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  • 1.
    Aaen, Ragnhild
    et al.
    Norwegian University of Science and Technology, Norway.
    Simon, Sebastien
    Norwegian University of Science and Technology, Norway.
    Wernersson Brodin, Fredrik
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Syverud, Kristin
    RISE - Research Institutes of Sweden, Bioeconomy, PFI. Norwegian University of Science and Technology, Norway.
    The potential of TEMPO-oxidized cellulose nanofibrils as rheology modifiers in food systems2019In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 26, no 9, p. 5483-5496Article in journal (Refereed)
    Abstract [en]

    Abstract: Cellulose nanofibrils (CNFs) have been proposed for use in low-fat food products due to their availability and excellent viscosifying and gel forming abilities. As the CNFs are negatively charged, the presence of other components in foods, such as electrolytes and food additives such as xanthan gum is likely to affect their rheological properties. Hence, the study of these interactions can contribute valuable information of the suitability of CNFs as rheology modifiers and fat replacers. Rheological measurements on aqueous dispersions of TEMPO-oxidized CNFs were performed with variations in concentration of CNFs, concentration of electrolytes and with varying CNF/xanthan ratios. UV–Vis Spectroscopy was used to evaluate the onset of CNF flocculation/aggregation in the presence of electrolytes. The CNF dispersions followed a power-law dependency for viscosity and moduli on CNF concentration. Low electrolyte additions strengthened the CNF network by allowing for stronger interactions, while higher additions led to fibril aggregation, and loss of viscosity, especially under shear. The CNF/xanthan ratio, as well as the presence of electrolytes were shown to be key factors in determining whether the viscosity and storage modulus of CNF dispersions increased or decreased when xanthan was added. Graphical abstract: [Figure not available: see fulltext.].

  • 2.
    Alakalhunmaa, Suvi
    et al.
    University of Helsinki, Finland.
    Parikka, Kristi
    University of Helsinki, Finland.
    Penttilä, Paavo A.
    University of Helsinki, Finland.
    Cuberes, M. Teressa
    University of Castilla-La Mancha, Spain.
    Willför, Stefan
    Åbo Akademi University, Finland.
    Salmen, Lennart
    RISE, Innventia.
    Mikkonen, Kristi S.
    University of Helsinki, Finland.
    Softwood-based sponge gels2016In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 23, no 5, p. 3221-3238Article in journal (Refereed)
    Abstract [en]

    Crosslinking-aided gelation was utilized to prepare hydrogels from softwood polysaccharides, with spruce galactoglucomannans (GGM)—a group of largely unexploited hemicelluloses—as the main component, aiming at conversion into sponge-like aerogels. Cellulose nanofibrils were used for the formation of a reinforcing network, which was further crosslinked together with a GGM matrix by ammonium zirconium carbonate, an inorganic salt that is regarded as safe for use in food packaging. The hydrogels were freeze-dried into stiff, low-density aerogels with 98 % of their volume composed of air-filled pores. When immersed in water, the aerogels absorbed water up to 37 times their initial weight, demonstrating elasticity and repeatable and reversible sponge capacity. The developed concept reassembles the wood polysaccharides in a new way, creating interesting possibilities for utilizing the abundant “green gold,” GGM. The obtained biobased materials could find application potential, for example, in the field of food packaging and could contribute in the reduction of the usage of petroleum-based plastics in the future.

  • 3.
    Aldaeus, Fredrik
    et al.
    RISE, Innventia.
    Larsson, Karolina
    RISE, Innventia.
    Stevanic Srndovic, Jasna
    RISE, Innventia.
    Kubat, Mikaela
    RISE, Innventia.
    Karlström, Katarina
    RISE, Innventia.
    Peciulyte, Ausra
    Chalmers University of Technology, Sweden.
    Olsson, Lilsbeth
    Chalmers University of Technology, Sweden.
    Larsson, Per Tomas
    RISE, Innventia.
    The supramolecular structure of cellulose-rich wood pulps can be a determinative factor for enzymatic hydrolysability2015In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 22, no 6, p. 3991-4002Article in journal (Refereed)
    Abstract [en]

    The enzymatic hydrolysability of three industrial pulps, five lab made pulps, and one microcrystalline cellulose powder was assessed using commercial cellulolytic enzymes. To gain insight into the factors that influence the hydrolysability, a thorough characterization of the samples was done, including their chemical properties (cellulose content, hemicellulose content, lignin content, and kappa number), their macromolecular properties (peak molar mass, number-average molar mass, weight-average molar mass, polydispersity, and limiting viscosity) and their supramolecular properties (fibre saturation point, specific surface area, average pore size, and crystallinity). The hydrolysability was assessed by determination of initial conversion rate and final conversion yield, with conversion yield defined as the amount of glucose in solution per unit of glucose in the substrate. Multivariate data analysis revealed that for the investigated samples the conversion of cellulose to glucose was mainly dependent on the supramolecular properties, such as specific surface area and average pore size. The molar mass distribution, the crystallinity, and the lignin content of the pulps had no significant effect on the hydrolysability of the investigated samples.

  • 4. Alexandrescu, L.
    et al.
    Syverud, Kristin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Gatti, A.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Cytotoxicity tests of cellulose nanofibril-based structures2013In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 20Article in journal (Refereed)
  • 5. Aulin, Christian
    et al.
    Gällstedt, Mikael
    RISE, Innventia.
    Lindström, Tom
    RISE, Innventia.
    Oxygen and oil barrier properties of microfibrillated cellulose films and coatings2010In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 17, no 3, p. 559-574Article in journal (Refereed)
    Abstract [en]

    The preparation of carboxymethylated microfibrillated cellulose (MFC) films by dispersion-casting from aqueous dispersions and by surface coating on base papers is described. The oxygen permeability of MFC films were studied at different relative humidity (RH). At low RH (0%), the MFC films showed very low oxygen permeability as compared with films prepared from plasticized starch, whey protein and arabinoxylan and values in the same range as that of conventional synthetic films, e.g., ethylene vinyl alcohol. At higher RH’s, the oxygen permeability increased exponentially, presumably due to the plasticizing and swelling of the carboxymethylated nanofibers by water molecules. The effect of moisture on the barrier and mechanical properties of the films was further studied using water vapor sorption isotherms and by humidity scans in dynamic mechanical analysis. The influences of the degree of nanofibrillation/dispersion on the microstructure and optical properties of the films were evaluated by field-emission scanning electron microscopy (FE-SEM) and light transmittance measurements, respectively. FE-SEM micrographs showed that the MFC films consisted of randomly assembled nanofibers with a thickness of 5-10 nm, although some larger aggregates were also formed. The use of MFC as surface coating on various base papers considerably reduced the air permeability. Environmental scanning electron microscopy (E-SEM) micrographs indicated that the MFC layer reduced sheet porosity, i.e., the dense structure formed by the nanofibers resulted in superior oil barrier properties.

  • 6.
    Bardet, Raphael
    et al.
    Université Grenoble Alpes, France; CNRS, France.
    Reverdy, Charlène
    Université Grenoble Alpes, France; CNRS, France.
    Belgacem, Naceur
    Université Grenoble Alpes, France; CNRS, France.
    Leirset, Ingebjørg
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Syverud, Kristin
    RISE, Innventia, PFI – Paper and Fiber Research Institute. NTNU Norwegian University of Science and Technology, Norway.
    Bardet, Michel
    Université Grenoble Alpes, France; CEA, France.
    Bras, Julien
    Université Grenoble Alpes, France; CNRS, France.
    Substitution of nanoclay in high gas barrier films of cellulose nanofibrils with cellulose nanocrystals and thermal treatment2015In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 22, no 2, p. 1227-1241Article in journal (Refereed)
    Abstract [en]

    The aim of this study is to design a nanocellulose based barrier film. For this purpose, cellulose nanofibrils (CNFs) are used as a matrix to create an entangled nanoporous network that is filled with two different nanofillers: nanoclay (reference), i.e. the mineral montmorillonite (MMT) and the bio-based TEMPO-oxidized cellulose nanocrystal (CNC-T), to produce different types of nanocelluloses and their main physical and chemical features were assessed. As expected, films based on neat CNFs exhibit good mechanical performance and excellent barrier properties at low moisture content. The introduction of 32.5 wt% of either nanofiller results in a significant improvement of barrier properties at high moisture content. Finally, thermal treatment of a dried CNF/CNC-T film results in a decrease of the oxygen permeability even at high moisture content (>70 %). This is mainly attributed to the hornification of nanocellulose. A key result of this study is that the oxygen permeability of an all-nanocellulose film in 85 % relative humidity (RH), is similar to CNF film with mineral nanoclay (MMT), i.e. 2.1 instead of 1.7 cm3 µm m−2 day−1 kPa−1, respectively.

  • 7. Bergenstråhle-Wohlert, M.
    et al.
    Berglund, L.A.
    Brady, J.W.
    Larsson, P.T.
    RISE, Innventia.
    Westlund, P.-O.
    Wohlert, J.
    Concentration enrichment of urea at cellulose surfaces: Results from molecular dynamics simulations and NMR spectroscopy2012In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, no 1, p. 1-12Article in journal (Refereed)
  • 8.
    Bergström, L
    et al.
    YKI – Ytkemiska institutet.
    Stemme, S
    Dahlfors, T
    Arwin, H
    Ödberg, L
    Spectroscopic ellipsometry characterisation and estimation of the Hamaker constant of cellulose1999In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 6, p. 1-13Article in journal (Refereed)
    Abstract [en]

    Calculations of Hamaker constants using Lifshitz theory require the availability of accurate dielectric data, especially in the visible-ultraviolet region. We present spectroscopic ellipsometry data on well defined cellulose films of a limited thickness range (100–140 layers) deposited on an oxidised and hydrophobised silicon substrate. The spectral data, representing measurements from a perpendicular orientation to the fibre deposition direction, was used for estimates of the necessary spectral parameters, i.e. the oscillator strengths and characteristic frequencies in the UV-range. Our calculations show that cellulose has a relatively low Hamaker constant in air (58 zJ) and water (8.0 zJ). The implications for the surface energy estimates of cellulose and colloidal interactions between cellulose and various types of fillers and coating colours were discussed.

  • 9.
    Carlsson, Linn
    et al.
    KTH Royal Institute of Technology, Sweden.
    Ingverud, Tobias
    KTH Royal Institute of Technology, Sweden.
    Blomberg, Hanna
    KTH Royal Institute of Technology, Sweden.
    Carlmark, Anna
    KTH Royal Institute of Technology, Sweden.
    Larsson, Per Tomas
    RISE, Innventia. KTH Royal Institute of Technology, Sweden.
    Malmström, Eva
    KTH Royal Institute of Technology, Sweden.
    Surface characteristics of cellulose nanoparticles grafted by surface-initiated ring-opening polymerization of ε-caprolactone2015In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 22, no 2, p. 1063-1074Article in journal (Refereed)
    Abstract [en]

    In this study, surface-initiated ring-opening polymerization has been employed for the grafting of e-caprolactone from cellulose nanoparticles, made by partial hydrolysis of cellulose cotton linters. A sacrificial initiator was employed during the grafting reactions, to form free polymer in parallel to the grafting reaction. The degree of polymerization of the polymer grafts, and of the free polymer, was varied by varying the reaction time. The aim of this study was to estimate the cellulose nanoparticle degree of surface substitution at different reaction times. This was accomplished by combining measurement results from spectroscopy and chromatography. The prepared cellulose nanoparticles were shown to have 3.1 (±0.3) % of the total anhydroglucose unit content present at the cellulose nanoparticle surfaces. This effectively limits the amount of cellulose that can be targeted by the SI-ROP reactions. For a certain SIROP reaction time, it was assumed that the resulting degree of polymerization (DP) of the grafts and the DP of the free polymer were equal. Based on this assumption it was shown that the cellulose nanoparticle surface degree of substitution remained approximately constant (3–7 %) and seemingly independent of SI-ROP reaction time. We believe this work to be an important step towards a deeper understanding of the processes and properties controlling SI-ROP reactions occurring at cellulose surfaces.

  • 10. Cervin, N.T.
    et al.
    Aulin, C.
    RISE, Innventia.
    Larsson, P.T.
    RISE, Innventia.
    Wågberg, L.
    Ultra porous nanocellulose aerogels as separation medium for mixtures of oil/water liquids2012In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, no 2, p. 401-410Article in journal (Refereed)
  • 11. Cunha, A.G.
    et al.
    Zhou, Q.
    Larsson, P.T.
    RISE, Innventia.
    Berglund, L.A.
    Topochemical acetylation of cellulose nanopaper structures for biocomposites: Mechanisms for reduced water vapour sorption2014In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 21, no 4, p. 2773-2787Article in journal (Refereed)
  • 12.
    Dahlman, Olof
    et al.
    STFI.
    Jacobs, Anna
    STFI.
    Sjöberg, John
    STFI.
    Molecular properties of hemicelluloses located in the surface and inner layers of hardwood and softwood pulps2003In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 10, no 4, p. 325-334Article in journal (Refereed)
  • 13.
    Djafari Petroudy, Seyed Rahman
    et al.
    Shahid Beheshti University, Iran.
    Ghasemian, Ali
    Gorgan University of Agricultural Sciences and Natural Resources, Iran.
    Resalati, Hossein
    Sari University of Agricultural Sciences and Natural Resources, Iran.
    Syverud, Kristin
    RISE, Innventia, PFI – Paper and Fiber Research Institute. NTNU Norwegian University of Science and Technology, Norway.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    The effect of xylan on the fibrillation efficiency of DED bleached soda bagasse pulp and on nanopaper characteristics2015In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 22, no 1, p. 385-395Article in journal (Refereed)
    Abstract [en]

    Xylan is the second most abundant polysaccharide and the most abundant hemicellulose component of soda bagasse pulp. In this study, bleached soda bagasse pulp (SB) and bleached bagasse dissolving pulp (DB) with varying amounts of xylan were fibrillated with a homogenization process. The produced fibrillated materials were used for making nanopaper structures. The surface, physical, mechanical and optical properties of the nanopaper were measured, and the effect of xylan was assessed. Laser profilometry (LP) and field emission scanning electron microscopy were applied to study the degree of the fibrillation. The pulp having the highest xylan content, SB, showed the highest yield of cellulose nanofibrils. Nanopaper produced from SB had a more consolidated structure than that produced from DB. Additionally, SB nanopaper yielded higher tensile strength, lower LP roughness, a higher barrier against oxygen and lower opacity. These results indicate a higher degree of fibrillation of the SB pulp compared to the DB pulp. Hence, the positive effect of xylan for facilitating the fibrillation of the starting pulp fibers was demonstrated.

  • 14.
    Geng, Lihong
    et al.
    South China University of Technology, China; Stony Brook University, USA.
    Peng, Xiangfang
    South China University of Technology, China.
    Zhan, Chengbo
    Stony Brook University, USA.
    Naderi, Ali
    RISE - Research Institutes of Sweden, Bioeconomy. RISE, Innventia.
    Sharma, Priyanka R.
    Stony Brook University, USA.
    Mao, Yimin
    University of Maryland, USA; National Institute of Standards and Technology, USA.
    Hsiao, Benjamin S.
    Stony Brook University, USA.
    Structure characterization of cellulose nanofiber hydrogel as functions of concentration and ionic strength2017In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 24, no 12, p. 5417-5429Article in journal (Refereed)
    Abstract [en]

    Carboxylated cellulose nanofibers (CNFs), having an average width of 7 nm and thickness of 1.5 nm, were produced by TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical)-mediated oxidation method. The fiber cross-sectional dimensions were determined using small-angle X-ray scattering (SAXS), transmission electron microscopy and atomic force microscopy techniques, where the rheological properties under different concentration and ionic strength were also investigated. The formation of hydrogel was evidenced by increasing the CNF concentration or ionic strength of the solvent (water), while the gel structure in ion-induced CNF hydrogels was found to be relatively inhomogeneous. The gelation behavior was closely related to the segmental aggregation of charged CNF, which could be quantitatively characterized by the correlation length (Ο) from the low-angle scattering profile and the scattering invariant (Q) in SAXS.

  • 15. Gonzalez, I
    et al.
    Alcalá, M
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Vilaseca, F
    Boufi, S
    From paper to nanopaper: evolution of mechanical and physical properties2014In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882XArticle in journal (Refereed)
  • 16.
    Halonen, H.
    et al.
    RISE, Innventia.
    Larsson, P.T.
    RISE, Innventia.
    Iversen, T.
    RISE, Innventia.
    Mercerized cellulose biocomposites: A study of influence of mercerization on cellulose supramolecular structure, water retention value and tensile properties2013In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, no 1, p. 57-65Article in journal (Refereed)
  • 17.
    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.].

  • 18.
    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).

  • 19.
    Heggset, Ellinor B
    et al.
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Strand, Berit L.
    NTNU Norwegian University of Science and Technology, Norway.
    Sundby, Kristin W.
    Borregaard, Norway.
    Simon, Sebastien
    NTNU Norwegian University of Science and Technology, Norway.
    Chinga-Carrasco, Gary
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Syverud, Kristin
    RISE - Research Institutes of Sweden, Bioeconomy, PFI. NTNU Norwegian University of Science and Technology, Norway.
    Viscoelastic properties of nanocellulose based inks for 3D printing and mechanical properties of CNF/alginate biocomposite gels2019In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, no 1, p. 581-595Article in journal (Refereed)
    Abstract [en]

    Inks for 3D printing based on cellulose nanofibrils (CNFs) or mixtures of CNFs and either cellulose nanocrystals (CNCs) or alginate were assessed by determining their viscoelastic properties i.e. complex viscosity and storage and loss moduli (G′ and G″). Two types of alginates were used, i.e. from Laminaria hyperborea stipe and Macrocystis pyrifera. Shape fidelity of 3D printed grids were qualitatively evaluated and compared to the viscoelastic properties of the inks. The biocomposite gels containing alginate were post stabilized by crosslinking with Ca2+. Mechanical properties of the crosslinked biocomposite gels were assessed. The complex viscosity, G′ and G″ of CNF suspensions increased when the solid content was increased from 3.5 to 4.0 wt%, but levelled off by further increase in CNF solid content. The complex viscosity at low angular frequency at 4 wt% was as high as 104 Pa·s. This seemed to be the necessary viscosity level for obtaining good shape fidelity of the printed structures for the studied systems. By replacing part of the CNFs with CNCs, the complex viscosity, G′ and G″ were reduced and so was also the shape fidelity of the printed grids. The changes in complex viscosity and moduli when CNFs was replaced with alginate depended on the relative amounts of CNFs/alginate. The type of alginate (from either L. hyp. stipe or M. pyr.) did not play a role for the viscoelastic properties of the inks, nor for the printed grids before post stabilization. Replacing CNFs with up to 1.5 wt% alginate gave satisfactory shape fidelity. The effect of adding alginate and subsequent crosslinking with Ca2+, strongly affected the strength properties of the gels. By appropriate choice of relative amounts of CNFs and alginate and type of alginate, the Young’s modulus and rupture strength could be controlled within the range of 30–150 kPa and 1.5–6 kg, respectively. The deformation at rupture was around 55%. The alginate from L. hyp. stipe yields higher Young’s modulus and lower syneresis compared to M. pyr. This shows that the choice of alginate plays a significant role for the mechanical properties of the final product, although it does not influence on the viscoelastic properties of the ink. The choice of alginate should be L. hyp. stipe if high strength is desired.

  • 20.
    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.

  • 21. Jansson, M.
    et al.
    Danielsson, S.
    RISE, Innventia.
    Saadatmand, S.
    Edlund, U.
    Albertsson, A.-C.
    Upgrading of wood pre-hydrolysis liquor for renewable barrier design: A techno-economic consideration2014In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 21, no 3, p. 2045-2062Article in journal (Refereed)
  • 22. Junka, K.
    et al.
    Filpponen, I.
    Lindström, T.
    RISE, Innventia.
    Laine, J.
    Titrimetric methods for the determination of surface and total charge of functionalized nanofibrillated/microfibrillated cellulose (NFC/MFC)2013In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, no 6, p. 2887-2895Article in journal (Refereed)
  • 23.
    Kaldeus, Tahani
    et al.
    Wallenberg Wood Science Center, Sweden.
    Larsson, Per Tomas
    RISE - Research Institutes of Sweden, Bioeconomy, Biorefinery and Energy.
    Boujemaoui, Assya
    KTH Royal institute of technology, Sweden.
    Malmström, Eva
    KTH Royal institute of technology, Sweden.
    One-pot preparation of bi-functional cellulose nanofibrils2018In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882XArticle in journal (Refereed)
    Abstract [en]

    Herein, we present a route to obtain bi-functional cellulose nanofibrils (CNF) by a one-pot approach using an already established functionalisation route, carboxymethylation, to which a subsequent functionalisation step, allylation or alkynation, has been added in the same reaction pot, eliminating the need of solvent exchange procedures. The total charge of the fibres and the total surface charge of the nanofibrils were determined by conductometric and polyelectrolyte titration, respectively. Furthermore, the allyl and alkyne functionalised cellulose were reacted with methyl 3-mercaptopropionate and azide-functionalised disperse red, respectively, to estimate the degree of functionalisation. The samples were further assessed by XPS and FT-IR. Physical characteristics were evaluated by CP/MAS 13C-NMR, XRD, AFM and DLS. This new approach of obtaining bi-functionalised CNF allows for a facile and rapid functionalisation of CNF where chemical handles can easily be attached and used for further modification of the fibrils. Graphical abstract: [Figure not available: see fulltext.

  • 24.
    Karlsson, Kristina
    et al.
    Chalmers University of Technology, Sweden.
    Kádár, Roland
    Chalmers University of Technology, Sweden.
    Stading, Mats
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Food and Bioscience. Chalmers University of Technology, Sweden.
    Rigdahl, Mikael
    Chalmers University of Technology, Sweden.
    Processing window for extrusion foaming of hydroxypropyl methylcellulose2016In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 23, no 3, p. 1675-1685Article in journal (Refereed)
    Abstract [en]

    Foamed materials are gaining an increased interest due to their good mechanical properties in relation to their low densities and an increased industrial demand can be expected. A few less attractive issues can however be associated with commodity foamed products. For instance the raw-material often originates from non-renewable, fossil-based, sources. Furthermore, degradation in nature is slow, therefor the disposed product is burned or end up in landfills. One possibility to reduce the impact on nature could be to produce foams from natural polymers such as starch or cellulose. In this study the possibility to produce foams from hydroxypropyl methylcellulose (HPMC) with water as blowing agent, by continuous extrusion, was investigated. A pre-study using a capillary viscometer, batch-extruder, was conducted to evaluate the foamability of HPMC. Due to promising results further experiments were conducted with a single-screw extruder. The goal was to find an adequate processing window for foaming. It was concluded that HPMC could successfully be foamed by continuous extrusion, although a careful tailoring of the processing parameters was required. Crucial parameters were here the temperature, pressure and residence time distribution in the extruder. Regions of the extruded foams were examined using optical and scanning electron microscopy and HPMC foams with a density in the range of that of fossil-based polymeric foams could be produced.

  • 25.
    Karlsson, Kristina
    et al.
    Chalmers University of Technology, Sweden.
    Schuster, Erich
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Food and Bioscience, Structure Design.
    Stading, Mats
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Food and Bioscience, Structure Design. Chalmers University of Technology, Sweden.
    Rigdahl, Mikael
    Chalmers University of Technology, Sweden.
    Foaming behavior of water-soluble cellulose derivatives: hydroxypropyl methylcellulose and ethyl hydroxyethyl cellulose2015In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 22, no 4, p. 2651-2664Article in journal (Refereed)
    Abstract [en]

    Hydroxypropyl methylcellulose and ethyl hydroxyethyl cellulose could be interesting candidates for production of lightweight, foamed packaging material originating from non-fossil, renewable resources. The foaming ability of nine different grades of the two cellulose derivatives, using water as the blowing agent, was investigated using a hot-mold process. The foaming process was studied by evaluating the water loss during the heating, both in a real-time experiment and by thermal gravimetric analysis. Further, the development of the rheological properties of the derivative-water mixtures during a simulated foaming process was assessed using dynamical mechanical thermal analysis and viscosity measurements. Five of the studied derivatives showed promising properties for hot-mold foaming and the final foams were characterized with regard to their apparent density. It was concluded that the foamability of these systems seems to require a rather careful tailoring of the viscoelastic properties in relation to the water content in order to ensure that a network structure is built up and expanded during the water evaporation.

  • 26.
    Koppolu, Rajesh
    et al.
    Åbo Akademi University, Finland.
    Abitbol, Tiffany
    RISE - Research Institutes of Sweden, Bioscience and Materials, Surface, Process and Formulation.
    Kumar, Vinay
    Åbo Akademi University, Finland.
    Jaiswal, Aayush K.
    Åbo Akademi University, Finland.
    Swerin, Agne
    RISE - Research Institutes of Sweden, Bioscience and Materials, Surface, Process and Formulation. KTH Royal Institute of Technology, Sweden.
    Toivakka, Martti
    Åbo Akademi University, Finland; VTT Technical Research Center of Finland Ltd, Finland.
    Continuous roll-to-roll coating of cellulose nanocrystals onto paperboard2018In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 25, no 10, p. 6055-6069Article in journal (Refereed)
    Abstract [en]

    There is an increased interest in the use of cellulose nanocrystal (CNC) films and coatings for a range of functional applications in the fields of material science, biomedical engineering, and pharmaceutical sciences. Most of these applications have been demonstrated on films and coatings produced using laboratory-scale batch processes, such as solvent casting, dip coating, or spin coating. For successful coating application of CNC suspensions using a high throughput process, several challenges need to be addressed: relatively high viscosity at low solids content, coating brittleness, and potentially poor adhesion to the substrate. This work aims to address these problems. The impact of plasticizer on suspension rheology, coating adhesion, and barrier properties was quantified, and the effect of different pre-coatings on the wettability and adhesion of CNC coatings to paperboard substrates was explored. CNC suspensions were coated onto pre-coated paperboard in a roll-to-roll process using a custom-built slot die. The addition of sorbitol reduced the brittleness of the CNC coatings, and a thin cationic starch pre-coating improved their adhesion to the paperboard. The final coat weight, dry coating thickness, and coating line speed were varied between 1–11 g/m2, 900 nm–7 µm, and 2.5–10 m/min, respectively. The barrier properties, adhesive strength, coating coverage, and smoothness of the CNC coatings were characterized. SEM images show full coating coverage at coat weights as low as 1.5 g/m2. With sorbitol as plasticizer and at coat weights above 3.5 g/m2, heptane vapor and water vapor transmission rates were reduced by as much as 99% and 75% respectively. Compared to other film casting techniques, the process employed in this work deposits a relatively thick coating in significantly less time, and may therefore pave the way toward various functional applications based on CNCs.

  • 27.
    Kulasinski, Karol
    et al.
    ETH Zurich, Switzerland; Empa Swiss Federal Laboratories for Materials Science and Technology, Switzerland.
    Salmén, Lennart
    RISE, Innventia.
    Derome, Dominique
    Empa Swiss Federal Laboratories for Materials Science and Technology, Switzerland.
    Carmeliet, Jan
    ETH Zurich, Switzerland; Empa Swiss Federal Laboratories for Materials Science and Technology, Switzerland.
    Moisture adsorption of glucomannan and xylan hemicelluloses2016In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 23, no 3, p. 1629-1637Article in journal (Refereed)
    Abstract [en]

    Wood and wood materials are highly sensitive to moisture in the environment. To a large extent this relates to the hygroscopicity of wood hemicelluloses. In order to increase our understanding of the effects of moisture sorption of the major wood hemicelluloses, glucomannan and xylan, model experiments using films of amorphous konjak glucomannan and rye arabinoxylan were conducted. Moisture-induced expansion and stiffness softening were characterized using dynamic mechanical testing. Both hemicelluloses showed a threshold around 5 % of moisture content above which swelling increased whereas the modulus decreased by more than 70 %. FTIR spectra, using H2O and D2O, indicated that even at high RH about 15 % of the hydroxyl groups were not accessible to hydrogen exchange by D2O. For xylan both hydroxyl groups were found to exchange in the same manner while for the glucomannan the O(6)H group seemed to be the most accessible.

  • 28. Laine, J
    et al.
    Stenius, P
    YKI – Ytkemiska institutet.
    Carlsson, G
    Ström, G
    Surface characterization of unbleached kraft pulps by means of ESCA1994In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 1, p. 145-160Article in journal (Refereed)
    Abstract [en]

    The effect of digestion conditions (amount of effective alkali, digestion time) on the surface compositions of unbleached softwood (Pinus sylvestris) kraft pulp has been investigated by ESCA analysis. The quantities monitored were the angular dependence of the total O/C ratio, the relative amounts of carbons in different states of oxidation and the adsorption of Al and Ca ions to the carboxyl groups in the surface. Analysis of the angular dependence of ESCA intensities shows that the concentration of alkyl carbon is high in a very thin surface layer. This enrichment becomes more marked as the lignin content (kappa number) decreases, but it is not affected by extraction of the fibres with dichloromethane. It is concluded that the observed distribution is due to re-precipitation of lignin. In pulp that has not been extracted, there is also strong enrichment of extractives in the surface. This amount increases with increasing effective alkali but is relatively independent of the time of digestion. ESCA analysis of the Al and Ca bound to the carboxyl groups shows that the amount of these depends on digestion time; the results are consistent with the notion that the reprecipitated lignin contains carboxyl groups.

  • 29.
    Larsson, P.T.
    et al.
    RISE, Innventia.
    Svensson, A.
    Wågberg, L.
    A new, robust method for measuring average fibre wall pore sizes in cellulose I rich plant fibre walls2013In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, no 2, p. 623-631Article in journal (Refereed)
  • 30.
    Lindh, Erik
    et al.
    RISE - Research Institutes of Sweden, Bioeconomy. RISE, Innventia. KTH Royal Institute of Technology, Sweden.
    Salmen, Lennart
    RISE - Research Institutes of Sweden, Bioeconomy. RISE, Innventia. KTH Royal Institute of Technology, Sweden.
    Surface accessibility of cellulose fibrils studied by hydrogena€“deuterium exchange with water2017In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 24, no 1, p. 21-33Article in journal (Refereed)
    Abstract [en]

    A problem with cellulose-based materials is that they are highly influenced by moisture, leading to reduced strength properties with increasing moisture content. By achieving a more detailed understanding of the water–cellulose interactions, the usage of cellulose-based materials could be better optimized. Two different exchange processes of cellulose hydroxyl/deuteroxyl groups have been monitored by transmission FT-IR spectroscopy. By using line-shape-assisted deconvolution of the changing intensities, we have been able to follow the exchange kinetics in a very detailed and controlled manner. The findings reveal a hydrogen exchange that mainly is located at two different kinds of fibril surfaces, where the differences arise from the water accessibility of that specific surface. The slowly accessible regions are proposed to be located between the fibrils inside of the aggregates, and the readily accessible regions are suggested to be at the surfaces of the fibril aggregates. It was also possible to identify the ratio of slowly and readily accessible surfaces, which indicated that the average aggregate of cotton cellulose is built up by approximately three fibrils with an assumed average size of 12 × 12 cellulose chains. Additionally, the experimental setup enabled visualizing and discussing the implications of some of the deviating spectral features that are pronounced when recording FT-IR spectra of deuterium-exchanging cellulose: the insufficient red shift of the stretching vibrations and the vastly decreasing line widths.

  • 31.
    Liu, Jun
    et al.
    Åbo Akademi University, Finland.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Cheng, Fang
    Åbo Akademi University, Finland; University of Turku, Finland.
    Xu, Wenyang
    Åbo Akademi University, Finland.
    Willför, Stefan
    Åbo Akademi University, Finland.
    Syverud, Kristin
    RISE, Innventia, PFI – Paper and Fiber Research Institute. NTNU Norwegian University of Science and Technology, Norway.
    Xu, Chunlin
    Åbo Akademi University, Finland.
    Hemicellulose-reinforced nanocellulose hydrogels for wound healing application2016In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 23, no 5, p. 3129-3143Article in journal (Refereed)
    Abstract [en]

    Polysaccharides are finding an increasing number of applications in medical and pharmaceutical fields thanks to their biodegradability, biocompatibility, and in some cases bioactivity. Two approaches were applied to use hemicelluloses as crosslinkers to tune the structural and mechanical properties of nanofibrillated cellulose (NFC) hydrogel scaffolds, and thus to investigate the effect of these properties on the cellular behavior during wound healing application. Different types of hemicellulose (galactoglucomannan (GGM), xyloglucan (XG), and xylan) were introduced into the NFC network via pre-sorption (Method I) and in situ adsorption (Method II) to reinforce the NFC hydrogels. The charge density of the NFC, the incorporated hemicellulose type and amount, and the swelling time of the hydrogels were found to affect the pore structure, the mechanical strength, and thus the cells’ growth on the composite hydrogel scaffolds. The XG showed the highest adsorption capacity on the NFC, the highest reinforcement effect, and facilitated/promoted cell growth. The pre-sorbed XG in the low-charged NFC network with a lower weight ratio (NFC/XG-90:10) showed the highest efficacy in supporting the growth and proliferation of fibroblast cells (NIH 3T3). These all-polysaccharide composite hydrogels may work as promising scaffolds in wound healing applications to provide supporting networks and to promote cells adhesion, growth, and proliferation.

  • 32. Mikkonen, K.S.
    et al.
    Pitkänen, L.
    Liljeström, V.
    Bergström E., Mabasa
    Serimaa, R.
    Salmen, L
    RISE, Innventia.
    Tenkanen, M.
    Arabinoxylan structure affects the reinforcement of films by microfibrillated cellulose2012In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, no 2, p. 467-480Article in journal (Refereed)
  • 33. Mikkonen, K.S.
    et al.
    Stevanic, J.S.
    RISE, Innventia.
    Joly, C.
    Dole, P.
    Pirkkalainen, K.
    Serimaa, R.
    Salmen, L.
    RISE, Innventia.
    Tenkanen, M.
    Composite films from spruce galactoglucomannans with microfibrillated spruce wood cellulose2011In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, no 3, p. 713-726Article in journal (Refereed)
  • 34.
    Molnes, Silje N.
    et al.
    University of Stavanger, Norway; NTNU Norwegian University of Science and Technology, Norway.
    Mamonov, Aleksandr
    University of Stavanger, Norway.
    Paso, Kristofer G.
    NTNU Norwegian University of Science and Technology, Norway.
    Strand, Skule
    University of Stavanger, Norway.
    Syverud, Kristin
    RISE - Research Institutes of Sweden, Bioeconomy, PFI. NTNU Norwegian University of Science and Technology, Norway.
    Investigation of a new application for cellulose nanocrystals: a study of the enhanced oil recovery potential by use of a green additive2018In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 25, no 4, p. 2289-2301Article in journal (Refereed)
    Abstract [en]

    Cellulose nanocrystals (CNC) were investigated for use in a potential new application, enhanced oil recovery. Core flooding experiments were performed on outcrop sandstone cores using CNC particles dispersed in low salinity brine (CNC-LS). Core flooding experiments performed on fully water-saturated cores confirm that a majority of viscosity-generating CNC particles successfully traverse the cores at temperature conditions ranging from 60 to 120 A degrees C. Oil recovery tests performed on crude oil saturated sandstone cores at 60 and 90 A degrees C show that when CNC-LS is applied in tertiary mode, ultimate oil recovery increases. During tertiary CNC-LS injection, CNC particles exacerbate differential pressure fluctuations, a phenomenon attributable to log jamming in pore throats, causing remobilisation of oil trapped within pore space regions. Results from the current work indicate that CNC particles dispersed in low saline brine remain promising for implementation in enhanced oil recovery operations.

  • 35.
    Molnes, Silje N.
    et al.
    NTNU Norwegian University of Science and Technology, Norway; University of Stavanger, Norway.
    Paso, Kristofer G.
    NTNU Norwegian University of Science and Technology, Norway.
    Strand, Skule
    University of Stavanger, Norway.
    Syverud, Kristin
    RISE - Research Institutes of Sweden, Bioeconomy, PFI. NTNU Norwegian University of Science and Technology, Norway.
    The effects of pH, time and temperature on the stability and viscosity of cellulose nanocrystal (CNC) dispersions: implications for use in enhanced oil recovery2017In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 24, no 10, p. 4479-4491Article in journal (Refereed)
    Abstract [en]

    Cellulose nanocrystals (CNC) are currently being investigated as potential additives for enhanced oil recovery (EOR). Presented in this paper is a study investigating the effects of different physical and chemical environments that low concentration CNC dispersions may be subjected to at oil reservoir conditions. Different concentrations of CNC dispersed in de-ionized water and in a 1000 ppm NaCl brine were subjected to variations in pH and temperature, and the results showed that the dispersions remained stable in the pH range expected in oil reservoirs (between 5 and 9). Stable dispersions were also observed when heated to temperatures ranging from 50 to 90 °C. At extended heat aging at 90 and 120 °C for seven days; beginning degradation was observed for both types of CNC dispersions; with viscosity increase and pH decrease as the most important indicators. CNC dispersed in 1000 ppm NaCl brine was generally more heat tolerant than the CNC dispersed in de-ionized water. The increase in viscosity during heat aging can be very interesting for EOR applications. A fluid that increases its viscosity with heat and time will be easier to inject due to a low initial viscosity, and when the viscosity increases in the porous reservoir, the effect can be a stable waterfront and less viscous fingering, which again can lead to increased sweep efficiency and better oil recovery.

  • 36.
    Naderi, A.
    et al.
    RISE, Innventia.
    Lindström, T.
    RISE, Innventia.
    Carboxymethylated nanofibrillated cellulose: Effect of monovalent electrolytes on the rheological properties2014In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, no 3, p. 1561-1571Article in journal (Refereed)
  • 37.
    Naderi, A.
    et al.
    RISE, Innventia.
    Lindström, T.
    RISE, Innventia.
    Pettersson, T.
    The state of carboxymethylated nanofibrils after homogenization-aided dilution from concentrated suspensions: A rheological perspective2014In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 21, no 4, p. 2357-2368Article in journal (Refereed)
  • 38.
    Naderi, A.
    et al.
    RISE, Innventia.
    Lindström, T.
    RISE, Innventia.
    Sundström, J.
    RISE, Innventia.
    Carboxymethylated nanofibrillated cellulose: Rheological studies2014In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 21, no 3, p. 1561-1571Article in journal (Refereed)
  • 39.
    Naderi, Ali
    et al.
    RISE - Research Institutes of Sweden, Bioeconomy. RISE, Innventia.
    Larsson, Per Tomas
    RISE - Research Institutes of Sweden, Bioeconomy. RISE, Innventia.
    Stevanic Srndovic, Jasna
    RISE - Research Institutes of Sweden, Bioeconomy. RISE, Innventia.
    Lindström, Tom
    RISE - Research Institutes of Sweden, Bioeconomy. RISE, Innventia.
    Erlandsson, Johan
    KTH Royal Institute of Technology, Sweden.
    Effect of the size of the charged group on the properties of alkoxylated NFCs2017In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 24, no 3, p. 1307-1317Article in journal (Refereed)
    Abstract [en]

    The impact of the size of the charged group on the properties of alkoxylated NFC was studied by two chloroalkyl acid reagents. It was found that the employment of the larger 2-chloropropionic acid reagent leads to improved properties, e.g. higher fraction of nano-sized materials, and significantly better redispersion as compared to when the smaller monochloroacetic acid was employed. The differences in the impacts of the different reagents were hypothesized to be due to a more efficient disruption of the cohesion between the nanofibrils when a larger charged group was employed. 

  • 40.
    Naderi, Ali
    et al.
    RISE, Innventia.
    Lindström, Tom
    RISE, Innventia.
    Erratum to: Nanofibrillated cellulose: properties reinvestigated2017In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 24, no 12, p. 5713-5713Article in journal (Refereed)
    Abstract [en]

    In the original publication of the article, the co-author name Tom Lindströ¶m was mistakenly missed out. Also the affiliation of the corresponding author was provided incorrectly. It has been updated in this erratum.

  • 41.
    Naderi, Ali
    et al.
    RISE, Innventia.
    Lindström, Tom
    RISE, Innventia.
    Sundström, Jonas
    RISE, Innventia.
    Repeated homogenization, a route for decreasing the energy consumption in the manufacturing process of carboxymethylated nanofibrillated cellulose?2015In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 22, no 2, p. 1147-1157Article in journal (Refereed)
    Abstract [en]

    Energy-efficient manufacturing is a requirement for the large-scale production of nanofibrillated cellulose systems. Today, most strides involve the development of new physicochemical pre-treatment processes or invention of new or further-development of existing mechanical delamination processes; these approaches are often costly. In this communication, it was shown that significant reduction in energy consumption (~30–50 %) of the nanofibrillated cellulose (NFC) manufacturing process is possible by the wise employment of existing machinery and processes—without deterioration of the attractive properties of the NFC product. The suggested approach has further the additional advantage of increasing the yield of nanofibrillation, robustness of the manufacturing process, and increasing the out-put of the process. These notions can lead to significant energy savings in the NFC production. The novel manufacturing protocol involved repeated homogenization of the pulp suspension at low (~400 bar) applied homogenization pressures (as compared to those currently applied, ~1700 bar). It was hypothesized that this manufacturing protocol leads to a more homogeneous and effective shearing of the fibres, than is achievable by one time homogenization of the pulp slurry at high applied pressures. The investigations further showed that there exists an apparent yield of fibrillation (of about 40 %), above which the rheological properties of the NFC systems and the mechanical properties of the resulting NFC films remain unaffected. This observation [which is in accordance to published observations by e.g. Fall (2013)] can be employed to reduce the specific energy consumption in the NFC manufacturing process. Finally, the investigations also showed that the route that is used for dilution of concentrated NFC systems can significantly alter the properties of resulting NFC-films. It was postulated that a protocol based on the severe shearing of the NFC suspension (prior to NFC-film formation), e.g. by high pressure homogenization, can lead to a more homogeneous and better fibrillated system, which in turn might lead to the overestimation of the actual properties of the studied NFC system.

  • 42.
    Naderi, Ali
    et al.
    RISE, Innventia.
    Lindström, Tom
    RISE, Innventia.
    Sundström, Jonas
    RISE, Innventia.
    Pettersson, Torbjörn
    KTH Royal Institute of Technology, Sweden.
    Flodberg, Göran
    RISE, Innventia.
    Erlandsson, Johan
    KTH Royal Institute of Technology, Sweden.
    Microfluidized carboxymethyl cellulose modified pulp: a nanofibrillated cellulose system with some attractive properties2015In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 22, no 2, p. 1159-1173Article in journal (Refereed)
    Abstract [en]

    A method (Ankerfors and Lindström in Method for providing nanocellulose comprising modified cellulose fibers, 2009) was employed to physically attach anionic carboxymethyl cellulose (CMC) chains onto wood pulp, upon which it was fibrillated by a microfluidizer-type homogenizer at high applied pressures and at dilute conditions [<3 % (w/w)]. It was found that the CMC-modified pulp can be fibrillated at the same consistencies as many of the commercially available NFC products. The NFC manufacturing process was also deemed to be energy efficient, as it lacked the need for mechanical pre-treatment, which is often a prerequisite for the production of many existing NFC systems. The CMC-based NFC was studied with respect to the rheological characteristics, and was also characterized using AFM-imaging. Further, The NFC was made into films, and its tensile strength was determined together with its barrier properties. In general, the rheological characteristics (viscosity and storage modulus) together with the tensile strength and oxygen barrier properties of the films were improved with increasing the number of passes through the microfluidizer. The fibrillated CMC-modified pulp was found to be as efficient as other NFC systems when employed as dry strength additive. The employment of the investigated material, which can be produced at acceptable costs and through environmentally benign and industrially relevant processes can, hence, potentially lead to significant future savings in the energy consumption levels in the paper and cardboard manufacturing processes, which have been recognized as major application areas of NFC products.

  • 43. Nilsson, H.
    et al.
    Galland, S.
    Larsson, P.T.
    RISE, Innventia.
    Gamstedt, E.K.
    Iversen, T.
    RISE, Innventia.
    Compression molded wood pulp biocomposites: A study of hemicellulose influence on cellulose supramolecular structure and material properties2012In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, no 3, p. 751-760Article in journal (Refereed)
  • 44. Olszewska, A.
    et al.
    Eronen, P.
    Johansson, L.-S.
    Malho, J.-M.
    Ankerfors, M.
    RISE, Innventia.
    Lindström, T.
    RISE, Innventia.
    Ruokolainen, J.
    Laine, J.
    Österberg, M.
    The behaviour of cationic NanoFibrillar Cellulose in aqueous media2011In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, no 5, p. 1213-1226Article in journal (Refereed)
  • 45.
    Ottesen, Vegar
    et al.
    NTNU, Norway.
    Larsson, Per Tomas
    KTH Royal Institute of Technology,´Sweden.
    Chinga-Carrasco, Gary
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Syverud, Kristin
    RISE - Research Institutes of Sweden, Bioeconomy, PFI. NTNU, Norway.
    Gregersen, Öyvind
    NTNU, Norway.
    Mechanical properties of cellulose nanofibril films: effects of crystallinity and its modification by treatment with liquid anhydrous ammonia2019In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 26, no 11, p. 6615-27Article in journal (Refereed)
    Abstract [en]

    The influence of cellulose crystallinity on mechanical properties of cellulose nano-fibrils (CNF) was investigated. Degree of crystallinity (DoC) was modified using liquid anhydrous ammonia. Such treatment changes crystal allomorph from cellulose I to cellulose III, a change which was reversed by subsequent boiling in water. DoC was measured using solid state nuclear magnetic resonance (NMR). Crystalline index (CI) was also measured using wide angle X-ray scattering (WAXS). Cotton linters were used as the raw material. The cotton linter was ammonia treated prior to fibrillation. Reduced DoC is seen to associate with an increased yield point and decreased Young modulus. Young modulus is here defined as the maximal slope of the stress–strain curves. The association between DoC and Young modulus or DoC and yield point are both statistically significant. We cannot conclude there has been an effect on strainability. While mechanical properties were affected, we found no indication that ammonia treatment affected degree of fibrillation. CNF was also studied in air and liquid using atomic force microscopy (AFM). Swelling of the nanofibers was observed, with a mean diameter increase of 48.9%.

  • 46.
    Peciulyte, Ausra
    et al.
    Chalmers University of Technology, Sweden.
    Kiskis, Juris
    Chalmers University of Technology, Sweden.
    Larsson, Per Tomas
    RISE, Innventia. KTH Royal Institute of Technology, Sweden.
    Olsson, Lisbeth
    Chalmers University of Technology, Sweden.
    Enejder, Annika
    Chalmers University of Technology, Sweden.
    Visualization of structural changes in cellulosic substrates during enzymatic hydrolysis using multimodal nonlinear microscopy2016In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 23, no 3, p. 1521-1536Article in journal (Refereed)
    Abstract [en]

    Enzymatic hydrolysis of cellulose provides a renewable source of monosaccharides for production of variety of biochemicals and biopolymers. Unfortunately, the enzymatic hydrolysis of cellulose is often incomplete, and the reasons are not fully understood. We have monitored enzymatic hydrolysis in terms of molecular density, ordering and autofluorescence of cellulose structures in real time using simultaneous CARS, SHG and MPEF microscopy with the aim of contributing to the understanding and optimization of the enzymatic hydrolysis of cellulose. Three cellulose-rich substrates with different supramolecular structures, pulp fibre, acid-treated pulp fibre and Avicel, were studied at microscopic level. The microscopy studies revealed that before enzymatic hydrolysis Avicel had the greatest carbon-hydrogen density, while pulp fibre and acid-treated fibre had similar density. Monitoring of the substrates during enzymatic hydrolysis revealed the double exponential SHG decay for pulp fibre and acid-treated fibre indicating two phases of the process. Acid-treated fibre was hydrolysed most rapidly and the hydrolysis of pulp fibre was spatially non-uniform leading to fractioning of the particles, while the hydrolysis of Avicel was more than an order of magnitude slower than that of both fibres.

  • 47. Rezayati Charani, P.
    et al.
    Dehghani-Firouzabadi, M.
    Afra, E.
    Blademo, Åsa
    RISE, Innventia.
    Naderi, Ali
    RISE, Innventia.
    Lindström, Tom
    RISE, Innventia.
    Production of microfibrillated cellulose from unbleached kraft pulp of Kenaf and Scotch Pine and its effect on the properties of hardwood kraft:: Microfibrillated cellulose paper2013In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, no 5, p. 2559-2567Article in journal (Refereed)
  • 48. Rodionova, G.
    et al.
    Eriksen, Ø.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Gregersen, Ø.
    TEMPO-oxidized cellulose nanofiber films:: effect of surface morphology on water resistance2012In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 19Article in journal (Refereed)
  • 49. Rodionova, G.
    et al.
    Hoff, B.
    Lenes, M.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Eriksen, Ø.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Gregersen, Ø.
    Gas-phase esterification of microfibrillated cellulose (MFC) films2013In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 20Article in journal (Refereed)
  • 50. Rodionova, G.
    et al.
    Lenes, M.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Eriksen, Ø.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Gregersen, Ø.
    Surface chemical modification of microfibrillated cellulose: improvement of barrier properties for packaging applications2011In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 18Article in journal (Refereed)
12 1 - 50 of 65
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