.
    Sjöholm, Elisabeth
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy, Biobased Materials.
    Improved yield of carbon fibres from cellulose and kraft lignin2018In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 72, no 12, p. 1007-1016Article in journal (Refereed)
    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.

  • 3.
    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.

  • 4.
    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.

  • 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.
    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)
  • 6.
    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)
  • 7.
    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)
  • 8.
    Idström, Alexander
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Materials and Production, IVF.
    Gentile, Luigi
    Lund University, Sweden.
    Gubitosi, Marta
    Lund University, Sweden.
    Olsson, Carina
    RISE - Research Institutes of Sweden (2017-2019), 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.

  • 9.
    Idström, Alexander
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Materials and Production, IVF.
    Gentile, Luigi
    Lund University, Sweden.
    Gubitosi, Marta
    Lund University, Sweden.
    Olsson, Carina
    RISE - Research Institutes of Sweden (2017-2019), 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 (2017-2019), Materials and Production, IVF.
    Bialik, Erik
    Lund University, Sweden.
    On the dissolution of cellulose in tetrabutylammonium acetate/dimethyl sulfoxide: a frustrated solvent2017In: Cellulose, 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.

  • 10.
    Jönsson, Christin
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Materials and Production, IVF, Energi och miljö.
    Posner, Stefan
    RISE - Research Institutes of Sweden (2017-2019), Materials and Production, IVF, Energi och miljö.
    Olsson, Carina
    RISE - Research Institutes of Sweden (2017-2019), Materials and Production, IVF.
    Köhnke, Tobias
    RISE - Research Institutes of Sweden (2017-2019), Materials and Production, IVF.
    Kristinsdottir, Anna Runa
    RISE - Research Institutes of Sweden (2017-2019), Materials and Production, IVF.
    Strååt, Martin
    RISE - Research Institutes of Sweden (2017-2019), Materials and Production, IVF.
    Schwarz, Lisa
    RISE - Research Institutes of Sweden (2017-2019), Materials and Production, IVF.
    Guo, Zengwei
    RISE - Research Institutes of Sweden (2017-2019), 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

    Download full text (pdf)
    Swerea IVF-rapport 17001 Återvinning av textilier
  • 11.
    Määttänen, Marjo
    et al.
    VTT Technical Research Centre of Finland, Finland.
    Gunnarsson, Maria
    RISE Research Institutes of Sweden, Bioeconomy and Health.
    Wedin, Helena
    RISE Research Institutes of Sweden, Bioeconomy and Health.
    Stibing, Sara
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Olsson, Carina
    RISE Research Institutes of Sweden.
    Köhnke, Tobias
    RISE Research Institutes of Sweden, Materials and Production, Chemistry, Biomaterials and Textiles.
    Asikainen, Sari
    VTT Technical Research Centre of Finland, Finland; Fortum Power and Heat Oy, Finland.
    Vehviläinen, Marianna
    VTT Technical Research Centre of Finland, Finland.
    Harlin, Ali
    VTT Technical Research Centre of Finland, Finland.
    Pre-treatments of pre-consumer cotton-based textile waste for production of textile fibres in the cold NaOH(aq) and cellulose carbamate processes2021In: Cellulose, ISSN 0969-0239, E-ISSN 1572-882X, Vol. 28, p. 3869-3886Article in journal (Refereed)
    Abstract [en]

    Recycling of textiles is of importance due to the large amount of waste generated from  the increasing consumption and use worldwide. Cotton-rich pre-consumer textiles are  considered as potential raw material for production of man-made regenerated fibres, but demands purification from the blends with synthetic fibres as well as the dyes and  finishing chemicals. In this study we explore the use of different pre-treatments of pre-consumer textiles to meet specific parameters for production of fibres in the cold  NaOH(aq) or cellulose carbamate process. The pre-treatments consisted of different  bleaching sequences and were performed on both uncoloured and coloured pre-consumer textiles. For the uncoloured textile, degree of polymerisation and amount of  inorganic content was efficiently reduced making the material suitable for both the cold  NaOH(aq) and the cellulose carbamate process. In case of the coloured textile, the pre-treatments were able to remove the dye and decrease the inorganic content as well as  reduce the degree of polymerisation but only sufficiently enough for production of fibres  in the cellulose carbamate process. The work was able to prove a fibre-to-fibre concept  while further optimisation of the regeneration steps is expected to improve the  mechanical properties of the produced fibres in future studies.

  • 12.
    Olsson, Carina
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Biobaserade fibrer från skog och återvunnen textil2015Conference paper (Other academic)
  • 13.
    Olsson, Carina
    et al.
    RISE, Swerea, IVF.
    Hagström, Bengt
    RISE, Swerea, IVF.
    Sjöholm, Elisabeth
    RISE, Innventia.
    Reimann, Anders
    RISE, Innventia.
    Carbon fibres from lignin-cellulose precursor2015In: 18th International Symposium on Wood, Fiber and Pulping Chemistry, September 9-11, 2015, Vienna, 2015, Vol. Poster, p. 126-129Conference paper (Other academic)
    Abstract [en]

    A series of two-component precursor fibres for carbon fibre production has been produced by air-gap spinning of kraft lignin with cellulose as the fibreforming polymer, the latter from paper grade or dissolving grade pulps. The spun precursor fibres,containing 70% lignin and 30% cellulose, demonstrate mechanical properties equivalent to commercial textile fibres. Precursor fibres based on softwood kraft lignin were treated thermally in twosteps to carbon fibres, which had mechanical properties equal to or greater than those reported for neat lignin-based carbon fibres produced by melt spinning. An advantage of the wet-spun precursor fibres developed in this project is that they are more flexible and easier to handle with a decreased risk ofbrittle fracture. The potential for further improvement for the new type of carbon fibre is very high.

  • 14.
    Olsson, Carina
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Materials and Production, IVF.
    Hagström, Bengt
    RISE - Research Institutes of Sweden (2017-2019), Materials and Production, IVF.
    Sjöholm, Elisabeth
    RISE, Innventia.
    Reimann, Anders
    RISE, Innventia.
    Carbon fibres from lignin-cellulose precursor: Proceedings of the 18th International symposium on Wood2015In: Proceedings of the 18th International symposium onWood, Fiber and Pulping Chemistry, 2015Conference paper (Other academic)
  • 15.
    Olsson, Carina
    et al.
    Chalmers University of Technology, Sweden.
    Hedlund, Artur
    RISE - Research Institutes of Sweden (2017-2019), Materials and Production, IVF.
    Idström, Alexander
    Chalmers University of Technology, Sweden.
    Westman, Gunnar
    Chalmers University of Technology, Sweden.
    Effect of methylimidazole on cellulose/ionic liquid solutions and regenerated material therefrom2014In: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 49, no 9, p. 3423-3433Article in journal (Refereed)
    Abstract [en]

    Cellulose, especially wood-based cellulose, is increasingly important for making everyday materials such as man-made-regenerated textile fibers, produced via dissolution and subsequent precipitation. In this paper, the effect of cosolvents in ionic liquid-facilitated cellulose dissolution is discussed. Both microcrystalline cellulose and dissolving grade hardwood pulp were studied. Three different cosolvents in combination with ionic liquid were evaluated using turbidity measurements and viscosity. The ionic liquid precursor N-methylimidazole proved to be a promising cosolvent candidate and was thus selected for further studies together with the ionic liquid 1-ethyl-3- methylimidazolium acetate. Results show that dissolution rate can be increased by cosolvent addition, and the viscosity can be significantly reduced. The solutions were stable over time at room temperature and could be converted to regenerated textile fibers with good mechanical properties via airgap spinning and traditional wet spinning. Fibers spun from binary solvents exhibited significantly higher crystallinity than the fibers from neat ionic liquid.

  • 16.
    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)
  • 17.
    Olsson, Carina
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Materials and Production, IVF.
    Köhnke, Tobias
    RISE - Research Institutes of Sweden (2017-2019), 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)
  • 18.
    Olsson, Carina
    et al.
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Sjöholm, Elisabeth
    RISE - Research Institutes of Sweden, Bioeconomy.
    Reimann, Anders
    RISE - Research Institutes of Sweden, Bioeconomy.
    Carbon fibres from precursors produced by dry-jet wet-spinning of kraft lignin blended with kraft pulps2017In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 71, no 4, p. 275-283Article in journal (Refereed)
    Abstract [en]

    A part of kraft lignin (KL) can be used as a value-added product without detracting the chemical recovery and the energy balance of the kraft mill. The focus of this study is the production of light-weight carbon fibres (CFS) from KL obtained by the LignoBoost process. For this purpose, crude KL and various cellulose products from kraft pulping of hardwood (HW) and softwood (SW) were dissolved in 1-ethyl-3-methylimidazolium acetate ([EMIm][OAc]) and submitted to dry-jet wet-spun to obtain precursor fibres containing 70% KL and 30% cellulose, which were thermally stabilised and further converted by thermal treatments into CF. The initial and final products were characterised with respect to, e.g. mole mass distribution, thermal properties, tensile strength and tensile modulus determination. The optimised precursor fibres are smooth and flexible with similar mechanical properties as commercial textile fibres. The best CFS made had a tensile strength of 780 MPa and a tensile modulus of 68 GPa and are thus stronger and stiffer than those produced by melt-spinning of SW-based lignins alone. The new CFS based on dry-jet wet-spun precursors still have a high potential for further improvements.

  • 19.
    Östlund, Åsa
    et al.
    Chalmers University of Technology, Sweden.
    Idström, Alexander
    Chalmers University of Technology, Sweden.
    Olsson, Carina
    Chalmers University of Technology, Sweden.
    Larsson, Per Tomas
    RISE, Innventia. KTH Royal Institute of Technology, Sweden.
    Nordstierna, Lars
    Chalmers University of Technology, Sweden.
    Modification of crystallinity and pore size distribution in coagulated cellulose films2013In: Cellulose, ISSN 0969-0239, E-ISSN 1572-882X, Vol. 20, no 4, p. 1657-1667Article in journal (Refereed)
    Abstract [en]

    In this study the effects of altering the coagulation medium during regeneration of cellulose dissolved in the ionic liquid 1-ethyl-3-methylimidazolium acetate, were investigated using solid-state NMR spectroscopy and NMR cryoporometry. In addition, the influence of drying procedure on the structure of regenerated cellulose was studied. Complete conversion of the starting material into regenerated cellulose was seen regardless of the choice of coagulation medium. Coagulation in water predominantly formed cellulose II, whereas coagulation in alcohols mainly generated non-crystalline structures. Subsequent drying of the regenerated cellulose films, induced hornification effects in the form of irreversible aggregation. This was indicated by solid-state NMR as an increase in signal intensity originating from crystalline structures accompanied by a decrease of signal intensity originating from cellulose surfaces. This phenomenon was observed for all used coagulants in this study, but to various degrees with regard to the polarity of the coagulant. From NMR cryoporometry, it was concluded that drying induced hornification generates an increase of nano-sized pores. A bimodal pore size distribution with pore radius maxima of a few nanometers was observed, and this pattern increased as a function of drying. Additionally, cyclic drying and rewetting generated a narrow monomodal pore size pattern. This study implies that the porosity and crystallinity of regenerated cellulose can be manipulated by the choice of drying condition.

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