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  • 1.
    Aadland, Reidun C.
    et al.
    NTNU Norwegian University of Science and Technology, Norway.
    Dziuba, Carter J.
    University of Calgary, Canada.
    Heggset, Ellinor B
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Syverud, Kristin
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Torsæter, Ole
    NTNU Norwegian University of Science and Technology, Norway.
    Holt, Thorleif
    SINTEF, Norway.
    Gates, Ian D.
    University of Calgary, Canada.
    Bryant, Steven L.
    University of Calgary, Canada.
    Identification of nanocellulose retention characteristics in porous media2018In: Nanomaterials, ISSN 2079-4991, Vol. 8, no 7, article id 547Article in journal (Refereed)
    Abstract [en]

    The application of nanotechnology to the petroleum industry has sparked recent interest in increasing oil recovery, while reducing environmental impact. Nanocellulose is an emerging nanoparticle that is derived from trees or waste stream from wood and fiber industries. Thus, it is taken from a renewable and sustainable source, and could therefore serve as a good alternative to current Enhanced Oil Recovery (EOR) technologies. However, before nanocellulose can be applied as an EOR technique, further understanding of its transport behavior and retention in porous media is required. The research documented in this paper examines retention mechanisms that occur during nanocellulose transport. In a series of experiments, nanocellulose particles dispersed in brine were injected into sandpacks and Berea sandstone cores. The resulting retention and permeability reduction were measured. The experimental parameters that were varied include sand grain size, nanocellulose type, salinity, and flow rate. Under low salinity conditions, the dominant retention mechanism was adsorption and when salinity was increased, the dominant retention mechanism shifted towards log-jamming. Retention and permeability reduction increased as grain size decreased, which results from increased straining of nanocellulose aggregates. In addition, each type of nanocellulose was found to have significantly different transport properties. Experiments with Berea sandstone cores indicate that some pore volume was inaccessible to the nanocellulose. As a general trend, the larger the size of aggregates in bulk solution, the greater the observed retention and permeability reduction. Salinity was found to be the most important parameter affecting transport. Increased salinity caused additional aggregation, which led to increased straining and filter cake formation. Higher flow rates were found to reduce retention and permeability reduction. Increased velocity was accompanied by an increase in shear, which is believed to promote breakdown of nanocellulose aggregates. © 2018 by the authors.

  • 2.
    Aadland, Reidun
    et al.
    NTNU Norwegian University of Science and Technology, Norway.
    Jakobsen, Trygve
    NTNU Norwegian University of Science and Technology, Norway.
    Heggset, Ellinor B
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Long-Sanouiller, Haili
    NTNU Norwegian University of Science and Technology, Norway.
    Simon, Sebastien
    NTNU Norwegian University of Science and Technology, Norway.
    Paso, Kristofer
    NTNU Norwegian University of Science and Technology, Norway.
    Syverud, Kristin
    RISE - Research Institutes of Sweden, Bioeconomy, PFI. NTNU Norwegian University of Science and Technology, Norway.
    Torsæter, Ole
    NTNU Norwegian University of Science and Technology, Norway.
    High-temperature core flood investigation of nanocellulose as a green additive for enhanced oil recovery2019In: Nanomaterials, ISSN 2079-4991, Vol. 9, no 5, article id 665Article in journal (Refereed)
    Abstract [en]

    Recent studies have discovered a substantial viscosity increase of aqueous cellulose nanocrystal (CNC) dispersions upon heat aging at temperatures above 90 °C. This distinct change in material properties at very low concentrations in water has been proposed as an active mechanism for enhanced oil recovery (EOR), as highly viscous fluid may improve macroscopic sweep efficiencies and mitigate viscous fingering. A high-temperature (120 °C) core flood experiment was carried out with 1 wt.% CNC in low salinity brine on a 60 cm-long sandstone core outcrop initially saturated with crude oil. A flow rate corresponding to 24 h per pore volume was applied to ensure sufficient viscosification time within the porous media. The total oil recovery was 62.2%, including 1.2% oil being produced during CNC flooding. Creation of local log-jams inside the porous media appears to be the dominant mechanism for additional oil recovery during nano flooding. The permeability was reduced by 89.5% during the core flood, and a thin layer of nanocellulose film was observed at the inlet of the core plug. CNC fluid and core flood effluent was analyzed using atomic force microscopy (AFM), particle size analysis, and shear rheology. The effluent was largely unchanged after passing through the core over a time period of 24 h. After the core outcrop was rinsed, a micro computed tomography (micro-CT) was used to examine heterogeneity of the core. The core was found to be homogeneous. © 2019 by the authors.

  • 3.
    Aaen, Ragnhild
    et al.
    Norwegian University of Science and Technology, Norway.
    Brodin, Fredrik Wernersson
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Simon, Sébastien
    Norwegian University of Science and Technology, Norway.
    Heggset, Ellinor B
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Syverud, Kristin
    RISE - Research Institutes of Sweden, Bioeconomy, PFI. Norwegian University of Science and Technology, Norway.
    Oil-in-Water Emulsions Stabilized by Cellulose Nanofibrils-The Effects of Ionic Strength and pH.2019In: Nanomaterials (Basel, Switzerland), ISSN 2079-4991, Vol. 9, no 2, article id E259Article in journal (Refereed)
    Abstract [en]

    Pickering o/w emulsions prepared with 40 wt % rapeseed oil were stabilized with the use of low charged enzymatically treated cellulose nanofibrils (CNFs) and highly charged 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidized CNFs. The emulsion-forming abilities and storage stability of the two qualities were tested in the presence of NaCl and acetic acid, at concentrations relevant to food applications. Food emulsions may be an important future application area for CNFs due to their availability and excellent viscosifying abilities. The emulsion characterization was carried out by visual inspection, light microscopy, viscosity measurements, dynamic light scattering and mild centrifugation, which showed that stable emulsions could be obtained for both CNF qualities in the absence of salt and acid. In addition, the enzymatically stabilized CNFs were able to stabilize emulsions in the presence of acid and NaCl, with little change in the appearance or droplet size distribution over one month of storage at room temperature. The work showed that enzymatically treated CNFs could be suitable for use in food systems where NaCl and acid are present, while the more highly charged TEMPO-CNFs might be more suited for other applications, where they can contribute to a high emulsion viscosity even at low concentrations.

  • 4.
    Aaen, Ragnhild
    et al.
    Norwegian University of Science and Technology, Norway.
    Simon, Sebastien
    Norwegian University of Science and Technology, Norway.
    Wernersson Brodin, Fredrik
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Syverud, Kristin
    RISE - Research Institutes of Sweden, Bioeconomy, PFI. Norwegian University of Science and Technology, Norway.
    The potential of TEMPO-oxidized cellulose nanofibrils as rheology modifiers in food systems2019In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 26, no 9, p. 5483-5496Article in journal (Refereed)
    Abstract [en]

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

  • 5.
    Aarstad, Olav
    et al.
    NTNU Norwegian University of Science and Technology, Norway.
    Heggset, Ellinor B
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Pedersen, Ina Sander
    NTNU Norwegian University of Science and Technology, Norway.
    Björnöy, Sindre H.
    NTNU Norwegian University of Science and Technology, Norway.
    Syverud, Kristin
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Strand, Berit L.
    NTNU Norwegian University of Science and Technology, Norway.
    Mechanical properties of composite hydrogels of alginate and cellulose nanofibrils2017In: Polymers, ISSN 2073-4360, E-ISSN 2073-4360, Vol. 9, no 8, article id 378Article in journal (Refereed)
    Abstract [en]

    Alginate and cellulose nanofibrils (CNF) are attractive materials for tissue engineering and regenerative medicine. CNF gels are generally weaker and more brittle than alginate gels, while alginate gels are elastic and have high rupture strength. Alginate properties depend on their guluronan and mannuronan content and their sequence pattern and molecular weight. Likewise, CNF exists in various qualities with properties depending on, e.g., morphology and charge density. In this study combinations of three types of alginate with different composition and two types of CNF with different charge and degree of fibrillation have been studied. Assessments of the composite gels revealed that attractive properties like high rupture strength, high compressibility, high gel rigidity at small deformations (Young’s modulus), and low syneresis was obtained compared to the pure gels. The effects varied with relative amounts of CNF and alginate, alginate type, and CNF quality. The largest effects were obtained by combining oxidized CNF with the alginates. Hence, by combining the two biopolymers in composite gels, it is possible to tune the rupture strength, Young’s modulus, syneresis, as well as stability in physiological saline solution, which are all important properties for the use as scaffolds in tissue engineering.

  • 6.
    Brod, E
    et al.
    NIBIO Norwegian Institute of Bioeconomy Research, Norway.
    Toven, Kai
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Haraldsen, TK
    NIBIO Norwegian Institute of Bioeconomy Research, Norway.
    Krogstad, T
    Norwegian University of Life Sciences, Norway.
    Unbalanced nutrient ratios in pelleted compound recycling fertilizers2018In: Soil use and management, ISSN 0266-0032, E-ISSN 1475-2743, Vol. 34, no 1, p. 18-27Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to contribute to the development of pelleted compound recycling fertilizers with favourable handling and spreading characteristics and balanced nutrient ratios by combining nitrogen (N)- and phosphorus (P)-rich waste resources (meat bone meal, fish sludge or food waste) with potassium (K)-rich bottom wood ash. Pelleted compound recycling fertilizers with good durability and low dusting tendency were produced by roll-pelleting preheated waste resources at a suitable moisture content. However, the nutrient ratios in the final products were insufficiently balanced, with too low N concentrations relative to P and K to meet crop demands. In a bioassay using barley (Hordeum vulgare) and a nutrient-deficient sand/peat mixture, the relative agronomic effectiveness (RAE) of pelleted compound recycling fertilizers and reference recycling fertilizers was 22-42% of that of mineral compound fertilizer. Growth limitation was due to reduced N availability (mineral fertilizer equivalent - MFE=35-57%) or reduced P availability (MFE=20-115%), with the greatest P fertilizer value obtained for digestate based on dairy manure and fish sludge. Availability of K in bottom wood ash was masked by the experimental soil.

  • 7.
    Brodin, Fredrik W.
    et al.
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Celaya Romeo, Javier
    NTNU Norwegian University of Science and Technology, Norway.
    Toven, K.
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Dewatered pyrolysis oil as fuel component in marine fuel blends2016In: European Biomass Conference and Exhibition Proceedings 2016, 2016, no 24thEUBCE, p. 1122-1124Conference paper (Other academic)
    Abstract [en]

    Forest-based fast pyrolysis liquids constitute a potential low-sulphur fuel alternative for the marine sector. However, it is a challenge to meet the marine fuel quality demands set by current infrastructure, engines and fuels standards. The aim of this work has been to explore the potential for producing a new and more sustainable marine fuel quality. This new fuel quality is based on upgraded pyrolysis oil which is used as a fuel component in three-component blends. Low-water containing pine pyrolysis oil samples were formed by vacuum-assisted dewatering and in the next step three-component blends were prepared by mixing pyrolysis oil with bio-diesel and nbutanol. The results showed that less amount of butanol is required to form homogenous and storage stable blends when using dewatered pyrolysis oil as a blend component as compared to using crude pyrolysis oil. Dewatering also reduced the corrosiveness dramatically indicating that fuel blends based on dewatered pyrolysis oils are more compatible with marine engines than fuel blend based on crude pyrolysis oil.

  • 8.
    Brodin, Malin
    et al.
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Vallejos, Maria
    Instituto de Materiales de Misiones (IMAM), Argentina.
    Opedal, Mihaela Tanase
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Area, Maria C.
    Instituto de Materiales de Misiones (IMAM), Argentina.
    Chinga-Carrasco, Gary
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Lignocellulosics as sustainable resources for production of bioplastics: a review2017In: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 162, p. 646-664Article, review/survey (Refereed)
    Abstract [en]

    The bio-based economy requires a sustainable utilization of bioresources for production of a range of products, including pulp, paper, chemicals, biofuel and bioplastics. Currently, various types of bioplastics are produced industrially, competing in performance and price with the conventional fossil-oil based plastics. However, there is also a major interest in utilizing non-food crops, such as lignocellulosics, for production of drop-in polymers or new dedicated bioplastics. Lignocellulosic resources have a potential to replace plastics and materials, which have been traditionally based on fossil resources. This is important, as the development of high performance bio-based and renewable materials is one important factor for sustainable growth of the bio-based industry. However, production of bioplastics from forestry biomass requires a dedicated fractionation into the major components, i.e. cellulose, hemicelluloses and lignin, effective purification processes and cost-effective routes for conversion into monomers and platform molecules, utilized as a basis for bioplastics production. These processes are now technologically demanding and not profitable. The intention of this work was thus to review the current advances that have been made during the years within fractionation and purification of lignocelluloses and the processes that may feasible for production of bioplastics, based on wood components.

  • 9.
    Campodoni, Elisabetta
    et al.
    Institute of Science and Technology for Ceramics-National Research Council (ISTEC-CNR), Italy.
    Heggset, Ellinor B
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Rashad, Ahmad
    University of Bergen, Norway.
    Ramírez-Rodríguez, Gloria B.
    Universidad de Granada, Spain.
    Mustafa, Kamal
    University of Bergen, Norway.
    Syverud, Kristin
    RISE - Research Institutes of Sweden, Bioeconomy, PFI. Norwegian University of Science and Technology, Norway.
    Tampieri, Anna
    Institute of Science and Technology for Ceramics-National Research Council (ISTEC-CNR), Italy.
    Sandri, Monica
    Institute of Science and Technology for Ceramics-National Research Council (ISTEC-CNR), Italy.
    Polymeric 3D scaffolds for tissue regeneration: Evaluation of biopolymer nanocomposite reinforced with cellulose nanofibrils2019In: Materials science & engineering. C, biomimetic materials, sensors and systems, ISSN 0928-4931, E-ISSN 1873-0191, Vol. 94, p. 867-878Article in journal (Refereed)
    Abstract [en]

    Biopolymers such as gelatin (Gel) and cellulose nanofibrils (CNF) have many of the essential requirements for being used as scaffolding materials in tissue regeneration; biocompatibility, surface chemistry, ability to generate homogeneous hydrogels and 3D structures with suitable pore size and interconnection, which allows cell colonization and proliferation. The purpose of this study was to investigate whether the mechanical behaviour of the Gel matrix can be improved by means of functionalization with cellulose nanofibrils and proper cross-linking treatments. Blending processes were developed to achieve a polymer nanocomposite incorporating the best features of both biopolymers: biomimicry of the Gel and structural reinforcement by the CNF. The designed 3D structures underline interconnected porosity achieved by freeze-drying process, improved mechanical properties and chemical stability that are tailored by CNF addition and different cross-linking approaches. In vitro evaluations reveal the preservation of the biocompatibility of Gel and its good interaction with cells by promoting cell colonization and proliferation. The results support the addition of cellulose nanofibrils to improve the mechanical behaviour of 3D porous structures suitable as scaffolding for tissue regeneration.

  • 10.
    Celaya Romeo, Javier
    et al.
    NTNU Norwegian University of Science and Technology, Norway.
    Wernersson Brodin, Fredrik
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Toven, Kai
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Pyrolysis oil based fuel emulsions for marine engines2016In: European Biomass Conference and Exhibition Proceedings, 2016, no 24thEUBCE, p. 1740-1745Conference paper (Other academic)
    Abstract [en]

    The International Convention for the Prevention of Pollution from Ships (MARPOL) is reducing the allowed amount of sulphur in marine fuels and these reductions will continue in the future. Bio-oil is a sulphur-free liquid fuel and it constitutes a potential biofuel for the marine sector because it may be produced at industrial scale through pyrolysis of residues coming from the wood processing industry. Due to some of its challenging characteristics, it cannot substitute conventional fuels directly or be blended with them, but it might be used as a component of an emulsified drop-in fuel. The objective of this work is to determine the best conditions to produce an emulsified marine drop-in fuel. These conditions include the percentages of each component (marine gas oil or biodiesel, bio-oil, surfactant, type and combination of surfactants and the hydrophilic-lipophilic value (HLB) of the surfactant blend. Stability of the emulsions has been analysed by light scattering and visual observation at different times. This work forms part of the ReShip Project partly funded by the Research Council of Norway (The ENERGIX programme).

  • 11.
    Cernencu, Alexandra
    et al.
    University Politehnica of Bucharest, Romania.
    Lungu, Adriana
    University Politehnica of Bucharest, Romania.
    Stancu, Izabela
    University Politehnica of Bucharest, Romania.
    Serafim, Andrada
    University Politehnica of Bucharest, Romania.
    Heggset, Ellinor B
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Syverud, Kristin
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Iovu, Horia
    University Politehnica of Bucharest, Romania; Academy of Romanian Scientists, Romania.
    Bioinspired 3D printable pectin-nanocellulose ink formulations2019In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 220, p. 12-21Article in journal (Refereed)
    Abstract [en]

    The assessment of several ink formulations for 3D printing based on two natural macromolecular compounds is presented. In the current research we have exploited the fast crosslinking potential of pectin and the remarkable shear-thinning properties of carboxylated cellulose nanofibrils, which is known to induce a desired viscoelastic behavior. Prior to 3D printing, the viscoelastic properties of the polysaccharide inks were evaluated by rheological measurements and injectability tests. The reliance of the printing parameters on the ink composition was established through one-dimensional lines printing, the base units of 3D-structures. The performance of the 3D-printed structures after ionic cross-linking was evaluated in terms of mechanical properties and rehydration behavior. MicroCT was also used to evaluate the morphology of the 3D-printed objects regarding the effect of pectin/nanocellulose ratio on the geometrical features of scaffolds. The proportionality between the two polymers proved to be the determining factor for the firmness and strength of the printed objects. © 2019

  • 12.
    Chinga-Carrasco, Gary
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Novel biocomposite engineering and bio-applications2018In: Bioengineering, ISSN 2306-5354, Vol. 5, no 4, p. 80-Article in journal (Other academic)
  • 13.
    Chinga-Carrasco, Gary
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Por una ciencia integrada2018In: Celulosa Y Papel, ISSN 0716-2308, Vol. 34, no 4, p. 12-15Article in journal (Other academic)
  • 14.
    Chinga-Carrasco, Gary
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Potential and Limitations of Nanocelluloses as Components in Biocomposite Inks for Three-Dimensional Bioprinting and for Biomedical Devices.2018In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 19, no 3, p. 701-711Article in journal (Refereed)
    Abstract [en]

    Three-dimensional (3D) printing has rapidly emerged as a new technology with a wide range of applications that includes biomedicine. Some common 3D printing methods are based on the suitability of biopolymers to be extruded through a nozzle to construct a 3D structure layer by layer. Nanocelluloses with specific rheological characteristics are suitable components to form inks for 3D printing. This review considers various nanocelluloses that have been proposed for 3D printing with a focus on the potential advantages, limitations, and requirements when used for biomedical devices and when used in contact with the human body.

  • 15.
    Chinga-Carrasco, Gary
    et al.
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Ehman, Nanci
    IMAM, Argentina.
    Filgueira, Daniel
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Johansson, Jenny
    RISE - Research Institutes of Sweden, Bioscience and Materials, Chemistry and Materials.
    Vallejos, Maria
    IMAM, Argentina.
    Felissia, Fernando
    IMAM, Argentina.
    Håkansson, Joakim
    RISE - Research Institutes of Sweden, Bioscience and Materials, Chemistry and Materials.
    Area, Maria
    IMAM, Argentina.
    Bagasse—A major agro-industrial residue as potential resource for nanocellulose inks for 3D printing of wound dressing devices2019In: Additive Manufacturing, ISSN 2214-8604, Vol. 28, p. 267-274Article in journal (Refereed)
    Abstract [en]

    Sugarcane bagasse, an abundant residue, is usually burned as an energy source. However, provided that appropriate and sustainable pulping and fractionation processes are applied, bagasse can be utilized as a main source of cellulose nanofibrils (CNF). We explored in this study the production of CNF inks for 3D printing by direct-ink-writing technology. The CNF were tested against L929 fibroblasts cell line and we confirmed that the CNF from soda bagasse fibers were found not to have a cytotoxic potential. Additionally, we demonstrated that the alginate and Ca 2+ caused significant dimensional changes to the 3D printed constructs. The CNF-alginate grids exhibited a lateral expansion after printing and then shrank due to the cross-linking with the Ca 2+ . The release of Ca 2+ from the CNF and CNF-alginate constructs was quantified thus providing more insight about the CNF as carrier for Ca 2+ . This, combined with 3D printing, offers potential for personalized wound dressing devices, i.e. tailor-made constructs that can be adapted to a specific shape, depending on the characteristics of the wound healing treatment.

  • 16.
    Chinga-Carrasco, Gary
    et al.
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Ehman, Nanci V.
    IMAM Instituto de Materiales de Misiones, Argentina.
    Pettersson, Jennifer
    RISE - Research Institutes of Sweden, Bioscience and Materials, Chemistry and Materials.
    Vallejos, Maria E.
    IMAM Instituto de Materiales de Misiones, Argentina.
    Brodin, Malin
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Felissia, Fernando E.
    IMAM Instituto de Materiales de Misiones, Argentina.
    Håkansson, Joakim
    RISE - Research Institutes of Sweden, Bioscience and Materials, Chemistry and Materials.
    Area, Maria C.
    IMAM Instituto de Materiales de Misiones, Argentina.
    Pulping and Pretreatment Affect the Characteristics of Bagasse Inks for Three-dimensional Printing2018In: ACS Sustainable Chemistry and Engineering, ISSN 2168-0485, Vol. 6, no 3, p. 4068-4075Article in journal (Refereed)
    Abstract [en]

    Bagasse is an underutilized agro-industrial residue with great potential as raw material for the production of cellulose nanofibrils (CNF) for a range of applications. In this study, we have assessed the suitability of bagasse for production of CNF for three-dimensional (3D) printing. First, pulp fibers were obtained from the bagasse raw material using two fractionation methods, i.e. soda and hydrothermal treatment combined with soda. Second, the pulp fibers were pretreated by TEMPO-mediated oxidation using two levels of oxidation for comparison purposes. Finally, the CNF were characterized in detail and assessed as inks for 3D printing. The results show that CNF produced from fibers obtained by hydrothermal and soda pulping were less nanofibrillated than the corresponding material produced by soda pulping. However, the CNF sample obtained from soda pulp was cytotoxic, apparently due to a larger content of silica particles. All the CNF materials were 3D printable. We conclude that the noncytotoxic CNF produced from hydrothermally and soda treated pulp can potentially be used as inks for 3D printing of biomedical devices. 

  • 17.
    Courtade, Gaston
    et al.
    NTNU Norwegian University of Science and Technology, Norway.
    Forsberg, Zarah
    NMBU Norwegian University of Life Sciences, Norway.
    Heggset, Ellinor B
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Eijsink, Vincent G H
    NMBU Norwegian University of Life Sciences, Norway.
    Aachmann, Finn L
    NTNU Norwegian University of Science and Technology, Norway.
    The carbohydrate-binding module and linker of a modular lytic polysaccharide monooxygenase promote localized cellulose oxidation2018In: Journal of Biological Chemistry, ISSN 0021-9258, E-ISSN 1083-351X, Vol. 293, no 34, p. 13006-13015Article in journal (Refereed)
    Abstract [en]

    Lytic polysaccharide monooxygenases (LPMOs) are copper-dependent enzymes that catalyze the oxidative cleavage of polysaccharides such as cellulose and chitin, a feature that makes them key tools in industrial biomass conversion processes. The catalytic domains of a considerable fraction of LPMOs and other carbohydrate-active enzymes (CAZymes) are tethered to carbohydrate-binding modules (CBMs) by flexible linkers. These linkers preclude X-ray crystallographic studies, and the functional implications of these modular assemblies remain partly unknown. Here, we used NMR spectroscopy to characterize structural and dynamic features of full-length modular ScLPMO10C from Streptomyces coelicolor We observed that the linker is disordered and extended, creating distance between the CBM and the catalytic domain and allowing these domains to move independently of each other. Functional studies with cellulose nanofibrils revealed that most of the substrate-binding affinity of full-length ScLPMO10C resides in the CBM. Comparison of the catalytic performance of full-length ScLPMO10C and its isolated catalytic domain revealed that the CBM is beneficial for LPMO activity at lower substrate concentrations and promotes localized and repeated oxidation of the substrate. Taken together, these results provide a mechanistic basis for understanding the interplay between catalytic domains linked to CBMs in LPMOs and CAZymes in general.

  • 18.
    Espinosa, Eduardo
    et al.
    Universidad de Cordoba, Spain.
    Filgueira, Daniel
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Rodríguez, Alejandro
    Universidad de Cordoba, Spain.
    Chinga-Carrasco, Gary
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Nanocellulose-Based Inks-Effect of Alginate Content on the Water Absorption of 3D Printed Constructs.2019In: Bioengineering (Basel, Switzerland), ISSN 2306-5354, Vol. 6, no 3, article id E65Article in journal (Refereed)
    Abstract [en]

    2,2,6,6-tetramethylpyperidine-1-oxyl (TEMPO) oxidized cellulose nanofibrils (CNF) were used as ink for three-dimensional (3D) printing of porous structures with potential as wound dressings. Alginate (10, 20, 30 and 40 wt%) was incorporated into the formulation to facilitate the ionic cross-linking with calcium chloride (CaCl2). The effect of two different concentrations of CaCl2 (50 and 100 mM) was studied. The 3D printed hydrogels were freeze-dried to produce aerogels which were tested for water absorption. Scanning Electronic Microscopy (SEM) pictures demonstrated that the higher the concentration of the cross-linker the higher the definition of the printed tracks. CNF-based aerogels showed a remarkable water absorption capability. Although the incorporation of alginate and the cross-linking with CaCl2 led to shrinkage of the 3D printed constructs, the approach yielded suitable porous structures for water and moisture absorption. It is concluded that the 3D printed biocomposite structures developed in this study have characteristics that are promising for wound dressings devices.

  • 19.
    Filgueira, Daniel
    et al.
    University of Vigo, Spain.
    Holmen, Solveig
    NTNU, Norway.
    Melbø, Johnny K.
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Moldes, Diego
    University of Vigo, Spain.
    Echtermeyer, Andreas T.
    NTNU, Norway.
    Chinga-Carrasco, Gary
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    3D printable filaments made of biobased polyethylene biocomposites2018In: Polymers, ISSN 2073-4360, E-ISSN 2073-4360, Vol. 10, no 3, article id 314Article in journal (Refereed)
    Abstract [en]

    Two different series of biobased polyethylene (BioPE) were used for the manufacturing of biocomposites, complemented with thermomechanical pulp (TMP) fibers. The intrinsic hydrophilic character of the TMP fibers was previously modified by grafting hydrophobic compounds (octyl gallate and lauryl gallate) by means of an enzymatic-assisted treatment. BioPE with low melt flow index (MFI) yielded filaments with low void fraction and relatively low thickness variation. The water absorption of the biocomposites was remarkably improved when the enzymatically-hydrophobized TMP fibers were used. Importantly, the 3D printing of BioPE was improved by adding 10% and 20% TMP fibers to the composition. Thus, 3D printable biocomposites with low water uptake can be manufactured by using fully biobased materials and environmentally-friendly processes.

  • 20.
    Filgueira, Daniel
    et al.
    University of Vigo, Spain.
    Holmen, Solveig
    NTNU, Norway.
    Melbø, Johnny K.
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Moldes, Diego
    University of Vigo, Spain.
    Echtermeyer, Andreas T.
    NTNU, Norway.
    Chinga-Carrasco, Gary
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Enzymatic-Assisted Modification of Thermomechanical Pulp Fibers to Improve the Interfacial Adhesion with Poly(lactic acid) for 3D Printing2017In: ACS Sustainable Chemistry and Engineering, ISSN 2168-0485, Vol. 5, no 10, p. 9338-9346Article in journal (Refereed)
    Abstract [en]

    The present study is about the enzymatic modification of thermomechanical pulp (TMP) fibers for reduction of water uptake and their use in bio-based filaments for 3D printing. Additionally, TMP was used as a fiber reinforcing material and poly(lactic acid) (PLA) as the polymer matrix. The hydrophilic TMP fibers were treated via laccase-assisted grafting of octyl gallate (OG) or lauryl gallate (LG) onto the fiber surface. The modified TMP fibers showed remarkable hydrophobic properties, as demonstrated by water contact angle measurements. Filaments reinforced with OG-treated fibers exhibited the lowest water absorption and the best interfacial adhesion with the PLA matrix. Such higher chemical compatibility between the OG-treated fibers and the PLA enabled better stress transfer from the matrix to the fibers during mechanical testing, which led to the manufacture of strong filaments for 3D printing. All of the manufactured filaments were 3D-printable, although the filaments containing OG-treated fibers yielded the best results. Hence, laccase-mediated grafting of OG onto TMP fibers is a sustainable and environmentally friendly pathway for the manufacture of fully bio-based filaments for 3D printing.

  • 21.
    Heggset, Ellinor B
    et al.
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Chinga-Carrasco, Gary
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Syverud, Kristin
    RISE - Research Institutes of Sweden, Bioeconomy, PFI. NTNU Norwegian University of Science and Technology, Norway.
    Temperature stability of nanocellulose dispersions2017In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 157, p. 114-121Article in journal (Refereed)
    Abstract [en]

    Cellulose nanofibrils (CNF) have potential as rheology modifiers of water based fluids, e.g. drilling fluids for use in oil wells or as additives in injection water for enhanced oil recovery (EOR). The temperature in oil wells can be high (>100 °C), and the retention time long; days for drilling fluids and months for EOR fluids. Hence, it is important to assess the temperature stability over time of nanocellulose dispersions to clarify their suitability as rheology modifiers of water based fluids at such harsh conditions. Dispersions of CNF produced mechanically, by using TEMPO mediated oxidation and by using carboxymethylation as pretreatment, in addition to cellulose nanocrystals (CNC), have been subjected to heat aging. Temperature stability was best for CNC and for mechanically produced CNF that were stable after heating to 140 °C for three days. The effect of additives was evaluated; cesium formate and sodium formate increased the temperature stability of the dispersions, while there was no effect of using phosphate buffer.

  • 22.
    Heggset, Ellinor B
    et al.
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Strand, Berit L.
    NTNU Norwegian University of Science and Technology, Norway.
    Sundby, Kristin W.
    Borregaard, Norway.
    Simon, Sebastien
    NTNU Norwegian University of Science and Technology, Norway.
    Chinga-Carrasco, Gary
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Syverud, Kristin
    RISE - Research Institutes of Sweden, Bioeconomy, PFI. NTNU Norwegian University of Science and Technology, Norway.
    Viscoelastic properties of nanocellulose based inks for 3D printing and mechanical properties of CNF/alginate biocomposite gels2019In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, no 1, p. 581-595Article in journal (Refereed)
    Abstract [en]

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

  • 23.
    Hegnar, Olav
    et al.
    Norwegian Institute for Bioeconomy Research, Norway.
    Goodell, Barry
    University of Massachusetts, US.
    Felby, Claus
    University of Copenhagen, Denmark.
    Johansson, Lars
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Labbé, Nicole
    University of Tennessee, US.
    Kim, Keonhee
    University of Tennessee, US.
    Eijsink, Vincent
    Norwegian University of Life Sciences, Norway.
    Alfredsen, Gry
    Norwegian Institute for Bioeconomy Research, Norway; Norwegian University of Life Sciences, Norway.
    Várnai, Aniko
    Norwegian University of Life Sciences, Norway.
    Challenges and opportunities in mimicking non-enzymatic brown-rot decay mechanisms for pretreatment of Norway spruce2019In: Wood Science and Technology, ISSN 0043-7719, E-ISSN 1432-5225, Vol. 53, no 2, p. 291-311Article in journal (Refereed)
    Abstract [en]

    The recalcitrance bottleneck of lignocellulosic materials presents a major challenge for biorefineries, including second-generation biofuel production. Because of their abundance in the northern hemisphere, softwoods, such as Norway spruce, are of major interest as a potential feedstock for biorefineries. In nature, softwoods are primarily degraded by basidiomycetous fungi causing brown rot. These fungi employ a non-enzymatic oxidative system to depolymerize wood cell wall components prior to depolymerization by a limited set of hydrolytic and oxidative enzymes. Here, it is shown that Norway spruce pretreated with two species of brown-rot fungi yielded more than 250% increase in glucose release when treated with a commercial enzyme cocktail and that there is a good correlation between mass loss and the degree of digestibility. A series of experiments was performed aimed at mimicking the brown-rot pretreatment, using a modified version of the Fenton reaction. A small increase in digestibility after pretreatment was shown where the aim was to generate reactive oxygen species within the wood cell wall matrix. Further experiments were performed to assess the possibility of performing pretreatment and saccharification in a single system, and the results indicated the need for a complete separation of oxidative pretreatment and saccharification. A more severe pretreatment was also completed, which interestingly did not yield a more digestible material. It was concluded that a biomimicking approach to pretreatment of softwoods using brown-rot fungal mechanisms is possible, but that there are additional factors of the system that need to be known and optimized before serious advances can be made to compete with already existing pretreatment methods.

  • 24.
    Hill, Jan
    et al.
    QualTech AB, Sweden.
    Johansson, Lars
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Mörseburg, Kathrin
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    ATMP pulping of Norway spruce: Pulp property development and energy efficiency2017In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 32, no 1, p. 70-86Article in journal (Refereed)
    Abstract [en]

    ATMP pilot refining trials on Norway spruce were conducted. The ATMP configuration consists of selective wood disintegration and targeted application of chemicals when defibration already is initiated in order to achieve energy-efficient final fibre separation and development. ATMP was compared to TMP and RTS. The TMP like character was maintained despite of differences in pre-treatment, chemicals and primary stage refining energies. The fractional composition of the pulps was, however, altered. Bauer McNett R14 fraction exhibited the largest differences followed by P200 fraction. Thus different process alternatives produced pulps with different fingerprints. The amount of the R14 fibres is important as these tend to cause surface roughness impairing printability. Regardless of strategy, the ATMP pulp properties at equal tensile index (44 Nm/g) were equal or superior to those achieved by TMP or RTS refining. The main difference was the required specific energy input, ranging from 1.71 (TMP) to 1.05 MWh/BDT (ATMP with bisulphite addition). Primary stage refining was explored from multiple trials with the same process configuration and chemistry. The higher the specific energy applied the better is the energy efficiency. Furthermore established refining theories appear inadequate in describing the differences between process alternatives with respect to energy efficiency and pulp property development.

  • 25.
    Jack, Alison A
    et al.
    Cardiff University School of Dentistry, UK.
    Nordli, Henriette R
    NTNU, Norway.
    Powell, Lydia C
    Cardiff University School of Dentistry, UK.
    Farnell, Damian J J
    Cardiff University School of Dentistry, UK.
    Pukstad, Brita
    NTNU, Norway; Trondheim University Hospital, Norway.
    Rye, Philip D
    AlgiPharma AS, Norway.
    Thomas, David W
    Cardiff University School of Dentistry, UK.
    Chinga-Carrasco, Gary
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Hill, Katja E
    Cardiff University School of Dentistry, UK.
    Cellulose Nanofibril Formulations Incorporating a Low-Molecular-Weight Alginate Oligosaccharide Modify Bacterial Biofilm Development.2019In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602Article in journal (Refereed)
    Abstract [en]

    Cellulose nanofibrils (CNFs) from wood pulp are a renewable material possessing advantages for biomedical applications because of their customizable porosity, mechanical strength, translucency, and environmental biodegradability. Here, we investigated the growth of multispecies wound biofilms on CNF formulated as aerogels and films incorporating the low-molecular-weight alginate oligosaccharide OligoG CF-5/20 to evaluate their structural and antimicrobial properties. Overnight microbial cultures were adjusted to 2.8 × 109 colony-forming units (cfu) mL-1 in Mueller Hinton broth and growth rates of Pseudomonas aeruginosa PAO1 and Staphylococcus aureus 1061A monitored for 24 h in CNF dispersions sterilized by γ-irradiation. Two CNF formulations were prepared (20 g m-2) with CNF as air-dried films or freeze-dried aerogels, with or without incorporation of an antimicrobial alginate oligosaccharide (OligoG CF-5/20) as a surface coating or bionanocomposite, respectively. The materials were structurally characterized by scanning electron microscopy (SEM) and laser profilometry (LP). The antimicrobial properties of the formulations were assessed using single- and mixed-species biofilms grown on the materials and analyzed using LIVE/DEAD staining with confocal laser scanning microscopy (CLSM) and COMSTAT software. OligoG-CNF suspensions significantly decreased the growth of both bacterial strains at OligoG concentrations >2.58% (P < 0.05). SEM showed that aerogel-OligoG bionanocomposite formulations had a more open three-dimensional structure, whereas LP showed that film formulations coated with OligoG were significantly smoother than untreated films or films incorporating PEG400 as a plasticizer (P < 0.05). CLSM of biofilms grown on films incorporating OligoG demonstrated altered biofilm architecture, with reduced biomass and decreased cell viability. The OligoG-CNF formulations as aerogels or films both inhibited pyocyanin production (P < 0.05). These novel CNF formulations or bionanocomposites were able to modify bacterial growth, biofilm development, and virulence factor production in vitro. These data support the potential of OligoG and CNF bionanocomposites for use in biomedical applications where prevention of infection or biofilm growth is required.

  • 26.
    Jack, Alison A.
    et al.
    Cardiff University School of Dentistry, UK.
    Nordli, Henriette R.
    NTNU, Norway.
    Powell, Lydia C.
    Cardiff University School of Dentistry, UK.
    Powell, Kate A.
    Cardiff University School of Dentistry, UK.
    Kishnani, Himanshu
    Cardiff University School of Dentistry, UK.
    Johnsen, Per Olav
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Pukstad, Brita
    Trondheim University Hospital, Norway.
    Thomas, David W.
    Cardiff University School of Dentistry, UK.
    Chinga-Carrasco, Gary
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Hill, Katja E.
    Cardiff University School of Dentistry, UK.
    The interaction of wood nanocellulose dressings and the wound pathogen P. aeruginosa2017In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 157, p. 1955-1962Article in journal (Refereed)
    Abstract [en]

    Chronic wounds pose an increasingly significant worldwide economic burden (over £1 billion per annum in the UK alone). With the escalation in global obesity and diabetes, chronic wounds will increasingly be a significant cause of morbidity and mortality. Cellulose nanofibrils (CNF) are highly versatile and can be tailored with specific physical properties to produce an assortment of three-dimensional structures (hydrogels, aerogels or films), for subsequent utilization as wound dressing materials. Growth curves using CNF (diameter &lt;20 nm) in suspension demonstrated an interesting dose-dependent inhibition of bacterial growth. In addition, analysis of biofilm formation (Pseudomonas aeruginosa PAO1) on nanocellulose aerogels (20 g/m2) revealed significantly less biofilm biomass with decreasing aerogel porosity and surface roughness. Importantly, virulence factor production by P. aeruginosa in the presence of nanocellulose materials, quantified for the first time, was unaffected (p &gt; 0.05) over 24 h. These data demonstrate the potential of nanocellulose materials in the development of novel dressings that may afford significant clinical potential.

  • 27.
    Jakobsen, Trygve Dagsloth
    et al.
    NTNU Norwegian University of Science and Technology, Norway.
    Simon, Sebastien
    NTNU Norwegian University of Science and Technology, Norway.
    Heggset, Ellinor B
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Syverud, Kristin
    RISE - Research Institutes of Sweden, Bioeconomy, PFI. NTNU Norwegian University of Science and Technology, Norway.
    Paso, Kristofer
    NTNU Norwegian University of Science and Technology, Norway.
    Interactions between surfactants and cellulose nanofibrils for enhanced oil recovery2018In: Industrial & Engineering Chemistry Research, ISSN 0888-5885, E-ISSN 1520-5045, Vol. 57, no 46, p. 15749-15758Article in journal (Refereed)
    Abstract [en]

    Chemical enhanced oil recovery (EOR) represents a series of potential solutions for extracting more oil from resources with already known locations and magnitudes. Unfortunately, many of the chemical additives in use today are not environmentally friendly. In the study a "greener" alternative for increasing viscosity of the injection water is investigated, namely cellulose nanofibrils (CNF). The nanofibrils are combined in systems with anionic sulfonate surfactants, SDBS and AOT, in order to decrease interfacial tension (IFT) between oil and water. In combination, the increase of water viscosity and decrease of IFT should result in higher ultimate oil recovery than if only conventional water flooding was applied. Interactions between cellulose nanofibrils and the surfactants have been investigated through adsorption studies, rheology, and IFT measurements. An observed synergy effect between CNF and surfactants upon viscosity of injection water, as well as with substantial decrease in IFT, leads the authors to the conclusion that an EOR system consisting of CNF and sulfonate surfactants has good potential for future applications.

  • 28.
    Kangas, Heli
    et al.
    VTT, Finland.
    Felissia, Fernando E
    IMAM Instituto de Materiales de Misiones, Argentina.
    Filgueira, Daniel
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Ehman, Nanci V
    IMAM Instituto de Materiales de Misiones, Argentina.
    Vallejos, María E
    IMAM Instituto de Materiales de Misiones, Argentina.
    Imlauer, Camila M
    IMAM Instituto de Materiales de Misiones, Argentina.
    Lahtinen, Panu
    VTT, Finland.
    Area, María C
    IMAM Instituto de Materiales de Misiones, Argentina.
    Chinga-Carrasco, Gary
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    3D Printing High-Consistency Enzymatic Nanocellulose Obtained from a Soda-Ethanol-O2 Pine Sawdust Pulp.2019In: Bioengineering (Basel, Switzerland), ISSN 2306-5354, Vol. 6, no 3, article id E60Article in journal (Refereed)
    Abstract [en]

    Soda-ethanol pulps, prepared from a forestry residue pine sawdust, were treated according to high-consistency enzymatic fibrillation technology to manufacture nanocellulose. The obtained nanocellulose was characterized and used as ink for three-dimensional (3D) printing of various structures. It was also tested for its moisture sorption capacity and cytotoxicity, as preliminary tests for evaluating its suitability for wound dressing and similar applications. During the high-consistency enzymatic treatment it was found that only the treatment of the O2-delignified pine pulp resulted in fibrillation into nano-scale. For 3D printing trials, the material needed to be fluidized further. By 3D printing, it was possible to fabricate various structures from the high-consistency enzymatic nanocellulose. However, the water sorption capacity of the structures was lower than previously seen with porous nanocellulose structures, indicating that further optimization of the material is needed. The material was found not to be cytotoxic, thus showing potential as material, e.g., for wound dressings and for printing tissue models.

  • 29.
    Karlström, Anders
    et al.
    Chalmers University of Technology, Sweden.
    Johansson, Lars
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Hill, Jan
    QualTech, Sweden.
    On the modeling of tensile index from larger data sets2019In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669Article in journal (Refereed)
    Abstract [en]

    The objective of this study is to analyze and foresee potential outliers in pulp and handsheet properties for larger data sets. The method is divided into two parts comprising a generalized Extreme Studentized Deviate (ESD) procedure for laboratory data followed by an analysis of the findings using a multivariable model based on internal variables (i. e. process variables like consistency and fiber residence time inside the refiner) as predictors. The process data used in this has been obtained from CD-82 refiners and from a laboratory test program perspective, the test series were extensive. In the procedure more than 290 samples were analyzed to get a stable outlier detection. Note, this set was obtained from pulp at one specific operating condition. When comparing such "secured data sets" with process data it is shown that an extended procedure must be performed to get data sets which cover different operating points. Here 100 pulp samples at different process conditions were analyzed. It is shown that only about 60 percent of all tensile index measurements were accepted in the procedure which indicates the need to oversample when performing extensive trials to get reliable pulp and handsheet properties in TMP and CTMP processes.

  • 30.
    Kumar, Vinay
    et al.
    Åbo Akademi University, Finland.
    Ottesen, Vegar
    NTNU, Norway.
    Syverud, Kristin
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Gregersen, Öyvind Weiby
    NTNU, Norway.
    Toivakka, Martti
    Åba Akademi University, Finland.
    Coatability of cellulose nanofibril suspensions: Role of rheology and water retention2017In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 12, no 4, p. 7656-7679Article in journal (Refereed)
    Abstract [en]

    Cellulose nanofibril (CNF) suspensions are not easily coatable because of their excessively high viscosity and yield stress, even at low solids concentrations. In addition, CNF suspensions vary widely in their properties depending on the production process used, which can affect their processability. This work reports roll-to-roll coating of three different types of CNF suspensions with a slot-die, and the influence of rheology and water retention on coatability is addressed. The impact of CMC addition on the high and low shear rate rheology, water retention, coatability, and final coating quality of these suspensions is reported. All three CNF suspensions were coated successfully using the slot-die coating process. CMC addition further improved the coatability by positively influencing both the low and high shear rate viscosity and water retention of the CNF suspensions. All CNF coatings significantly improved the air, heptane vapor, grease and oil barrier, while reducing the water vapor transmission rate to some extent.

  • 31.
    Mihiretu, Gezahegn T.
    et al.
    RISE - Research Institutes of Sweden, Bioeconomy, PFI. Stellenbosch University, South Africa.
    Brodin, Malin
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Chimphango, Annie F.
    Stellenbosch University, South Africa.
    ֘yaas, Karin
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Hoff, Bård H
    NTNU Norwegian University of Science and Technology, Norway.
    Görgens, Johann F.
    Stellenbosch University, South Africa.
    Single-step microwave-assisted hot water extraction of hemicelluloses from selected lignocellulosic materials: A biorefinery approach2017In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 241, p. 669-680Article in journal (Refereed)
    Abstract [en]

    The viability of single-step microwave-induced pressurized hot water conditions for co-production of xylan-based biopolymers and bioethanol from aspenwood sawdust and sugarcane trash was investigated. Extraction of hemicelluloses was conducted using microwave-assisted pressurized hot water system. The effects of temperature and time on extraction yield and enzymatic digestibility of resulting solids were determined. Temperatures between 170–200 °C for aspenwood and 165–195 °C for sugarcane trash; retention times between 8–22 min for both feedstocks, were selected for optimization purpose. Maximum xylan extraction yields of 66 and 50%, and highest cellulose digestibilities of 78 and 74%, were attained for aspenwood and sugarcane trash respectively. Monomeric xylose yields for both feedstocks were below 7%, showing that the xylan extracts were predominantly in non-monomeric form. Thus, single-step microwave-assisted hot water method is viable biorefinery approach to extract xylan from lignocelluloses while rendering the solid residues sufficiently digestible for ethanol production.

  • 32.
    Molnes, Silje N.
    et al.
    University of Stavanger, Norway; NTNU Norwegian University of Science and Technology, Norway.
    Mamonov, Aleksandr
    University of Stavanger, Norway.
    Paso, Kristofer G.
    NTNU Norwegian University of Science and Technology, Norway.
    Strand, Skule
    University of Stavanger, Norway.
    Syverud, Kristin
    RISE - Research Institutes of Sweden, Bioeconomy, PFI. NTNU Norwegian University of Science and Technology, Norway.
    Investigation of a new application for cellulose nanocrystals: a study of the enhanced oil recovery potential by use of a green additive2018In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 25, no 4, p. 2289-2301Article in journal (Refereed)
    Abstract [en]

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

  • 33.
    Molnes, Silje N.
    et al.
    NTNU Norwegian University of Science and Technology, Norway; University of Stavanger, Norway.
    Paso, Kristofer G.
    NTNU Norwegian University of Science and Technology, Norway.
    Strand, Skule
    University of Stavanger, Norway.
    Syverud, Kristin
    RISE - Research Institutes of Sweden, Bioeconomy, PFI. NTNU Norwegian University of Science and Technology, Norway.
    The effects of pH, time and temperature on the stability and viscosity of cellulose nanocrystal (CNC) dispersions: implications for use in enhanced oil recovery2017In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 24, no 10, p. 4479-4491Article in journal (Refereed)
    Abstract [en]

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

  • 34.
    Ojansivu, Miina
    et al.
    Tampere University, Finland.
    Rashad, Ahmad
    University of Bergen, Norway.
    Ahlinder, Astrid Elisabet
    KTH Royal institute of technology, Sweden.
    Massera, Jonathan
    Tampere University, Finland.
    Mishra, Ayush
    Tampere University, Finland.
    Syverud, Kristin
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Finne-Wistrand, Anna
    KTH Royal institute of technology, Sweden.
    Miettinen, Susanna
    Tampere University, Finland.
    Mustafa, Kamal
    University of Bergen, Norway.
    Wood-based nanocellulose and bioactive glass modified gelatin-alginate bioinks for 3D bioprinting of bone cells2019In: Biofabrication, ISSN 1758-5082, E-ISSN 1758-5090, Vol. 11, no 3Article in journal (Refereed)
    Abstract [en]

    A challenge in the extrusion-based bioprinting is to find a bioink with optimal biological and physicochemical properties. The aim of this study was to evaluate the influence of wood-based cellulose nanofibrils (CNF) and bioactive glass on the rheological properties of gelatin-alginate bioinks and the initial responses of bone cells embedded in these inks. CNF modulated the flow behavior of the hydrogels, thus improving their printability. Chemical characterization by SEM-EDX and ion release analysis confirmed the reactivity of the BaG in the hydrogels. The cytocompatibility of the hydrogels was shown to be good, as evidenced by the viability of human osteoblast-like cells (Saos-2) in cast hydrogels. For bioprinting, 4-layer structures were printed from cell-containing gels and crosslinked with CaCl2. Viability, proliferation and alkaline phosphatase activity (ALP) were monitored over 14 days. In the BaG-free gels, Saos-2 cells remained viable, but in the presence of BaG the viability and proliferation decreased in correlation with the increased viscosity. Still, there was a constant increase in the ALP activity in all the hydrogels. Further bioprinting experiments were conducted using human bone marrow-derived mesenchymal stem cells (hBMSCs), a clinically relevant cell type. Interestingly, hBMSCs tolerated the printing process better than Saos-2 cells and the ALP indicated BaG-stimulated early osteogenic commitment. The addition of CNF and BaG to gelatin-alginate bioinks hold great potential for bone tissue engineering applications.

  • 35.
    Ottesen, Vegar
    et al.
    NTNU Norwegian University of Science and Technology, Norway.
    Kumar, Vinay Santhosh
    Åbo Akademi University, Finland.
    Toivakka, Martti
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Chinga-Carrasco, Gary
    Syverud, Kristin
    RISE - Research Institutes of Sweden, Bioeconomy, PFI. NTNU Norwegian University of Science and Technology, Norway.
    Weiby Gregersen, Öyvind
    NTNU Norwegian University of Science and Technology, Norway.
    Viability and properties of roll-to-roll coating of cellulose nanofibrils on recycled paperboard2017In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 32, no 2, p. 179-188Article in journal (Refereed)
    Abstract [en]

    Cellulose nanofibrils (CNF) are, due in large part to excellent gas barrier properties, a potential environmentally friendly alternative to inorganic and petrochemical coatings of e.g. paperboard in packaging applications. In the current paper successful roll-to-roll coating of three qualities of CNF is demonstrated on a recycled quality, porous paperboard using a custom-built pilot machine. Single layers of three different thicknesses were applied for each coating. The three CNF qualities used were carboxymethylated CNF (CNF-C), TEMPOoxidized CNF (CNF-T) and mechanically produced CNF without chemical pre-treatment (CNF-M). All three qualities, which have a range of surface charge, fibril size and fibril size distribution, are shown to produce films that adhere well to the base board. It is revealed that the coating is suspended across surface pores in the base board, as opposed to penetrate into the base board pore structure. Samples were investigated for air and water permeability, gloss, surface roughness and hole density in the coating. Chemically pretreated qualities outperform CNF-M. Addition of 5 wt% carboxy-methyl cellulose (CMC) was shown to reduce hole formation, improve gloss and reduce surface roughness. For thick applications of pre-treated CNF, in particular CNF-C, mechanical strength of the board in and out of the plane increase beyond the un-treated or water treated base board. Possibly a consequence of matter migrating through the base board from the CNF suspension.

  • 36.
    Ottesen, Vegar
    et al.
    NTNU, Norway.
    Larsson, Per Tomas
    KTH Royal Institute of Technology,´Sweden.
    Chinga-Carrasco, Gary
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Syverud, Kristin
    RISE - Research Institutes of Sweden, Bioeconomy, PFI. NTNU, Norway.
    Gregersen, Öyvind
    NTNU, Norway.
    Mechanical properties of cellulose nanofibril films: effects of crystallinity and its modification by treatment with liquid anhydrous ammonia2019In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 26, no 11, p. 6615-27Article in journal (Refereed)
    Abstract [en]

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

  • 37.
    Ottesen, Vegar
    et al.
    NTNU Norwegian university of science and technology, Norway.
    Roede, Erik Dobloug
    NTNU Norwegian university of science and technology, Norway.
    Syverud, Kristin
    RISE - Research Institutes of Sweden, Bioeconomy, PFI. NTNU Norwegian university of science and technology, Norway.
    Gregersen, Øyvind Weiby
    NTNU Norwegian university of science and technology, Norway.
    Focused ion beam tomography as a means for characterization of CNF in a paper matrix2017In: 16th Fundamental Research symposium, 2017, p. 595-609Conference paper (Refereed)
  • 38.
    Rashad, Ahmad
    et al.
    University of Bergen, Norway.
    Mohamed-Ahmed, Samih
    University of Bergen, Norway.
    Ojansivu, Miina
    University of Bergen, Norway; University of Tampere, Finland.
    Berstad, Kaia
    University of Bergen, Norway.
    Yassin, Mohammad
    University of Bergen, Norway.
    Kivijärvi, Tove
    KTH Royal Institute of Technology, Sweden.
    Heggset, Ellinor B
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Syverud, Kristin
    RISE - Research Institutes of Sweden, Bioeconomy, PFI. NTNU Norwegian University of Science and Technology, Norway.
    Mustafa, Kamal
    University of Bergen, Norway.
    Coating 3D Printed Polycaprolactone Scaffolds with Nanocellulose Promotes Growth and Differentiation of Mesenchymal Stem Cells2018In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 19, no 11, p. 4307-4319Article in journal (Refereed)
    Abstract [en]

    3D printed polycaprolactone (PCL) has potential as a scaffold for bone tissue engineering, but the hydrophobic surface may hinder optimal cell responses. The surface properties can be improved by coating the scaffold with cellulose nanofibrils material (CNF), a multiscale hydrophilic biocompatible biomaterial derived from wood. In this study, human bone marrow-derived mesenchymal stem cells were cultured on tissue culture plates (TCP) and 3D printed PCL scaffolds coated with CNF. Cellular responses to the surfaces (viability, attachment, proliferation, and osteogenic differentiation) were documented. CNF significantly enhanced the hydrophilic properties of PCL scaffolds and promoted protein adsorption. Live/dead staining and lactate dehydrogenase release assays confirmed that CNF did not inhibit cellular viability. The CNF between the 3D printed PCL strands and pores acted as a hydrophilic barrier, enhancing cell seeding efficiency, and proliferation. CNF supported the formation of a well-organized actin cytoskeleton and cellular production of vinculin protein on the surfaces of TCP and PCL scaffolds. Moreover, CNF-coated surfaces enhanced not only alkaline phosphatase activity, but also collagen Type-I and mineral formation. It is concluded that CNF coating enhances cell attachment, proliferation, and osteogenic differentiation and has the potential to improve the performance of 3D printed PCL scaffolds for bone tissue engineering.

  • 39.
    Rashad, Ahmad
    et al.
    University of Bergen, Norway.
    Suliman, Salwa
    University of Bergen, Norway.
    Mustafa, Manal
    Oral Health Centre of Expertise in Western Norway, Norway.
    Pedersen, Torbjörn
    University of Bergen, Norway.
    Campodoni, Elisabetta
    National Research Council of Italy, Italy.
    Sandri, Monica
    National Research Council of Italy, Italy.
    Syverud, Kristin
    RISE - Research Institutes of Sweden, Bioeconomy, PFI. NTNU Norwegian University of Science and Technology, Norway.
    Mustafa, Kamal
    University of Bergen, Norway.
    Inflammatory responses and tissue reactions to wood-Based nanocellulose scaffolds2019In: Materials science & engineering. C, biomimetic materials, sensors and systems, ISSN 0928-4931, E-ISSN 1873-0191, Vol. 97, p. 208-221Article in journal (Refereed)
    Abstract [en]

    Two wood-derived cellulose nanofibril (CNF) porous scaffolds were prepared by TEMPO-oxidation and carboxymethylation. The effects of these scaffolds on the production of inflammatory cytokines by human macrophage-like cells (U937) was profiled in vitro after 1 and 3 days and in subcutaneous tissues of rats after 4 and 30 days, using PCR and Multiplex arrays. Tissue culture plates (TCP) and gelatin scaffolds served as controls in vitro and in vivo respectively. After 3 days in vitro, there was no significant difference between the effects of CNF scaffolds and TCP on the production of chemokines/growth factors and pro-inflammatory cytokines. At day 4 in vivo there was significantly higher gene expression of the anti-inflammatory IL-1Ra in the CNF scaffolds than the gelatin scaffold. Production of IL-1β, IL-6, MCP-1, MIP-1α CXCL-1 and M-CSF was significantly less than in the gelatin, demonstrating an early mild inflammatory response. At day 30, both CNF scaffolds significantly stimulated the production of the anti-inflammatory cytokine IL-10. Unlike gelatin, neither CNF scaffold had degraded 180 days post-implantation. The slow degradation of CNF scaffolds resulted in a foreign body reaction, with high production of IL-1β, IL-2, TNF-α, IFN-ϒ, MCP-1, MIP-1α, M-CSF, VEGF cytokines and expression of MMP-9 gene. The surface chemistry of the CNF scaffolds elicited a modest effect on cytokine production and did not shift the inflammatory profile in vitro or in vivo. The decisive role in development of the foreign body reaction was the slow degradation of the CNF scaffolds.

  • 40.
    Rashad, Amad
    et al.
    University of Bergen, Norway.
    Mustafa, Kamal
    University of Bergen, Norway.
    Heggset, Ellinor B
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Syverud, Kristin
    RISE - Research Institutes of Sweden, Bioeconomy, PFI. NTNU Norwegian University of Science and Technology, Norway.
    Cytocompatibility of Wood-Derived Cellulose Nanofibril Hydrogels with Different Surface Chemistry2017In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 18, no 4, p. 1238-1248Article in journal (Refereed)
    Abstract [en]

    The current study aims to demonstrate the influence of the surface chemistry of wood-derived cellulose nanofibril (CNF) hydrogels on fibroblasts for tissue engineering applications. TEMPO-mediated oxidation or carboxymethylation pretreatments were employed to produce hydrogels with different surface chemistry. This study demonstrates the following: first, the gelation of CNF with cell culture medium and formation of stable hydrogels with improved rheological properties; second, the response of mouse fibroblasts cultured on the surface of the hydrogels or sandwiched within the materials with respect to cytotoxicity, cell attachment, proliferation, morphology, and migration. Indirect cytotoxicity tests showed no toxic effect of either hydrogel. The direct contact with the carboxymethylated hydrogel adversely influenced the morphology of the cells and limited their spreading, while typical morphology and spreading of cells were observed with the TEMPO-oxidized hydrogel. The porous fibrous structure may be a key to cell proliferation and migration in the hydrogels.

  • 41.
    Rusu, Caterina
    et al.
    NTNU, Norway.
    Brodin, Malin
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Hausvik, Tor Inge
    Berry Alloc, Norway.
    Hindersland, Leif Kåre
    Berry Alloc, Norway.
    Chinga-Carrasco, Gary
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Einarsrud, Mary Anne
    NTNU, Norway.
    Lein, Hilde
    NTNU, Norway.
    The potential of functionalized ceramic particles in coatings for improved scratch resistance2018In: Coatings, ISSN 2079-6412, Vol. 8, no 6, article id 224Article in journal (Refereed)
    Abstract [en]

    The top layer of a typical high pressure floor laminate (HPL) consists of a melamine formaldehyde (MF) impregnated special wear layer (overlay) with alumina particles. This top layer plays a crucial role in determining the mechanical properties of the laminate. For HPLs, scratch resistance and scratch visibility are particularly important properties. This study aimed to improve the mechanical properties, particularly the scratch resistance, by adjusting the composition of the overlay. Laminates containing alumina particles were prepared and tested. These alumina particles were additionally functionalized with a silane coupling agent to ensure better adhesion between the particles and the resin. The functionalized particles led to enhanced scratch resistance of the laminates as well as improved dispersion of the particles within the resin. Micro scratch testing revealed that by using functionalized particles, the scratch surface damage was reduced and the recovery characteristics of the surface layer were improved. Higher scratch resistance and scratch hardness were thus obtained, along with a reduced scratch visibility.

  • 42.
    Silva, Filomena
    et al.
    ARAID Agencia Aragonesa para la Investigación y el Desarollo, Spain; University of Zaragoza, Spain; University of Beira Interior, Portugal .
    Gracia, Nicolas
    University of Zaragoza, Spain.
    McDonagh, Birgitte
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Domingues, Fernanda
    University of Beira Interior, Portugal.
    Nerín, Cristina
    University of Zaragoza, Spain.
    Chinga-Carrasco, Gary
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Antimicrobial activity of biocomposite films containing cellulose nanofibrils and ethyl lauroyl arginate2019In: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 54, no 18, p. 12159-70Article in journal (Refereed)
    Abstract [en]

    Food packaging is tailored to keep food fresh by increasing shelf life and preventing microbial deterioration. However, traditional food packaging is commonly made from non-degradable polymers without antimicrobial properties and that pose an environmental threat if not disposed properly. To address this issue, here we describe the preparation of cellulose nanofibril (CNF) films and hydrogels with antimicrobial activity against common foodborne pathogens such as verotoxigenic E. coli, L. monocytogenes and S. Typhimurium. Furthermore, two grades of negatively charged CNFs with different fibrillation degrees were modified with ethyl lauroyl arginate (LAE), which is an antimicrobial agent. CNF films were able to bind LAE molecules up to a maximum concentration of 145–160 ppm. LAE–CNF biocomposite films exerted a bactericidal activity against a major foodborne pathogen present in ready-to-eat food (L. monocytogenes) even at 1% LAE. Our work describes a novel biopolymer-based strategy that overcomes the current hurdles with LAE incorporation into packaging materials, offering a green and antimicrobial alternative for packaging of ready-to-eat (RTE) meat products. .

  • 43.
    Sun, Fengzhen
    et al.
    Uppsala University, Sweden.
    Nordli, Henriette R.
    NTNU Norwegian University of Science and Technology, Norway.
    Pukstad, Brita
    NTNU Norwegian University of Science and Technology, Norway ; Trondheim University Hospital, Norway.
    Gamstedt, E. Kristofer
    Uppsala University, Sweden.
    Chinga-Carrasco, Gary
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Mechanical characteristics of nanocellulose-PEG bionanocomposite wound dressings in wet conditions2017In: Journal of The Mechanical Behavior of Biomedical Materials, ISSN 1751-6161, E-ISSN 1878-0180, Vol. 69, p. 377-384Article in journal (Refereed)
    Abstract [en]

    Wood nanocellulose has been proposed for wound dressing applications partly based on its capability to form translucent films with good liquid absorption capabilities. Such properties are adequate for non-healing and chronic wounds where adequate management of exudates is a requirement. In addition, the translucency will allow to follow the wound development without the necessity to remove the dressing from the wound. Understanding the mechanical properties of nanocellulose films and dressings are also most important for tailoring optimizing wound dressing structures with adequate strength, conformability, porosity and exudate management. Mechanical properties are usually assessed in standard conditions (50% relative humidity, RH), which is not relevant in a wound management situation. In this study we have assessed the mechanical properties of three nanocellulose grades varying in the degree of nanofibrillation. The effect of nanofibrillation and of polyethylene glycol (PEG) addition, on the tensile strength, elongation and elastic modulus were assessed after 24 h in water and in phosphate-buffered saline (PBS). The results reveal the behavior of the nanocellulose dressings after wetting and shed light into the development of mechanical properties in environments, which are relevant from a wound management point of view.

  • 44.
    Syrový, Tomas
    et al.
    University of Pardubice, Czech Republic.
    Maronová, Stanislava
    University of Pardubice, Czech Republic.
    Kuberský, Petr
    University of West Bohemia, Czech Republic.
    Ehman, Nanci
    Instituto de Materiales de Misiones, Argentina.
    Vallejos, Maria
    Instituto de Materiales de Misiones, Argentina.
    Pretl, Silvan
    University of West Bohemia, Czech Republic.
    Felissia, Fernando
    Instituto de Materiales de Misiones, Argentina.
    Area, Maria
    Instituto de Materiales de Misiones, Argentina.
    Chinga-Carrasco, Gary
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Wide range humidity sensors printed on biocomposite films of cellulose nanofibril and poly(ethylene glycol)2019In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, article id 47920Article in journal (Refereed)
    Abstract [en]

    Cellulose nanofibril (CNF) films were prepared from side streams generated by the sugarcane industry, that is, bagasse. Two fractionation processes were utilized for comparison purposes: (1) soda and (2) hot water and soda pretreatments. 2,2,6,6-Tetramethylpiperidinyl-1-oxyl-mediated oxidation was applied to facilitate the nanofibrillation of the bagasse fibers. Poly(ethylene glycol) (PEG) was chosen as plasticizer to improve the ductility of CNF films. The neat CNF and biocomposite films (CNF and 40% PEG) were used for fabrication of self-standing humidity sensors. CNF-based humidity sensors exhibited high change of impedance, within four orders of magnitude, in response to relative humidity (RH) from 20 to 90%. The use of plasticizer had an impact on sensor kinetics. While the biocomposite film sensors showed slightly longer response time, the recovery time of these plasticized sensors was two times shorter in comparison to sensors without PEG. This study demonstrated that agroindustrial side streams can form the basis for high-end applications such as humidity sensors, with potential for, for example, packaging and wound dressing applications. 

  • 45.
    Tanase-Opedal, Mikaela
    et al.
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Eriksen, Öyvind
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Toven, Kai
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Increase accessibility for enzymatic hydrolysis of Norway spruce by organosolv pre-treatment in a novel reactor2018In: The 8th Nordic Wood Biorefinery Conference: NWBC 2018: proceedings / [ed] Hytönen Eemeli, Vepsäläinen Jessica, Espoo: VTT Technical Research Centre of Finland , 2018, p. 177-177Conference paper (Refereed)
  • 46.
    Tarrés, Q.
    et al.
    University of Girona, Italy.
    Melbø, Johnny Kvakland
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Delgado-Aguilar, M.
    University of Girona, Italy.
    Espinach, F. X.
    University of Girona, Italy.
    Mutjé, P.
    University of Girona, Italy.
    Chinga-Carrasco, Gary
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Bio-polyethylene reinforced with thermomechanical pulp fibers: Mechanical and micromechanical characterization and its application in 3D-printing by fused deposition modelling2018In: Composites Part B: Engineering, ISSN 1359-8368, E-ISSN 1879-1069, Vol. 153, p. 70-77Article in journal (Refereed)
    Abstract [en]

    Two biobased polyethylenes (BioPE) and thermomechanical pulp (TMP) fibers were used to produce biocomposites. The impact of TMP fibers on the mechanical properties was assessed in detail. An increase on the viscosity of the melted biocomposites was quantified and was related to the incorporation of the TMP fibers (0–30% w/w). The impact of polyethylene functionalized with maleic anhydride (MAPE) on the mechanical properties was quantified. Compared to neat BioPEs, a maximum increase of tensile strength between 115 and 127% was obtained, for the biocomposites containing 6% w/w of MAPE and 30% w/w TMP fibers. The formulated biocomposites containing 10 and 20% TMP fibers were three-dimensional (3D) printed, by fused deposition modelling. We confirmed that TMP fibers facilitated the 3D printing and correspondingly improved the mechanical properties of the biocomposite materials.

  • 47.
    Torstensen, Jonathan
    et al.
    Norwegian University of Science and Technology, Norway.
    Helberg, Ragne M. L.
    Norwegian University of Science and Technology, Norway.
    Deng, Liyuan
    Norwegian University of Science and Technology, Norway.
    Gregersen, Öyvind W.
    Norwegian University of Science and Technology, Norway.
    Syverud, Kristin
    RISE - Research Institutes of Sweden, Bioeconomy, PFI. Norwegian University of Science and Technology, Norway.
    PVA/nanocellulose nanocomposite membranes for CO2 separation from flue gas2019In: International Journal of Greenhouse Gas Control, ISSN 1750-5836, E-ISSN 1878-0148, Vol. 81, p. 93-102Article in journal (Refereed)
    Abstract [en]

    In this paper, we explore the use of nanocelluloses as an additive to poly (vinyl alcohol) (PVA) nanocomposite membranes for CO2/N2 mixed-gas separation. Our findings are that several types of nanocellulose can be used to improve membrane performance. PVA/cellulose nanocrystals (CNC) nanocomposite membranes have the most promising performance, with increased CO2 permeance (127.8 ± 5.5 GPU) and increased CO2/N2 separation factor (39 ± 0.4) compared to PVA composite membranes, with permeance 105.5 ± 1.9 GPU and separation factor 36 ± 0.5. The performance of PVA/CNC membranes is similar compared to PVA/carbon nanotubes (CNTs) membranes shown earlier. Thus, CNTs can be replaced by CNC that is biodegradable and non-toxic. Investigating several different nanocellulose types reveal that a high nanocellulose charge and small nanocellulose particles are important nanocellulose traits that improve membrane performance. 

  • 48.
    Torstensen, Jonathan Ø
    et al.
    NTNU Norwegian University of Science and Technology, Norway.
    Johnsen, Per Olav
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Riis, Henrik
    University of Oslo, Norway.
    Spontak, Richard J.
    North Carolina State University, USA.
    Deng, Liyuan
    NTNU Norwegian University of Science and Technology, Norway.
    Gregersen, Öyvind
    NTNU Norwegian University of Science and Technology, Norway.
    Syverud, Kristin
    RISE - Research Institutes of Sweden, Bioeconomy, PFI. NTNU Norwegian University of Science and Technology, Norway.
    Preparation of cellulose nanofibrils for imaging purposes: comparison of liquid cryogens for rapid vitrification2018In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 25, no 8, p. 4269-4274Article in journal (Refereed)
    Abstract [en]

    Artifact-free imaging of cellulose nanofibrils (CNFs) from aqueous nanocellulose suspensions is nontrivial due to frequent irreversible agglomeration and structure damage during the course of sample preparation, especially as water is solidified prior to freeze-drying. In this study, we have examined the morphologies of CNF suspensions prepared by rapid vitrification in two different liquid cryogens—nitrogen and ethane—followed by freeze-drying. Results obtained by scanning electron microscopy confirm that vitrification in liquid ethane not only greatly improves the survivability of fine-scale CNF structural elements but also significantly reduces the propensity for CNF to agglomerate.

  • 49.
    Torstensen, Jonathan Ø
    et al.
    NTNU Norwegian University of Science and Technology, Norway.
    Liu, Ming
    North Carolina State University, USA.
    Jin, Soo-Ah
    North Carolina State University, USA.
    Deng, Liyuan
    NTNU Norwegian University of Science and Technology, Norway.
    Hawari, Ayman I
    North Carolina State University, USA.
    Syverud, Kristin
    RISE - Research Institutes of Sweden, Bioeconomy, PFI. NTNU Norwegian University of Science and Technology, Norway.
    Spontak, Richard J
    North Carolina State University, USA.
    Gregersen, Øyvind W
    NTNU Norwegian University of Science and Technology, Norway.
    Swelling and Free-Volume Characteristics of TEMPO-Oxidized Cellulose Nanofibril Films.2018In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 19, no 3, p. 1016-1025Article in journal (Refereed)
    Abstract [en]

    Cellulose nanofibrils (CNFs) are becoming increasingly ubiquitous in diverse technologies requiring sustainable nanoscale species to form or modify films. The objective of the present study is to investigate the swelling behavior and accompanying free volume of self-standing TEMPO-oxidized (TO) CNF films in the presence of water vapor. For this purpose, we have performed time-resolved swelling experiments on films, prepared according to different experimental protocols, at 90% relative humidity (RH) and ambient temperature. Corresponding free-volume characteristics are elucidated by positron annihilation lifetime spectroscopy (PALS) conducted at ambient temperature and several RH levels. Increasing the drying temperature of the films (from ambient to 50 °C) is observed to promote an increase in film density, which serves to reduce bulk swelling. These elevated drying temperatures likewise cause the free-volume pore size measured by PALS to decrease, while the corresponding total free-volume fraction remains nearly constant. Similarly, dispersion of TO-CNF into aqueous suspensions by ultrasonication prior to film formation increases both the total free-volume fraction and pore size but reduces the size of individual nanofibrils with little net change in bulk swelling. The swelling and concurrent free-volume measurements reported here generally reveal an increase in the free volume of TO-CNF films with increasing RH.

  • 50.
    Valdebenito, Fabiola
    et al.
    Universidad de la Frontera, Chile.
    García, Rafael
    Universidad de Concepción, Chile.
    Cruces, Karen
    Universidad de Concepción, Chile.
    Ciudad, Gustavo
    Universidad de la Frontera, Chile.
    Chinga-Carrasco, Gary
    RISE - Research Institutes of Sweden, Bioeconomy, PFI. Universidad de la Frontera, Chile.
    Habibi, Youssef
    Luxembourg Institute of Science and Technology (LIST), Luxembourg.
    CO2 Adsorption of Surface-Modified Cellulose Nanofibril Films Derived from Agricultural Wastes2018In: ACS Sustainable Chemistry and Engineering, ISSN 2168-0485, Vol. 6, no 10, p. 12603-12612Article in journal (Refereed)
    Abstract [en]

    The present work demonstrates a simple and straightforward chemical modification of cellulose nanofibril (CNF) films in order to produce CO2 adsorbent materials. The CNF films were obtained from two agricultural residues, i.e. corn husks and oat hulls. CNF from kraft pulp was used for comparison purposes. Controlled surface silylation was conducted on the preformed CNF films in aqueous media under mild conditions using three aminosilanes bearing mono, di, and triamine groups. The success of the grafting of the aminosilanes on the CNF films was demonstrated by Fourier transform infrared and X-ray photoelectron spectroscopy analyses. The results of the contact angle measurements and field emission scanning electron microscopy coupled with energy dispersive spectroscopy showed homogeneous coverage by the amino groups on the surface of the modified CNF films, particularly with the diaminosilane N-[3-(trimethoxysilyl)propyl]ethylenediamine (DAMO). The produced films were thermally stable, and when subjected to 99.9% CO2 flow at 25 °C, these modified films showed good adsorption of CO2. Indeed, after 3 h of exposure the adsorbed concentration of CO2 of the CNF films modified with DAMO was 0.90, 1.27, and 2.11 mmol CO2 g-1 polymer for CNF films from corn husks, oat hulls, and kraft pulp, respectively.

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