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  • 1.
    Ahlberg, Charlotte
    et al.
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Lundell, Fredrik
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Soderberg, L. Daniel
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    SELF-ORGANIZATION OF FIBERS IN A SUSPENSION BETWEEN TWO COUNTER-ROTATING DISCS2009In: PROCEEDINGS OF THE ASME FLUIDS ENGINEERING DIVISION SUMMER CONFERENCE, VOL 1, PTS A-C, NEW YORK: AMER SOC MECHANICAL ENGINEERS , 2009, p. 585-592Conference paper (Refereed)
    Abstract [en]

    The behavior of fibers suspended in a flow between two flat counter-rotating discs has been studied experimentally. Captured images of the fibers in the flow were analyzed by steerable filters, to extract positions and orientations of the fibers. Experiments were performed for gaps between the discs of less than one fiber length, and for equal absolute values of the angular velocities for the discs. The length-to-diameter ratio of the fibers was approximately 14. During certain conditions, the fibers organized themselves in a distinct manner, which we will denote as fiber trains, in which three or more fibers are aligned next to each other, at the same radial position, with a short fiber-to-fiber distance. The direction of the individual fibers is radial and the direction of the whole train is tangential. Trains containing more than 60 fibers have been observed and are quite impressing.

  • 2. Ankerfors, M.
    et al.
    Lindström, T.
    Söderberg, Daniel
    KTH, School of Engineering Sciences (SCI), Mechanics.
    The use of microfibrillated cellulose in high filler fine papers2013In: Pap. Conf. Trade Show, PaperCon, 2013, p. 1129-1132Conference paper (Refereed)
    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.

  • 3.
    Ankerfors, Mikael
    et al.
    Innventia AB, Sweden.
    Llindström, Tom
    Innventia AB, Sweden.
    Söderberg, Daniel
    KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. Innventia AB, Sweden.
    The use of microfibrillated cellulose in fine paper manufacturing: Results from a pilot scale papermaking trial2014In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 29, no 3, p. 476-483Article in journal (Refereed)
    Abstract [en]

    In this work the strength enhancing capabilities of microfibrillated cellulose (MFC) in highly filled papers was studied. Both the MFC production and the paper making were done in pilot scale under realistic industrial conditions. The results clearly show that MFC (2.5 - 5.0wt-%) could improve the mechanical properties of highly filled papers (20 - 35 wt-% filler contents). All studied dry mechanical properties were improved and the improvements were most pronounced for Z-strength and fracture toughness. By combining the MFC with a C-starch dosage further improvements in mechanical properties could be achieved. The improvements in mechanical properties enabled increased filler content with retained properties. The filler increase could be achieved at the same time as the sheet formation and the dry content after pressing were improved.

  • 4. Athley, Karin
    et al.
    Granlöf, Lars
    Söderberg, Daniel
    Innventia AB, Box 5604,, Stockholm, Sweden.
    Ankerfors, Mikael
    Ström, Göran
    Mechanical retention – Influence of filler floc size and grammage of the fibre web2012In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 27, no 2Article in journal (Refereed)
  • 5.
    Bellani, Gabriele
    et al.
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Bach, Roland
    Lundell, Fredrik
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Söderberg, L. Daniel
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Experimental study of filtration of fiber suspensions: Part II: combined PIV and pressure drop measurements2011Report (Other academic)
    Abstract [en]

    The filtration of a fiber suspension has been studied experimentally. Typical applications where pressure filtration occurs are: papermaking, air cleaners, production of composite materials, etc. In particular, in papermaking, the quality of the final product depends on the fiber orientation and mass distribution in the filtered material. Micro-variations of these properties can strongly affect the quality of the final product and they can occur during filtration, thus it is important to predict how this can happen. However, this is not an easy task, first because the filtered cake is a non-homogeneous compressible porous media, second because the filtration flow is non-stationary, since the cake is continuously evolving in time. Therefore in this work we focus on the filtration flow through formed steady fiber networks. For each grammage (i.e. mass of fibers per unit area), we simultaneously measure the pressure drop across the network and velocity field on top and below the fiber network using Particle Image Velocimetry (PIV). Compression of the fiber network can also be extracted from the PIV images. Normalized filtration resistance was found to be decreasing with increasing network thickness, as well as network compressibility. From the PIV data the influence of the formed fiber network on the flow field was analyzed and characteristic scales of the flow structures are quantified.

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  • 6.
    Bellani, Gabriele
    et al.
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Lundell, Fredrik
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Söderberg, L. Daniel
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Experimental study of filtration of fiber suspensions: Part I: fluid velocity and fluid-fiber interactionmeasurements2008Report (Other academic)
    Abstract [en]

    A study of the flow in the direct vicinity of a forming wire and a fiber network during forming is reported. The measurements are performed with Particle Image Velocimetry in a scaled system. Index-of-refraction matching is used to gain optical access to the flow. Time resolved measurements of the flow velocity in the vertical and horizontal direction is obtained in a plane with a size of 60×40 fiber diameters. Data is obtained for three drainage velocities and two different lengths of the fibers. The relative level of the velocity fluctuationsis found to decrease with drainage velocity and is higher in the flow above a network mat of shorter fibers compared to the network made of longer fibers

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  • 7.
    Bellani, Gabriele
    et al.
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Lundell, Fredrik
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Söderberg, L. Daniel
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Experimental study of the forming process: Fluid velocity and fluid-fiber interaction measurements2008Conference paper (Refereed)
    Abstract [en]

    A study of the flow in the direct vicinity of a forming wire and a fiber network during forming is reported. The measurements are performed with Particle Image Velocimetry in a scaled system. Index-of-refraction matching is used to gain optical access to the flow. Time resolved measurements of the flow velocity in the vertical and horizontal direction is obtained in a plane with a size of 60 × 40 fiber diameters. The spatial resolution is 2 fiber diameters. Data is obtained for three drainage velocities and two different lengths of the fibers. The relative level of the velocity fluctuations are found to decrease with drainage velocity and is higher in the flow above a network mat of shorter fibers compared to the network made of longer fibers. The size of the flow structures is obtained by spectral analysis and compared for the six cases.

  • 8.
    Betker, Marie
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg, Germany, Notkestr. 85.
    Harder, Constantin
    Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg, Germany, Notkestr. 85; Chair for Functional Materials, TUM School of Natural Sciences, Technical University of Munich, James-Franck-Straße 1, 85748 Garching, Germany, James-Franck-Straße 1.
    Erbes, Elisabeth
    Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg, Germany, Notkestr. 85; Institute for X-ray Physics, Goettingen University, Friedrich Hund Platz 1, 37077 Goettingen, Germany, Friedrich Hund Platz 1.
    Heger, Julian Eliah
    Chair for Functional Materials, TUM School of Natural Sciences, Technical University of Munich, James-Franck-Straße 1, 85748 Garching, Germany, James-Franck-Straße 1.
    Alexakis, Alexandros Efraim
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Sochor, Benedikt
    Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg, Germany, Notkestr. 85.
    Chen, Qing
    Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg, Germany, Notkestr. 85.
    Schwartzkopf, Matthias
    Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg, Germany, Notkestr. 85.
    Körstgens, Volker
    Chair for Functional Materials, TUM School of Natural Sciences, Technical University of Munich, James-Franck-Straße 1, 85748 Garching, Germany, James-Franck-Straße 1.
    Müller-Buschbaum, Peter
    Chair for Functional Materials, TUM School of Natural Sciences, Technical University of Munich, James-Franck-Straße 1, 85748 Garching, Germany, James-Franck-Straße 1; Heinz Maier-Leibnitz Zentrum (MLZ), Technical University of Munich, Lichtenbergstr. 1, 85748 Garching, Germany, Lichtenbergstr. 1.
    Schneider, Konrad
    Abteilung Werkstofftechnik, Leibniz-Institut für Polymerforschung Dresden e.V., 01069 Dresden, Germany.
    Techert, Simone Agnes
    Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg, Germany, Notkestr. 85; Institute for X-ray Physics, Goettingen University, Friedrich Hund Platz 1, 37077 Goettingen, Germany, Friedrich Hund Platz 1.
    Söderberg, Daniel
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fiberprocesser.
    Roth, Stephan V.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg, Germany, Notkestr. 85.
    Sprayed Hybrid Cellulose Nanofibril-Silver Nanowire Transparent Electrodes for Organic Electronic Applications2023In: ACS Applied Nano Materials, E-ISSN 2574-0970, Vol. 6, no 14, p. 13677-13688Article in journal (Refereed)
    Abstract [en]

    In times of climate change and resource scarcity, researchers are aiming to find sustainable alternatives to synthetic polymers for the fabrication of biodegradable, eco-friendly, and, at the same time, high-performance materials. Nanocomposites have the ability to combine several favorable properties of different materials in a single device. Here, we evaluate the suitability of two kinds of inks containing silver nanowires for the fast, facile, and industrial-relevant fabrication of two different types of cellulose-based silver nanowire electrodes via layer-by-layer spray deposition only. The Type I electrode has a layered structure, which is composed of a network of silver nanowires sprayed on top of a cellulose nanofibrils layer, while the Type II electrode consists of a homogeneous mixture of silver nanowires and cellulose nanofibrils. A correlation between the surface structure, conductivity, and transparency of both types of electrodes is established. We use the Haacke figure of merit for transparent electrode materials to demonstrate the favorable influence of cellulose nanofibrils in the spray ink by identifying Type II as the electrode with the lowest sheet resistance (minimum 5 ± 0.04 Ω/sq), while at the same time having a lower surface roughness and shorter fabrication time than Type I. Finally, we prove the mechanical stability of the Type II electrode by bending tests and its long-time stability under ambient conditions. The results demonstrate that the mixed spray ink of silver nanowires and cellulose nanofibrils is perfectly suitable for the fast fabrication of highly conductive organic nanoelectronics on an industrial scale.

  • 9.
    Bragone, Federica
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Computational Science and Technology (CST).
    Rosén, Tomas
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Morozovska, Kateryna
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Computational Science and Technology (CST). KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.), Sustainability, Industrial Dynamics & Entrepreneurship.
    Laneryd, Tor
    Hitachi Energy, Västerås, Sweden.
    Söderberg, Daniel
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences (SCI), Engineering Mechanics. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fiberprocesser.
    Markidis, Stefano
    KTH, Centres, SeRC - Swedish e-Science Research Centre. KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Computational Science and Technology (CST).
    Unsupervised Learning Analysis of Flow-Induced Birefringence in Nanocellulose: Differentiating Materials and ConcentrationsManuscript (preprint) (Other academic)
    Abstract [en]

    Cellulose nanofibrils (CNFs) can be used as building blocks for future sustainable materials including strong and stiff filaments. The goal of this paper is to introduce a data analysis of flow-induced birefringence experiments by means of unsupervised learning techniques. By reducing the dimensionality of the data with Principal Component Analysis (PCA) we are able to exploit information for the different cellulose materials at several concentrations and compare them to each other. Our approach aims at classifying the CNF materials at different concentrations by applying unsupervised machine learning algorithms, like k-means and Gaussian Mixture Models (GMMs). Finally, we analyze the autocorrelation function (ACF) and the partial autocorrelation function (PACF) of the first principal component, detecting seasonality in lower concentrations. The focus is given to the initial relaxation of birefringence after the flow is stopped to have a better understanding of the Brownian dynamics for the given materials and concentrations.

    Our method can be used to distinguish the different materials at specific concentrations and could help to identify possible advantages and drawbacks of one material over the other. 

  • 10.
    Brett, Calvin
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. Deutsches Elektronen Synchrotron, Notkestraße 85, Hamburg, Germany.
    Forslund, Ola Kenji
    KTH, School of Engineering Sciences (SCI), Applied Physics, Materials and Nanophysics.
    Nocerino, Elisabetta
    KTH, School of Engineering Sciences (SCI), Applied Physics, Materials and Nanophysics.
    Kreuzer, L.P
    TU München, Germany.
    Widmann, T.
    TU München, Germany.
    Porcar, L.
    Institut Laue-Langevin, 71 Avenue des Martyrs, Grenoble, France.
    Yamada, N. L.
    High Energy Accelerator Research Organization (KEK), 203-1 Shirakata, Tokai, Naka 319-1106, Japan.
    Matsubara, Nami
    KTH, School of Engineering Sciences (SCI), Applied Physics, Materials and Nanophysics.
    Månsson, Martin
    KTH, School of Engineering Sciences (SCI), Applied Physics, Materials and Nanophysics.
    Müller-Buschbaum, P.
    TU München, Germany.
    Söderberg, Daniel
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences (SCI), Engineering Mechanics.
    Roth, Stephan V.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. Deutsches Elektronen Synchrotron, Notkestraße 85, Hamburg, Germany.
    Humidity-Induced Nanoscale Restructuring in PEDOT:PSS and Cellulose Nanofibrils Reinforced Biobased Organic Electronics2021In: Advanced Electronic Materials, E-ISSN 2199-160X, Vol. 7, no 6, p. 2100137-, article id 2100137Article in journal (Refereed)
    Abstract [en]

    In times where research focuses on the use of organic polymers as a base for complex organic electronic applications and improving device efficiencies, degradation is still less intensively addressed in fundamental studies. Hence, advanced neutron scattering methods are applied to investigate a model system for organic electronics composed of the widely used conductive polymer blend poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) together with nanocellulose as flexible reinforcing template material. In particular, the impact of relative humidity (RH) on the nanostructure evolution is studied in detail. The implications are discussed from a device performance point of view and the changing nanostructure is correlated with macroscale physical properties such as conductivity. The first humidification (95% RH) leads to an irreversible decrease of conductivity. After the first humidification cycle, however, the conductivity can be reversibly regained when returning to low humidity values (5% RH), which is important for device manufacturing. This finding can directly contribute to an improved usability of emerging organic electronics in daily live.

  • 11.
    Brett, Calvin
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Forslund, Ola Kenji
    KTH, School of Engineering Sciences (SCI), Applied Physics, Materials and Nanophysics.
    Nocerino, Elisabetta
    KTH, School of Engineering Sciences (SCI), Applied Physics, Materials and Nanophysics.
    Kreuzer, Lucas
    Wiedmann, Tobias
    Porcar, Lionel
    Yamada, Norifumi
    Matsubara, Nami
    KTH, School of Engineering Sciences (SCI), Applied Physics, Materials and Nanophysics.
    Månsson, Martin
    KTH, School of Engineering Sciences (SCI), Applied Physics, Materials and Nanophysics.
    Müller-Buschbaum, Peter
    Söderberg, Daniel
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fiberprocesser.
    Roth, Stephan V.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites.
    Humidity-induced Nanoscale Restructuring in PEDOT:PSS and Cellulose reinforced Bio-based Organic ElectronicsManuscript (preprint) (Other academic)
  • 12.
    Brett, Calvin
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. Deutsches Elektronen-Synchrotron DESY, Hamburg 22607, Germany.
    Mittal, Nitesh
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences (SCI), Mechanics.
    Ohm, Wiebke
    Deutsches Elektronen-Synchrotron (DESY), Notkestr. 85, 22607, Hamburg, Germany.
    Gensch, Marc
    Deutsches Elektronen-Synchrotron (DESY), Notkestr. 85, 22607, Hamburg, Germany.
    Kreuzer, Lucas P.
    Deutsches Elektronen-Synchrotron (DESY), Notkestr. 85, 22607, Hamburg, Germany.
    Körstgens, Volker
    Lehrstuhl für Funktionelle Materialien, Physik-Department, and ¶ Heinz Maier-Leibnitz Zentrum (MLZ), Technische Universitat ̈ München, Garching 85748, Germany.
    Månsson, Martin
    KTH, School of Engineering Sciences (SCI), Applied Physics, Materials and Nanophysics.
    Frielinghaus, Henrich
    Jülich Centre for Neutron Science at MLZ.
    Müller-Buschbaum, Peter
    Lehrstuhl für Funktionelle Materialien, Physik-Department, and ¶ Heinz Maier-Leibnitz Zentrum (MLZ), Technische Universitat ̈ München, Garching 85748, Germany.
    Söderberg, Daniel
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences (SCI), Engineering Mechanics.
    Roth, Stephan V.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites.
    Water-Induced Structural Rearrangements on the Nanoscale in Ultrathin Nanocellulose Films2019In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 52, no 12, p. 4721-4728Article in journal (Refereed)
    Abstract [en]

    Many nanoscale biopolymer building blocks with defect-free molecular structure and exceptional mechanical properties have the potential to surpass the performance of existing fossil-based materials with respect to barrier properties, load-bearing substrates for advanced functionalities, as well as light-weight construction. Comprehension and control of performance variations of macroscopic biopolymer materials caused by humidity-driven structural changes at the nanoscale are imperative and challenging. A long-lasting challenge is the interaction with water molecules causing reversible changes in the intrinsic molecular structures that adversely affects the macroscale performance. Using in situ advanced X-ray and neutron scattering techniques, we reveal the structural rearrangements at the nanoscale in ultrathin nanocellulose films with humidity variations. These reversible rearrangements are then correlated with wettability that can be tuned. The results and methodology have general implications not only on the performance of cellulose-based materials but also for hierarchical materials fabricated with other organic and inorganic moisture-sensitive building blocks.

  • 13.
    Brett, Calvin
    et al.
    KTH, School of Engineering Sciences (SCI), Mechanics, Fluid Physics.
    Mittal, Nitesh
    KTH, School of Engineering Sciences (SCI), Mechanics, Fluid Physics. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Ohm, Wiebke
    DESY, Hamburg, Germany..
    Söderberg, Daniel
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences (SCI), Mechanics, Fluid Physics.
    Roth, Stephan V.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites. DESY, Hamburg, Germany..
    GISAS study of spray deposited metal precursor ink on a cellulose template2019In: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 257Article in journal (Other academic)
  • 14.
    Brett, Calvin
    et al.
    KTH, School of Engineering Sciences (SCI), Mechanics, Fluid Physics. DESY, Photon Sci, Hamburg, Germany.
    Mittal, Nitesh
    KTH, School of Engineering Sciences (SCI), Mechanics, Fluid Physics. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Ohm, Wiebke
    DESY, Photon Sci, Hamburg, Germany..
    Söderberg, Daniel
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences (SCI), Mechanics, Fluid Physics.
    Roth, Stephan V.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites. DESY, Photon Sci, Hamburg, Germany..
    In situ self-assembly study in bio-based thin films2018In: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 255Article in journal (Other academic)
  • 15.
    Brett, Calvin
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. Forschungszentrum Helmholtz Gemeinschaft, Deutsch Elektronen Synchrotron DESY, D-22607 Hamburg, Germany.
    Ohm, Wiebke
    Forschungszentrum Helmholtz Gemeinschaft, Deutsch Elektronen Synchrotron DESY, D-22607 Hamburg, Germany..
    Fricke, Bjorn
    Forschungszentrum Helmholtz Gemeinschaft, Deutsch Elektronen Synchrotron DESY, D-22607 Hamburg, Germany..
    Alexakis, Alexandros Efraim
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Laarmann, Tim
    Forschungszentrum Helmholtz Gemeinschaft, Deutsch Elektronen Synchrotron DESY, D-22607 Hamburg, Germany.;Hamburg Ctr Ultrafast Imaging CUI, D-22761 Hamburg, Germany..
    Korstgens, Volker
    Tech Univ Munich, Phys Dept, Lehrstuhl Funkt Materialien, D-85748 Garching, Germany..
    Muller-Buschbaum, Peter
    Tech Univ Munich, Phys Dept, Lehrstuhl Funkt Materialien, D-85748 Garching, Germany.;Tech Univ Munich, Heinz Maier Leibnitz Zentrum MLZ, D-85748 Garching, Germany..
    Söderberg, Daniel
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences (SCI), Engineering Mechanics. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fiberprocesser.
    Roth, Stephan, V
    Forschungszentrum Helmholtz Gemeinschaft, Deutsch Elektronen Synchrotron DESY, D-22607 Hamburg, Germany.;Dept Fibre & Polymer Technol, Div Coating Technol, S-10044 Stockholm, Sweden..
    Nanocellulose-Assisted Thermally Induced Growth of Silver Nanoparticles for Optical Applications2021In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 13, no 23, p. 27696-27704Article in journal (Refereed)
    Abstract [en]

    Optically responsive materials are present in everyday life, from screens to sensors. However, fabricating large-area, fossil-free materials for functional biocompatible applications is still a challenge today. Nanocelluloses from various sources, such as wood, can provide biocompatibility and are emerging candidates for templating organic optoelectronics. Silver (Ag) in its nanoscale form shows excellent optical properties. Herein, we combine both materials using thin-film large-area spray-coating to study the fabrication of optical response applications. We characterize the Ag nanoparticle formation by X-ray scattering and UV-vis spectroscopy in situ during growth on the nanocellulose template. The morphology and optical properties of the nanocellulose film are compared to the rigid reference surface SiO2. Our results clearly show the potential to tailor the energy band gap of the resulting hybrid material.

  • 16.
    Brett, Calvin
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics.
    Ohm, Wiebke
    Fricke, Björn
    Laarmann, Tim
    Körstgens, Volker
    Müller-Buschbaum, Peter
    Söderberg, Daniel
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fiberprocesser.
    Roth, Stephan V.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites.
    Nanocellulose-Assisted Thermally-Induced Growth of Silver Nanoparticles for Optical ApplicationsManuscript (preprint) (Other academic)
  • 17.
    Brouzet, Christophe
    et al.
    KTH.
    Mittal, Nitesh
    KTH.
    Lundell, Fredrik
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Söderberg, Daniel
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Characterizing the Orientational and Network Dynamics of Polydisperse Nanofibers at the Nanoscale.Manuscript (preprint) (Other academic)
  • 18.
    Brouzet, Christophe
    et al.
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Mittal, Nitesh
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Lundell, Fredrik
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Söderberg, Daniel
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Characterizing the Orientational and Network Dynamics of Polydisperse Nanofibers on the Nanoscale2019In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 52, no 6, p. 2286-2295Article in journal (Refereed)
    Abstract [en]

    Polydisperse fiber networks are the basis of many natural and manufactured structures, ranging from high-performance biobased materials to components of living cells and tissues. The formation and behavior of such networks are given by fiber properties such as length and stiffness as well as the number density and fiber-fiber interactions. Studies of fiber network behavior, such as connectivity or rigidity thresholds, typically assume monodisperse fiber lengths and isotropic fiber orientation distributions, specifically for nano scale fibers, where the methods providing time-resolved measurements are limited. Using birefringence measurements in a microfluidic flow-focusing channel combined with a flow stop procedure, we here propose a methodology allowing investigations of length-dependent rotational dynamics of nanoscale polydisperse fiber suspensions, including the effects of initial nonisotropic orientation distributions. Transition from rotational mobility to rigidity at entanglement thresholds is specifically addressed for a number of nanocellulose suspensions, which are used as model nanofiber systems. The results show that the proposed method allows the characterization of the subtle interplay between Brownian diffusion and nanoparticle alignment on network dynamics.

  • 19.
    Brouzet, Christophe
    et al.
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Mittal, Nitesh
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Rosén, Tomas
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Takeda, Yusuke
    Tohoku Univ, Inst Fluid Sci, Sendai, Miyagi 9808577, Japan..
    Söderberg, Daniel
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Lundell, Fredrik
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Takana, Hidemasa
    Tohoku Univ, Inst Fluid Sci, Sendai, Miyagi 9808577, Japan..
    Effect of Electric Field on the Hydrodynamic Assembly of Polydisperse and Entangled Fibrillar Suspensions2021In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 37, no 27, p. 8339-8347Article in journal (Refereed)
    Abstract [en]

    Dynamics of colloidal particles can be controlled by the application of electric fields at micrometer-nanometer length scales. Here, an electric field-coupled microfluidic flow-focusing device is designed for investigating the effect of an externally applied alternating current (AC) electric field on the hydrodynamic assembly of cellulose nanofibrils (CNFs). We first discuss how the nanofibrils align parallel to the direction of the applied field without flow. Then, we apply an electric field during hydrodynamic assembly in the microfluidic channel and observe the effects on the mechanical properties of the assembled nanostructures. We further discuss the nanoscale orientational dynamics of the polydisperse and entangled fibrillar suspension of CNFs in the channel. It is shown that electric fields induced with the electrodes locally increase the degree of orientation. However, hydrodynamic alignment is demonstrated to be much more efficient than the electric field for aligning CNFs. The results are useful for understanding the development of the nanostructure when designing high-performance materials with microfluidics in the presence of external stimuli.

  • 20.
    Brouzet, Christophe
    et al.
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Mittal, Nitesh
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Söderberg, Daniel
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences (SCI), Mechanics.
    Lundell, Fredrik
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences (SCI), Mechanics.
    Size-Dependent Orientational Dynamics of Brownian Nanorods2018In: ACS Macro Letters, E-ISSN 2161-1653, Vol. 7, no 8, p. 1022-1027Article in journal (Refereed)
    Abstract [en]

    Successful assembly of suspended nanoscale rod-like particles depends on fundamental phenomena controlling rotational and translational diffusion. Despite the significant developments in fluidic fabrication of nanostructured materials, the ability to quantify the dynamics in processing systems remains challenging. Here we demonstrate an experimental method for characterization of the orientation dynamics of nanorod suspensions in assembly flows using orientation relaxation. This relaxation, measured by birefringence and obtained after rapidly stopping the flow, is deconvoluted with an inverse Laplace transform to extract a length distribution of aligned nanorods. The methodology is illustrated using nanocelluloses as model systems, where the coupling of rotational diffusion coefficients to particle size distributions as well as flow-induced orientation mechanisms are elucidated. 

  • 21.
    Carlsson, Allan
    et al.
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Håkansson, Karl
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Kvick, Mathias
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Lundell, Fredrik
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Söderberg, Daniel
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Evaluation of steerable filter for detection of fibres in flowing suspensions2011In: Experiments in Fluids, ISSN 0723-4864, E-ISSN 1432-1114, Vol. 51, no 4, p. 987-996Article in journal (Refereed)
    Abstract [en]

    Steerable filters are concluded to be useful in order to determine the orientation of fibers captured in digital images. The fiber orientation is a key variable in the study of flowing fiber suspensions. Here, digital image analysis based on a filter within the class of steerable filters is evaluated for suitability of finding the position and orientation of fibers suspended in flowing suspensions. In sharp images with small noise levels, the steerable filter succeeds in determining the orientation of artificially generated fibers with well-defined angles. The influence of reduced image quality on the orientation has been quantified. The effect of unsharpness and noise is studied and the results show that the error in orientation is less than 1° for moderate levels. Images from two flow cases, one laminar shear flow and one turbulent, are also analyzed. The fiber orientation distribution is determined in the flow-vorticity plane. For the laminar case a comparison is made to a robust, but computationally more expensive, method involving convolutions with an oriented elliptic filter. A good agreement is found when comparing the resulting fiber orientation distributions obtained with the two methods. For the turbulent case, it is demonstrated that correct results are obtained and that the method can handle overlapping fibers. 

  • 22.
    Carlsson, Allan
    et al.
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Lundell, Fredrik
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Söderberg, Daniel
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Evaluation of steerable filters for detection of rod-like particles in flowing suspensionsManuscript (Other academic)
  • 23.
    Carlsson, Allan
    et al.
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Lundell, Fredrik
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Söderberg, Daniel
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Fibre orientation control related to papermaking2007In: Journal of Fluids Engineering, ISSN 0098-2202, E-ISSN 1528-901X, Vol. 129, no 4, p. 457-465Article in journal (Refereed)
    Abstract [en]

    The orientation of fibers suspended in a shear flow flowing over a solid wall has been studied experimentally. The possibility to control this orientation with physical surface modifications, ridges, has also been studied. The fiber suspension was driven by gravity down a slightly inclined glass plate and a CCD-camera was used to capture images of the fibers in the flow. Image analysis based on the concept of steerable filters extracted the position and orientation of the fibers in the plane of the image. From these data, the velocity of the fibers was determined. When viewing the flow from the side, the velocity of the fibers at different heights was measured and found to agree with the theoretical solution for Newtonian flow down an inclined plate. Moving the camera so that the flow was filmed from below, the orientation and velocity of fibers in the plane parallel to the solid surface was determined. The known relationship between the velocity and the wall normal position of the fibers made it possible to determine the height above the plate for each identified fiber. Far away from the wall, the fibers were aligned with the flow direction in both cases. In a region close to the smooth plate surface the fibers oriented themselves perpendicular to the flow direction. This change in orientation did not occur when the surface structure was modified with ridges.

  • 24.
    Carlsson, Allan
    et al.
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Lundell, Fredrik
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Söderberg, Daniel
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Orientation of fibres in a flowing suspension near a plane wallManuscript (Other academic)
  • 25. Carlsson, Allan
    et al.
    Lundell, Fredrik
    KTH, Superseded Departments (pre-2005), Mechanics.
    Söderberg, Daniel
    KTH, Superseded Departments (pre-2005), Mechanics.
    The wall effect on the orientation of fibres in a shear flow2006In: ANNUAL TRANSACTIONS OF THE NORDIC RHEOLOGY SOCIETY, 2006, Vol. 14Conference paper (Refereed)
  • 26.
    Carlsson, Allan
    et al.
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Lundell, Fredrik
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Söderberg, L. Daniel
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Evaluation of a steerable filter for detection of fibres in flowing suspensionsManuscript (Other academic)
    Abstract [en]

    Steerable filters are concluded to be useful in order to determine the orientation of fibres captured in digital images. The fibre orientation is a key variable in the study of flowing fibre suspensions. Here digital image analysis based on a filter within the class of steerable filters is evaluated for suitability of finding the position and orientation of fibres suspended in flowing suspensions. In sharp images with small noise levels the steerable filter succeeds in determining the orientation of artificially generated fibres with well-defined angles. The influence of reduced image quality on the orientation has been quantified. The effect of unsharpness and noise is studied and the results show that the error in orientation is less than 1◦ for moderate levels. A set of images with fibres suspended in a shear flow is also analyzed. The fibre orientation distribution is determined in the flow-vorticity plane. In this analysis a comparison is also made to a robust, but computationally more expensive, method involving convolutions with an oriented elliptic filter. A good agreement is found when comparing the resulting fibre orientation distributions obtained with the two methods.

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    FULLTEXT01
  • 27.
    Carlsson, Allan
    et al.
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Lundell, Fredrik
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Söderberg, L. Daniel
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Orientation of slowly sedimenting fibers in a flowing suspensionnear a plane wall2007In: Svenska Mekanikdagarna, 2007Conference paper (Refereed)
    Abstract [en]

    The effect of a wall on the orientation of slowly sedimenting fibers suspended in a shear flow has been studied experimentally. Experiments were performed at two concentrations with two aspect ratios, rp ≈ 7 and rp ≈ 30, where rp is defined as the fiber length divided by the diameter. For all cases the majority of the fibers were oriented close to parallel to the flow direction for distances farther away from the wall than half a fiber length. As the distance from the wall decreased a change in orientation was observed. At distances from the wall closer than about an eighth of a fiber length a significant amount of the fibers were oriented close to perpendicular to the flow. This was particularly clear for the shorter fibers. Due to the density difference between the fibers and the surrounding fluid the fiber concentration was increased in the near wall region. An increased concentration was found in a limited region close to half a fiber length from the wall. For the shorter fibers a large number of fibers was also detected in the very proximity of the wall.

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    FULLTEXT01
  • 28.
    Carlsson, Allan
    et al.
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Söderberg, Daniel
    Lundell, Fredrik
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Fibre Orientation Control Related To Papermaking2006In: PROCEEDINGS OF THE ASME FLUIDS ENGINEERING DIVISION SUMMER CONFERENCE, VOL 1, PTS A AND B, 2006, p. 1501-1509Conference paper (Refereed)
    Abstract [en]

    The wall effect on the orientation of fibres suspended in a shear flow has been studied experimentally. A fibre suspension, driven by gravity down an inclined glass plate, constitutes the shear flow field. A CCD-camera was mounted underneath the flow in order to visualize the flow. The orientation of fibres in the plane perpendicular to the plate was determined, by using the concept of steerable filters. In a region close to the smooth plate surface the fibres oriented themselves perpendicular to the flow direction. This did not occur when the surface structure was modified with ridges.

  • 29.
    Carlsson, Allan
    et al.
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Söderberg, Daniel
    Innventia AB, Box 5604, SE–114 86 Stockholm.
    Lundell, Fredrik
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Fibre orientation measurements near a headbox wall2010In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 25, no 2, p. 204-212Article in journal (Refereed)
    Abstract [en]

    Experimental results on the fibre orientation in a laboratory scale headbox are reported. Images containing fibres in approximately 1 mm thick slices parallel to the wall were captured at different wall distances. A steerable filter was used to determine the orientation of bleached and unbeaten birch fibres, suspended in water, at different distances from one of the inclined walls of the headbox contraction. Due to optical limitations only dilute suspensions were studied. It is shown that the fibre orientation distribution varies with the distance from the wall. Sufficiently far upstream in the headbox a more anisotropic distribution is found closer to the wall.

  • 30.
    Carlsson, Allan
    et al.
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Söderberg, L. Daniel
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. STFI-Packforsk AB, Sweden.
    Lundell, Fredrik
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Fibre orientation in the boundary layers of a planar converging channel2008In: TAPPI Press - Paper Conference and Trade Show, PaperCon '08, 2008, p. 384-408Conference paper (Refereed)
    Abstract [en]

    Experimental results on the fibre orientation in a laboratory scale headbox are reported. A steerable filter was used to determine the orientation of bleached and unbeaten birch fibres at different distances from one of the inclined walls of the headbox contraction. Due to optical limitations only low concentrations were studied. It is shown that the orientation varies with the distance from the wall. For most studied cases a more anisotropic profile was found closer to the wall.

  • 31.
    Carlsson, Allan
    et al.
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences (SCI), Mechanics.
    Söderberg, L. Daniel
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. STFI-Packforsk AB, SE - 114 86 Stockholm, Sweden.
    Lundell, Fredrik
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Fibre orientation near a wall of a headbox.2010Conference paper (Refereed)
    Abstract [en]

    Experimental results on the fibre orientation in a laboratory scale headbox are reported. A steerable filter was used to determine the orientation of bleached unbeaten birch fibres at different distances from one of the inclined walls of the headbox contraction. Due to optical limitations only dilute suspensions were studied. It is shown that the fibre orientation distribution varies with the distance from the wall. Sufficiently far upstream in the headbox a more anisotropic distribution is found closer to the wall as compared to farther away from the wall.

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    fulltext
  • 32.
    Castro, Daniele Oliveira
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. MoRe Research Örnsköldsvik AB, Örnsköldsvik, Sweden.
    Karim, Zoheb
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. MoRe Research Örnsköldsvik AB, Örnsköldsvik, Sweden.
    Medina, Lilian
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Häggström, J. -O
    Carosio, F.
    Svedberg, A.
    Wågberg, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Söderberg, Daniel
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fiberprocesser.
    Berglund, Lars A.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    The use of a pilot-scale continuous paper process for fire retardant cellulose-kaolinite nanocomposites2018In: Composites Science And Technology, ISSN 0266-3538, E-ISSN 1879-1050, Vol. 162, p. 215-224Article in journal (Refereed)
    Abstract [en]

    Nanostructured materials are difficult to prepare rapidly and at large scale. Melt-processed polymer-clay nanocomposites are an exception, but the clay content is typically below 5 wt%. An approach for manufacturing of microfibrillated cellulose (MFC)/kaolinite nanocomposites is here demonstrated in pilot-scale by continuous production of hybrid nanopaper structures with thickness of around 100 μm. The colloidal nature of MFC suspensions disintegrated from chemical wood fiber pulp offers the possibility to add kaolinite clay platelet particles of nanoscale thickness. For initial lab scale optimization purposes, nanocomposite processing (dewatering, small particle retention etc) and characterization (mechanical properties, density etc) were investigated using a sheet former (Rapid Köthen). This was followed by a continuous fabrication of composite paper structures using a pilot-scale web former. Nanocomposite morphology was assessed by scanning electron microscopy (SEM). Mechanical properties were measured in uniaxial tension. The fire retardancy was evaluated by cone calorimetry. Inorganic hybrid composites with high content of in-plane oriented nanocellulose, nanoclay and wood fibers were successfully produced at pilot scale. Potential applications include fire retardant paperboard for semi structural applications.

  • 33. Chen, Q.
    et al.
    Betker, Marie
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, Hamburg, 22607, Germany.
    Harder, C.
    Brett, Calvin J.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, Hamburg, 22607, Germany.
    Schwartzkopf, M.
    Ulrich, N. M.
    Toimil-Molares, M. E.
    Trautmann, C.
    Söderberg, Daniel
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Weindl, C. L.
    Körstgens, V.
    Müller-Buschbaum, P.
    Ma, M.
    Roth, Stephan V.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology. Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, Hamburg, 22607, Germany.
    Biopolymer-Templated Deposition of Ordered and Polymorph Titanium Dioxide Thin Films for Improved Surface-Enhanced Raman Scattering Sensitivity2022In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 32, no 6, article id 2108556Article in journal (Refereed)
    Abstract [en]

    Titanium dioxide (TiO2) is an excellent candidate material for semiconductor metal oxide-based substrates for surface-enhanced Raman scattering (SERS). Biotemplated fabrication of TiO2 thin films with a 3D network is a promising route for effectively transferring the morphology and ordering of the template into the TiO2 layer. The control over the crystallinity of TiO2 remains a challenge due to the low thermal stability of biopolymers. Here is reported a novel strategy of the cellulose nanofibril (CNF)-directed assembly of TiO2/CNF thin films with tailored morphology and crystallinity as SERS substrates. Polymorphous TiO2/CNF thin films with well-defined morphology are obtained by combining atomic layer deposition and thermal annealing. A high enhancement factor of 1.79 × 106 in terms of semiconductor metal oxide nanomaterial (SMON)-based SERS substrates is obtained from the annealed TiO2/CNF thin films with a TiO2 layer thickness of 10 nm fabricated on indium tin oxide (ITO), when probed by 4-mercaptobenzoic acid molecules. Common SERS probes down to 10 nm can be detected on these TiO2/CNF substrates, indicating superior sensitivity of TiO2/CNF thin films among SMON SERS substrates. This improvement in SERS sensitivity is realized through a cooperative modulation of the template morphology of the CNF network and the crystalline state of TiO2.

  • 34. Chen, Q.
    et al.
    Sochor, B.
    Chumakov, A.
    Betker, Marie
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Ulrich, N. M.
    Toimil-Molares, M. E.
    Gordeyeva, Korneliya
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Söderberg, Daniel
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Roth, Stephan V.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Cellulose-Reinforced Programmable and Stretch-Healable Actuators for Smart Packaging2022In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 32, no 49, p. 2208074-, article id 2208074Article in journal (Refereed)
    Abstract [en]

    Biomimetic actuators are promising candidates for smart soft robotics. The applications of state-of-the-art actuators require the combination of programmable stimuli-responsiveness, excellent robustness, and efficient self-healing ability in a wide-range of working conditions. However, these properties may be mutually exclusive. Inspired by biological tissues, two kinds of polyelectrolytes including polyvinyl alcohol (PVA) and polystyrene sulfonate (PSS) are exploited as the fillers of cellulose nanofibrils (CNFs) for the fabrication of the CNF/PVA/PSS (CAS) film via the assembly of the physically-crosslinked network through multiple H-bonding and electrostatic interactions. Achieved by a casting-evaporation strategy, internal stress is stored within the polymer matrix and transforms into reversible anisotropic bending deformations in response to a humidity gradient. The speed, direction, and pitch of the bending can be programmed by tailoring the internal stresses and geometry of the samples. Moreover, the H-bonded network also contributes to the effective energy dissipation toward high toughness during tensile stretching, as well as self-healing ability during moisture saturation of the CAS films. This enables the fabrication of a humidity-sensitive flower-shaped actuator and self-healable packaging paper. This study presents a biomimetic strategy for the fabrication of multi-functional soft robotics, which holds great promise for applications in the fields of biosensors and smart packaging. 

  • 35.
    Chen, Qing
    et al.
    DESY, D-22607 Hamburg, Germany.;Univ Sci & Technol China, Sch Chem & Mat Sci, Hefei 230026, Peoples R China..
    Brett, Calvin
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. DESY, D-22607 Hamburg, Germany..
    Chumakov, Andrei
    DESY, D-22607 Hamburg, Germany..
    Gensch, Marc
    DESY, D-22607 Hamburg, Germany.;Tech Univ Munich, Phys Dept, Lehrstuhl Funkt Mat, D-85748 Garching, Germany..
    Schwartzkopf, Matthias
    DESY, D-22607 Hamburg, Germany..
    Koerstgens, Volker
    Tech Univ Munich, Phys Dept, Lehrstuhl Funkt Mat, D-85748 Garching, Germany..
    Söderberg, Daniel
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences (SCI), Engineering Mechanics. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fiberprocesser.
    Plech, Anton
    Karlsruhe Inst Technol KIT, Inst Photon Sci & Synchrotron Radiat, D-76021 Karlsruhe, Germany..
    Zhang, Peng
    Sun Yat Sen Univ, Sch Mat Sci & Engn, PCFM Lab, Guangzhou 510275, Peoples R China..
    Mueller-Buschbaum, Peter
    Tech Univ Munich, Phys Dept, Lehrstuhl Funkt Mat, D-85748 Garching, Germany.;Tech Univ Munich, Heinz Maier Leibniz Zentrum MLZ, D-85748 Garching, Germany..
    Roth, Stephan V.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. DESY, D-22607 Hamburg, Germany..
    Layer-by-Layer Spray-Coating of Cellulose Nanofibrils and Silver Nanoparticles for Hydrophilic Interfaces2021In: ACS Applied Nano Materials, E-ISSN 2574-0970, Vol. 4, no 1, p. 503-513Article in journal (Refereed)
    Abstract [en]

    Silver nanoparticles (AgNPs) and AgNP-based composite materials have attracted growing interest due to their structure-dependent optical, electrical, catalytic, and stimuli-responsive properties. For practical applications, polymeric materials are often combined with AgNPs to provide flexibility and offer a scaffold for homogenous distribution of the AgNPs. However, the control over the assembly process of AgNPs on polymeric substrates remains a big challenge. Herein, we report the fabrication of AgNP/cellulose nanofibril (CNF) thin films via layer-by-layer (LBL) spray-coating. The morphology and self-assembly of AgNPs with increasing number of spray cycles are characterized by atomic force microscopy (AFM), grazing-incidence small-angle X-ray scattering (GISAXS), and grazing-incidence wide-angle X-ray scattering (GIWAXS). We deduce that an individual AgNP (radius = 15 +/- 3 nm) is composed of multiple nanocrystallites (diameter = 2.4 +/- 0.9 nm). Our results suggest that AgNPs are assembled into large agglomerates on SiO2 substrates during spray-coating, which is disadvantageous for AgNP functionalization. However, the incorporation of CNF substrates contributes to a more uniform distribution of AgNP agglomerates and individual AgNPs by its network structure and by absorbing the partially dissolved AgNP agglomerates. Furthermore, we demonstrate that the spray-coating of the AgNP/CNF mixture results in similar topography and agglomeration patterns of AgNPs compared to depositing AgNPs onto a precoated CNF thin film. Contact-angle measurements and UV/vis spectroscopy suggest that the deposition of AgNPs onto or within CNFs could increase the hydrophilicity of AgNP-containing surfaces and the localized surface plasmon resonance (LSPR) intensity of AgNP compared to AgNPs sprayed on SiO(2 )substrates, suggesting their potential applications in antifouling coatings or label-free biosensors. Thereby, our approach provides a platform for a facile and scalable production of AgNP/CNF films with a low agglomeration rate by two different methods as follows: (1) multistep layer-by-layer (LBL) spray-coating and (2) direct spray-coating of the AgNP/CNF mixture. We also demonstrate the ability of CNFs as a flexible framework for directing the uniform assembly of AgNPs with tailorable wettability and plasmonic properties.

  • 36.
    Fällman, Monika
    et al.
    KTH, Superseded Departments (pre-2005), Mechanics.
    Lundell, Fredrik
    KTH, Superseded Departments (pre-2005), Mechanics.
    Holm, Richard
    KTH, Superseded Departments (pre-2005), Mechanics.
    Söderberg, L. Daniel
    STFI-Packforsk.
    A critical evaluation of ultrasound velocity profiling aiming towards measurements in fibre suspensionsManuscript (preprint) (Other academic)
  • 37. Geng, Lihong
    et al.
    Mittal, Nitesh
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Zhan, Chengbo
    Ansari, Farhan
    Sharma, Priyanka R.
    Peng, Xiangfang
    Hsiao, Benjamin S.
    Söderberg, Daniel
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Understanding the Mechanistic Behavior of Highly Charged Cellulose Nanofibers in Aqueous Systems2018In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 51, no 4, p. 1498-1506Article in journal (Refereed)
    Abstract [en]

    Mechanistic behavior and flow properties of cellulose nanofibers (CNFs) in aqueous systems can be described by the crowding factor and the concept of contact points, which are functions of the aspect ratio and concentration of CNF in the suspension. In this study, CNFs with a range of aspect ratio and surface charge density (380-1360 mu mol/g) were used to demonstrate this methodology. It was shown that the critical networking point of the CNF suspension, determined by rheological measurements, was consistent with the gel crowding factor, which was 16. Correlated to the crowding factor, both viscosity and modulus of the systems were found to decrease by increasing the charge density of CNF, which also affected the flocculation behavior. Interestingly, an anomalous rheological behavior was observed near the overlap concentration (0.05 wt %) of CNF, at which the crowding factor was below the gel crowding factor, and the storage modulus (G') decreased dramatically at a given frequency threshold. This behavior is discussed in relation to the breakup of the entangled flocs and network in the suspension. The analysis of the mechanistic behavior of CNF aqueous suspensions by the crowding factor provides useful insight for fabricating high-performance nanocellulose-based materials.

  • 38.
    Gowda, V. Krishne
    et al.
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences (SCI), Engineering Mechanics.
    Brouzet, Christophe
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Lefranc, Thibault
    Univ Claude Bernard, Univ Lyon, ENS Lyon, CNRS,Lab Phys, F-69342 Lyon, France..
    Söderberg, Daniel
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Lundell, Fredrik
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Effective interfacial tension in flow-focusing of colloidal dispersions: 3-D numerical simulations and experiments2019In: Journal of Fluid Mechanics, ISSN 0022-1120, E-ISSN 1469-7645, Vol. 876, p. 1052-1076, article id PII S0022112019005664Article in journal (Refereed)
    Abstract [en]

    An interface between two miscible fluids is transient, existing as a non-equilibrium state before complete molecular mixing is reached. However, during the existence of such an interface, which typically occurs at relatively short time scales, composition gradients at the boundary between the two liquids cause stresses effectively mimicking an interfacial tension. Here, we combine numerical modelling and experiments to study the influence of an effective interfacial tension between a colloidal fibre dispersion and its own solvent on the flow in a microfluidic system. In a flow-focusing channel, the dispersion is injected as core flow that is hydrodynamically focused by its solvent as sheath flows. This leads to the formation of a long fluid thread, which is characterized in three dimensions using optical coherence tomography and simulated using a volume of fluid method. The simulated flow and thread geometries very closely reproduce the experimental results in terms of thread topology and velocity flow fields. By varying the interfacial tension numerically, we show that it controls the thread development, which can be described by an effective capillary number. Furthermore, we demonstrate that the applied methodology provide the means to measure the ultra-low but dynamically highly significant effective interfacial tension.

  • 39.
    Gowda, V. Krishne
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Rosén, Tomas
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Roth, Stephan V.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. DESY, D-22607 Hamburg, Germany..
    Söderberg, Daniel
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences (SCI), Engineering Mechanics. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fiberprocesser.
    Lundell, Fredrik
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences (SCI), Engineering Mechanics.
    Nanofibril Alignment during Assembly Revealed by an X-ray Scattering-Based Digital Twin2022In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 16, no 2, p. 2120-2132Article in journal (Refereed)
    Abstract [en]

    The nanostructure, primarily particle orientation, controls mechanical and functional (e.g., mouthfeel, cell compatibility, optical, morphing) properties when macroscopic materials are assembled from nanofibrils. Understanding and controlling the nanostructure is therefore an important key for the continued development of nanotechnology. We merge recent developments in the assembly of biological nanofibrils, X-ray diffraction orientation measurements, and computational fluid dynamics of complex flows. The result is a digital twin, which reveals the complete particle orientation in complex and transient flow situations, in particular the local alignment and spatial variation of the orientation distributions of different length fractions, both along the process and over a specific cross section. The methodology forms a necessary foundation for analysis and optimization of assembly involving anisotropic particles. Furthermore, it provides a bridge between advanced in operandi measurements of nanostructures and phenomena such as transitions between liquid crystal states and in silico studies of particle interactions and agglomeration.

  • 40.
    Gowda, V. Krishne
    et al.
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences (SCI), Engineering Mechanics.
    Rosén, Tomas
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fiberprocesser. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Söderberg, Daniel
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fiberprocesser.
    Lundell, Fredrik
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences (SCI), Engineering Mechanics.
    Effects of fluid properties, flow parameters and geometrical variations on viscous threads in microfluidic channelsManuscript (preprint) (Other academic)
    Abstract [en]

    We report a combined experimental and numerical investigation to decipher and delineate the role of fluid properties, flow parameters, and geometries on the dynamics of viscous thread formation in microchannels with miscible solvents. A methodological analysis based on the evolution of viscous threads unveils the significance of effective interfacial tension (EIT) induced by the virtue of concentration gradients between the non-equilibrium miscible fluid pair colloidal dispersions and their own solvent.  Functional scaling relationships developed with dimensionless capillary and Weber numbers, together with thread quantities thread detachment length, and thread width, shed light on the complex interplay of hydrodynamic effects and viscous microflow processes. The detachment of viscous threads inside microchannels is governed by the unified hydrodynamic effects of inertia, capillary, and viscous stresses in contrast to the natural phenomenon of self-lubrication,  bringing new insights to the physical phenomena involved in the confined microsystems. Exploiting the experimentally measured thread quantities, the scaling laws are practically applied to estimate the inherent fluid properties such as EIT between two inhomogeneous miscible fluids, and the fluid viscosities. In addition, the cross-sectional aspect ratio of the channels is varied numerically in conjunction with the converging shaped sections.  For specified flow rates and given rheologies of the fluids,  a flow-focusing configuration producing the shortest thread detachment length, and a longer region of strain rate along the centreline is identified. Overall, this work provides a consolidated description of the effect of fluid properties, flow parameters, and geometry on the formation of miscible viscous threads in microchannel flows. 

  • 41.
    Gowda, V. Krishne
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Rydefalk, Cecilia
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Söderberg, Daniel
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Lundell, Fredrik
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Formation of colloidal threads in geometrically varying flow-focusing channels2021In: Physical Review Fluids, E-ISSN 2469-990X, Vol. 6, no 11, article id 114001Article in journal (Refereed)
    Abstract [en]

    Threads of colloidal dispersions can be formed in microfluidic channel systems and are often used for analytical purposes or to assemble macroscopic structures from colloidal particles. Here, we report a combined experimental and numerical study of thread formation in channel systems with varying geometry. In the reference flow-focusing configuration, the sheath flows impinge the core flow orthogonally while in four other channel configurations, the sheath flows impinge the core flow at different confluence angles, which are both positive and negative with respect to the reference sheath direction. Tomographic measurements of the thread development are made using optical coherence tomography (OCT) and are compared to numerically simulated 3D data. The numerical simulations performed with an immiscible fluid solver show good agreement with the experiments in terms of 3D thread shapes, wetted region morphologies, and velocity fields provided an ultralow interfacial tension is applied between the low viscosity (solvent) sheath flows and the high viscosity (dispersion) core flow. Such an ultralow interfacial tension is motivated by the so-called Korteweg stresses induced as a result of the concentration gradient between two miscible fluids in nonequilibrium state. These stresses mimic the effect of interfacial tension, and are often modeled as an effective interfacial tension (EIT), an approach chosen in the present work as well. The value of interfacial tension applied in the simulations was determined through an optimization procedure and compares well with a value deduced from a scaling analysis utilizing the downstream development of experimentally determined thread shape. The experimental and numerical results show that for channel configurations with modest deviations from orthogonal sheath flows, the effect on the thread is similar regardless of whether the sheath flows are co- or counterflowing the core flow. In fact, for these cases, the effect of co- and counterflowing sheath flows can be reproduced with orthogonal sheath flows, if the sheath channel width is increased. However, for channel configurations with larger deviations from orthogonal sheath flows, the effects on the thread are direction dependent. The one-to-one comparison and analysis of numerical and experimental results bring useful insights to understand the behavior of miscible systems involving high-viscosity contrast fluids. These key results provide the foundation to tune the flow-focusing for specific applications, for example in tailoring the assembly of nanostruc-tured materials.

  • 42.
    Harder, Constantin
    et al.
    Deutsch Elekt Synchrot DESY, D-22607 Hamburg, Germany.;Tech Univ Munich, TUM Sch Nat Sci, Dept Phys, Chair Funct Mat, D-85748 Garching, Germany..
    Betker, Marie
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fiberprocesser. Deutsch Elekt Synchrot DESY, D-22607 Hamburg, Germany.
    Alexakis, Alexandros Efraim
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Bulut, Yusuf
    Deutsch Elekt Synchrot DESY, D-22607 Hamburg, Germany.;Tech Univ Munich, TUM Sch Nat Sci, Dept Phys, Chair Funct Mat, D-85748 Garching, Germany..
    Sochor, Benedikt
    Deutsch Elekt Synchrot DESY, D-22607 Hamburg, Germany..
    Söderberg, Daniel
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fiberprocesser. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Malmström, Eva
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Muller-Buschbaum, Peter
    Tech Univ Munich, TUM Sch Nat Sci, Dept Phys, Chair Funct Mat, D-85748 Garching, Germany.;Tech Univ Munich, Heinz Maier Leibnitz Zent MLZ, D-85748 Garching, Germany..
    Roth, Stephan V.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fiberprocesser. Deutsch Elekt Synchrot DESY, D-22607 Hamburg, Germany.
    Poly(sobrerol methacrylate) Colloidal Inks Sprayed onto Cellulose Nanofibril Thin Films for Anticounterfeiting Applications2024In: ACS Applied Nano Materials, E-ISSN 2574-0970, Vol. 7, no 9, p. 10840-10851Article in journal (Refereed)
    Abstract [en]

    The colloidal layer formation on porous materials is a crucial step for printing and applying functional coatings, which can be used to fabricate anticounterfeiting paper. The deposition of colloidal layers and subsequent thermal treatment allows for modifying the hydrophilicity of the surface of a material. In the present work, wood-based colloidal inks are applied by spray deposition on spray-deposited porous cellulose nanofibrils (CNF) films. The surface modification by thermal annealing of the fabricated colloid-cellulose hybrid thin films is investigated in terms of layering and hydrophobicity. The polymer colloids in the inks are core-shell nanoparticles with different sizes and glass transition temperatures (T-g), thus enabling different and low thermal treatment temperatures. The ratio between the core polymers, poly(sobrerol methacrylate) (PSobMA), and poly(-butyl methacrylate) (PBMA) determines the T-g and hence allows for tailoring of the T-g. The layer formation of the colloidal inks on the porous CNF layer depends on the imbibition properties of the CNF layer which is determined by their morphology. The water adhesion of the CNF layer decreases due to the deposition of the colloids and thermal treatment except for the colloids with a size smaller than the void size of the porous CNF film. In this case, the colloids are imbibed into the CNF layer when T-g of the colloids is reached and the polymer chains transit in a mobile phase. Tailored aggregate and nanoscale-embedded hybrid structures are achieved depending on the colloid properties. The imbibition of these colloids into the porous CNF films is verified with grazing incidence small-angle X-ray scattering. This study shows a route for tuning the nanoscale structure and macroscopic physicochemical properties useful for anticounterfeiting paper.

  • 43.
    Holm, Richard
    et al.
    KTH, Superseded Departments (pre-2005), Mechanics.
    Storey, S.
    Martinez, Mark
    Söderberg, L. Daniel
    KTH, Superseded Departments (pre-2005), Mechanics.
    Visualization of streaming-like structures during settling of dilute and semi-dilute rigid fibre suspensions2004In: Physics of fluids, ISSN 1070-6631, E-ISSN 1089-7666Article in journal (Other academic)
  • 44.
    Holm, Richard
    et al.
    KTH, School of Engineering Sciences (SCI), Centres, Faxén Laboratory. KTH, School of Engineering Sciences (SCI), Mechanics.
    Söderberg, L. Daniel
    KTH, School of Engineering Sciences (SCI), Mechanics.
    A theoretical analysis of the flow stability in roll forming of paper2005In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 20, no 2, p. 212-216Article in journal (Refereed)
    Abstract [en]

    This paper deals with the fundamental mechanisms that control partial roll dewatering in papermaking. The flow around the forming cylinder is modelled in a cylindrical coordinate system and the wire is assumed to be impermeable. The governing equations are reduced based on a discussion where the magnitude of the different terms is estimated. Given this reduced set of equations a non-linear equation for the position of the wire is deduced. This clearly shows that one of the most important parameters is the Weber number, We, which is the non-dimensional number that can be obtained by comparing the effect of wire tension in relation to the momentum of the incoming headbox jet. The characteristics of the non-linear equation are discussed and the equation is linearized around the trivial solution to the equations, which gives that the wire is displaced a constant distance from the roll along the whole wrap. The linear equation has a standing wave solution with a specific wavelength that scales with We. This solution is compared to previously measured profiles regarding the wavelength of the waves.

  • 45.
    Holm, Richard
    et al.
    KTH, Superseded Departments (pre-2005), Mechanics.
    Söderberg, L. Daniel
    STFI-Packforsk.
    Influence of shear on fibre orientation in the near wall region2004Article in journal (Other academic)
  • 46.
    Holm, Richard
    et al.
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Söderberg, L. Daniel
    STFI-Packforsk.
    Shear influence on fibre orientation: Dilute suspension in the near wall region2007In: Rheologica Acta, ISSN 0035-4511, E-ISSN 1435-1528, Vol. 46, no 5, p. 721-729Article in journal (Refereed)
    Abstract [en]

    The purpose of this experimental work was to study the influence of shear close to a solid boundary on the fibre orientation in suspensions with different fibre aspect ratios and concentrations. We have studied a laminar suspension flow down an inclined plate. The fibre orientation in different wall parallel planes were measured. We applied an index-of-refraction (IR) matching method together with particle tracking techniques to obtain the fibre motion. The fibre orientation was extracted using a two-dimensional wavelet transform. The shear flow resulted in fibres perpendicularly oriented to the streamwise direction (rollers) in the near wall region. These rollers were observed in the experiment to perform a rolling-sliding motion down the inclined plate around a stable perpendicular orientation. As the distance to the wall increased the number of rollers decreased and the fibre orientation was unaffected from its initial streamwise orientation. As the aspect ratio increased the influence of shear on the fibre orientation decreased for all measured wall parallel planes. This was also the case for higher fibre concentrations. The purpose of this study was to contribute to the development of the capacity to control the sheet network structure in papermaking.

  • 47.
    Holm, Richard
    et al.
    KTH, School of Engineering Sciences (SCI), Centres, Faxén Laboratory. KTH, School of Engineering Sciences (SCI), Mechanics.
    Söderberg, L. Daniel
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Norman, Bo
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Paper Technology.
    Experimental studies on dewatering during roll forming of paper2005In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 20, no 2, p. 205-211Article in journal (Refereed)
    Abstract [en]

    Pressure and wire position measurements have been performed in an experimental facility, the KTH-Former, which intends to model the roll-forming zone of a paper machine. The measured pressure distributions in the forming zone are shown to have more complex patterns than the simple model p=T/R, which normally is referred to as the nominal pressure. It is also shown that an increase in wire tension has a similar effect as a decrease in flow-rate on the shape of the pressure distribution. This is a consequence of that the flow to a large extent is governed by the relation between the dynamic pressure and the nominal pressure. For the case of partial dewatering the suction peak that appears at the roll-wire separation point has a strong influence on the pressure distribution upstream. Finally, it is shown that the drainage has a stabilizing effect on the dewatering pressure.

  • 48. Holmqvist, C.
    et al.
    Rosén, F.
    Söderberg, Daniel
    KTH, School of Engineering Sciences (SCI), Mechanics.
    In-situ measurements of stock flow conditions in the twin-wire forming zone2018In: Paper Conference and Trade Show, PaperCon 2018, TAPPI Press , 2018, p. 59-72Conference paper (Refereed)
    Abstract [en]

    In the present study, we report results from in-situ investigations of the forming process performed in the roll-blade section of a pilot machine. Direct measurements of the drainage pressure along the forming zone were obtained using a miniature fibre-optic pressure transducer inserted into the flow through the headbox jet. High-speed imaging of tracer particles using a transmitted light setup was performed to in an attempt to obtain direct measurements of the local stock speed. By replacing one section of a ceramic blade with a quartz glass piece, access was also obtained to the region on top of the blade. The combined picture that emerges from these measurements is that the pressure distribution and the velocity field along a twin-wire forming zone is significantly more complex than usually assumed, and that much remains to be understood about the dynamics of twin-wire forming.

  • 49.
    Håkansson, Karl
    et al.
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Fall, Andreas
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Lundell, Fredrik
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Yu, Sun
    DESY, Hamburg Germany.
    Krywka, Christina
    Institute of experimental and applied physics. Kiel Germany.
    Roth, Stephan
    DESY, Hamburg Germany.
    Santoro, Gonzalo
    DESY, Hamburg Germany.
    Kvick, Mathias
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Prahl Wittberg, Lisa
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Söderberg, Daniel
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. Innventia AB, Stockholm Sweden.
    Hydrodynamic alignment and assembly of nanofibrils resulting in strong cellulose filaments2014In: Nature Communications, E-ISSN 2041-1723, Vol. 5, p. 4018-Article in journal (Refereed)
    Abstract [en]

    Cellulose nanofibrils can be obtained from trees and have considerable potential as a building block for biobased materials. In order to achieve good properties of these materials, the nanostructure must be controlled. Here we present a process combining hydrodynamic alignment with a dispersion-gel transition that produces homogeneous and smooth filaments from a low-concentration dispersion of cellulose nanofibrils in water. The preferential fibril orientation along the filament direction can be controlled by the process parameters. The specific ultimate strength is considerably higher than previously reported filaments made of cellulose nanofibrils. The strength is even in line with the strongest cellulose pulp fibres extracted from wood with the same degree of fibril alignment. Successful nanoscale alignment before gelation demands a proper separation of the timescales involved. Somewhat surprisingly, the device must not be too small if this is to be achieved.

  • 50.
    Håkansson, Karl
    et al.
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Kvick, Mathias
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Lundell, Fredrik
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Prahl Wittberg, Lisa
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Söderberg, Daniel
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Measurement of width and streakiness of particle streaks in turbulent flowsArticle in journal (Other academic)
123 1 - 50 of 131
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