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  • 1. Alakalhunmaa, S.
    et al.
    Parikka, K.
    Penttilä, P. A.
    Cuberes, M. T.
    Willför, S.
    Salmen, L.
    RISE, Innventia.
    Mikkonen, K. S.
    Softwood-based sponge gels2016In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 23, no 5, 3221-3238 p.Article 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.

  • 2. 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)
  • 3. 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, 559-574 p.Article 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.

  • 4. Bardet, R.
    et al.
    Reverdy, C.
    Belgacem, N.
    Leirset, Ingebjörg
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Syverud, Kristin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Bardet, M.
    Bras, J.
    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, 1227-1241 p.Article 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.

  • 5. 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, 1-12 p.Article in journal (Refereed)
  • 6.
    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, 1-13 p.Article 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.

  • 7. Carlsson, L.
    et al.
    Ingverud, T.
    Blomberg, H.
    Carlmark, A.
    Larsson, Per Tomas
    RISE, Innventia.
    Malmström, E.
    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, 1063-1074 p.Article 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.

  • 8. 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, 401-410 p.Article in journal (Refereed)
  • 9. 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, 2773-2787 p.Article in journal (Refereed)
  • 10. Djafari Petroudy, S.R.
    et al.
    Ghasemian, A.
    Resalati, H.
    Syverud, Kristin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    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, 385-395 p.Article 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.

  • 11.
    Geng, Lihong
    et al.
    South China University of Technology, China ; Stony Brook University, US.
    Peng, Xiangfang
    South China University of Technology, China.
    Zhan, Chengbo
    Stony Brook University, US.
    Naderi, Ali
    RISE, Innventia. RISE - Research Institutes of Sweden, Bioeconomy.
    Sharma, Priyanka R.
    Stony Brook University, US.
    Mao, Yimin
    University of Maryland, US ; National Institute of Standards and Technology, US.
    Hsiao, Benjamin S.
    Stony Brook University, US.
    Structure characterization of cellulose nanofiber hydrogel as functions of concentration and ionic strength2017In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882XArticle 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.

  • 12. 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)
  • 13.
    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, 57-65 p.Article in journal (Refereed)
  • 14.
    Idström, Alexander
    et al.
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Gentile, Luigi
    Lund University, Sweden.
    Gubitosi, Marta
    Lund University, Sweden.
    Olsson, Carina
    RISE - Research Institutes of Sweden, Swerea, Swerea 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, Swerea, Swerea 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, 3645-3657 p.Article 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.

  • 15. 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, 2045-2062 p.Article in journal (Refereed)
  • 16. 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, 2887-2895 p.Article in journal (Refereed)
  • 17.
    Karlsson, K
    et al.
    Department of Materials and Manufacturing Technology, Chalmers University of Technology.
    Kádár, R
    Department of Materials and Manufacturing Technology, Chalmers University of Technology.
    Stading, M
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Food and Bioscience. Department of Materials and Manufacturing Technology, Chalmers University of Technology.
    Rigdahl, M
    Department of Materials and Manufacturing Technology, Chalmers University of Technology.
    Processing window for extrusion foaming of hydroxypropyl methylcellulose2016In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 23, no 3, 1675-1685 p.Article 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. © 2016, Springer Science+Business Media Dordrecht.

  • 18. Kulasinski, K.
    et al.
    Salmenn, Lennart
    RISE, Innventia.
    Derome, D.
    Carmeliet, J.
    Moisture adsorption of glucomannan and xylan hemicelluloses2016In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 23, no 3, 1629-1637 p.Article 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.

  • 19. 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, 145-160 p.Article 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.

  • 20.
    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, 623-631 p.Article in journal (Refereed)
  • 21.
    Lindh, Erik
    et al.
    RISE, Innventia. RISE - Research Institutes of Sweden, Bioeconomy. KTH Royal Institute of Technology, Sweden.
    Salmén, Lennart
    RISE, Innventia. RISE - Research Institutes of Sweden, Bioeconomy. 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, 21-33 p.Article 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.

  • 22. Liu, J.
    et al.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Cheng, F.
    Xu, W.
    Willför, S.
    Syverud, Kristin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Xu, C.
    Hemicellulose-reinforced nanocellulose hydrogels for wound healing application2016In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 23, no 5, 3129-3143 p.Article 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.

  • 23. 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, 467-480 p.Article in journal (Refereed)
  • 24. 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, 713-726 p.Article in journal (Refereed)
  • 25.
    Molnes, Silje N.
    et al.
    Norwegian University of Science and Technology, Norway ; University of Stavanger, Norway.
    Paso, Kristofer G.
    Norwegian University of Science and Technology, Norway.
    Strand, Skule
    University of Stavanger, Norway.
    Syverud, Kristin
    RISE - Research Institutes of Sweden, Bioeconomy, PFI. 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, 4479-4491 p.Article 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.

  • 26.
    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, 1561-1571 p.Article in journal (Refereed)
  • 27.
    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, 2357-2368 p.Article in journal (Refereed)
  • 28.
    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, 1561-1571 p.Article in journal (Refereed)
  • 29.
    Naderi, Ali
    et al.
    RISE, Innventia. RISE - Research Institutes of Sweden, Bioeconomy.
    Larsson, Per Tomas
    RISE, Innventia. RISE - Research Institutes of Sweden, Bioeconomy.
    Stevanic Srndovic, Jasna
    RISE, Innventia. RISE - Research Institutes of Sweden, Bioeconomy.
    Lindström, Tom
    RISE, Innventia. RISE - Research Institutes of Sweden, Bioeconomy.
    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, 1307-1317 p.Article 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. 

  • 30.
    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, 5713-5713 p.Article 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.

  • 31.
    Naderi, Ali
    et al.
    RISE, Innventia.
    Lindström, Tom
    RISE, Innventia.
    Sundström, Jonas
    RISE, Innventia.
    Pettersson, T.
    Flodberg, Göran
    RISE, Innventia.
    Erlandsson, J.
    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, 1159-1173 p.Article 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.

  • 32. 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, 751-760 p.Article in journal (Refereed)
  • 33. 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, 1213-1226 p.Article in journal (Refereed)
  • 34. Peciulyte, A
    et al.
    Kiskis, J
    Larsson, Per Tomas
    RISE, Innventia.
    Olsson, Lars
    RISE, Innventia.
    Enejder, A
    Visualization of structural changes in cellulosic substrates during enzymatic hydrolysis using multimodal nonlinear microscopy2016In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, 1-16 p.Article 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.

  • 35. 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, 2559-2567 p.Article in journal (Refereed)
  • 36. 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)
  • 37. 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)
  • 38. 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)
  • 39. Rodionova, G.
    et al.
    Saito, T.
    Lenes, M.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Eriksen, Ø.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Gregersen, Ø.
    Mechanical and oxygen barrier properties of films prepared from fibrillated dispersions of TEMPO-oxidized Norway spruce and Eucalyptus pulps2012In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 19Article in journal (Refereed)
  • 40.
    Salmén, Lennart
    et al.
    RISE, Innventia.
    Bergström, E.
    RISE, Innventia.
    Cellulose structural arrangement in relation to spectral changes in tensile loading FTIR2009In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 16, no 6, 975-982 p.Article in journal (Refereed)
    Abstract [en]

    In order to utilise wood and wood fibres in advanced materials, a better understanding of the mechanical material characteristics and the interactions among the components is necessary. For this purpose, FTIR was explored together with mechanical loading as a means of studying the molecular responses to the loading of spruce wood and cellulose paper material. A linear shift of absorption bands was detected as the loading was applied. In relation to the applied stress these shifts were higher under moist conditions than under dry ones but they were similar with regard to the strains applied. There were no shifts detected in bands related to lignin or the hemicelluloses. The results are interpreted as reflecting a parallel arrangement of the load bearing component, the cellulose ordered structure, and the moisture accessible regions in the cellulose microfibril structure. This therefore represents an equal strain loaded system.

  • 41. Simonovic, J.
    et al.
    Stevanic, J.
    RISE, Innventia.
    Djikanovic, D.
    Salmen, L.
    RISE, Innventia.
    Radotic, K.
    Anisotropy of cell wall polymers in branches of hardwood and softwood: A polarized FTIR study2011In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, no 6, 1433-1440 p.Article in journal (Refereed)
  • 42. Sjöstedt, Anna
    et al.
    Wohlert, J.
    Larsson, Per Tomas
    RISE, Innventia.
    Wågberg, L.
    Structural changes during swelling of highly charged cellulose fibres2015In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 22, no 5, 2943-2953 p.Article in journal (Refereed)
    Abstract [en]

    Structural changes of fibrils and fibril aggregates in the fibre wall were studied after oxidation of the cellulose by 2,2,6,6-tetramethyl-1-piperidinyloxy to high charge densities (highest charge density: 1300 μeq/g). The increase in pore volume was measured by mini-WRV at two different pH levels, and the supramolecular structure in the fibre wall in terms of aggregate size, specific surface area and average pore size was measured by solid state NMR, DVS desorption and BET N2 gas adsorption. A structural change in the arrangement of the fibrils inside the fibril aggregates was observed although the oxidation did not lead to a complete liberation of individual fibrils, i.e. they still exist as an aggregated structure after oxidation. Theoretical estimates suggest that the electrostatic repulsion energy connected with the increase in surface charge of the fibrils can be sufficient to gradually separate the fibrils enough to expose all fibril surfaces to oxidation chemicals.

  • 43. Srinivasa, P.
    et al.
    Kulachenko, A.
    Aulin, Christian
    RISE, Innventia.
    Experimental characterisation of nanofibrillated cellulose foams2015In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 22, no 6, 3739-3753 p.Article in journal (Refereed)
    Abstract [en]

    There is a growing interest in applications for nanofibrillated cellulose based materials owing to their exceptional mechanical properties. Nanofibrillated cellulose (NFC) foam is one such derivative which has potential applications in a wide array of fields. Here, we characterise the mechanical properties of two particular high porosity NFC foams (98.13 and 98.96 %) prepared by a freeze drying process. We evaluate their behaviour in uni-axial and bi-axial compression with cyclic loading. The secondary loading cycles reveal complete irreversible damage of the microstructure, with the secondary loading path being characterised by near zero plateau stress. In force controlled tests, negligible hysteresis corroborates the idea that there is no energy dissipation owing to near complete microstructural damage. Furthermore, we observe no indications of preferential orientation of the microstructure in these tests. The stress responses in mutually perpendicular directions are seen to be identical, within statistical considerations. We then utilise the “pseudo-elastic” model developed and adopt it to the case of highly compressible Ogden strain energy formulation with a modified neo-Hookean for the unloading, with a view of fitting a continuum hyperelastic model to the experimental data. The material parameters obtained from uni-axial data are seen to be insufficient to describe the more general bi-axial deformation. The parameters obtained from the bi-axial test describe uni-axial deformation up to stretches of ~0.5 but overestimate the stress levels beyond that point.

  • 44.
    Stevanic, Jasna S.
    et al.
    RISE, STFI-Packforsk.
    Salmén, Lennart
    RISE, STFI-Packforsk.
    Characterizing wood polymers in the primary cell wall of Norway spruce (Picea abies (L.) Karst.) using dynamic FT-IR spectroscopy2008In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 15, no 2, 285-295 p.Article in journal (Refereed)
    Abstract [en]

    Dynamic Fourier Transform Infra-Red (FT-IR) spectroscopy was used to examine the interactions among cellulose, xyloglucan, pectin, protein and lignin in the outer fibre wall layers of spruce wood tracheids. Knowledge regarding these interactions is fundamental for understanding the fibre separation in a mechanical pulping process. Sheets made from an enriched primary cell wall material were used for studying the viscoelastic response of the polymers. The results indicated that strong interactions exist among lignin, protein, pectin, xyloglucan and cellulose in the primary cell wall. This signified a closely linked network structure of the components on the fibre surface. This ultrastructural arrangement in the primary cell wall and the relatively high content of lignin, pectin and protein in it, means that the primary cell wall is more submissive to selective chemical attacks, when compared to the secondary cell wall. A low ratio of cellulose Iα to cellulose Iβ in the primary cell wall was also found.

  • 45. Testova, L.
    et al.
    Borrega, M.
    Tolonen, L.K.
    Penttila, P.A.
    Serimaa, R.
    Larsson, P.T.
    RISE, Innventia.
    Sixta, H.
    Dissolving-grade birch pulps produced under various prehydrolysis intensities: Quality, structure and applications2014In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 21, no 3, 2007-2021 p.Article in journal (Refereed)
  • 46.
    Thorvaldsson, Anna
    et al.
    RISE, Swerea, Swerea IVF.
    Edvinsson, P.
    Chalmers University of Technology.
    Glantz, A.
    Chalmers University of Technology.
    Rodriguez, K.
    Chalmers University of Technology.
    Walkenström, Pernilla
    RISE, Swerea, Swerea IVF.
    Gatenholm, P.
    Chalmers University of Technology.
    Superhydrophobic behaviour of plasma modified electrospun cellulose nanofiber-coated microfibers2012In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 19, no 5, 1743-1748 p.Article in journal (Refereed)
    Abstract [en]

    In this work, a method is presented for production of a textile cellulose fiber with non-wetting properties suitable for applications ranging from wound care and tissue engineering to clothing and other textile applications. Non-wettability is achieved by coating a textile cellulose microfiber with electrospun cellulose nanofibers, creating a large and rough surface area that is further plasma treated with fluorine plasma. High surface roughness and efficient deposition of covalently bound fluorine groups results in the fiber exhibiting non-wetting properties with contact angle measurements indicating superhydrophobicity (<150° water contact angle). It is an environmentally friendly method and the flexibility of the electrospinning process allows for careful design of material properties regarding everything from material choice and surface chemistry to fiber morphology and fiber assembly, pointing to the potential of the method and the developed fibers within a wide range of applications. © 2012 Springer Science+Business Media B.V.

  • 47. Xhanari, K.
    et al.
    Syverud, Kristin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Paso, K.
    Stenius, P.
    Reduction of water wettability of nanofibrillated cellulose by adsorption of cationic surfactants2011In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 18Article in journal (Refereed)
  • 48. Zhou, Q
    et al.
    Rutland, MW
    YKI – Ytkemiska institutet.
    Teeri, TT
    Brumer, H
    Xyloglucan in cellulose modification2007In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 14, no 6, 625-641 p.Article in journal (Refereed)
    Abstract [en]

    Xyloglucans are the principal polysaccharides coating and crosslinking cellulose microfibrills in the majority of land plants. This review summarizes current knowledge of xyloglucan structures, solution properties, and the mechanism of interaction of xyloglucans with cellulose. This knowledge base forms the platform for new biomimetic methods of cellulose surface modification with applications within the fields of textile manufacture, papermaking, and materials science. Recent advances using the enzyme xyloglucan endo-transglycosylase (XET, EC 2.4.1.207) to introduce varied chemical functionality onto cellulose surfaces are highlighted.

  • 49. Östlund, A.
    et al.
    Idström, A.
    Olsson, C.
    Larsson, P.T.
    RISE, Innventia.
    Nordstierna, L.
    Modification of crystallinity and pore size distribution in coagulated cellulose films2013In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, no 4, 1657-1667 p.Article in journal (Refereed)
  • 50.
    Östlund, Åsa
    et al.
    Chalmers, Göteborg, Sweden.
    Idström, Alexander
    Chalmers, Göteborg, Sweden.
    Olsson, Carina
    Chalmers, Göteborg, Sweden.
    Larsson, Per Tomas
    RISE, Innventia.
    Nordstierna, Lars
    KTH, Stockholm, Sweden.
    Modification of crystallinity and pore size distribution in coagulated cellulose films2013In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 20, no 4, 1657-1667 p.Article in journal (Refereed)
1 - 50 of 50
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