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  • 51. Gorski, D.
    et al.
    Mörseburg, Kathrin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Axelsson, P.
    Engstrand, P.
    Peroxide-based ATMP refining of Spruce: Energy efficiency, fibre properties and pulp quality2011In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 26, p. 47-63Article in journal (Refereed)
  • 52. Gorski, D.
    et al.
    Mörseburg, Kathrin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Johansson, Lars
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Role of equipment configuration and process chemicals in peroxide-based ATMP refining of spruce2011In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 26, p. 233-247Article in journal (Refereed)
  • 53.
    Gorski, Dmitri
    et al.
    Norske Skog Saugbrugs, Norway.
    Mörseburg, Kathrin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Olson, James
    University of British Columbia, Canada.
    Luukkonen, Antti
    Andritz Inc., USA.
    Fibre and fines quality development in pilot scale high and low consistency refining of ATMP2012In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 27, p. 872-881Article in journal (Refereed)
    Abstract [en]

    The objective of this study was to characterise and compare the development of fibre and fines properties in high consistency (HC) and low consistency (LC) refining of mechanical pulp. Primary refined pulp was produced using the Advanced Thermo-Mechanical Pulp (ATMP) refining process. Pulps were characterized to evaluate external and internal fibrillation, fibre shape and dimensions, surface area of fines and the proportion of split fibres. Based on the results, a different mode of fibre development was proposed for LC and HC refining. The LC refining resulted in a greater reduction in the shives content and R30 Bauer-McNett fibre fraction. The reduced R30 fraction considerably increased the middle fibre fractions; however it showed no further development in terms of surface fibrillation. While HC refining resulted in a significant reduction in fibre wall thickness associated with fibre collapse and increase in external fibrillation, LC refining mainly generated structural changes, seen in fibre straightening and increased flexibility. The HC and LC refined pulps had different property profiles compared at equal handsheet tensile index. The LC refined pulps contained less long fibres and fines but significantly more middle fraction particles. Extensive internal fibrillation of the straighter LC refined fibres appeared to have compensated for lower fines content and external fibrillation, producing well bonded sheets with good tensile strength.

  • 54.
    Gulbrandsen, Torea A.
    et al.
    NTNU Norwegian University of Science and Technology, Norway.
    Johnsen, Ingvild A.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Opedal, Mihaela Tanase
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Toven, Kai
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Øyaas, Karin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Pranovich, Andrey V.
    Åbo Akademi University, Finland.
    Mikkola, Jyri Pekka T.
    Åbo Akademi University, Finland; Umeå University, Sweden.
    Hoff, Bård H.
    NTNU Norwegian University of Science and Technology, Norway.
    Extracting hemicelluloses from softwood and bagasse as oligosaccharides using pure water and microwave heating2015In: Cellulose Chemistry and Technology, ISSN 0576-9787, Vol. 49, no 2, p. 117-126Article in journal (Refereed)
    Abstract [en]

    The objective of the study was to identify conditions for hemicelluloses extraction in oligomeric form. Using microwave assisted hot water extraction (HWE), the effects of both retention time and temperature on hemicelluloses yields, as well as the degree of polymerization (DP) as analyzed by SEC-MALLS, were investigated using both softwood (sawmill shavings) and sugarcane bagasse. The results are discussed in the light of the unavoidable yield-DP compromise resulting from the application of batch mode operations. Nevertheless, significant differences between the two raw materials could be observed, as expected. For softwood shavings, data interpolation indicated that about 50% of the hemicelluloses could be obtained as oligomers at an average DP of 30 when extracted at 183 °C for 5 minutes. For bagasse, longer extraction times seemed optimal. After hot water extraction at 183 °C for 12 minutes, about 62% of the bagasse hemicelluloses were extracted as oligomers at an average DP of about 100.

  • 55. Heggset, Ellinor B
    et al.
    Syverud, Kristin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Øyaas, Karin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Novel pretreatment pathways for dissolution of lignocellulosic biomass based on ionic liquid and low temperature alkaline treatment2016In: Biomass and Bioenergy, ISSN 0961-9534, E-ISSN 1873-2909, Vol. 93, p. 194-200Article in journal (Refereed)
    Abstract [en]

    Pretreatment, fractionation and hydrolysis remains costly and challenging process steps in biochemical conversion of softwoods. Here, ionic liquid pretreatment using 1-ethyl-3-methylimidazolium acetate (EMIM-OAc) at high temperature (100 °C, 6 h) and alkali based (NaOH/urea) pretreatment at sub-zero temperature (−18 °C, 24 h) were compared and combined in studies of Norway Spruce biomass deconstruction. Both treatments significantly improved the enzymatic digestibility of the biomass. EMIM-OAc gave higher glucan than mannan digestibility, indicating a more pronounced effect on the cellulose polymer than on the hemicellulose polymer. In contrast, low temperature alkali pretreatment using NaOH or NaOH + urea gave a more pronounced effect on mannan than on glucan digestibility. By combining the two methods the total monosugar yield after enzymatic hydrolysis was improved by 20–50% as compared to using ionic liquid or alkali based pretreatment alone. Lignin dissolution was low for both methods under the conditions studied.

  • 56. Hii, C
    et al.
    Gregersen, Ø
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Eriksen, Öyvind
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Toven, Kai
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Rosén, Fredrik
    RISE, Innventia.
    Vomhoff, Hannes
    RISE, Innventia.
    Quantification of the web structure in relation to process conditions during wet pressing and furnish composition2011In: / [ed] Hirn, U., 2011, , p. 2Conference paper (Refereed)
  • 57. Hii, C.
    et al.
    Gregersen, Ø.W.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Eriksen, Öyvind
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    The effect of microfibrillated cellulose on the pressability of TMP and filler mixtures and on paper properties2012Conference paper (Refereed)
  • 58.
    Hii, Collin
    et al.
    NTNU Norwegian University of Science and Technology, Norway.
    Gregersen, Øyvind Weiby
    NTNU Norwegian University of Science and Technology, Norway.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Eriksen, Öyvind
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    The effect of MFC on the pressability and paper properties of TMP and GCC based sheets2012In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 27, no 2, p. 388-396Article in journal (Refereed)
    Abstract [en]

    Different qualities of microfibrillated cellulose (MFC) were blended with thermomechanical pulp (TMP) and ground calcium carbonate (GCC) filler. The addition of MFC reduced the drainage of the pulp suspension but improved strength properties. Wet pressing experiments showed that optimal use of MFC and filler could enhance the strength and optical properties without reducing the solids content after wet pressing. Field-emission scanning electron microscopy (FESEM) revealed that MFC adsorbed onto and contributed to the bonding of the filler particles and fibres. The MFC binds the filler-MFC-fines aggregates to the fibre network and partially filled the pore network. As a result, MFC addition increased the air resistance and internal bonding of the sheet.

  • 59.
    Hii, Collin
    et al.
    NTNU Norwegian University of Science and Technology, Norway.
    Gregersen, Øyvind Weiby
    NTNU Norwegian University of Science and Technology, Norway.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Eriksen, Öyvind
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    The effect of Newsprint furnish composition and sheet structure on wet pressing efficiency2012In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 27, no 4, p. 790-797Article in journal (Refereed)
    Abstract [en]

    The dewatering ability and wet sheet structure after pressing was studied using a dynamic wet pressing simulator in combination with electron microscopy and image analysis. Deinked pulp (DIP) that contains 5% ash dewaters more easily than thermo-mechanical pulp (TMP) when pressed with single roll pulse. The in-plane moisture flow (crushing) in DIP samples started at higher peak pressure and higher solids content compared to TMP samples. The TMP sample showed higher springback after wet pressing compared to DIP samples. When both TMP and DIP samples were designed to have a higher amount of small pores at the dewatering side surface layers, the samples with coarser TMP pulp could achieve similar dryness as DIP samples when pressed with higher nip pressure. In addition, the DIP samples with higher number of small pores in the outermost 10 μm thick surface layer in the dewatering side resulted in lower dryness after pressing with a single roll pulse. The effect of filler distribution in paper z-direction on dryness and sheet structure after wet pressing using an 8 milliseconds roll pulse was also studied. In this study the distribution of filler does not affect the maximum achievable dryness (41%) after wet pressing when the total amount of filler in the sheets remains constant, 13.5%. In addition, the samples with more filler in the dewatering layer dewater more easily and yield the maximum achievable dryness (40%) after wet pressing at lower nip pressure (2.5 MPa) when compared to samples made from TMP (36% at 4.4 MPa) and DIP pulps (40% at 4.9 MPa).

  • 60.
    Hii, Collin
    et al.
    NTNU Norwegian University of Science and Technology, Norway.
    Gregersen, Øyvind Weiby
    NTNU Norwegian University of Science and Technology, Norway.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Eriksen, Öyvind
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Toven, Kai
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    The web structure in relation to the furnish composition and shoe press pulse profiles during wet pressing2012In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 27, no 4, p. 798-805Article in journal (Refereed)
    Abstract [en]

    This study shows that wet-pressing TMP and DIP with a shoe press pulse may yield similar after-press solids, provided that an adequate shoe pulse length with similar pressure profile is applied. A wet web with more porous structure in the sheet dewatering (felt) layer seems to contribute to the increased dewatering during wet pressing. In addition, a shoe press pulse with high peak pressure at the end yields higher solids content after wet-pressing and higher bulk compared to a pulse with a peak pressure in the beginning. The increased dewatering during wet-pressing implies a reduction of steam consumption in the dryer.

  • 61.
    Iotti, M.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Klimatre: Wood for a better climate and higher value-added products2011Conference paper (Refereed)
  • 62.
    Iotti, M.
    et al.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Lenes, M.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Gregersen, Ø.
    Rheological studies of nanofibrillar cellulose water dispersions for industrial applications2011Conference paper (Refereed)
  • 63.
    Janga, Kando K.
    et al.
    NTNU Norwegian University of Science and Technology, Norway.
    Öyaas, Karin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Hertzberg, Terje
    NTNU Norwegian University of Science and Technology, Norway.
    Moe, Stærker T.
    NTNU Norwegian University of Science and Technology, Norway.
    Application of a pseudo-kinetic generalized severity model to the concentrated sulfuric acid hydrolysis of pinewood and aspenwood2012In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 7, p. 2728-2741Article in journal (Refereed)
    Abstract [en]

    The yield of monosaccharides after two-stage concentrated sulfuric acid hydrolysis of softwood (Scots pine) and hardwood (trembling aspen) was modeled using a generalized severity parameter with a time-independent rate constant. The severity parameter, which combines the major operating variables acid concentration, temperature, and reaction time in the decrystallization stage into a single reaction ordinate, was successfully used to describe monosaccharide yields after a standardized hydrolysis stage. Conversion of cellulose to glucose demanded a higher severity to reach maximum glucose yields than the conversion of hemicelluloses to their respective monosaccharides, and the conversion of pine demanded a higher severity to obtain maximum monosaccharide yields as compared to aspen. The results indicate that the generalized severity parameter can be a useful tool for the prediction of sugar yields in a two-stage concentrated sulfuric acid hydrolysis process.

  • 64.
    Johansson, Lars
    et al.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Hill, J.
    Gorski, D.
    Axelsson, P.
    Improvement of energy efficiency in TMP refining by selective wood disintegration and targeted application of chemicals2011In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 26, p. 31-46Article in journal (Refereed)
  • 65.
    Josefsson, Gabriella
    et al.
    Uppsala University, Sweden.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Gamstedt, E. Kristofer
    Uppsala University, Sweden.
    Elastic models coupling the cellulose nanofibril to the macroscopic film level2015In: RSC Advances, E-ISSN 2046-2069, Vol. 5, no 71, p. 58091-58099Article in journal (Refereed)
    Abstract [en]

    The mechanical behaviour of cellulose nanofibrils is typically characterized by casting thin films and performing tensile tests on strips cut from these films. When comparing the stiffness of different films, the stiffness of the nanofibrils is only qualitatively and indirectly compared. This study provides some schemes based on various models of fibre networks, or laminated films, which can be used to assess the inherent stiffness of the nanofibrils from the stiffness of the films. Films of cellulose nanofibrils from different raw materials were manufactured and the elastic properties were measured. The expressions relating the nanofibril stiffness and the film stiffness were compared for the presented models. A model based on classical laminate theory showed the best balance between simplicity and adequacy of the underlying assumptions among the presented models. Using this model, the contributing nanofibril stiffness was found to range from 20 to 27 GPa. The nanofibril stiffness was also calculated from mechanical properties of nanofibril films found in the literature and compared with measurements from independent test methods of nanofibril stiffness. All stiffness values were found to be comparable and within the same order of magnitude.

  • 66. Kaombe, D.D.
    et al.
    Lenes, M.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Toven, K.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Hägg, M.-B.
    Glomm, W. R.
    Turbiscan as a tool for studying phase separation tendency of pyrolysis oil2012Conference paper (Refereed)
  • 67.
    Kaombe, Divina D.
    et al.
    NTNU Norwegian University of Science and Technology, Norway.
    Lenes, Marianne
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Toven, Kai
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Glomm, Wilhelm Robert
    NTNU Norwegian University of Science and Technology, Norway.
    Turbiscan as a tool for studying the phase separation tendency of pyrolysis oil2013In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 27, no 3, p. 1446-1452Article in journal (Refereed)
    Abstract [en]

    One of the main obstacles in using pyrolysis oils in heat and power applications is their instability upon storage, which leads to unacceptable quality, from the end user's point of view. Because of the opaque nature of pyrolysis oils, there are presently many challenges associated with determining their stability. Thus, techniques are needed for the characterization of the phase separation of pyrolysis oils, as well as determining the underlying mechanisms of their instability. Here, we present the application of the Turbiscan technique for the evaluation of phase separation tendency of pyrolysis oils over a period of 24 h at various temperatures, compared to the Karl Fischer method. A well-stored pyrolysis oil from poplar wood and fresh pyrolysis oil from forest residue were used for the investigation. For each of the oils, one batch was diluted with water in order to force phase separation, and a second batch was used without dilution. The study reveals that the Turbiscan technique makes it possible to study several aspects of phase separation in a single experiment; such as sedimentation, clarification, migration velocity and phase fraction. The advantages and potential limitation of the Turbiscan technique are discussed.

  • 68.
    Larsson, Per Tomas
    et al.
    RISE, Innventia.
    Syverud, Kristin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Wohlert, Jakob
    KTH Royal Institute of Technology, Sweden.
    Bergenstråhle, Malin
    KTH Royal Institute of Technology, Sweden.
    Changes in the supra-molecular structure of cellulose I during TEMPO-oxidation: bringing together NMR, MD and XRD results2016In: The 7th Workshop on cellulose, regenerated cellulose and cellulose derivatives, 2016, p. 35-35, article id 9Conference paper (Other academic)
  • 69.
    Lenes, M
    et al.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Gregersen, Ø
    Performance Properties and Micro-structural quantification of fibre-polypropylene composites2011In: Materials Science and Technologies, Fiber Reinforced Composites, West Wirginia University , 2011Chapter in book (Refereed)
  • 70.
    Lenes, Marianne
    et al.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Gregersen, Öjvind
    Performance properties and micro-structural quantification of cellulose fibre-polypropylene composites2012In: Fiber-reinforced composites / [ed] Cheng Q, Nova Science Publishers, Inc., 2012, p. 143-157Chapter in book (Other academic)
    Abstract [en]

    This study focuses on the effects of cellulose content and cellulose morphology on the structural and mechanical properties of PP/cellulose fibre composites. A detailed structural characterisation was performed, including SEM-BEI analysis of fibre spatial distribution and X-μCT analysis of fibre orientation. The results indicated that the fibres were well-dispersed and oriented mostly along the main direction of the PP/cellulose test specimen. Based on light microscopy it was found that the cellulose fibres acted as nucleators in the PP matrix. By use of DSC it was shown that addition of cellulose fibres increased both the crystallinity and Tc. The increased crystallinity is mainly a result of the transcrystallinity formation. The tensile properties of the composites were affected by the fibre dimensions and the fibre concentration. The long fibres yielded the highest increase of Young's modulus. Elongation at break was mostly affected by the fibre concentration. The results thus indicate that there is a major potential for improving the mechanical properties of fibre-reinforced composites, provided an adequate concentration of fibres is applied.

  • 71. Lilledahl, M
    et al.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Davies, C
    Three-Dimensional Visualization and Quantification of Structural Fibres for Biomedical Applications2013In: Confocal Laser Microscopy: Principles and Applications in Medicine, Biology and the Food Sciences, InTech , 2013Chapter in book (Refereed)
  • 72. Lilledahl, Magnus B
    et al.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Three-dimensional visualization and quantification of structural fibres for biomedical applications2013In: Confocal laser microscopy: Principles and applications in medicine, biology and the food sciences / [ed] Lagali Neil, InTech, 2013Chapter in book (Refereed)
  • 73.
    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, 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.

  • 74.
    Miettinen, Arttu
    et al.
    University of Jyväskylä, Finland.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Kataja, Markku
    University of Jyväskylä, Finland.
    Three-Dimensional Microstructural Properties of Nanofibrillated Cellulose Films2014In: International Journal of Molecular Sciences, ISSN 1661-6596, E-ISSN 1422-0067, Vol. 4, no 15, p. 6423-6440Article in journal (Refereed)
    Abstract [en]

    Nanofibrillated cellulose (NFC) films have potential as oxygen barriers for, e.g., food packaging applications, but their use is limited by their hygroscopic characteristics. The three-dimensional microstructure of NFC films made of Pinus radiata (Radiata Pine) kraft pulp fibres has been assessed in this study, considering the structural development as a function of relative humidity (RH). The surface roughness, micro-porosity, thickness and their correlations were analyzed using X-ray microtomography (X-μCT) and computerized image analysis. The results are compared to those from scanning electron microscopy and laser profilometry. Based on a series of films having varying amounts of 2,2,6,6-tetramethylpiperidinyl-1-oxyl (TEMPO)-mediated oxidated nanofibrils, it was demonstrated that X-μCT is suitable for assessing the surface and bulk 3D microstructure of the cellulose films. Additionally, one of the series was assessed at varying humidity levels, using the non-destructive capabilities of X-μCT and a newly developed humidity chamber for in-situ characterization. The oxygen transmission rate (OTR) of the films (20 g/m2) was below 3:7mLm-2 day-1 at humidity levels below 60% RH. However, the OTR increased considerably to 12:4mLm-2 day-1 when the humidity level increased to 80% RH. The increase in OTR was attributed to a change of the film porosity, which was reflected as an increase in local thickness. Hence, the characterization techniques applied in this study shed more light on the structures of NFC films and how they are affected by varying humidity levels. It was demonstrated that in increasing relative humidity the films swelled and the oxygen barrier properties decreased.

  • 75.
    Miettinen, Arttu
    et al.
    University of Jyvaskyla, Finland.
    Ekman, Axel
    University of Jyvaskyla, Finland.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Kataja, Markku
    University of Jyvaskyla, Finland.
    Measuring intrinsic thickness of rough membranes: application to nanofibrillated cellulose films2015In: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 50, no 21, p. 6926-6934Article in journal (Refereed)
    Abstract [en]

    Adequate measurement of thickness of sheet-like materials or membranes is most important for quantifying their properties such as density, barrier properties and mechanical strength. Depending on the surface roughness of the membrane, the thickness measured by standard micrometre devices (apparent thickness) may considerably overestimate the actual geometrical mean thickness (intrinsic thickness) required for such purposes. In this work, we present a method for correcting the measured apparent thickness value of thin membranes for their surface roughness, thereby obtaining an improved estimate of the intrinsic thickness. The surface roughness data required for the correction can be obtained by common surface profiling techniques. The method includes a calibration parameter, the value of which can be found experimentally by independent measurements, or can be estimated theoretically using results from standard mechanical contact theory. The method is tested on a set of nanofibrillated cellulose films with varying roughness levels controlled by pulp fibre content. The surface topography of film samples was measured using laser profilometry, and the method was calibrated experimentally using data from X-ray microtomographic images for one type of film. The intrinsic thickness estimates given by the new method are generally in good accordance with independent results obtained from X-ray microtomography.

  • 76.
    Miettinen, Arttu
    et al.
    University of Jyväskylä, Finland.
    Hendriks, Cris L.
    SLU Swedish University of Agricultural Sciences, Sweden.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Gamsted, Erik Kristofer
    Uppsala University, Sweden.
    Kataja, Markku
    University of Jyväskylä, Finland.
    A non-destructive X-ray microtomography approach for measuring fibre length in short-fibre composites2012In: Composites Science And Technology, ISSN 0266-3538, E-ISSN 1879-1050, Vol. 72, no 15, p. 1901-1908Article in journal (Refereed)
    Abstract [en]

    An improved method based on X-ray microtomography is developed for estimating fibre length distribution of short-fibre composite materials. In particular, a new method is proposed for correcting the biasing effects caused by the finite sample size as defined by the limited field of view of the tomographic devices. The method is first tested for computer generated fibre data and then applied in analyzing the fibre length distribution in three different types of wood fibre reinforced composite materials. The results were compared with those obtained by an independent method based on manual registration of fibres in images from a light microscope. The method can be applied in quality control and in verifying the effects of processing parameters on the fibre length and on the relevant mechanical properties of short fibre composite materials, e.g. stiffness, strength and fracture toughness.

  • 77. Mikczinski, M.
    et al.
    Josefsson, G.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Syverud, Kristin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Gamstedt, E.K.
    Fatikow, S.
    Introducing an in-situ microrobotic approach for assessing the stiffness properties of microfibrillated cellulose films2012Conference paper (Refereed)
  • 78.
    Mikczinski, Manuel R.
    et al.
    OFFIS – Institute for Information Technology, Germany.
    Josefsson, Gabriella
    Uppsala University, Sweden.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Gamstedt, Erik Kristofer
    Uppsala University, Sweden.
    Fatikow, Sergej
    OFFIS – Institute for Information Technology, Germany.
    Nanorobotic Testing to Assess the Stiffness Properties of Nanopaper2014In: IEEE Transactions on robotics, ISSN 1552-3098, E-ISSN 1941-0468, Vol. 30, no 1, p. 115-119Article in journal (Refereed)
    Abstract [en]

    This paper deals with the nanorobotic and nondestructive assessment of the stiffness properties of nanopaper made of microfibrillated cellulose. Back-calculations of the Young's modulus show the agreement of the newly found results with conventional tensile testing results, therewith proving nanorobotics as a reasonable complement for conventional testing.

  • 79.
    Molnes, Silje N.
    et al.
    UoS University of Stavanger, Norway; NTNU Norwegian University of Science and Technology, Norway.
    Torrijos, Ivan P.
    UoS University of Stavanger, Norway.
    Strand, Skule
    UoS University of Stavanger, Norway.
    Paso, Kristofer G.
    NTNU Norwegian University of Science and Technology, Norway.
    Syverud, Kristin
    RISE, Innventia, PFI – Paper and Fiber Research Institute. NTNU Norwegian University of Science and Technology, Norway.
    Sandstone injectivity and salt stability of cellulose nanocrystals (CNC) dispersions: Premises for use of CNC in enhanced oil recovery2016In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 93, p. 152-160Article in journal (Refereed)
    Abstract [en]

    Reservoir production is frequently supported by using flooding fluids, often seawater. The efficiency is affected by various factors, such as the wettability of the reservoir rock and the mobility ratio between reservoir oil and injected fluid phase. These factors again influence sweep efficiency, which is the fraction of the total reservoir oil volume in contact with injected fluid during oil recovery. Addition of nanoparticles can affect the sweep efficiency on a macroscopic level by increasing the volume of petroleum in contact with the flooding fluid. Presented here are core-flooding studies performed using cellulose nanocrystals (CNC) of different concentrations in low-saline water. The studies were performed to investigate the injectivity of CNC into a high-permeable sandstone core, and to observe the effects addition of electrolytes had on the rheological properties of a low concentration dispersion of CNC. Zeta- potential and shear viscosity of dilute dispersions containing CNC was investigated under increasing electrolyte concentration. The flooding experiments show that the CNC has good injectivity in sandstone for all concentrations used, and the viscosity measurements performed on the effluent prove that the particles are able to travel through the core. Being sufficiently small for injection into sandstone and showing good colloidal stability at low salinities, CNC particles have the premises necessary to function properly as a flooding additive for enhanced oil recovery (EOR) in sandstone reservoirs.

  • 80.
    Mörseburg, Kathrin
    et al.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Hill, J
    QualTech AB, Sweden.
    Nyseth, T-E
    BIM Kemi AB, Sweden.
    Johansson, Lars
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Understanding energy efficiency of different refining concepts from fibre and fines quality2014Conference paper (Refereed)
    Abstract [en]

    Comparative pilot refining trials with Norway spruce chips were conducted in order to gain a better understanding of the principal mechanisms on fibre level for achieving radical energy reduction in the novel ATMP refining concept. The ATMP pulping configurations proved superior energy efficiency in pulp quality development, compared to TMP, RTS and F-RTS concepts. Development of high tensile strength did not progress at the expense of light scattering, even with process chemicals present. Extensive testing of individual particles in long fibre, middle and fines fractions in combination with analyses of properties of fraction sheets has shown that Impressafiner/Fiberizer pre-treatment opens the wood structure, allowing for early development of desired single fibre properties and generation of fibrillar fines. Peroxide combined with magnesium hydroxide affected the interior of the fibre walls, thereby facilitating improved fibre flexibility, collapsibility and swelling. Bisulphite mainly affected the fibre length distribution, reducing the coarse fraction R14 and promoting the generation of considerable amounts of coarse fines and middle fraction particles.

  • 81.
    Mörseburg, Kathrin
    et al.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Hill, Jan
    QualTech AB, Sweden.
    Johansson, Lars
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    ATMP refining of Norway spruce - Defibration characteristics and fibre wall properties2016In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 31, no 3, p. 386-400Article in journal (Refereed)
    Abstract [en]

    Defibration and fibre development patterns were investigated for the novel ATMP refining process, based on pilot scale trials with Norway spruce chips. ATMP refining with different chemical agents was compared to RTS refining with and without Impressa-finer (RT) and Fiberizer (F) pre-treatment. RT-F pre-treatment significantly improved both initial defibration, axial fibre splitting and fibre flexibility, compared to RTS primary stage refining without pre-treatment. Both types of investigated ATMP process chemistry - hydrogen peroxide combined with magnesium hydroxide under alkaline conditions (P) or acid sodium bisulphite (S) added to the primary refiner dilution water - further improved the fibre separation of RT-F pre-treated wood during primary stage RTS refining. This is largely attributed to enhanced fibre swelling. S-treatment facilitated frequent fibre separation within or close to the S2 wall layer, yielding extremely low shive levels and well-fibrillated, thin-walled fibres early in the process. S-treatment also rendered stiffer fibres, which made them susceptible to breakage, axial splitting and internal delamination. P-application is proposed to affect primarily the interior layers of the fibre walls, facilitating rapid fibre wall swelling towards the lumen, fibre softening and flexibilization.

  • 82.
    Mörseburg, Kathrin
    et al.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Imppola, A.
    Johansson, Lars
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Ertsås, P.A.
    Effects of Inlet Pulp Quality and Specific Energy Consumption in Mill-Scale low consistency refining of Mechanical Pulp2013Conference paper (Refereed)
  • 83.
    Nordli, H.R
    et al.
    NTNU Norwegian University of Science and Technology, Norway.
    Rokstad, A.M
    NTNU Norwegian University of Science and Technology, Norway.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Pukstad, B
    NTNU Norwegian University of Science and Technology, Norway; Trondheim University Hospital, Norway.
    Immunogenic properties of TEMPO-treated wood nanocellulose2014Conference paper (Refereed)
    Abstract [en]

    Bacterial nanocellulose (BNC) has been shown to be a good candidate in wound healing applications. However, there exists to date no cost efficient mass production of BNC. On the other side, wood nanocellulose (WNC) can be produced in large-scale and has also been suggested as a potential substrate for wound dressings. In WNC the cellulose fibers are disintegrated into individualized nanofibrils with typical diameters < 20 nm. Chemical pretreatment such as TEMPO-mediated oxidation yields a homogenous nanofibril morphology and modifies the surface chemistry of cellulose by introducing carboxyl groups and a small amount of aldehyde groups. A difference between BNC and WNC is that the last one usually consists of hemicellulose and small amounts of lignin, in addition to cellulose. Recently, we have demonstrated that WNC is not cytotoxic to 3T3-cells (mouse fibroblasts). However, to properly assess the properties of WNC for wound healing it is necessary to measure the cytotoxicity towards human skin cells, i.e. keratinocytes and fibroblasts, which is performed in this study. Additionally, using the lepirudin whole blood model the effect a material has on the activation of the complement system and the coagulation pathway can be studied. In order to use this model it is crucial to have a material which is free from bacterial composites, such as lipopolysaccharides (LPS). Importantly, we have in this work developed a new protocol for producing ultrapure nanocellulose with LPS concentration below 100 EU/g. This presentation will give an overview of recent results within the testing of the cytotoxic and immunogenic properties of WNC, which is important to verify for advanced wound healing applications.

  • 84. Opedal, Mihaela Tanase
    et al.
    Stenius, P.
    Johansson, L.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Colloidal stability and removal of extractives from process water in thermomechanical pulping2011In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 26, p. 248-257Article in journal (Refereed)
  • 85. Opedal, Mihaela Tanase
    et al.
    Stenius, Per
    Gregersen, Øjvind
    Johansson, Lars
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Hill, J.
    Flocculation of colloidal wood extractives in process water from precompression of chips in thermo-mechanical pulping2011In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 26, p. 64-71Article in journal (Refereed)
  • 86. Opedal, Mihaela Tanase
    et al.
    Stenius, Per
    Gregersen, Øjvind
    Johansson, Lars
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Hill, J.
    Removal of dissolved and colloidal substances in water from compressive pre-treatment of chips using dissolved air flotation: Laboratory Tests.2011In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 26, p. 72-80Article in journal (Refereed)
  • 87. Opedal, Mihaela Tanase
    et al.
    Stenius, Per
    Johansson, Lars
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Hill, J
    Sandberg, C.
    Removal of dissolved and colloidal substances in water from compressive pre-treatment of chips using dissolved air flotation: Pilot Trial2011In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 26, p. 364-371Article in journal (Refereed)
  • 88.
    Ottesen, V
    et al.
    Norwegian University of Science and Technology (NTNU) Department of Chemical Engineering.
    Gregersen,  Ø
    Norwegian University of Science and Technology (NTNU) Department of Chemical Engineering;.
    Syverud, Kristin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Nanocellulose in Paper and Packaging2014Conference paper (Refereed)
    Abstract [en]

    One possible way to improve competitiveness of paper materials is through utilization of nanocellulose to achieve new properties or to reduce production cost. Several studies have shown that nanofibrillar cellulose (NFC) can act as strength enhancing additive in paper or for paper surface improvements. NFC has the potential to bind large amounts of inorganic fillers in the paper sheet, and by this reduce energy consumption during paper production considerably. However, there are challenges that need to be addressed before the novel concepts can be realized, e.g. impaired drainage and drying of paper resulting from addition of NFC. This may be solved by obtaining the right balance between NFC quality, chemicals and additives. Promising results in this respect have been obtained  but this is still in an early stage. Fiber-based packaging materials represent a “green” alternative to petroleum based packaging solutions. Depending on the packaging category, different properties are important. For the segment liquid packaging board, barrier against oxygen is important. Currently, this is obtained by using aluminum, or the petroleum-based polymer EVOH in combination with a water barrier. Replacing these materials with “green” alternatives would represent a large environmental achievement. While superior oxygen barrier properties has been demonstrated for NFC,  good barrier against water and oxygen requires the combination of nanofibrils with complementary materials. Adequate combinations with other materials and feasible application techniques are still challenges that need to be solved. Other packaging segments require other properties, e.g. high stiffness or fracture toughness. By development of appropriate nanocellulose qualities, such properties can be improved. By preparing fibrils with small diameter, translucent films can be prepared. This is an interesting property for food packaging, where transparency may be a desired trait.

  • 89.
    Ottesen, V
    et al.
    Norwegian University of Science and Technology (NTNU) Department of Chemical Engineering.
    Gregersen,  Ø
    Norwegian University of Science and Technology (NTNU) Department of Chemical Engineering;.
    Syverud, Kristin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Nanocellulose Properties of Interest for Paper and Packaging2014Conference paper (Refereed)
    Abstract [en]

    Cellulose Nano-Fibrils (CNF) is a biocompatible nano-material with appealing mechanical and optical properties. The high specific surface area (SSA) of nanofibrils ensure that a large fraction of the polymer chains in each fibril are surface fibrils, meaning numerous surface hydroxyl groups will be available to form bonds between components in the paper, ensuring high density and strength. CNF may be added to conventional paper as a strengthening agent. CNF films may be used as a barrier coating, or CNF sheets may be used in a number of products due to their potential transparency, strength and barrier properties. As a paper additive, CNF as a nanomaterial acts as a material that increases density and form bonds between fibers in the paper, providing an increased strength and stiffness whereas dusting and permeability is reduced. For papers where strength is chiefly limited by inter-fiber bonding strength, increases in excess of 100 % may be achieved by addition of small amounts of CNF. Less, but still significant contributions can be seen for papers whose strength is less dependent on inter-fiber bonding strength. Due to the pore-blocking properties of CNF coupled with Cellulose’s hydrophilic properties, dewatering on the paper machine is a challenge when CNF is used in this fashion. The high density, viz. the low porosity and small pore size (~0.47 nm), of CNF films provide a significant reduction in mass-transport. Applying such a film to a less efficient barrier material, or producing a pure CNF film presents oxygen transfer rates comparable with the best synthetic polymer films produced for this purpose. Sheets of pure CNF or a CNF composite may transmit 90 % of incident light with a wavelength of 600 nm. This transparency is due to the high density and small fibril size in sheets of pure CNF or a CNF-based composite, which results in a lower scattering coefficient compared to corresponding conventional fiber based sheets. Transparent sheets such as these may be of interest in packaging applications where the packaged goods, such as foodstuffs or luxury articles, is desired displayed to the end customer. The properties of CNF, whether as a film, a paper additive or a major paper or composite component may be of significant industrial interest due to the unique properties of the material.

  • 90.
    Ottesen, Vegar
    et al.
    NTNU Norwegian University of Science and Technology, Norway.
    Syverud, Kristin
    RISE, Innventia, PFI – Paper and Fiber Research Institute. NTNU Norwegian University of Science and Technology, Norway.
    Gregersen, Øyvind W.
    NTNU Norwegian University of Science and Technology, Norway.
    Mixing of cellulose nanofibrils and individual furnish components: Effects on paper properties and structure2016In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 31, no 3, p. 441-447Article in journal (Refereed)
    Abstract [en]

    Thermo-mechanical pulp (TMP) handsheets with different fractions of cellulose nano fibrils (CNF) and ground calcium carbonate (GCC) were made. CNF and retention chemicals were added in three different ways; to GCC, to long fibre fraction (LFF) or to complete furnish. The different addition strategies affected dewatering time, tensile strength and permeability, however opacity was not affected. Depending on filler and CNF levels, adding CNF to GCC produced the most beneficial effects on paper properties; CNF had a lower impact on dewatering times and permeability and GCC reduced strength less than for competing strategies. Adding CNF to LFF produced the least beneficial results using the same metrics. Scanning electron microscopy (SEM) analysis of the sheets reveal that sheets produced using the different strategies are structurally different; adding CNF and retention chemicals to GCC appears to have increased GCC clustering, whereas adding CNF and retention chemicals to LFF appears to have increased the fraction of GCC adsorbed on the fiber walls. CNF and retention chemical addition to complete furnish showed GCC clustering and adhering to the fiber walls, of which clustering appeared the most common.

  • 91.
    Powell, Lydia C.
    et al.
    Cardiff University, UK; Swansea University, UK.
    Khan, Saira
    Cardiff University, UK.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Wright, Chris J.
    Swansea University, UK.
    Hill, Katja E.
    Cardiff University, UK.
    Thomas, David W.
    Cardiff University, UK.
    An investigation of Pseudomonas aeruginosa biofilm growth on novel nanocellulose fibre dressings2016In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 137, p. 191-197Article in journal (Refereed)
    Abstract [en]

    Nanocellulose from wood is a novel biomaterial, which is highly fibrillated at the nanoscale. This affords the material a number of advantages, including self-assembly, biodegradability and the ability to absorb and retain moisture, which highlights its potential usefulness in clinical wound-dressing applications. In these in vitro studies, the wound pathogen Pseudomonas aeruginosa PAO1 was used to assess the ability of two nanocellulose materials to impair bacterial growth (&lt;48 h). The two nanocelluloses had a relatively small fraction of residual fibres (&lt;4%) and thus a large fraction of nanofibrils (widths &lt;20 nm). Scanning electron microscopy and confocal laser scanning microscopy imaging demonstrated impaired biofilm growth on the nanocellulose films and increased cell death when compared to a commercial control wound dressing, Aquacel®. Nanocellulose suspensions inhibited bacterial growth, whilst UV-vis spectrophotometry and laser profilometry also revealed the ability of nanocellulose to form smooth, translucent films. Atomic force microscopy studies of the surface properties of nanocellulose demonstrated that PAO1 exhibited markedly contrasting morphology when grown on the nanocellulose film surfaces compared to an Aquacel® control dressing (p &lt; 0.05). This study highlights the potential utility of these biodegradable materials, from a renewable source, for wound dressing applications in the prevention and treatment of biofilm development.

  • 92.
    Ragauskas, Arthur J.
    et al.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Lindström, Tom
    RISE, Innventia, Material Processes. KTH Royal Institute of Technology, Sweden.
    Nanocellulose and the future2014In: TAPPI Journal, ISSN 0734-1415, Vol. 13, no 5, p. 5-6Article in journal (Refereed)
  • 93.
    Rees, A
    et al.
    Swansea University WCPC.
    Powell, L.C
    Centre for NanoHealth, College of Engineering, Swansea University, Swansea, UK.; Tissue Engineering and Reparative Dentistry, Cardiff University School of Dentistry, Cardiff, UK..
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Gethin, D.T
    Swansea University WCPC.
    Claypole, T.C
    Swansea University WCPC.
    Deganello, D
    Swansea University WCPC.
    Syverud, Kristin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Studies on the 3D Printing of Nanocellulose Structures2014Conference paper (Refereed)
    Abstract [en]

    Nanocellulose has a variety of advantages, which make the material most suitable for use in biomedical devices such as wound dressings. The material is strong, can be used for producing transparent films, can keep a moist environment and form elastic gels with bio-responsive characteristics. In this study we explore the application of nanocellulose as a bioink for use in a bioprinting process. Two different nanocelluloses were used, prepared with TEMPO mediated oxidation and a combination of carboxymethylation and periodate oxidation. The combination of carboxymethylation and periodate oxidation produced a homogeneous material with short nanofibrils. The small dimensions of the nanofibrils reduced the viscosity of the nanocellulose thus yielding a material with good rheological properties for use as a bioink. We also demonstrated that both nanocelluloses inhibited bacterial growth, which is an interesting property of these novel materials.

  • 94.
    Rees, Adam
    et al.
    Swansea University, UK.
    Powell, Lydia C.
    Swansea University, UK; Cardiff University, UK.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Gethin, David T.
    Swansea University, UK.
    Syverud, Kristin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Hill, Katja E.
    Cardiff University, UK.
    Thomas, David W.
    Cardiff University, UK.
    3D bioprinting of carboxymethylated-periodate oxidized nanocellulose constructs for wound dressing applications2015In: BioMed Research International, ISSN 2314-6133, E-ISSN 2314-6141, Vol. 2015, article id 925757Article in journal (Refereed)
    Abstract [en]

    Nanocellulose has a variety of advantages, which make the material most suitable for use in biomedical devices such as wound dressings. The material is strong, allows for production of transparent films, provides a moist wound healing environment, and can form elastic gels with bioresponsive characteristics. In this study, we explore the application of nanocellulose as a bioink for modifying film surfaces by a bioprinting process. Two different nanocelluloses were used, prepared with TEMPO mediated oxidation and a combination of carboxymethylation and periodate oxidation. The combination of carboxymethylation and periodate oxidation produced a homogeneous material with short nanofibrils, having widths <20 nm and lengths <200 nm. The small dimensions of the nanofibrils reduced the viscosity of the nanocellulose, thus yielding a material with good rheological properties for use as a bioink. The nanocellulose bioink was thus used for printing 3D porous structures, which is exemplified in this study. We also demonstrated that both nanocelluloses did not support bacterial growth, which is an interesting property of these novel materials.

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  • 95. 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, ISSN 0969-0239, E-ISSN 1572-882X, Vol. 18Article in journal (Refereed)
  • 96. Rodionova, G.
    et al.
    Roudot, S.
    Eriksen, Ø.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Männle, F.
    Gregersen, Ø.
    The formation and characterisation of sustainable layered films incorporating microfibrillated cellulose (MFC)2012In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 7, p. 3690-3700Article in journal (Refereed)
  • 97.
    Rodionova, Galina
    et al.
    RISE, Innventia, PFI – Paper and Fiber Research Institute. NTNU Norwegian University of Science and Technology, Norway.
    Eriksen, Øyvind
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Gregersen, Øyvind Weiby
    RISE, Innventia, PFI – Paper and Fiber Research Institute. NTNU Norwegian University of Science and Technology, Norway.
    TEMPO-oxidized cellulose nanofiber films:: effect of surface morphology on water resistance2012In: Cellulose, ISSN 0969-0239, E-ISSN 1572-882X, Vol. 19, no 4, p. 1115-1123Article in journal (Refereed)
    Abstract [en]

    2,2,6,6-Tetramethylpiperidine-1-oxyl radical (TEMPO)-oxidized cellulose nanofibers were prepared from two kraft pulps (Norway spruce and mixed eucalyptus) using the TEMPO/NaBr/NaClO system at pH 10 and 22 °C. After reaction and mechanical treatment, the TEMPO-oxidized celluloses were used for preparation of self-standing films and coatings of laminate films on 50-μm-thick polyethylene terephthalate films. Characterization of the films was performed based on water contact angle measurements, laser profilometry, scanning electron microscopy, and field-emission scanning electron microscopy. The purpose of this study is to understand how the measured contact angles are affected by the film's physical properties (morphology, thickness, density, and roughness).

  • 98.
    Rodionova, Galina
    et al.
    NTNU Norwegian University of Science and Technology, Norway.
    Hoff, Bård H.
    NTNU Norwegian University of Science and Technology, Norway.
    Lenes, Marianne
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Eriksen, Øyvind
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Gregersen, Øyvind Weiby
    NTNU Norwegian University of Science and Technology, Norway.
    Gas-phase esterification of microfibrillated cellulose (MFC) films2013In: Cellulose, ISSN 0969-0239, E-ISSN 1572-882X, Vol. 20, no 3, p. 1167-1174Article in journal (Refereed)
    Abstract [en]

    The barrier properties of microfibrillated cellulose (MFC) films were improved by heterogeneous gas-phase esterification using various combinations of trifluoroacetic acid anhydride, acetic acid and acetic anhydride. The temperature, reagent ratio and reaction time were varied in the experimental design. The effects of two different purification procedures on the barrier properties of esterified MFC films were investigated. Washing with water did not affect the barrier properties compared to those of the films that were not washed, while the use of diethyl ether led to improved barrier properties as measured by the contact angle (CA) of water. The chemical composition of the modified films was studied by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. Alterations in hydrophobicity and oxygen permeability were evaluated using dynamic CA and oxygen transmission rate measurements, respectively.

  • 99.
    Rodionova, Galina
    et al.
    NTNU Norwegian University of Science and Technology, Norway.
    Roudot, Solenne
    NTNU Norwegian University of Science and Technology, Norway.
    Eriksen, Øyvind
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Männle, Ferdinand
    SINTEF, Norway.
    Gregersen, Øyvind Weiby
    NTNU Norwegian University of Science and Technology, Norway.
    The formation and characterization of sustainable layered films incorporating microfibrillated cellulose (mfc)2012In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 7, no 3, p. 3690-3700Article in journal (Refereed)
    Abstract [en]

    Microfibrillated cellulose (MFC), TEMPO-pretreated MFC, and hybrid polymer/MFC mix were used for the production of layered films with interesting properties for application in food packaging. The series of samples were prepared from MFC (base layers) using a dispersion-casting method. The same procedure as well as a bar coating technique was applied to form top layers of different basis weights. The barrier properties and formation of the layered films were investigated in relationship to the preparation procedures, combination of layers, and areal weight (basis weight). Characterization was done with respect to oxygen transmission rates (OTR), water vapor transmission rates (WVTR), tensile properties, and contact angles (CA) with water. The produced layered films yielded OTR values of 4 mL m-2 day-1 and fulfilled oxygen barrier requirements for a modified atmosphere packaging (MAP). Hornification of the MFC films, however, occurred during drying, which may result in a loss of the film's beneficial properties.

  • 100.
    Rodionova, Galina
    et al.
    NTNU Norwegian University of Science and Technology, Norway.
    Saito, Tsuguyuki
    University of Tokyo, Japan.
    Lenes, Marianne
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Eriksen, Øyvind
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Gregersen, Øyvind Weiby
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Fukuzumi, Hayaka
    University of Tokyo, Japan.
    Isogai, Akiara
    University of Tokyo, Japan.
    Mechanical and oxygen barrier properties of films prepared from fibrillated dispersions of TEMPO-oxidized Norway spruce and Eucalyptus pulps2012In: Cellulose, ISSN 0969-0239, E-ISSN 1572-882X, Vol. 19Article in journal (Refereed)
    Abstract [en]

    TEMPO-oxidized cellulose nanofibers (TOCN) were obtained from commercial Norway spruce and mixed Eucalyptus cellulose pulps using TEMPO/sodium bromide (NaBr)/sodium hypochlorite (NaClO) system at pH 10 and 22 °C. After reaction, the fibrillated TEMPO-oxidized celluloses were used for preparation of self-standing films and casting of laminate films on 50 μm thick polyethylene terephthalate. Significant differences between N. spruce and Eucalyptus TOCN were registered. The tensile strength of the films showed a maximum value for spruce samples oxidized with addition of 10 mmol g -1 of NaClO. Oxygen permeability decreased with increasing oxidation levels, being lower for N. spruce TOCN compared to Eucalyptus.

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