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  • 1.
    Aarstad, Olav
    et al.
    NTNU Norwegian University of Science and Technology, Norway.
    Heggset, Ellinor B
    RISE - Research Institutes of Sweden (2017-2019), Bioekonomi, 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 (2017-2019), Bioekonomi, PFI.
    Strand, Berit L.
    NTNU Norwegian University of Science and Technology, Norway.
    Mechanical properties of composite hydrogels of alginate and cellulose nanofibrils2017Ingår i: Polymers, E-ISSN 2073-4360, Vol. 9, nr 8, artikel-id 378Artikel i tidskrift (Refereegranskat)
    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.

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  • 2. Acciaro, R.
    et al.
    Aulin, C.
    RISE., Innventia.
    Wågberg, L.
    Lindström, T.
    RISE., Innventia.
    Claesson, P.M.
    Varga, I.
    Investigation of the formation structure and release characteristics of self-assembled composite films of cellulose nanofibrils and temperature responsive microgels2011Ingår i: Soft Matter, ISSN 1744-683X, E-ISSN 1744-6848, nr 4, s. 1369-1377Artikel i tidskrift (Refereegranskat)
  • 3. Alexandrescu, L.
    et al.
    Syverud, K.
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Belosi, F.
    Nanofibers against nanoparticles:: Cellulosic nanoparticles for nanoparticle aerosol filtration2012Konferensbidrag (Refereegranskat)
  • 4. Alexandrescu, L.
    et al.
    Syverud, Kristin
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Chinga-Carrasco, Gary
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Iotti, M.
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Gregersen, Ø.
    Belosi, F.
    Gatti, A.M.
    Air filtration of nano-particles using cellulose nanofibrils2012Konferensbidrag (Refereegranskat)
  • 5.
    Alexandrescu, Laura C.
    et al.
    NTNU Norwegian University of Science and Technology, Norway.
    Syverud, Kristin
    RISE., Innventia, PFI – Paper and Fiber Research Institute. NTNU Norwegian University of Science and Technology, Norway.
    Gatti, Antonietta Maria
    ISTEC-CNR, Italy.
    Chinga-Carrasco, Gary
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Cytotoxicity tests of cellulose nanofibril-based structures2013Ingår i: Cellulose, ISSN 0969-0239, E-ISSN 1572-882X, Vol. 20, nr 4, s. 1765-1775Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Cellulose nanofibrils based on wood pulp fibres are most promising for biomedical applications. Bacterial cellulose has been suggested for some medical applications and is presently used as wound dressing. However, cost-efficient processes for mass production of bacterial cellulose are lacking. Hence, fibrillation of cellulose wood fibres is most interesting, as the cellulose nanofibrils can efficiently be produced in large quantities. However, the utilization of cellulose nanofibrils from wood requires a thorough verification of its biocompatibility, especially with fibroblast cells which are important in regenerative tissue and particularly in wound healing. The cellulose nanofibril structures used in this study were based on Eucalyptus and Pinus radiata pulp fibres. The nanofibrillated materials were manufactured using a homogenizer without pre-treatment and with 2,2,6,6-tetramethylpiperidine-1-oxy radical as pre-treatment, thus yielding nanofibrils low and high level of anionic charge, respectively. From these materials, two types of nanofibril-based structures were formed; (1) thin and dense structures and (2) open and porous structures. Cytotoxicity tests were applied on the samples, which demonstrated that the nanofibrils do not exert acute toxic phenomena on the tested fibroblast cells (3T3 cells). The cell membrane, cell mitochondrial activity and the DNA proliferation remained unchanged during the tests, which involved direct and indirect contact between the nano-structured materials and the 3T3 cells. Some samples were modified using the crosslinking agent polyethyleneimine (PEI) or the surfactant cetyl trimethylammonium bromide (CTAB). The sample modified with CTAB showed a clear toxic behaviour, having negative effects on cell survival, viability and proliferation. CTAB is an antimicrobial component, and thus this result was as expected. The sample crosslinked with PEI also had a significant reduction in cell viability indicating a reduction in DNA proliferation. We conclude that the neat cellulose nanostructured materials tested in this study are not toxic against fibroblasts cells. This is most important as nano-structured materials based on nanofibrils from wood pulp fibres are promising as substrate for regenerative medicine and wound healing.

  • 6.
    Ankerfors, Mikael
    et al.
    RISE., Innventia.
    Aulin, Christian
    RISE., Innventia.
    Lindström, Tom
    RISE., Innventia.
    Nanocellulose research and developments at Innventia2011Konferensbidrag (Refereegranskat)
  • 7.
    Ankerfors, Mikael
    et al.
    RISE., Innventia.
    Lindström, Tom
    RISE., Innventia.
    Energy efficient manufacture of microfibrillated cellulose by attachment of carboxymethyl cellulose2013Konferensbidrag (Refereegranskat)
  • 8.
    Ankerfors, Mikael
    et al.
    RISE., Innventia.
    Lindström, Tom
    RISE., Innventia.
    Söderberg, L. Daniel
    RISE., Innventia. KTH Royal Institute of Technology, Sweden.
    The use of microfibrillated cellulose in high filler fine papers2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    The field of communication, printing and writing papers has become an increasingly competitive field during the latest years as the market demand of printing and writing papers and newsprint has finally started to decline in the developed economies. One obvious approach to stay competitive is to increase the filler content of such papers. High filler paper is not a new idea and numerous approaches have been tested over the years to produce such papers. In order to reach industrial implementation, pilot-scale research and development under industrial conditions is necessary as a step after laboratory studies. Therefore an environment has been developed in order to perform projects targeting existing technologies for high filler applications as well as the new possibilities incurred by e.g. microfibrillated cellulose.

  • 9.
    Ansari, Farhan
    et al.
    KTH Royal Institute of Technology, Sweden.
    Lindh, Erik L.
    RISE., Innventia. KTH Royal Institute of Technology, Sweden.
    Furo, Istvan
    KTH Royal Institute of Technology, Sweden.
    Johansson, Mats K. G.
    KTH Royal Institute of Technology, Sweden.
    Berglund, Lars A.
    KTH Royal Institute of Technology, Sweden.
    Interface tailoring through covalent hydroxyl-epoxy bonds improves hygromechanical stability in nanocellulose materials2016Ingår i: Composites Science And Technology, ISSN 0266-3538, E-ISSN 1879-1050, Vol. 134, s. 175-183Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Wide-spread use of cellulose nanofibril (CNF) biocomposites and nanomaterials is limited by CNF moisture sensitivity due to surface hydration. We report on a versatile and scalable interface tailoring route for CNF to address this, based on technically important epoxide chemistry. Bulk impregnation of epoxide-amine containing liquids is used to show that CNF hydroxyls can react with epoxides at high rates and high degree of conversion to form covalent bonds. Reactions take place inside nanostructured CNF networks under benign conditions, and are verified by solid state NMR. Epoxide modified CNF nanopaper shows significantly improved mechanical properties under moist and wet conditions. High resolution microscopy is used in fractography studies to relate the property differences to structural change. The cellulose-epoxide interface tailoring concept is versatile in that the functionality of molecules with epoxide end-groups can be varied over a wide range. Furthermore, epoxide reactions with nanocellulose can be readily implemented for processing of moisture-stable, tailored interface biocomposites in the form of coatings, adhesives and molded composites.

  • 10.
    Ansari, Farhan
    et al.
    KTH Royal Institute of Technology, Sweden.
    Sjöstedt, Anna
    KTH Royal Institute of Technology, Sweden.
    Larsson, Per Tomas
    RISE., Innventia. KTH Royal Institute of Technology, Sweden.
    Berglund, Lars A.
    KTH Royal Institute of Technology, Sweden.
    Wågberg, Lars
    KTH Royal Institute of Technology, Sweden.
    Hierarchical wood cellulose fiber/epoxy biocomposites: Materials design of fiber porosity and nanostructure2015Ingår i: Composites. Part A, Applied science and manufacturing, ISSN 1359-835X, E-ISSN 1878-5840, Vol. 74, s. 60-68Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Delignified chemical wood pulp fibers can be designed to have a controlled structure of cellulose fibril aggregates to serve as porous templates in biocomposites with unique properties. The potential of these fibers as reinforcement for an epoxy matrix (EP) was investigated in this work. Networks of porous wood fibers were impregnated with monomeric epoxy and cured. Microscopy images from ultramicrotomed cross sections and tensile fractured surfaces were used to study the distribution of matrix inside and around the fibers - at two different length scales. Mechanical characterization at different relative humidity showed much improved mechanical properties of biocomposites based on epoxy-impregnated fibers and they were rather insensitive to surrounding humidity. Furthermore, the mechanical properties of cellulose-fiber biocomposites were compared with those of cellulose-nanofibril (CNF) composites; strong similarities were found between the two materials. The reasons for this, some limitations and the role of specific surface area of the fiber are discussed.

  • 11. Aulin, C.
    et al.
    Johansson, E.
    Wågberg, L.
    Lindström, Tom
    RISE., Innventia.
    Self-organized films from cellulose i nanofibrils using the layer-by-layer technique2010Ingår i: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 11, nr 4, s. 872-882Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The possibility of forming self-organized films using only charge-stabilized dispersions of cellulose I nanofibrils with opposite charges is presented, that is, the multilayers were composed solely of anionically and cationically modified microfibrillated cellulose (MFC) with a low degree of substitution. The build-up behavior and the properties of the layer-by-layer (LbL)-constructed films were studied using a quartz crystal microbalance with dissipation (QCM-D) and stagnation point adsorption reflectometry (SPAR). The adsorption behavior of cationic/anionic MFC was compared with that of polyethyleneimine (PEI)/anionic MFC. The water contents of five bilayers of cationic/anionic MFC and PEI/anionic MFC were approximately 70 and 50%, respectively. The MFC surface coverage was studied by atomic force microscopy (AFM) measurements, which clearly showed a more dense fibrillar structure in the five bilayer PEI/anionic MFC than in the five bilayer cationic/anionic MFC. The forces between the cellulose-based multilayers were examined using the AFM colloidal probe technique. The forces on approach were characterized by a combination of electrostatic and steric repulsion. The wet adhesive forces were very long-range and were characterized by multiple adhesive events. Surfaces covered by PEI/anionic MFC multilayers required more energy to be separated than surfaces covered by cationic/anionic MFC multilayers.

  • 12. Aulin, C.
    et al.
    Netrval, J.
    Wågberg, L.
    Lindström, Tom
    RISE., Innventia.
    Aerogels from nanofibrillated cellulose with tunable oleophobicity2010Ingår i: Soft Matter, ISSN 1744-683X, E-ISSN 1744-6848, Vol. 6, nr 14, s. 3298-3305Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The formation of structured porous aerogels of nanofibrillated cellulose (NFC) by freeze-drying has been demonstrated. The aerogels have a high porosity, as shown by FE-SEM and nitrogen adsorption/desorption measurements, and a very low density (<0.03 g cm-3). The density and surface texture of the aerogels can be tuned by selecting the concentration of the NFC dispersions before freeze-drying. Chemical vapor deposition (CVD) of 1H,1H,2H,2H- perfluorodecyltrichlorosilane (PFOTS) was used to uniformly coat the aerogel to tune their wetting properties towards non-polar liquids. An XPS analysis of the chemical composition of the PFOTS-modified aerogels demonstrated the reproducibility of the PFOTS-coating and the high atomic fluorine concentration (ca. 51%) in the surfaces. The modified aerogels formed a robust composite interface with high apparent contact angles (* ≫ 90°) for castor oil (γlv = 35.8 mN m-1) and hexadecane (γlv = 27.5 mN m-1).

  • 13. Aulin, C.
    et al.
    Varga, I.
    Claesson, P. M.
    Wågberg, L.
    Lindström, Tom
    RISE., STFI-Packforsk.
    Buildup of polyelectrolyte multilayers of polyethyleneimine and microfibrillated cellulose studied by in situ dual-polarization interferometry and quartz crystal microbalance with dissipation2008Ingår i: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 24, nr 6, s. 2509-2518Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Polyethyleneimine (PEI) and Microfibrillated cellulose (MFC) have been used to buildup polyelectrolyte multilayers (PEM) on silicone oxide and silicone oxynitride surfaces at different pH values and with different electrolyte and polyelectrolyte/colloid concentrations of the components. Consecutive adsorption on these surfaces was studied by in situ dual-polarization interferometry (DPI) and quartz crystal microbalance measurements. The adsorption data obtained from both the techniques showed a steady buildup of multilayers. High pH and electrolyte concentration of the PEI solution was found to be beneficial for achieving a high adsorbed amount of PEI, and hence of MFC, during the buildup of the multilayer. On the other hand, an increase in the electrolyte concentration of the MFC dispersion was found to inhibit the adsorption of MFC onto PEL The adsorbed amount of MFC was independent of the bulk MFC concentration in the investigated concentration range (15-250 mg/L). Atomic force microscopy measurements were used to image a MFC-treated silicone oxynitride chip from DPI measurements. The surface was found to be almost fully covered by randomly oriented microfibrils after the adsorption of only one bilayer of PEI/MFC. The surface roughness expressed as the rms-roughness over 1 ÎŒm2 was calculated to be 4.6 nm (1 bilayer). The adsorbed amount of PEI and MFC and the amount of water entrapped by the individual layers in the multilayer structures were estimated by combining results from the two analytical techniques using the de Feijter formula. These results indicate a total water content of ca. 41% in the PEM.

  • 14. Aulin, Christian
    et al.
    Gällstedt, Mikael
    RISE., Innventia.
    Lindström, Tom
    RISE., Innventia.
    Oxygen and oil barrier properties of microfibrillated cellulose films and coatings2010Ingår i: Cellulose, ISSN 0969-0239, E-ISSN 1572-882X, Vol. 17, nr 3, s. 559-574Artikel i tidskrift (Refereegranskat)
    Abstract [en]

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

  • 15.
    Aulin, Christian
    et al.
    RISE., Innventia. KTH Royal Institute of Technology, Sweden.
    Karabulut, Erdem
    KTH Royal Institute of Technology, Sweden.
    Tran, Amy
    KTH Royal Institute of Technology, Sweden.
    Waisgberg, Lars
    KTH Royal Institute of Technology, Sweden.
    Lindström, Tom
    RISE., Innventia. KTH Royal Institute of Technology, Sweden.
    Transparent nanocellulosic multilayer thin films on polylactic acid with tunable gas barrier properties2013Ingår i: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, nr 15, s. 7352-7359Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The layer-by-layer (LbL) deposition method was used for the build-up of alternating layers of nanofibrillated cellulose (NFC) or carboxymethyl cellulose (CMC) with a branched, cationic polyelectrolyte, polyethyleneimine (PEI) on flexible poly (lactic acid) (PLA) substrates. With this procedure, optically transparent nanocellulosic films with tunable gas barrier properties were formed. 50 layer pairs of PEI/NFC and PEI/CMC deposited on PLA have oxygen permeabilities of 0.34 and 0.71 cm3·μm/m 2·day·kPa at 23 C and 50% relative humidity, respectively, which is in the same range as polyvinyl alcohol and ethylene vinyl alcohol. The oxygen permeability of these multilayer nanocomposites outperforms those of pure NFC films prepared by solvent-casting. The nanocellulosic LbL assemblies on PLA substrates was in detailed characterized using a quartz crystal microbalance with dissipation (QCM-D). Atomic force microscopy (AFM) reveals large structural differences between the PEI/NFC and the PEI/CMC assemblies, with the PEI/NFC assembly showing a highly entangled network of nanofibrils, whereas the PEI/CMC surfaces lacked structural features. Scanning electron microscopy images showed a nearly perfect uniformity of the nanocellulosic coatings on PLA, and light transmittance results revealed remarkable transparency of the LbL-coated PLA films. The present work demonstrates the first ever LbL films based on high aspect ratio, water-dispersible nanofibrillated cellulose, and water-soluble carboxymethyl cellulose polymers that can be used as multifunctional films and coatings with tailorable properties, such as gas barriers and transparency. Owing to its flexibility, transparency and high-performance gas barrier properties, these thin film assemblies are promising candidates for several large-scale applications, including flexible electronics and renewable packaging.

  • 16.
    Aulin, Christian
    et al.
    RISE., Innventia.
    Lindström, Tom
    RISE., Innventia.
    Ström, Göran
    RISE., Innventia.
    Nanocellulose films and coatings with tunable oxygen and water vapor permeability for use in renewable packaging solutions2013Konferensbidrag (Refereegranskat)
  • 17.
    Aulin, Christian
    et al.
    RISE., Innventia. KTH Royal Institute of Technology, Sweden.
    Salazar-Alvarez, German
    KTH Royal Institute of Technology, Sweden; Stockholm University, Sweden.
    Lindström, Tom
    RISE., Innventia. KTH Royal Institute of Technology, Sweden.
    High strength flexible and transparent nanofibrillated cellulose-nanoclay biohybrid films with tunable oxygen and water vapor permeability2012Ingår i: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 4, nr 20, s. 6622-6628Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A novel, technically and economically benign procedure to combine vermiculite nanoplatelets with nanocellulose fibre dispersions into functional biohybrid films is presented. Nanocellulose fibres of 20 nm diameters and several micrometers in length are mixed with high aspect ratio exfoliated vermiculite nanoplatelets through high-pressure homogenization. The resulting hybrid films obtained after solvent evaporation are stiff (tensile modulus of 17.3 GPa), strong (strength up to 257 MPa), and transparent. Scanning electron microscopy (SEM) shows that the hybrid films consist of stratified nacre-like layers with a homogenous distribution of nanoplatelets within the nanocellulose matrix. The oxygen barrier properties of the biohybrid films outperform commercial packaging materials and pure nanocellulose films showing an oxygen permeability of 0.07 cm3 μm m-2 d-1 kPa -1 at 50% relative humidity. The oxygen permeability of the hybrid films can be tuned by adjusting the composition of the films. Furthermore, the water vapor barrier properties of the biohybrid films were also significantly improved by the addition of nanoclay. The unique combination of excellent oxygen barrier behavior and optical transparency suggests the potential of these biohybrid materials as an alternative in flexible packaging of oxygen sensitive devices such as thin-film transistors or organic light-emitting diode displays, gas storage applications and as barrier coatings/laminations in large volume packaging applications.

  • 18.
    Aulin, Christian
    et al.
    RISE., Innventia. KTH Royal Institute of Technology, Sweden.
    Ström, Göran R.
    RISE., Innventia.
    Multilayered alkyd resin/nanocellulose coatings for use in renewable packaging solutions with a high level of moisture resistance2013Ingår i: Industrial & Engineering Chemistry Research, ISSN 0888-5885, E-ISSN 1520-5045, nr 7, s. 2582-2589Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A surprisingly simple and rapid methodology for large-area, lightweight, and thin laminate coatings with remarkable moisture barrier properties is introduced. Commercially available paperboards are coated with thin layers of nanocellulose. The nanocellulose coating induces a surface smoothening effect on the coated sheets as characterized by environmental scanning electron microscopy and white light interferometry. A moisture-protective layer of renewable alkyd resins is deposited on the nanocellulose precoated sheets using a water-borne dispersion coating process or lithographic printing. Through an auto-oxidation process, the applied alkyd resins are transformed into moisture sealant layers. The moisture barrier properties are characterized in detail by water vapor permeability measurements at different levels of relative humidity. The water vapor barrier properties of the nanocellulose precoated substrates were significantly improved by thin layers of renewable alkyd resins. The effect of the alkyd resin properties, coating technologies, and base paper substrates on the final barrier performance of the sheets were studied. It was found that the nanocellulose coating had a notable effect on the homogeneity and barrier performance of the alkyd resin layers and in particular those alkyd resin layers that were applied by printing. The concept is environmentally friendly, energy-efficient, and economic and is ready for scaling-up via continuous roll-to-roll processes. Large-scale renewable coatings applicable for sustainable packaging solutions are foreseen.

  • 19.
    Bardet, Raphael
    et al.
    Université Grenoble Alpes, France; CNRS, France.
    Reverdy, Charlène
    Université Grenoble Alpes, France; CNRS, France.
    Belgacem, Naceur
    Université Grenoble Alpes, France; CNRS, France.
    Leirset, Ingebjørg
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Syverud, Kristin
    RISE., Innventia, PFI – Paper and Fiber Research Institute. NTNU Norwegian University of Science and Technology, Norway.
    Bardet, Michel
    Université Grenoble Alpes, France; CEA, France.
    Bras, Julien
    Université Grenoble Alpes, France; CNRS, France.
    Substitution of nanoclay in high gas barrier films of cellulose nanofibrils with cellulose nanocrystals and thermal treatment2015Ingår i: Cellulose, ISSN 0969-0239, E-ISSN 1572-882X, Vol. 22, nr 2, s. 1227-1241Artikel i tidskrift (Refereegranskat)
    Abstract [en]

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

  • 20.
    Blell, Rebecca
    et al.
    CNRS Institut Charles Sadron, France.
    Lin, Xiaofeng
    CNRS Institut Charles Sadron, France.
    Lindström, Tom
    RISE - Research Institutes of Sweden (2017-2019), Bioekonomi. RISE., Innventia.
    Ankerfors, Mikael
    RISE - Research Institutes of Sweden (2017-2019), Bioekonomi. RISE., Innventia.
    Pauly, Matthias
    CNRS Institut Charles Sadron, France; Université de Strasbourg, France.
    Felix, Olivier
    CNRS Institut Charles Sadron, France.
    Decher, Gero
    CNRS Institut Charles Sadron, France; Université de Strasbourg, France; International Center for Frontier Research in Chemistry, France.
    Generating in-Plane Orientational Order in Multilayer Films Prepared by Spray-Assisted Layer-by-Layer Assembly2017Ingår i: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 11, nr 1, s. 84-94Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present a simple yet efficient method for orienting cellulose nanofibrils in layer-by-layer assembled films through spray-assisted alignment. While spraying at 90° against a receiving surface produces films with homogeneous in-plane orientation, spraying at smaller angles causes a macroscopic directional surface flow of liquid on the receiving surface and leads to films with substantial in-plane anisotropy when nanoscale objects with anisotropic shapes are used as components. First results with cellulose nanofibrils demonstrate that such fibrils are easily aligned by grazing incidence spraying to yield optically birefringent films over large surface areas. We show that the cellulosic nanofibrils are oriented parallel to the spraying direction and that the orientational order depends for example on the distance of the receiving surface from the spray nozzle. The alignment of the nanofibrils and the in-plane anisotropy of the films were independently confirmed by atomic force microscopy, optical microscopy between crossed polarizers, and the ellipsometric determination of the apparent refractive index of the film as a function of the in-plane rotation of the sample with respect to the plane of incidence of the ellipsometer.

  • 21.
    Butchosa, Nuria
    et al.
    KTH Royal Institute of Technology, Sweden.
    Brown, Christian J.L.
    KTH Royal Institute of Technology, Sweden.
    Larsson, Per Tomas
    RISE., Innventia. KTH Royal Institute of Technology, Sweden.
    Berglund, Lars A.
    KTH Royal Institute of Technology, Sweden.
    Bulone, Vincent
    KTH Royal Institute of Technology, Sweden.
    Zhou, Q.
    KTH Royal Institute of Technology, Sweden.
    Nanocomposites of bacterial cellulose nanofibers and chitin nanocrystals: Fabrication, characterization and bacterial activity2013Ingår i: Green Chemistry, ISSN 1463-9262, E-ISSN 1463-9270, nr 12, s. 3404-3413Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An environmentally friendly approach was implemented for the production of nanocomposites with bactericidal activity, using bacterial cellulose (BC) nanofibers and chitin nanocrystals (ChNCs). The antibacterial activity of ChNCs prepared by acid hydrolysis, TEMPO-mediated oxidation or partial deacetylation of α-chitin powder was assessed and the structure of the ChNC nanoparticles was characterized by X-ray diffraction, atomic force microscopy, and solid-state 13C-NMR. The partially deacetylated ChNCs (D-ChNC) showed the strongest antibacterial activity, with 99 ± 1% inhibition of bacterial growth compared to control samples. Nanocomposites were prepared from BC nanofibers and D-ChNC by (i) in situ biosynthesis with the addition of D-ChNC nanoparticles in the culture medium of Acetobacter aceti, and (ii) post-modification by mixing D-ChNC with disintegrated BC in an aqueous suspension. The structure and mechanical properties of the BC/D-ChNC nanocomposites were characterized by Fourier transform infrared spectroscopy, elemental analysis, field-emission scanning electron microscopy, and an Instron universal testing machine. The bactericidal activity of the nanocomposites increased with the D-ChNC content, with a reduction in bacterial growth by 3.0 log units when the D-ChNC content was 50%. D-ChNC nanoparticles have great potential as substitutes for unfriendly antimicrobial compounds such as heavy metal nanoparticles and synthetic polymers to introduce antibacterial properties to cellulosic materials.

  • 22.
    Carlmark, Anna
    RISE - Research Institutes of Sweden, Bioekonomi, Bioraffinaderi och energi.
    Modification of nanocellulose with tailored latex nanoparticles2018Ingår i: Recent advances in cellulose nanotechnology research: production, characterization and applications, Trondheim: RISE PFI , 2018Konferensbidrag (Övrigt vetenskapligt)
  • 23.
    Carlsson, Linn
    et al.
    KTH Royal Institute of Technology, Sweden.
    Ingverud, Tobias
    KTH Royal Institute of Technology, Sweden.
    Blomberg, Hanna
    KTH Royal Institute of Technology, Sweden.
    Carlmark, Anna
    KTH Royal Institute of Technology, Sweden.
    Larsson, Per Tomas
    RISE., Innventia. KTH Royal Institute of Technology, Sweden.
    Malmström, Eva
    KTH Royal Institute of Technology, Sweden.
    Surface characteristics of cellulose nanoparticles grafted by surface-initiated ring-opening polymerization of ε-caprolactone2015Ingår i: Cellulose, ISSN 0969-0239, E-ISSN 1572-882X, Vol. 22, nr 2, s. 1063-1074Artikel i tidskrift (Refereegranskat)
    Abstract [en]

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

  • 24. Cervin, N.T.
    et al.
    Aulin, C.
    RISE., Innventia.
    Larsson, P.T.
    RISE., Innventia.
    Wågberg, L.
    Ultra porous nanocellulose aerogels as separation medium for mixtures of oil/water liquids2012Ingår i: Cellulose, ISSN 0969-0239, E-ISSN 1572-882X, nr 2, s. 401-410Artikel i tidskrift (Refereegranskat)
  • 25.
    Chinga-Carrasco, Gary
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Advanced biomaterials based on nanofibrillated cellulose: from nanopapers to nanomedicine2014Konferensbidrag (Refereegranskat)
    Abstract [en]

    Nanofibrillated cellulose (NFC) offers a wide range of interesting opportunities and advantages, being biodegradable, renewable and thus environmentally sound. Extensive research has been performed on the effective production and application of NFC. The proposed applications extend from being a component in paper, coatings and composite materials to being applied in bio-medicine as part of wound dressings or in drug delivery systems. Some of the major advantages of NFC are the dimensions and the structural and chemical composition of nanofibrils, which lead to the formation of dense networks with optimized optical and mechanical properties. In this respect, the concept of nanopaper has been introduced. Nanopapers are strong structures, with high light transmittance and smooth surfaces. These characteristics open for novel applications, including the formation of smooth substrates for printing functionality. A recently explored example is the printing of bioactive biomacromolecules and conductive structures on tailor-made nanopapers, which could form the basis for novel biosensors. Additionally, nanobarriers are most promising in novel packaging applications where the self-assembly properties of the material facilitate the formation of dense structures with high barrier against oxygen. However, NFC alone does not seem to be sufficient for the formation of adequate nanobarriers due to the brittle and hygroscopic characteristics of the material. Novel biocomposite concepts need thus closer attention, where the strong and high barrier properties of NFC could be complemented with adequate bioplastics and additives for the formation of ductile films, suitable for conversion processes. From the biomedical point of view, NFC offers several advantages. Depending on the structural and chemical composition of the material and the cross-linking with adequate polymers and particles, micro-porous and elastic gels can be formed. Such gels can hold a considerable amount of water, thus being an excellent material for keeping a moist environment during wound healing and for facilitating the regeneration process of human tissue. Additionally, NFC gels based on oxidized nanofibrils can have pH-sensitive characteristics, a property with potential in drug delivery. With the intention of giving an extensive description of NFC and its modern applications, this presentation will be divided into three main sections; i) production and definition, ii) characterization including structural, chemical and biological aspects and iii) novel applications of NFC from nanopapers to biomedical devices.

  • 26.
    Chinga-Carrasco, Gary
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Cellulose fibres, nanofibrils and microfibrils: The morphological sequence of MFC components from a plant physiology and fibre technology point of view2011Ingår i: Nanoscale Research Letters, ISSN 1931-7573, E-ISSN 1556-276X, Vol. 6Artikel i tidskrift (Refereegranskat)
  • 27.
    Chinga-Carrasco, Gary
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Optical methods for the quantification of the fibrillation degree of bleached MFC materials2013Ingår i: Micron, ISSN 0968-4328, E-ISSN 1878-4291, Vol. 48, s. 42-48Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this study, the suitability of optical devices for quantification of the fibrillation degree of bleached microfibrillated cellulose (MFC) materials has been assessed. The techniques for optical assessment include optical scanner, UV-vis spectrophotometry, turbidity, quantification of the fiber fraction and a camera system for dynamic measurements. The results show that the assessed optical devices are most adequate for quantification of the light transmittance of bleached MFC materials. Such quantification yields an estimation of the fibrillation degree. Films made of poorly fibrillated materials are opaque, while films made of highly fibrillated materials containing a major fraction of nanofibrils are translucent, with light transmittance larger than 90%. Finally, the concept of using images acquired with a CCD camera system, for estimating the fibrillation degree in dynamic conditions was exemplified. Such systems are most interesting as this will widen the applicability of optical methods for quantification of fibrillation degree online in production lines, which is expected to appear in the years to come.

  • 28.
    Chinga-Carrasco, Gary
    et al.
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Averianova, Natalia V.
    Kazan National Research Technological University, Russia.
    Gibadullin, Marat R.
    Kazan National Research Technological University, Russia.
    Petrov, Vladimir A.
    Kazan National Research Technological University, Russia.
    Leirset, Ingebjörg
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Syverud, Kristin
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Micro-structural characterisation of homogeneous and layered MFC nano-composites2013Ingår i: Micron, ISSN 0968-4328, E-ISSN 1878-4291, Vol. 44, nr 1, s. 331-338Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The complementary capabilities of various characterisation methods for micro-structural assessment are demonstrated. The assessed structures were composed of unbleached microfibrillated cellulose (MFC) in combination with bleached and 2,2,6,6-tetramethylpiperidinyl-1-oxyl (TEMPO) pre-treated MFC materials. The biodegradable nano-composites were thus characterised in detail, including laser profilometry, scanning electron microscopy (SEM) in high and low vacuum modes, and field-emission SEM. The distribution of the unbleached MFC materials was assessed by staining the unbleached MFC with osmium tetroxide (OsO4), which reacts with CC double bonds encountered in lignin. In addition, some properties of the MFC nano-composite films were tested, i.e. tensile properties, water wettability and oxygen permeability. In general, the group of characteristics of the nano-composite MFC films was better than the properties of the films made of the neat MFC qualities. This indicates that mixing complementary MFC qualities could give synergetic effects that are not exploited completely when using the MFC qualities separately. The study thus confirms the suitability of unbleached MFC materials as a component in multilayer structures, for example biodegradable packaging applications.

  • 29.
    Chinga-Carrasco, Gary
    et al.
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Averianova, Natalia V.
    Kazan National Research Technological University, Russia.
    Kondalenko, Olga
    Kazan National Research Technological University, Russia.
    Garaeva, Milyausha
    Kazan National Research Technological University, Russia.
    Petrov, Vladimir A.
    Kazan National Research Technological University, Russia.
    Leinsvang, Berit
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Karlsen, Trond
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    The effect of residual fibres on the micro-topography of cellulose nanopaper2014Ingår i: Micron, ISSN 0968-4328, E-ISSN 1878-4291, Vol. 56, s. 80-84Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Nanopaper is a new material concept composed of nanocellulose, which has been proposed for a series of applications. Recently, the surface of nanopapers has also been emphasized as an important structure to control. This is due to the potential of nanopaper structures as a substrate for printing functionality, which could expand the applicability of nanopaper as a functionalized biomaterial. In this study, we demonstrate how the roughness of nanopaper is affected by the fraction of residual fibres that were not fibrillated into nanofibrils after a homogenization procedure. The topography and morphology were assessed with laser profilometry, atomic force microscopy and scanning (transmission) electron microscopy. The results show a linear correlation between the estimated fraction of residual fibres and the roughness of the assessed nanopapers. Furthermore, the fraction of residual fibres can be reduced by fractionating the nanocellulose, which is demonstrated in the present work. Such knowledge will be valuable for designing nanopaper surfaces with specific structural characteristics.

  • 30.
    Chinga-Carrasco, Gary
    et al.
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Brodin, Malin
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Karlsen, Trond
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Wood pulp fibres and nanocellulose: Characterization and application in biocomposite materials2014Konferensbidrag (Refereegranskat)
    Abstract [en]

    A composite can be defined as a material composed of two or more components having distinct morphology and chemistry, and giving synergetic effects. In this paper the term biocomposite is used, referring to i) a material having at least one bio-component (e.g. wood pulp fibres and nanofibrils) or ii) biomaterials intended for biomedical applications. The utilization of wood pulp fibres in composite materials has gained major interest during the last years. There are various wood pulp fibres that can be used as reinforcement in composites, e.g. thermo-mechanical pulp (TMP), chemi-thermo-mechanical pulp (CTMP) and kraft pulp fibres. Depending on the pulping process (TMP, CTMP or kraft pulp), the pulp fibres differ greatly with respect to the fibre morphology and chemistry. Kraft pulp fibres have been one of the most used raw materials for producing nanocellulose. Nanocellulose from wood refers to various cellulose nano-materials such as cellulose nanocrystals and nanofibrillated cellulose. Nanofibrillated cellulose is composed of a major fraction of structurally homogeneous nanofibrils having typical widths in the nanometre scale and lengths in the micrometre scale. Wood pulp fibres and nanofibrils have been proposed as reinforcement in composite materials. Some of the major motivations have been the potential improvements by using fibres and nanofibrillated materials with respect to e.g. strength, biodegradability and functionality. The purpose of the present work is to review some advances in biocomposite research and development, including three focus areas; structured biocomposites, flexible biocomposites and biomaterials.

  • 31.
    Chinga-Carrasco, Gary
    et al.
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Kirsebom, H.
    Syverud, Kristin
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Designing nanocellulose qualities for wound dressings2013Konferensbidrag (Refereegranskat)
  • 32.
    Chinga-Carrasco, Gary
    et al.
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Kuznetsova, Nina V.
    Kazan National Research Technological University, Russia.
    Garaeva, Milyausha
    Kazan National Research Technological University, Russia.
    Leirset, Ingebjörg
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Galiullina, Guzaliya
    Kazan National Research Technological University, Russia.
    Kostochko, Anatoliy V.
    Kazan National Research Technological University, Russia.
    Syverud, Kristin
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Bleached and unbleached MFC nanobarriers:: Properties and hydrophobisation with hexamethyldisilazane2012Ingår i: Journal of nanoparticle research, ISSN 1388-0764, E-ISSN 1572-896X, Vol. 14, nr 12, artikel-id 1280Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study explores the production and surface modification of microfibrillated cellulose (MFC), based on unbleached and bleached Pinus radiata pulp fibres. Unbleached Pinus radiata pulp fibres tend to fibrillate easier by homogenisation without pre-treatment, compared to the corresponding bleached MFC. The resulting unbleached MFC films have higher barrier against oxygen, lower water wettability and higher tensile strength than the corresponding bleached MFC qualities. In addition, it is demonstrated that carboxymethylation can also be applied for production of highly fibrillated unbleached MFC. The nanofibril size distribution of the carboxymethylated MFC is narrow with diameters less than 20 nm, as quantified on high-resolution field-emission scanning electron microscopy images. The carboxymetylation had a larger fibrillation effect on the bleached pulp fibres than on the unbleached one. Importantly, the suitability of hexamethyldisilazane (HMDS) as a new alternative for rendering MFC films hydrophobic was demonstrated. TheHMDS-modifiedfilmsmade of carboxymethylated MFC had oxygen permeability levels better than 0.06 mL mm m-2 day-1 atm-1,which is a good property for some packaging applications.

  • 33.
    Chinga-Carrasco, Gary
    et al.
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Miettinen, A.
    Hendriks, C. L. L
    Gamstedt, K.
    Kataka, M.
    Structural characterisation of kraft pulp fibres and their nanofibrillated materials for biodegradable composite applications2011Ingår i: Nanocomposites and Polymers with Analytical Methods, InTech , 2011Kapitel i bok, del av antologi (Refereegranskat)
  • 34.
    Chinga-Carrasco, Gary
    et al.
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Powell, L.C
    Cardiff University School of Dentistry, UK; Swansea University, UK.
    Khan, S
    Cardiff University, UK.
    Hill, K.E
    Cardiff University UK.
    Thomas, D.W
    Cardiff University, UK.
    Wood nanocellulose: Characterization and potential application as barrier against wound bacteria2014Konferensbidrag (Refereegranskat)
    Abstract [en]

    Wood nanocellulose is a novel biomaterial for wound dressing applications. Wood nanocellulose was produced from never-dried P. radiata pulp fibres. The applied pre-treatment was 2,2,6,6-tetramethylpiperidinyl-1-oxyl  (TEMPO) mediated oxidation. To characterise bacterial growth, P. aeruginosa PAO1 biofilms were grown in Mueller Hinton broth on air-dried films. Various microscopy techniques, including atomic force microscopy (AFM), confocal laser scanning microscopy (CLSM) and field-emission scanning electron microscopy (FESEM), were applied to characterise the nanocellulose material and the bacterial-nanocellulose interactions.   Multiscale assessments, including FESEM and AFM, revealed the effective fibrillation of the fibre wall structure, yielding nanofibrils with diameters less than 20 nm and lengths in the micrometre-scale. Importantly, we have demonstrated that the growth of PAO1 was inhibited in the presence of the nanocellulose suspensions when compared to the control. Additionally, SEM imaging revealed distinct clusters of PAO1 cells growing on the surfaces of nanocellulose films. This work highlights the potential usefulness of novel nanocellulose materials in wound dressings with optimized characteristics.

  • 35.
    Chinga-Carrasco, Gary
    et al.
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Powell, L.C
    Cardiff University School of Dentistry, UK; Swansea University, UK.
    Nordli, H.R
    NTNU Norwegian University of Science and Technology, Norway.
    Khan, S
    Cardiff University, UK.
    Hill, K.E
    Cardiff University, UK.
    Syverud, Kristin
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Thomas, D.W
    Cardiff University, UK.
    Nanocellulose from wood as a biomaterial for biomedical applications2014Konferensbidrag (Refereegranskat)
    Abstract [en]

    During the last decades major efforts have been made to produce nanocellulose from wood, where the cellulose fibres are disintegrated into individualized nanofibrils with diameters < 20 nm and lengths in the micrometre scale. Production procedures include various pre-treatments, which yield nanocelluloses with varying chemical and structural properties. One important area of research is nanocellulose as a biomaterial with potential applications within the health sector. As an example, the superior mechanical properties, good moisture retention capability and the ability to form elastic macro-porous structures are advantageous properties for utilizing nanocellulose substrates for wound dressings. However, the utilization of nanocellulose as a substrate for wound dressings requires a thorough assessment of the biocompatibility of the material.  In this respect, it has been demonstrated in-vitro that nanocellulose does not exert acute toxic phenomena on fibroblast cells. However, in addition to in-vitro cytotoxicity testing, in-vivo testing of nanocellulose and the ability of nanocellulose to resist bacterial colonization need a closer attention. This presentation will give an overview of the current research on nanocellulose as a biomaterial for wound dressing applications, considering the morphology of nanocellulose structures, mechanical properties, moisture absorption, cytotoxicity tests and nanocellulose-bacteria interactions.

  • 36.
    Chinga-Carrasco, Gary
    et al.
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Syverud, Kristin
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Cellulose nanofibrils: production, characterization and applications2011Ingår i: Fine Structure of Papermaking Fibres, Swedish University of Agricultural Sciences , 2011, , s. 13Kapitel i bok, del av antologi (Refereegranskat)
  • 37.
    Chinga-Carrasco, Gary
    et al.
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Syverud, Kristin
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    On the porosity and oxygen barrier properties of cellulose nanofibril-based films2011Konferensbidrag (Refereegranskat)
  • 38.
    Chinga-Carrasco, Gary
    et al.
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Syverud, Kristin
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    On the structure and oxygen transmission rate of biodegradable cellulose nanobarriers2012Ingår i: Nanoscale Research Letters, ISSN 1931-7573, E-ISSN 1556-276X, Vol. 7Artikel i tidskrift (Refereegranskat)
  • 39.
    Chinga-Carrasco, Gary
    et al.
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Syverud, Kristin
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Pretreatment-dependent surface chemistry of wood nanocellulose for pH-sensitive hydrogels2014Ingår i: Journal of biomaterials applications, ISSN 0885-3282, E-ISSN 1530-8022, Vol. 3, nr 29, s. 423-432Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Nanocellulose from wood is a promising material with potential in various technological areas. Within biomedical applications, nanocellulose has been proposed as a suitable nano-material for wound dressings. This is based on the capability of the material to self-assemble into 3D micro-porous structures, which among others have an excellent capacity of maintaining a moist environment. In addition, the surface chemistry of nanocellulose is suitable for various applications. First, OH-groups are abundant in nanocellulose materials, making the material strongly hydrophilic. Second, the surface chemistry can be modified, introducing aldehyde and carboxyl groups, which have major potential for surface functionalization. In this study, we demonstrate the production of nanocellulose with tailor-made surface chemistry, by pre-treating the raw cellulose fibres with carboxymethylation and periodate oxidation. The pre-treatments yielded a highly nanofibrillated material, with significant amounts of aldehyde and carboxyl groups. Importantly, the poly-anionic surface of the oxidized nanocellulose opens up for novel applications, i.e. micro-porous materials with pH-responsive characteristics. This is due to the swelling capacity of the 3D micro-porous structures, which have ionisable functional groups. In this study, we demonstrated that nanocellulose gels have a significantly higher swelling degree in neutral and alkaline conditions, compared to an acid environment (pH 3). Such a capability can potentially be applied in chronic wounds for controlled and intelligent release of antibacterial components into biofilms.

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  • 40.
    Chinga-Carrasco, Gary
    et al.
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Tobjörk, Daniel
    Åbo Akademi University, Finland.
    Österbacka, Ronald
    Åbo Akademi University, Finland.
    Inkjet-printed silver nanoparticles on nano-engineered cellulose films for electrically conducting structures and organic transistors:: concept and challenges2012Ingår i: Journal of nanoparticle research, ISSN 1388-0764, E-ISSN 1572-896X, Vol. 14, nr 11, artikel-id 1213Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study explores the suitability of microfibrillated cellulose (MFC) films as a substrate for printing electrically conductive structures and multilayer electronic structures such as organic field effect transistors. Various MFC qualities were tested, including mechanically produced MFC, 2,2,6,6-tetramethylpiperidinyl- 1-oxyl pre-treated MFC and carboxymethylated- MFC. The films differed significantly with respect to the surface structure. In addition, the carboxymethylated-MFC films were surface modified with hexamethyldisilazane (HMDS) to reduce the water-wettability of the films, and thus, improve the print resolution of the inkjet-printed silver (Ag) nanoparticles. The Ag-particles (diameter>50 nm) were printed on the HMDS-modified films, which were mainly composed of nanofibrils with diameters >20 nm. The effect of surface roughness and surface chemical characteristics on the ink spreading and print resolution of the Ag-structures was explored. It was demonstrated that organic transistors operating at low voltages can be fabricated on nano-engineered MFC films.

  • 41.
    Chinga-Carrasco, Gary
    et al.
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Yu, Y.
    Diserud, O.
    Quantitative Electron Microscopy of Cellulose Nanofibril Structures from Eucalyptus and Pinus Radiata Kraft Pulp Fibres2011Ingår i: Microscopy and Microanalysis, ISSN 1431-9276, E-ISSN 1435-8115, Vol. 17Artikel i tidskrift (Refereegranskat)
  • 42. Cho, S.-W.
    et al.
    Gällstedt, M.
    RISE., Innventia.
    Johansson, E.
    Hedenqvist, M.S.
    Injection-molded nanocomposites and materials based on wheat gluten2011Ingår i: International Journal of Biological Macromolecules, ISSN 0141-8130, E-ISSN 1879-0003, nr 1, s. 146-152Artikel i tidskrift (Refereegranskat)
  • 43.
    Claesson, Åsa
    et al.
    RISE - Research Institutes of Sweden (2017-2019), ICT, Acreo.
    Lyckfeldt, Ola
    RISE - Research Institutes of Sweden (2017-2019), ICT, Acreo.
    Lindqvist, Jonas
    RISE - Research Institutes of Sweden (2017-2019), ICT, Acreo.
    Kardeby, Victor
    RISE - Research Institutes of Sweden (2017-2019), ICT, Acreo.
    Lejon, Erik
    Gestamp HardTech AB, Sweden.
    Ulfberg, Petter
    Proximion AB, Sweden.
    Rendall, Helen
    Proximion AB, Sweden.
    Hedin, Gunnar
    RISE - Research Institutes of Sweden (2017-2019), ICT, Acreo.
    Ottosson, Peter
    RISE - Research Institutes of Sweden (2017-2019), ICT, Acreo.
    Ohlsson, David
    RISE - Research Institutes of Sweden (2017-2019), ICT, Acreo.
    Kvarned, Anders
    Uddeholms AB, Sweden.
    Karamchedu, Seshendra
    Uddeholms AB, Sweden.
    Brinkfeldt, Klas
    RISE - Research Institutes of Sweden (2017-2019), ICT, Acreo.
    Hosseini, Seyed
    RISE - Research Institutes of Sweden (2017-2019), ICT, Acreo.
    lntegrated Optical Fiber Sensors in Additive Manufactured Metal Components for Smart Manufacturing Applications2019Ingår i: Smart Systems Integration; 13th International Conference and Exhibition on Integration Issues of Miniaturized Systems, 2019Konferensbidrag (Refereegranskat)
    Abstract [en]

    This work combines fiber optic sensors with additive manufacturing to enable integration of temperature and strain sensors in metal components. In this paper, we present a fiber optic sensor network integrated in press hardening tools to monitor the contact between the tool and the metal sheet during forming operation. The tools are manufactured through metal powder bed fusion using laser melting processes (PBF-SLM), after which the tools are prepared for sensor integration. A demonstrator press hardening tool with integrated fiber optic sensors was heated using an electric heat foil and the sensor measurements was compared to a thermal simulation model. The sensor technology is based on Fiber Bragg Gratings (FBGs), integrated at several positions along the optical fiber. FBGs are in-fiber sensors that are multiplexed. lt is possible to place hundreds of FBG sensors along one single fiber, thus allowing for quasidistributed sensing of temperature or strain. The optical fiber itself can be less than 100 micrometer in diameter, allowing for sensing at several points in a minimally invasive way, when integrated in a tool or component.

  • 44.
    Coseri, Sergiu
    et al.
    Romanian Academy, Romania.
    Biliuta, Gabriela
    Romanian Academy, Romania.
    Zemlijic, Lidija Fras
    University of Maribor, Slovenia.
    Stevanic Srndovic, Jasna
    RISE., Innventia.
    Larsson, Per Tomas
    RISE., Innventia.
    Strnad, Simona
    University of Maribor, Slovenia.
    Kreze, Tatjana
    University of Maribor, Slovenia.
    Naderi, Ali
    RISE., Innventia.
    Lindström, Tom
    RISE., Innventia.
    Correction: One-shot carboxylation of microcrystalline cellulose in the presence of nitroxyl radicals and sodium periodate2015Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 5, nr 117, s. 96927-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Correction for ‘One-shot carboxylation of microcrystalline cellulose in the presence of nitroxyl radicals and sodium periodate’ by Sergiu Coseri et al.RSC Adv., 2015, 5, 85889–85897.

    The authors regret that the images presented for Fig. 1 and 3 in the original article present incorrect carbohydrate structures. The amended versions of these images, in which the 3-position hydroxyl groups are equatorial rather than axial, are presented below.

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  • 45.
    Coseri, Sergiu
    et al.
    Romanian Academy, Romania.
    Biliuta, Gabriela
    Romanian Academy, Romania.
    Zemlijic, Lidija Fras
    University of Maribor, Slovenia.
    Stevanic Srndovic, Jasna
    RISE., Innventia.
    Larsson, Per Tomas
    RISE., Innventia.
    Strnad, Simona
    University of Maribor, Slovenia.
    Kreze, Tatjana
    University of Maribor, Slovenia.
    Naderi, Ali
    RISE., Innventia.
    Lindström, Tom
    RISE., Innventia.
    One-shot carboxylation of microcrystalline cellulose in the presence of nitroxyl radicals and sodium periodate2015Ingår i: RSC Advances, E-ISSN 2046-2069, Vol. 5, nr 104, s. 85889-85897Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Water soluble cellulose derivatives are highly required products for many practical purposes, expanding the limited applications of pure cellulose caused by the highly ordered hydrogen bond network and high crystallinity. In this connection, this paper, presents a new approach to obtain water soluble carboxyl-functionalized cellulosic materials, combining two of the most common selective oxidation protocols for cellulose, i.e. nitroxyl mediated reaction and periodate oxidation, in a one-shot reaction. It was found that, under specific reaction conditions, fully oxidized, 2,3,6-tricarboxy cellulose can be obtained in large amounts. The other valuable oxidized fractions were found to possess large amounts of carboxylic groups, as determined by potentiometric titration. 13C-NMR evidenced the presence of three distinctive carboxylic groups in the fully oxidized product, whereas for the partially oxidized samples, 13C CP-MAS solid-state NMR did not detect any carbonyl signals. The oxidized products were characterized by means of FTIR and X-ray photoelectron spectroscopy (XPS). Moreover, the changes of the degree of polymerization occurring after oxidative treatments were viscometrically determined.

  • 46.
    Cozzolino, Carlo A.
    et al.
    RISE., Innventia, PFI – Paper and Fiber Research Institute. University of Sassari, Italy.
    Nilsson, Fritjof
    KTH Royal Institute of Technology, Sweden.
    Iotti, Marco
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Sacchi, Benedetta
    University of Milan, Italy.
    Piga, Antonio
    University of Sassari, Italy.
    Farris, Stefano
    University of Milan, Italy.
    Exploiting the nano-sized features of microfibrillated cellulose (MFC) for the development of controlled-release packaging2013Ingår i: Colloids and Surfaces B: Biointerfaces, ISSN 0927-7765, E-ISSN 1873-4367, Vol. 110, s. 208-216Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Microfibrillated cellulose (MFC) was used in this study to prepare films containing an active molecule, lysozyme, which is a natural antimicrobial agent. The main goal of this research was to assess the potential for exploiting the nano-sized dimension of cellulose fibrils to slow the release of the antimicrobial molecule, thus avoiding a too-quick release into the surrounding medium, which is a major disadvantage of most release systems. For this purpose, the release kinetics of lysozyme over a 10-day period in two different media (pure water and water/ethanol 10. wt.%) were obtained, and the experimental data was fitted with a solution of Fick's second law to quantify the apparent diffusion coefficient (D). The results indicate that the MFC retained lysozyme, presumably due to electrostatic, hydrogen, and ion-dipole interactions, with the largest release of lysozyme-approximately 14%-occurring from the initial amount loaded on the films. As expected, ethanol as a co-solvent slightly decreased the diffusion of lysozyme from the MFC polymer network. The addition of two potential modulating release agents-glycerol and sodium chloride-was also evaluated. Findings from this work suggest that MFC-based films can be considered a suitable candidate for use in controlled-release packaging systems.

  • 47.
    Cunha, Ana Gisela
    et al.
    KTH Royal Institute of Technology, Sweden.
    Zhou, Qi
    KTH Royal Institute of Technology, Sweden.
    Larsson, Per Tomas
    RISE., Innventia.
    Berglund, Lars A.
    KTH Royal Institute of Technology, Sweden.
    Topochemical acetylation of cellulose nanopaper structures for biocomposites: Mechanisms for reduced water vapour sorption2014Ingår i: Cellulose, ISSN 0969-0239, E-ISSN 1572-882X, Vol. 21, nr 4, s. 2773-2787Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Moisture sorption decreases dimensional stability and mechanical properties of polymer matrix biocomposites based on plant fibers. Cellulose nanofiber reinforcement may offer advantages in this respect. Here, wood-based nanofibrillated cellulose (NFC) and bacterial cellulose (BC) nanopaper structures, with different specific surface area (SSA), ranging from 0.03 to 173.3 m2/g, were topochemically acetylated and characterized by ATR-FTIR, XRD, solid-state CP/MAS 13C-NMR and moisture sorption studies. Polymer matrix nanocomposites based on NFC were also prepared as demonstrators. The surface degree of substitution (surface-DS) of the acetylated cellulose nanofibers is a key parameter, which increased with increasing SSA. Successful topochemical acetylation was confirmed and significantly reduced the moisture sorption in nanopaper structures, especially at RH = 53 %. BC nanopaper sorbed less moisture than the NFC counterpart, and mechanisms are discussed. Topochemical NFC nanopaper acetylation can be used to prepare moisture-stable nanocellulose biocomposites.

  • 48.
    Djafari Petroudy, Seyed Rahman
    et al.
    Shahid Beheshti University, Iran.
    Ghasemian, Ali
    Gorgan University of Agricultural Sciences and Natural Resources, Iran.
    Resalati, Hossein
    Sari University of Agricultural Sciences and Natural Resources, Iran.
    Syverud, Kristin
    RISE., Innventia, PFI – Paper and Fiber Research Institute. NTNU Norwegian University of Science and Technology, Norway.
    Chinga-Carrasco, Gary
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    The effect of xylan on the fibrillation efficiency of DED bleached soda bagasse pulp and on nanopaper characteristics2015Ingår i: Cellulose, ISSN 0969-0239, E-ISSN 1572-882X, Vol. 22, nr 1, s. 385-395Artikel i tidskrift (Refereegranskat)
    Abstract [en]

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

  • 49.
    Djafari Petroudy, Seyed Rahman
    et al.
    NTNU Norwegian University of Science and Technology, Norway; Gorgan University of Agricultural Sciences and Natural Resources, Iran.
    Syverud, Kristin
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Chinga-Carrasco, Gary
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Ghasemain, Ali
    Gorgan University of Agricultural Sciences and Natural Resources, Iran.
    Resalati, Hossein
    Gorgan University of Agricultural Sciences and Natural Resources, Iran.
    Effects of bagasse microfibrillated cellulose and cationic polyacrylamide on key properties of bagasse paper2014Ingår i: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 99, s. 311-318Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study explores the benefits of using bagasse microfibrillated cellulose (MFC) in bagasse paper. Two different types of MFC were produced from DED bleached soda bagasse pulp. The MFC was added to soda bagasse pulp furnishes in different amounts. Cationic polyacrylamide (C-PAM) was selected as retention aid. The results show that addition of MFC increased the strength of paper as expected. Interestingly, 1% MFC in combination with 0.1% C-PAM yielded similar drainage time as the reference pulp, which did not contain MFC. In addition, the samples containing 1% MFC and 0.1% C-PAM yielded (i) a significant increment of the tensile index, (ii) a minor decrease of opacity and (iii) preserved Gurley porosity. Hence, this study proves that small fractions of MFC in combination with adequate retention aids can have positive effects with respect to paper properties, which is most interesting from an industrial point of view.

  • 50. Djafari Petroudy, S.R.
    et al.
    Syverud, Kristin
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Chinga-Carrasco, Gary
    RISE., Innventia, PFI – Paper and Fiber Research Institute.
    Ghasemain, A.
    Resalati, H.
    Gregersen, Ø.W.
    Oriented nanopaper (ONP) made of bagasse nanofibrils2012Konferensbidrag (Refereegranskat)
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