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  • 1.
    Anderfors, Mikael
    et al.
    Innventia AB, Sweden.
    Llindström, Tom
    Innventia AB, Sweden.
    On the manufacture of carboxymethylated microfibrillated cellulose from different pulp typesManuscript (preprint) (Other academic)
  • 2.
    Anderfors, 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.

  • 3.
    Ankerfors, Mikael
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Lindström, Tom
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Method for providing a nanocellulose involving modifying cellulose fibers2009Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    The present invention provides a method for the manufacturing of nanocellulose. The method includes a first modification of the cellulose material, where the cellulose fibres are treated with an aqueous electrolyte-containing solution of an amphoteric cellulose derivative. The modification is followed by a mechanical treatment. By using this method for manufacturing nanocellulose, clogging of the mechanical apparatus is avoided. Also disclosed is nanocellulose manufactured in accordance with said method and uses of said cellulose.

  • 4.
    Aulin, Christian
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Karabulut, Erdem
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Tran, Amy
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Lindström, Tom
    KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Transparent Nanocellulosic Multilayer Thin Films on Polylactic Acid with Tunable Gas Barrier Properties2013In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 5, no 15, p. 7352-7359Article in journal (Refereed)
    Abstract [en]

    The layer-by-layer (LbL) deposition method was used for the build-up of alternating layers of nanofibrillated cellulose (NFC) or carboxymethyl cellulose (CMC) with a branched, cationic polyelectrolyte, polyethyleneimine (PEI) on flexible poly (lactic acid) (PLA) substrates. With this procedure, optically transparent nanocellulosic films with tunable gas barrier properties were formed. 50 layer pairs of PEI/NFC and PEI/CMC deposited on PLA have oxygen permeabilities of 0.34 and 0.71 cm(3).mu m/m(2).day.kPa at 23 degrees C and 50% relative humidity, respectively, which is in the same range as polyvinyl alcohol and ethylene vinyl alcohol. The oxygen permeability of these multilayer nanocomposites outperforms those of pure NFC films prepared by solvent-casting. The nanocellulosic LbL assemblies on PLA substrates was in detailed characterized using a quartz crystal microbalance with dissipation (QCM-D). Atomic force microscopy (AFM) reveals large structural differences between the PEI/NFC and the PEI/CMC assemblies, with the PEI/NFC assembly showing a highly entangled network of nanofibrils, whereas the PEI/CMC surfaces lacked structural features. Scanning electron microscopy images showed a nearly perfect uniformity of the nanocellulosic coatings on PLA, and light transmittance results revealed remarkable transparency of the LbL-coated PLA films. The present work demonstrates the first ever LbL films based on high aspect ratio, water-dispersible nanofibrillated cellulose, and water-soluble carboxymethyl cellulose polymers that can be used as multifunctional films and coatings with tailorable properties, such as gas barriers and transparency. Owing to its flexibility, transparency and high-performance gas barrier properties, these thin film assemblies are promising candidates for several large-scale applications, including flexible electronics and renewable packaging.

  • 5.
    Aulin, Christian
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Lindström, Tom
    KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Biopolymer Coatings for Paper and Paperboard2011In: Biopolymers: New Materials for Sustainable Films and Coatings / [ed] David Plackett, Chichester: John Wiley & Sons, 2011, p. 255-276Chapter in book (Other academic)
  • 6.
    Aulin, Christian
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Salazar-Alvarez, German
    KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Lindström, Tom
    KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    High strength, flexible and transparent nanofibrillated cellulose-nanoclay biohybrid films with tunable oxygen and water vapor permeability2012In: Nanoscale, ISSN 2040-3364, Vol. 4, no 20, p. 6622-6628Article in journal (Refereed)
    Abstract [en]

    A novel, technically and economically benign procedure to combine vermiculite nanoplatelets with nanocellulose fibre dispersions into functional biohybrid films is presented. Nanocellulose fibres of 20 nm diameters and several micrometers in length are mixed with high aspect ratio exfoliated vermiculite nanoplatelets through high-pressure homogenization. The resulting hybrid films obtained after solvent evaporation are stiff (tensile modulus of 17.3 GPa), strong (strength up to 257 MPa), and transparent. Scanning electron microscopy (SEM) shows that the hybrid films consist of stratified nacre-like layers with a homogenous distribution of nanoplatelets within the nanocellulose matrix. The oxygen barrier properties of the biohybrid films outperform commercial packaging materials and pure nanocellulose films showing an oxygen permeability of 0.07 cm(3) mu m m(-2) d(-1) kPa(-1) at 50% relative humidity. The oxygen permeability of the hybrid films can be tuned by adjusting the composition of the films. Furthermore, the water vapor barrier properties of the biohybrid films were also significantly improved by the addition of nanoclay. The unique combination of excellent oxygen barrier behavior and optical transparency suggests the potential of these biohybrid materials as an alternative in flexible packaging of oxygen sensitive devices such as thin-film transistors or organic light-emitting diode displays, gas storage applications and as barrier coatings/laminations in large volume packaging applications.

  • 7. Carlsson, L. A.
    et al.
    Lindström, Tom
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    A shear-lag approach to the tensile strength of paper2005In: Composites Science And Technology, ISSN 0266-3538, E-ISSN 1879-1050, Vol. 65, no 2, p. 183-189Article in journal (Refereed)
    Abstract [en]

    A shear-lag approach to the prediction of the tensile strength of paper is outlined and examined. It is demonstrated that transition of fiber strength to paper strength requires long fibers for sheets with weak fiber-fiber bonds, or low relative bonded area. Fiber pull-out is encountered even for highly bonded sheets. Predictions of tensile strength for papers of the same fiber length, but with different beating degrees, and for papers with different fiber lengths and beating degrees, are in quantitative agreement with previously published data.

  • 8. Charani, P. Rezayati
    et al.
    Dehghani-Firouzabadi, M.
    Afra, E.
    Blademo, A.
    Naderi, A.
    Lindström, Tom
    KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Production of microfibrillated cellulose from unbleached kraft pulp of Kenaf and Scotch Pine and its effect on the properties of hardwood kraft: microfibrillated cellulose paper2013In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 20, no 5, p. 2559-2567Article in journal (Refereed)
    Abstract [en]

    This work investigated the effect of using Kenaf bast fibre kraft pulps compared to Scotch Pine kraft pulps for producing microfibrillated cellulose (MFC) and its employment for improving mechanical and physical properties of handsheets made from unbleached kraft hardwood pulp. It was shown that MFC based on Kenaf fibres can be produced at higher consistencies [> 5 % (w/w)] compared to when Scotch Pine is employed [a parts per thousand 2 % (w/w)] as raw material. The possibility of using a higher consistency when processing Kenaf is beneficial for the processing in microfluidizers. The rheological properties of the products were shown to be consistent with what is known for MFC-based systems. The studies indicate that the mechanical properties of handsheets from unbleached kraft hardwood pulp can be improved by replacing part of the unbleached kraft hardwood pulp fibres with either unbleached kraft Kenaf pulp or unbleached Scotch Pine kraft pulp. However, the same levels of improvements were obtained when using only a small amount [a parts per thousand 6 % (w/w)] of MFC based on Kenaf or Scotch Pine, when introduced into the system either as a dry strength additive or by coating pre-made handsheets. Finally, it was shown that the incorporation of MFC in handsheets decreases the air-permeability; this effect became amplified when the MFC was applied as a coating onto the handsheets.

  • 9.
    Ekevåg, Per
    et al.
    KTH, Superseded Departments, Fibre and Polymer Technology.
    Lindström, Tom
    KTH, Superseded Departments, Fibre and Polymer Technology.
    Gellerstedt, Göran
    KTH, Superseded Departments, Fibre and Polymer Technology.
    Lindström, Mikael
    KTH, Superseded Departments, Fibre and Polymer Technology.
    Addition of carboxymethylcellulose to the kraft cook2004In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 19, no 2, p. 200-207Article in journal (Refereed)
    Abstract [en]

    The physical attachment of carboxymethylcellulose (CMC) onto kraft pulps during cooking and the effects of subsequent bleaching in an OD(EOP)DD sequence were investigated. Two CMC grades with different molecular weights and different degrees of substitution (D.S.) were used, CMC Finnfix WRH and CMC Cekol DVG. The effect of the CMC was studied by measuring the increase in the total charge density as well as in the surface charge density. In this way, both the total amount of attached CMC and the amount of the CMC attached onto the surface of the fibres Could be determined. Hand-sheets were made to study the effects of CMC addition on the physical properties of the paper. Different amounts of CMC were added to find the optimum, which was determined to be 1% CMC on wood. The proportion of CMC attached at a level addition of 1% (on wood) was about 40%. It was, however, found that a large part of the CMC was degraded during the cook. Whereas high molecular weight CMC is attached onto the surface of fibres, the degraded CMC is attached to the interior of the cell wall, decreasing the efficiency of the CIVIC to enhance the joint strength between fibres. The tensile index increased significantly, approximately 10% after beating to 2000 PFI revolutions, when 1% CMC Finnfix WRH on wood was added. The CMC Cekol DVG grade showed the greatest increase in tensile index, approximately 12% at 2000 PFI revolutions. The results of the bleaching of a sample treated with CMC Finnfix WRH showed that a part of the effect of CMC remains after bleaching. Most of the reduction in the positive effect was due to a loss of CMC molecules from the fibre surface.

  • 10.
    Horvath, Andrew T.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Horvath, A. Elisabet
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Lindström, Tom
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Adsorption of Highly Charged Polyelectrolytes onto an Oppositely Charged Porous Substrate2008In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 24, no 15, p. 7857-7866Article in journal (Refereed)
    Abstract [en]

    The adsorption behavior of highly charged cationic polyelectrolytes onto porous substrates is electrostatic in nature and has been shown to be highly dependent on the polyelectrolyte properties. Copolymers of acrylamide (AM) and diallyldimethylammonium chloride (DADMAC) were synthesized to have a range of macromolecular properties (i.e., charge density and molecular mass). Traditional titration methods have been complemented by fluorescence labeling techniques that were developed to directly observe the extent that fluorescently labeled poly(AM-co-DADMAC) adsorbs into the pore structure of a cellulosic Substrate. Although contributing to the electrostatic driving force, the charge density acts to limit adsorption to the outermost surface under electrolyte-free conditions. However, adsorption into the pores call occur if both the molecular mass and charge density of poly(AM-co-DADMAC) are Sufficiently low. Adsorption initially increases as the electrolyte concentration is increased. However, the electrostatic persistence length of poly(AM-co-DADMAC) restricts the polyelectrolyte from entering the pores. Therefore, changes ill the adsorption behavior at moderate electrolyte concentrations have been attributed to swelling of the polyelectrolyte layer at the fiber exterior. The adsorption behavior changes again at high electrolyte concentrations Such that poly(AM-co-DADMAC) could adsorb into the pore Structure. This occurred when the electrolyte concentration was sufficient to screen the electrostatic persistence length of poly(AM-co-DADMAC), provided that the entropic driving force for adsorption still existed. It is suggested that adsorption into the pore structure is a kinetic process that is governed by localized electrostatic interactions between poly(AM-co-DADMAC) and the charges located within the pores.

  • 11.
    Horvath, Andrew T.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Horvath, A. Elisabet
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Lindström, Tom
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Adsorption of Low Charge Density Polyelectrolytes to an Oppositely Charged Porous Substrate2008In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 24, no 13, p. 6585-6594Article in journal (Refereed)
    Abstract [en]

    The adsorption behavior of a low charge density cationic polyelectrolyte to cellulosic fibers has been studied. Cationic dextran served as a model polyelectrolyte, as it can be prepared over a range in molecular mass and charge density. The adsorption behavior of the cationic dextran was measured in electrolyte-free conditions using polyelectrolyte titration techniques. By fluorescent labeling the cationic dextran, the extent to which adsorption occurs inside the porous structure was further determined by fluorescent confocal laser scanning microscopy. Cationic dextran having a sufficiently low charge density adsorbed into the pores, although the extent the cationic dextran adsorbed was governed by the molecular mass. The adsorption behavior of the cationic dextran was also studied in various electrolyte concentrations. The adsorbed mass monotonically decreased with increasing electrolyte, as the electrostatic interaction with the substrate was more effectively screened. This behavior also suggests that the interactions between adsorbed polyelectrolyte chains, i.e. lateral correlation effects, are negligible for low charge density polyelectrolytes. Finally, the effect of having a preadsorbed layer of cationic dextran on the adsorption behavior was determined in electrolyte-free conditions using fluorescent double staining techniques. The preadsorbed cationic dextran had almost no effect on the adsorption of low molecular mass fractions. Low molecular mass fractions directly adsorbed into the pore structure, as opposed to adsorbing to a free surface and diffusing into the pores. It was also shown that cationic dextran can be selectively adsorbed to different locations, such that the surface of a porous substrate can be treated uniquely from the bulk.

  • 12.
    Horvath, Andrew T.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Horvath, A. Elisabet
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Lindström, Tom
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Diffusion of cationic polyelectrolytes into cellulosic fibers2008In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 24, no 19, p. 10797-10806Article in journal (Refereed)
    Abstract [en]

    The penetration of cationic polyelectrolytes into anionic cellulosic fibers was evaluated with fluorescent imaging techniques in order to clarify the mechanism and time scales for the diffusion process. The bulk charge of the cellulosic fibers indirectly creates a driving force for diffusion into the porous fiber wall, which is entropic in nature due to a release of counterions as the polyelectrolyte adsorbs. The individual bulk charges in the fiber cell wall also interact with the diffusing polyelectrolyte, Such that the polyelectrolyte diffuses to the first available charge and consequently adsorbs and remains fixed. Thus, Subsequent polyelectrolyte chains must first diffuse through the adsorbed polyelectrolyte layer before adsorbing to the next available bulk charges. This behavior differs from earlier suggested diffusion mechanisms, by which polyelectrolytes were assumed to first adsorb to the outermost surface and then reptate into the pore structure. The time scales for polyelectrolyte diffusion were highly dependent on the flexibility of the chain, which was estimated from calculations of the persistence length. The persistence length ultimately depended on the charge density and electrolyte concentration. The charge density of the polyelectrolyte had a greater influence on the time scales for diffusion. High charge density polyelectrolytes were observed to diffuse on a time scale of months, whereas the diffusion of low charge density polyelectrolytes was measured on the order of hours. An influence of the chain length, that is, steric interactions due the persistence length of the polyelectrolyte and to the tortuosity of the porous structure of the fiber wall, could only be noted for low charge density polyelectrolytes. Increasing the electrolyte concentration increased the chain flexibility by screening the electrostatic contribution to the persistence length, in turn inducing a faster diffusion process. However, a significant change in the diffusion behavior was observed at high electrolyte concentrations, at which the interaction between the polyelectrolyte charges and the fiber charges was almost completely screened.

  • 13.
    Horvath, Andrew T.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Horvath, A. Elisabet
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Lindström, Tom
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Polyelectrolyte Diffusion Into an Oppositely Charged Porous Substrate2008In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827Article in journal (Refereed)
  • 14.
    Horvath, Elisabet
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Horvath, Andrew T.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Wågberg, L.ars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Lindström, Tom
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Polyelectrolyte adsorption on cellulosic fibers: I. High charge density polyelectrolytesManuscript (Other academic)
  • 15. Horvath, Elisabet
    et al.
    Lindström, Tom
    Indirect polyelectrolyte titration of cellulosic fibers. Surface and bulk charges of cellulosic fibers2007In: Nordic Pulp and Paper Research Journal, ISSN 0283-2631, Vol. 22, no 1, p. 87-92Article in journal (Refereed)
    Abstract [en]

    The polyelectrolyte titration technique was used to investigate the relationship between bulk and surface charges for various pulps and treatments. The total and surface charge content is different for hardwood and softwood pulps; however, the charge ratio is the same. Mechanical pulping gives a higher charge ratio than chemical pulping. Even though the amount of charges are changed during different bleaching sequences for chemical pulp, the charge ratio is not affected because the bleaching process is non-surface selective. fn order to change the charge ratio for chemical pulp, beating or surface carboxymethylation can be performed.

  • 16. Horvath, Elisabet
    et al.
    Lindström, Tom
    THe influence of colloidal interactions on fiber network strength2007In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 309, no 2, p. 511-517Article in journal (Refereed)
    Abstract [en]

    Various forces govern the fiber–fiber interaction in a flowing suspension, causing fibers to create flocs. The aim with this investigation was to examine the influence of colloidal interactions on the fiber network strength by varying surface charge density, electrolyte concentration, and type of counterion. This was accomplished by comparing surface force measurements, utilizing colloidal probe microscopy (CPM), with the apparent yield stress, using a parallel plate rheometer. Results show that by increasing the charge density by grafting carboxymethyl cellulose (CMC) to the surface, a large electrosteric repulsion is created, which gives weaker network strength. Increasing the electrolyte concentration decreases the repulsion. The network strength was, however, not affected by electrolyte concentration for untreated fibers whereas a high electrolyte concentration increased the yield stress for CMC-treated fibers. The change of counterions affect the repulsion, causing a change in network strength due to differences in the surface swelling of cellulose.

  • 17. Horvath, Elisabet
    et al.
    Lindström, Tom
    The influence of mechanical surface linking and elastic fiber bending on fiber network strength2007In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 22, no 3, p. 371-375Article in journal (Refereed)
    Abstract [en]

    The influence of mechanical surface linking and elastic fiber bending on the fiber network strength and elasticity (i.e. storage modulus and critical strain) was investigated for pulps with different lengths and stiffness, using a parallel plate rheometer. Results show that the storage modulus increases and critical strain decreases with increasing fiber length due to increased number of fiber contacts. Laboratory-cooked pulp has a higher storage modulus and a lower critical strain than commercial pulp because of straighter and stiffer fibers, which are more influenced by both mechanical surface linking and elastic fiber bending.

  • 18. Horvath, Elisabet
    et al.
    Lindström, Tom
    Laine, J.
    On the indirect polyelectrolyte titration of cellulosic fibers. Conditions for charge stoichiometry and comparison with ESCA2006In: Langmuir, ISSN 0743-7463, Vol. 22, no 2, p. 824-830Article in journal (Refereed)
    Abstract [en]

    The effect of electrolyte (NaHCO3) concentration on the adsorption of poly-DADMAC (poly-diallyldimethylammonium chloride) onto cellulosic fibers with different charge profiles was investigated. Surface carboxymethylated fibers were obtained by grafting carboxymethyl cellulose (CMC) onto the fiber surface and bulk carboxymethylated fibers were obtained by reacting the fibers with monochloroacetic acid. It was shown that nonionic interactions do not exist between cellulose and poly-DADMAC, rather electrostatic interactions govern the adsorption. Charge stoichiometry prevails under electrolyte-free conditions, whereas surface charge overcompensation occurs at higher electrolyte concentrations. It was shown that charge stoichiometry prevails if the thickness of the electric double layer kappa(-1) was larger than the mean distance between the charges on the fiber surface, as predicted by polyelectrolyte adsorption theories, taking lateral correlation effects into account. In a second set of experiments the ESCA technique served to independently calibrate the polyelectrolyte titrations for determining the surface charge of cellulosic fibers. Various molecular masses of poly-DADMAC were adsorbed to carboxymethylated fibers having different charge profiles. The adsorption of low M-w poly-DADMAC (7.0 x 10(3)), analyzed by polyelectrolyte titration, was about 10 times higher than that of the high M-w poly-DADMAC (9.2 x 10(5)). Despite the difference in accessibility of these two polyelectrolytes to the fiber cell wall, ESCA surface analysis showed, as expected, only slight differences between the two polyelectrolytes, This gives strong credibility to the idea that surface charge content of cellulosic fibers can be analyzed by means of adsorption of a high-molecular-mass cationic polymer, i.e., by polyelectrolyte titration.

  • 19. Klemm, Dieter
    et al.
    Kramer, Friederike
    Moritz, Sebastian
    Lindström, Tom
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Ankerfors, Mikael
    Material Processes, Innventia AB, Sweden.
    Gray, Derek
    Dorris, Annie
    Nanocelluloses: A New Family of Nature-Based Materials2011In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 50, no 24, p. 5438-5466Article, review/survey (Refereed)
    Abstract [en]

    Cellulose fibrils with widths in the nanometer range are nature-based materials with unique and potentially useful features. Most importantly, these novel nanocelluloses open up the strongly expanding fields of sustainable materials and nanocomposites, as well as medical and life-science devices, to the natural polymer cellulose. The nanodimensions of the structural elements result in a high surface area and hence the powerful interaction of these celluloses with surrounding species, such as water, organic and polymeric compounds, nanoparticles, and living cells. This Review assembles the current knowledge on the isolation of microfibrillated cellulose from wood and its application in nanocomposites; the preparation of nanocrystalline cellulose and its use as a reinforcing agent; and the biofabrication of bacterial nanocellulose, as well as its evaluation as a biomaterial for medical implants.

  • 20.
    Lindström, Tom
    Innventia AB, Sweden.
    Sizing2009In: Paper Chemistry and Technology, Walter de Gruyter, 2009, p. 275-318Chapter in book (Refereed)
  • 21.
    Lindström, Tom
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. STFI-Packforsk AB, Sweden.
    The paradigm shift in pulp and paper research Hindsight is easier than foresight2005In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 20, no 2, p. 260-261Article in journal (Refereed)
    Abstract [en]

    The revitalized paradigm shift in pulp and paper research in the papermaking industry, is discussed. The papermaking processes changed a lot and the old-fashioned beating operation disappeared. Slowly the recyclable 'Paper Solar' cells have become one of the epitomes of intelligent paper. Dramatic changes are also observed in the R&D structure which has started to evolve into new structure. Engineers realize that they had to do things in a different way, otherwise there could be no future for the industry.

  • 22.
    Lindström, Tom
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Towards new perspectives in paper chemistry2007In: International Paperworld IPW, ISSN 1615-1720, no 10, p. 32-36Article in journal (Other academic)
    Abstract [en]

    The area of paper chemistry is by many knowledgeable suppliers conceived as pretty mature as most classical concepts in wet-end chemistry are reasonably well understood, although not always efficiently practised by papermakers. Hence, this evolution calls for more radical changes and among these changes fibre modification by different means has called for attention during recent years. Such modifications invoke biochemical modification of carrier polymers, new types of grafting methods and polyelectrolyte multilayering, which have been investigated particularly in the Nordic countries and also brought to commercial practice. Surface charge grafting constitutes a powerful means of fibre modification and the potential in this field will be reviewed and upcoming nanotechnology issues will also be discussed.

  • 23.
    Lindström, Tom
    et al.
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.). KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation. Innventia AB, Paper Chem & Nanomat Grp, Sweden.
    Aulin, Christian
    Market and technical challenges and opportunities in the area of innovative new materials and composites based on nanocellulosics2014In: Scandinavian Journal of Forest Research, ISSN 0282-7581, E-ISSN 1651-1891, Vol. 29, no 4, p. 345-351Article in journal (Refereed)
    Abstract [en]

    This communication is a review over the major market and technical challenges and opportunities for nanocellulosic materials on a large scale but in low-to-medium-end markets. Basically, the potential use of nanocellulose as a wet-end strength additive in papermaking has been known for decades, but not come into operation because of the high-energy costs of producing these materials. Cost performance compared to starch derivatives is one challenge, and the other is to design suitable dewatering/retention aid systems. Other paper applications are as a surface-sizing agent and as a barrier coating material. Major challenges are associated with the high viscosity of nanocellulosic materials and how to apply the nanocellulose in order to obtain good surface coverage. There are several opportunities in the nanocomposite markets. The packaging sector together with the automotive sector and the building sector constitute large potential markets. Challenges are related to the mixing of hydrophobic and hydrophilic materials so that a good dispersion of nanocellulose is obtained. Scaling up of nanocellulose production processes and procedures for nanocomposite manufacturing in order to obtain price-performance in the various applications remains, as expected, the largest challenge.

  • 24.
    Lindström, Tom
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Centres, Biofibre Materials Centre, BiMaC. Innventia AB, Sweden.
    Aulin, Christian
    Gimåker, Magnus
    Persson, Torgny
    The emergence of practical nanocellulose applications for a more sustainable paper/board industry2014In: IPPTA: Quarterly Journal of Indian Pulp and Paper Technical Association, ISSN 0379-5462, Vol. 26, no 1, p. 53-61Article in journal (Refereed)
    Abstract [en]

    There has been extensive research and development activities in the field of nanofibrillated cellulose (NFC) materials during recent years, although microfibrillated cellulose was developed already during the late 1970s at ITT-Rayonier in USA. A major impediment for the large-scale use of NFC has been the high-energy use (excess of 30000 kWh/ton NFC in energy consumption). This problem has now been alleviated by a series of different pre-treatment procedures of the fibres prior to the subsequent mechanical cell wall delamination. The focus in practical papermaking applications of NFC is in the reinforcement of paper/board materials (dry strength wet-end additive) and in barrier coating applications. The driving forces in these applications are resource and energy efficiency in papermaking and the vision of substituting fossil-based films with nanocellulose barriers. Nanocellulose has excellent oil, fat and oxygen barrier properties in the dry state, but the oxygen barrier properties deteriorate at high relative humidities and the approaches to alleviate the moisture sensitivity will be discussed. Today, there are many companies in the process of commercializing NFC and several of them have pilot plants/pre-commercial operations and are planning for up scaling. A pilot plant for the nominal production of 100 kg/day (dry based NFC) was also taken into operation at Innventia AB in 2010. The current contribution will highlight critical issues in the production of NFC and discuss various applications and hurdles to be overcome in order to make NFC production for paper/board based end-use applications viable.

  • 25. Naderi, Ali
    et al.
    Lindström, Tom
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Biofibre Materials Centre, BiMaC.
    Sundstrom, Jonas
    Carboxymethylated nanofibrillated cellulose: rheological studies2014In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 21, no 3, p. 1561-1571Article in journal (Refereed)
    Abstract [en]

    The rheological properties of carboxymethylated nanofibrillated cellulose (NFC), investigated with controlled shear rate- and oscillatory measurements, are reported for the first time. It was shown that the rheological properties of the studied system are similar to those reported for other NFC systems. The carboxymethylated NFC systems showed among other things high elasticity and a shear thinning behaviour when subjected to increasing shear rates. Further, the shear viscosity and storage modulus of the system displayed power-law relations with respect to the dry content of the NFC suspension. The exponential values, 2 and 2.4 respectively, were found to be in good agreement with both theoretical predictions and published experimental work. Furthermore, it was found that the pulp consistency at which NFC is produced affects the properties of the system. The rheological studies imply that there exists a critical pulp concentration below which the efficiency of the delamination process diminishes; the same adverse effect is also observed when the critical concentration is significantly exceeded due to a lower energy input during delamination.

  • 26. Pääkkö, M.
    et al.
    Ankerfors, Mikael
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Kosonen, H.
    Nykänen, A.
    Ahola, S.
    Österberg, M.
    Ruokolainen, J.
    Laine, J.
    Larsson, Per Tomas
    Ikkala, O.
    Lindström, Tom
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Enzymatic hydrolysis combined with mechanical shearing and high-pressure homogenization for nanoscale cellulose fibrils and strong gels2007In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 8, no 6, p. 1934-1941Article in journal (Refereed)
    Abstract [en]

    Toward exploiting the attractive mechanical properties of cellulose I nanoelements, a novel route is demonstrated, which combines enzymatic hydrolysis and mechanical shearing. Previously, an aggressive acid hydrolysis and sonication of cellulose I containing fibers was shown to lead to a network of weakly hydrogen-bonded rodlike cellulose elements typically with a low aspect ratio. On the other hand, high mechanical shearing resulted in longer and entangled nanoscale cellulose elements leading to stronger networks and gels. Nevertheless, a widespread use of the latter concept has been hindered because of lack of feasible methods of preparation, suggesting a combination of mild hydrolysis and shearing to disintegrate cellulose I containing fibers into high aspect ratio cellulose I nanoscale elements. In this work, mild enzymatic hydrolysis has been introduced and combined with mechanical shearing and a high-pressure homogenization, leading to a controlled fibrillation down to nanoscale and a network of long and highly entangled cellulose I elements. The resulting strong aqueous gels exhibit more than 5 orders of magnitude tunable storage modulus G' upon changing the concentration. Cryotransmission electron microscopy, atomic force microscopy, and cross-polarization/magic-angle spinning (CP/MAS) C-13 NMR suggest that the cellulose I structural elements obtained are dominated by two fractions, one with lateral dimension of 5-6 nm and one with lateral dimensions of about 10-20 nm. The thicker diameter regions may act as the junction zones for the networks. The resulting material will herein be referred to as MFC (microfibrillated cellulose). Dynamical rheology showed that the aqueous suspensions behaved as gels in the whole investigated concentration range 0.125-5.9% w/w, G' ranging from 1.5 Pa to 10(5) Pa. The maximum G' was high, about 2 orders of magnitude larger than typically observed for the corresponding nonentangled low aspect ratio cellulose I gels, and G' scales with concentration with the power of approximately three. The described preparation method of MFC allows control over the final properties that opens novel applications in materials science, for example, as reinforcement in composites and as templates for surface modification.

  • 27. Ragauskas, Arthur J.
    et al.
    Lindström, Tom
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.).
    Nanocellulose and the future2014In: TAPPI Journal, ISSN 0734-1415, Vol. 13, no 5, p. 5-6Article in journal (Refereed)
  • 28. Song, Hainong
    et al.
    Anderfors, Mikael
    Innventia AB, Sweden.
    Hoc, Miroslav
    Llindström, Tom
    Reduction of the linting and dusting propensity of newspaper using starch and microfibrillated cellulose2010In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 25, no 4, p. 495-504Article in journal (Refereed)
    Abstract [en]

    It is well known that a high linting and dusting tendency of newsprint will almost certainly cause a higher frequency of production stops in offset printing. Such stops are connected with production losses, health hazards and high costs for blanket cleaning. This report deals with the area of surface and internal treatments of thermomechanical pulp (TMP) containing paper grades such as newsprint. The objective of such treatments was to reinforce the surface strength of the paper in order to decrease the linting and dusting of the paper during printing. Surface treatments are usually employed in commercial practice by applying modified starches to the paper surface using film-press technology. Internal treatments of modified starches may also reduce the delamination resistance. In this investigation, laboratory TMP-sheets and commercial newsprint sheets were coated with microfibrillated cellulose (MFC) and anionic starch (A-starch). The surface treatments were also compared with internally treated TMP-sheets using cationic starch. The linting propensity of the sheets was evaluated using the Innventia linting propensity tester (Innventia-LPT). Both MFC and A-starch treatments greatly improved the linting propensity of the coated sheets. It was also found that there is a strong synergistic effect of using a mixture of microfibrillated cellulose and anionic starch. A mixture of these two additives gave a lower linting propensity than if either additive was used alone. When using MFC alone, sheet delamination may occur, due to the strong water retention and hold-out properties of MFC, but if anionic starch was used together with MFC a film anchoring of the coating to the base sheet was achieved, improving the linting propensity without risk for delamination.

  • 29.
    Werner, Oskar
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Lindström, Tom
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Wetting of structured hydrophobic surfaces by water droplets2005In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 21, no 26, p. 12235-12243Article in journal (Refereed)
    Abstract [en]

    Super-hydrophobic surfaces may arise due to an interplay between the intrinsic, relatively high, contact angle of the more or less hydrophobic solid surface employed and the geometric features of the solid surface. In the present work, this relationship was investigated for a range of different surface geometries, making use of surface free energy minimization. As a rule, the free energy minima (and maxima) occur when the Laplace and Young conditions are simultaneously fulfilled. Special effort has been devoted to investigating the free energy barriers present between the Cassie-Baxter (heterogeneous wetting) and Wenzel (homogeneous wetting) modes. The predictions made on the basis of the model calculations compare favorably with experimental results presented in the literature.

1 - 29 of 29
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