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  • 301.
    Marais, Andrew
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi.
    Utsel, Simon
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi.
    Gustafsson, Emil
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Towards a super-strainable paper using the Layer-by-Layer technique2014Ingår i: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 100, s. 218-224Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Layer-by-Layer technique was used to build a polyelectrolyte multilayer on the surface of pulp fibres. The treated fibres were then used to prepare paper sheets and the mechanical properties of these sheets were evaluated as a function of the number of bi-layers on the fibres. Two different systems were studied: polyethyleneimine (PEI)/nanofibrillated cellulose (NFC), and polyallylamine hydrochloride (PAH)/hyaluronic acid (HA). Model experiments using dual polarization interferometry and SiO2 surfaces showed that the two systems gave different thicknesses for a given number of layers. The outer layer was found to be a key parameter in the PEI/NFC system, whereas it was less important in the PAH/HA system. The mechanical properties of the sheets made from the PAH/HA treated fibres were significantly greater than those made from untreated fibres, reaching 70 Nm/g in tensile index and 6.5% in strain at break. Such a modification could be very useful for 3D forming of paper, opening new perspectives in for example the packaging industry, with a renewable and biodegradable product as a potential substitute for some of the traditional oil-based plastics.

  • 302.
    Marais, Andrew
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Tailoring of the layer-by-layer structures for optimized adhesion2013Ingår i: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 245Artikel i tidskrift (Övrigt vetenskapligt)
  • 303.
    Marais, Andrew
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellens Centrum BiMaC Innovation.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    The use of polymeric amines to enhance the mechanical properties of lignocellulosic fibrous networks2012Ingår i: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 19, nr 4, s. 1437-1447Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Cationic polyelectrolytes (polyallylamine and polyvinylamine with different molecular masses) were adsorbed onto lignocellulosic fibres from unbleached and unbeaten spruce chemical fibres with different kappa numbers to investigate the effects on the mechanical properties of the final paper materials. Adsorption isotherms were first established to determine the maximum quantity of polymer that could be adsorbed onto each type of fibre. Paper sheets were then made with different amounts of added polyelectrolyte, and the structural and mechanical properties of the sheets were investigated, as well as the effect of an extra heating. The use of fibres with different kappa numbers led to different responses in terms of adsorption, and thus to differences in the mechanical properties of the resulting sheets. The tensile strength index was significantly increased (almost 50 % improvement in the best case) as a consequence of this polyelectrolyte adsorption onto the fibres, even at as low an adsorption level as 2 mg/g. The heating of paper sheets for 10 min at 160 A degrees C was also shown to improve the tensile strength index by about 10 % for pulps with high kappa number.

  • 304.
    Mittal, Nitesh
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Ansari, Farhan
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center. Department of Materials Science and Engineering, Stanford University, Stanford, CA, United States.
    Gowda, Krishne, V
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Brouzet, Christophe
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Chen, Pan
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Larsson, Per Tomas
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center. RISE Bioeconomy, P.O. Box 5604, Stockholm, SwedenRISE Bioeconomy, P.O. Box 5604, Stockholm, Sweden.
    Roth, Stephan Volkher
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Lundell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Wågberg, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Kotov, Nicholas Alexander
    Söderberg, Daniel
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Multiscale Control of Nanocellulose Assembly: Transferring Remarkable Nanoscale Fibril Mechanics to Macroscale Fibers2018Ingår i: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 12, nr 7, s. 6378-6388Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Nanoscale building blocks of many materials exhibit extraordinary mechanical properties due to their defect-free molecular structure. Translation of these high mechanical properties to macroscopic materials represents a difficult materials engineering challenge due to the necessity to organize these building blocks into multiscale patterns and mitigate defects emerging at larger scales. Cellulose nanofibrils (CNFs), the most abundant structural element in living systems, has impressively high strength and stiffness, but natural or artificial cellulose composites are 3-15 times weaker than the CNFs. Here, we report the flow-assisted organization of CNFs into macroscale fibers with nearly perfect unidirectional alignment. Efficient stress transfer from macroscale to individual CNF due to cross-linking and high degree of order enables their Young's modulus to reach up to 86 GPa and a tensile strength of 1.57 GPa, exceeding the mechanical properties of known natural or synthetic biopolymeric materials. The specific strength of our CNF fibers engineered at multiscale also exceeds that of metals, alloys, and glass fibers, enhancing the potential of sustainable lightweight high-performance materials with multiscale self-organization.

  • 305.
    Mittal, Nitesh
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Lundell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Wågberg, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Hedhammar, My
    Söderberg, Daniel
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Flow-assisted organization of nanostructured bio-based materials2018Ingår i: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 255Artikel i tidskrift (Övrigt vetenskapligt)
  • 306.
    Montañez, Maria I.
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellens Centrum BiMaC Innovation.
    Hed, Yvonne
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Utsel, Simon
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Ropponen, Jarmo
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Malmström, Eva
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Hult, Anders
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Malkoch, Michael
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Bifunctional Dendronized Cellulose Surfaces as Biosensors2011Ingår i: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 12, nr 6, s. 2114-2125Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Well-defined dendronized cellulose substrates displaying multiple representations of dual-functionality were constructed by taking advantage of the efficiency of the click reaction combined with traditional anhydride chemistry. First, activated cellulose surfaces were decorated with several generations of dendrons, and their peripheral reactive groups were subsequently reacted with a trifunctional orthogonal monomer. The generated substrate tool box was successfully explored by accurately tuning the surface function using a versatile orthogonal dual postfunctionalization approach. In general, the reactions were monitored by using a click-dye reagent or a quartz crystal microbalance (QCM) technique, and the resulting surfaces were well-characterized using XPS, and contact angle measurements. Utilizing this approach two different surfaces have been obtained; that is, triethylenglycol oligomers and amoxicillin molecules were efficiently introduced to the dendritic surface. As a second example, mannose-decorated hydroxyl functional surfaces illustrated their potential as biosensors by multivalent detection of lectin protein at concentration as low as 5 nM.

  • 307.
    Mystek, Katarzyna
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi.
    Larsson, Per
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi.
    Svagan, Anna Justina
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Wågberg, Lars
    KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellens Centrum BiMaC Innovation. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi. KTH Royal Inst Technol, Fibre & Polymer Technol, Stockholm, Sweden..
    Wet-expandable cellulose-based capsules2019Ingår i: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 257Artikel i tidskrift (Övrigt vetenskapligt)
  • 308.
    Nikjoo, Roya
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Hollertz, Rebecca
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Wåhlander, Martin
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Taylor, Nathaniel
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Edin, Hans
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Surface Discharge Characteristics of Oil-impregnated Paper with SiO2 and ZnO nanoparticles under AC with Superimposed ImpulseManuskript (preprint) (Övrigt vetenskapligt)
  • 309. Nikjoo, Roya
    et al.
    Taylor, Nathaniel
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Edin, Hans
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Hollertz, Rebecca
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Wåhlander, Martin
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Malmström, Eva
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Comparison of Oil-impregnated Papers with SiO2 and ZnO Nanoparticles or High Lignin Content, for the Effect of Superimposed Impulse Voltage on AC Surface PD2017Ingår i: IEEE transactions on dielectrics and electrical insulation, ISSN 1070-9878, E-ISSN 1558-4135, Vol. 24, nr 3, s. 1726-1734Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Surface discharge behavior of modified oil-impregnated paper (OIP) with nanoparticles (NPs), has been investigated under AC voltage with superimposed impulses. Surface Partial Discharges (PD) can develop at an oil-paper interface and lead to its degradation. Modified paper, made from fibers with adsorbed nanoparticles, can affect the partial discharge behavior of a paper in combination with oil at the interface between oil and fibers. Papers with two different concentrations (2 wt% and 6 wt%) of silica (SiO2), and paper with silanized zinc oxide (ZnO) nanoparticles (1 wt%) have been studied. Papers with SiO2 NPs showed lower impulse-induced surface PD activity. However, thorough purification during the production of SiO2 filled papers was necessary to achieve a good performance. With less purification, paper with 2 wt% of SiO2 did not show such significant improvements. Paper with 6 wt% of SiO2 NPs showed a large number of AC surface PDs, but low influence of impulse voltage on subsequent PD. Papers containing 1 wt% of silanized ZnO showed reduced relative permittivity, but no significant difference in surface PD behavior. The effect of high lignin content in Kraft paper has also been studied. Paper with higher lignin content showed better surface PD characteristics under the impulse. Paper with low concentrations of pure SiO2 NPs, and paper with high lignin content thus appear good candidates for further studies to improve the surface PD behavior of OIP.

  • 310.
    Nordenström, Malin
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Fall, Andreas
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Nyström, Gustav
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Formation of Colloidal Nanocellulose Glasses and Gels2017Ingår i: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 33, nr 38, s. 9772-9780Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Nanocellulose (NC) suspensions can form rigid volume-spanning arrested states (VASs) at very low volume fractions. The transition from a free-flowing dispersion to a VAS can be the result of either an increase in particle concentration or a reduction in interparticle repulsion. In this work, the concentration-induced transition has been studied with a special focus on the influence of the particle aspect ratio and surface charge density, and an attempt is made to classify these VASs. The results show that for these types of systems two general states can be identified: glasses and gels. These NC suspensions had threshold concentrations inversely proportional to the particle aspect ratio. This dependence indicates that the main reason for the transition is a mobility constraint that, together with the reversibility of the transition, classifies the VASs as colloidal glasses. If the interparticle repulsion is reduced, then the glasses can transform into gels. Thus, depending on the preparation route, either soft and reversible glasses or stiff and irreversible gels can be formed.

  • 311.
    Nordenström, Malin
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Nystrom, Gustav
    Empa, Lab Appl Wood Mat, Dubendorf, Switzerland..
    Fall, Andreas
    Res Inst Sweden, RISE, Bioecon, Stockholm, Sweden..
    Wågberg, Lars
    KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellens Centrum BiMaC Innovation. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Colloidal gels and glasses from nanocelluloses2019Ingår i: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 257Artikel i tidskrift (Övrigt vetenskapligt)
  • 312.
    Nordenström, Malin
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Ödberg, Lars Göran
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Colloidal interactions in nanocellulose systems2016Ingår i: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 251Artikel i tidskrift (Övrigt vetenskapligt)
  • 313.
    Nordgren, Niklas
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Johansson, Erik
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Xu, Chunlin
    KTH, Skolan för bioteknologi (BIO), Glykovetenskap.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Brumer, Harry
    KTH, Skolan för bioteknologi (BIO), Glykovetenskap.
    Functionalized xyloglucan assemblies on gold: A prospective biomimetic anchor for cellulose2011Ingår i: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 241Artikel i tidskrift (Övrigt vetenskapligt)
  • 314.
    Nordgren, Niklas
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi.
    Stiernstedt, Johanna
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi.
    Brumer, Harry
    KTH.
    Wågberg, Lars
    KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellens Centrum BiMaC Innovation. KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Gray, Derek G.
    Rutland, Mark W.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Yt- och korrosionsvetenskap.
    CELL 109-Interactions of cellulose surfaces: Friction, adhesion and polysaccharide adsorption2007Ingår i: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 233, s. 838-838Artikel i tidskrift (Övrigt vetenskapligt)
  • 315. Norgren, Magnus
    et al.
    Edlund, H.
    Wågberg, Lars
    Aggregation of lignin derivatives under alkaline conditions. Kinetics and aggregate structure2002Ingår i: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 18, nr 7, s. 2859-2865Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The kinetics of kraft lignin (KL) aggregation at alkaline conditions was studied by quasi-elastic light scattering (QELS) and turbidity measurements. Stability ratios (W) for HL were obtained at 70 degreesC and various concentrations of sodium chloride. By analyzing the early-time evolution data of aggregate growth obtained from QELS, fractal dimensions of flocs formed in both reaction-limited cluster-cluster aggregation regimes and diffusion-limited cluster-cluster aggregation regimes were determined. Correlations between the fractal dimension and the W-ratio were found in accordance to recent studies of a system containing monodisperse polystyrene colloids. By cryogenic transmission electron microscopy, the fractality of KL aggregate structures in the system was also shown. It was seen from stability studies of KL solutions that the effects of specific co- and counterions follow the Hofmeister series. From the outcome of the investigation, different modes of aggregation occurring in a KL system are proposed. Starting from the macromolecular state of KL and evolving through larger aggregates, the KL clusters finally exhibit a supramolecular structure similar to what earlier has been proposed for native softwood lignin.

  • 316. Norgren, Magnus
    et al.
    Edlund, H.
    Wågberg, Lars
    KTH, Tidigare Institutioner                               , Pappers- och massateknik.
    Annergren, G.
    Fundamental physical aspects on lignin dissolution2002Ingår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 17, nr 4, s. 370-373Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The aggregation of diluted kraft lignin (KL) solutions was studied by turbidity measurements at elevated temperatures, various sodium chloride and sodium hydroxide concentrations. Since adsorptive processes usually precede self-aggregation in macromolecular systems as the solution conditions act worse, the interaction between KL and pulp fibres was also investigated. When treating samples of fully bleached softwood pulp fibres in KL solutions under various solution conditions, the light-absorption coefficient increased and the brightness was found to decrease rapidly above pOH 1, as the temperature was elevated. At pOH 2 and 175degreesC, the adsorption of KL was LIP to about 6 mg g(-1). The results are also discussed theoretically in terms of lignin solubility and lignin coagulation.

  • 317. Norgren, Magnus
    et al.
    Edlund, H.
    Wågberg, Lars
    Lindström, B.
    Annergren, G.
    Aggregation of kraft lignin derivatives under conditions relevant to the process, part I: phase behaviour2001Ingår i: Colloids and Surfaces A: Physicochemical and Engineering Aspects, ISSN 0927-7757, E-ISSN 1873-4359, Vol. 194, nr 03-jan, s. 85-96Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Aggregation of a commercial, polydisperse softwood kraft lignin (Indulin AT) in diluted aqueous alkaline solutions was investigated experimentally, by means of turbidity measurements. The influence of temperature, salt concentration and pOH and the role of a divalent counterion on the aggregation behaviour were studied. When the temperature was increased, an increased tendency of aggregation in samples containing high concentrations of sodium chloride was found. Phase separation could be detected even at pOH = 2 at 175 degreesC and the effect was pronounced when the concentration of hydroxide ions decreased. The phase transition from soluble to precipitated lignin was found to be irreversible concerning temperature change. Small amounts of calcium ions were seen to induce dramatic effects on the system stability, even at relatively high hydroxide concentrations (pOH 1-2). At a given temperature and pOH, the coagulation was found to appear at a certain critical coagulation concentration (CCC) of the added electrolyte. Furthermore, calculations were carried out to compare with the outcome of the experimental observations. A theoretical model, based on the DLVO theory, was found to predict the kraft lignin solution behaviour well.

  • 318. Norgren, Magnus
    et al.
    Gärdlund, Linda
    Notley, Shannon M.
    Htun, Myat
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Smooth model surfaces from lignin derivatives. II. Adsorption of polyelectrolytes and PECs monitored by QCM-D2007Ingår i: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 23, nr 7, s. 3737-3743Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    For the first time to the knowledge of the authors, well-defined and stable lignin model surfaces have been utilized as substrates in polyelectrolyte adsorption studies. The adsorption of polyallylamine (PAH), poly(acrylic acid) (PAA), and polyelectrolyte complexes (PECs) was monitored using quartz crystal microgravimetry with dissipation (QCM-D). The PECs were prepared by mixing PAH and PAA at different ratios and sequences, creating both cationic and anionic PECs with different charge levels. The adsorption experiments were performed in 1 and 10 mM sodium chloride solutions at pH 5 and 7.5. The highest adsorption of PAH and cationic PECs was found at pH 7.5, where the slightly negatively charged nature of the lignin substrate is more pronounced, governing electrostatic attraction of oppositely charged polymeric substances. An increase in the adsorption was further found when the electrolyte concentration was increased. In comparison, both PAA and the anionic PEC showed remarkably high adsorption to the lignin model film. The adsorption of PAA was further studied on silica and was found to be relatively low even at high electrolyte concentrations. This indicated that the high PAA adsorption on the lignin films was not induced by a decreased solubility of the anionic polyelectrolyte. The high levels of adsorption on lignin model surfaces found both for PAA and the anionic PAA-PAH polyelectrolyte complex points to the presence of strong nonionic interactions in these systems.

  • 319. Notley, S. M.
    et al.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Morphology of modified regenerated model cellulose II surfaces studied by atomic force microscopy: Effect of carboxymethylation and heat treatment2005Ingår i: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 6, nr 3, s. 1586-1591Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Model cellulose II surfaces with different surface charge have been prepared from carboxymethylated wood pulp. AFM tapping-mode imaging in air showed that the introduction of charged groups into the film does not appreciably change the surface morphology. However, after a mild heat treatment (heating at 105 ° C for 6 h), an irreversible surface structure change, from near spherical-type aggregates to a fibrillar structure, was observed. This might be attributed to the formation of strong hydrogen bonds in the crystalline region of the films while the amorphous regions shrank upon drying. The suitability of these charged cellulose films for surface forces studies was also investigated. At pH below the pK(a) of the carboxyl groups present in the film, the interaction force could be fit by a van der Waals force interaction. At higher pH, the interaction was of a purely electrostatic nature with no van der Waals component observable due to the swelling of the surfaces.

  • 320.
    Notley, Shannon
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi.
    Eriksson, Malin
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi.
    Visco-elastic and adhesive properties of adsorbed polyelectrolyte multilayers determined in situ with QCM-D and AFM measurements2005Ingår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 292, nr 1, s. 29-37Artikel i tidskrift (Refereegranskat)
    Abstract [en]

     The build-up of multilayers constructed from polyallylamine hydrochloride (PAH) and polyacrylic acid (PAA) under different pH conditions was continuously monitored using the quartz crystal microbalance with dissipation. The adsorbed amount of polymer as well as the amount of coupled water was determined. Furthermore, from dissipation measurements, it was possible to determine the visco-elastic properties of the adsorbed multilayer. These properties were highly dependent on the polyelectrolyte present in the outermost layer. The multilayer was far more rigid and elastic with PAA as the outermost layer. Furthermore, a link has been established between the conformability or rigidity of a multilayer covered surface and the adhesion between such surfaces. Adhesion measurements Using the atomic force microscope showed a greater pull-off force when the more viscous PAH was present in the outermost layer.

  • 321.
    Notley, Shannon M.
    et al.
    KTH, Tidigare Institutioner, Fiber- och polymerteknologi.
    Biggs, S.
    Craig, V. S. J.
    Wågberg, Lars
    KTH, Tidigare Institutioner, Fiber- och polymerteknologi.
    Adsorbed layer structure of a weak polyelectrolyte studied by colloidal probe microscopy and QCM-D as a function of pH and ionic strength2004Ingår i: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 6, nr 9, s. 2379-2386Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The adsorbed layer structure of a weak polyelectrolyte poly(2-vinylpyridine), on silica and mica, has been studied using colloidal probe microscopy (CPM) and the quartz crystal microbalance (QCM-D). The adsorbed layer structure was found to be highly dependent on both the solution conditions from which it was adsorbed and the molecular weight. Conditions were altered to favour both flat adsorbed layers and the development of significant steric layers. The structural reconformation of the large steric layer was furthermore studied as a function of pH. The equilibrium interaction force, measured using CPM as a function of surface separation, was used to determine the relative extension of the polyelectrolyte away from the interface. At low pH (3.2) and high ionic strength, the adsorbed polyelectrolyte molecules adopt a highly extended conformation; as the pH is increased (to 4.6 then to 5.5) the polymer chains collapse progressively towards the interface. Reversal of this pH cycle causes a re-protonation of the adsorbed polymers and highlights the finite timescale for this process to occur. The kinetics of this process was measured from the amount of trapped solvent within the polyelectrolyte layer as determined from the QCM-D. Upon decrease in pH, the adsorbed chains swell before partially collapsing. We propose that this is due to cross-linking of the polymer in the protonated state. Furthermore, the combination of techniques used in this study, namely optical reflectometry, CPM and QCM-D, allows the determination of the solvent content of the adsorbed film of polyelectrolyte as well as the extension of the polymer from the interface as a function of pH.

  • 322.
    Notley, Shannon
    et al.
    KTH, Tidigare Institutioner, Fiber- och polymerteknologi.
    Pettersson, Bert
    KTH, Tidigare Institutioner, Fiber- och polymerteknologi.
    Wågberg, Lars
    KTH, Tidigare Institutioner, Fiber- och polymerteknologi.
    Direct measurement of attractive van der waals' forces between regenerated cellulose surfaces in an aqueous environment2004Ingår i: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 126, nr 43, s. 13930-13931Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The interaction between cellulose surfaces is of fundamental interest in various natural and industrial systems. In this study, we describe the first direct measurements of an attractive van der Waals-type interaction between cellulose surfaces under aqueous conditions. An atomic force microscope, operating in colloidal probe mode, has been used to measure these interactions. The interaction between the cellulose surfaces is monotonically attractive at all surface separations. This long-range attractive interaction can be satisfactorily fitted with a Hamaker constant of 3.5 × 10-21 J.

  • 323. Notley, S.M.
    et al.
    Eriksson, Malin
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi.
    Beck, S.
    Gray, D.G.
    Surface Forces Measurements of Spin-Coated Cellulose Thin Films with Different Crystallinity2006Ingår i: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 22, nr 7, s. 3154-3160Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A systematic study of the surface forces between a cellulose sphere and cellulose thin films of varying crystallinity has been conducted as a function of ionic strength and pH. Semicrystalline cellulose II surfaces and amorphous cellulose films were prepared by spin-coating of the precursor cellulose solutions onto oxidized silicon wafers before regeneration in water. Crystalline cellulose I surfaces were prepared by spin-coating wafers with aqueous suspensions of sulfate-stabilized cellulose I nanocrystals. These preparation methods produced thin, smooth films suitable for surface forces measurements. The interaction with the cellulose I was monotonically repulsive at pH 3.5, 5.8, and 8.5 and at 0.1, 1, and 10 mM ionic strengths. This was attributed to the presence of strongly ionizable sulfur-containing groups on the cellulose nanocrystal surfaces. The amorphous film typically showed a steric interaction up to 100 nm away from the interface that was independent of the solution conditions. A range of surface forces were successfully measured on the semicrystalline cellulose II films; attractive and repulsive regimes were observed, depending on pH and ionic strength, and were interpreted in terms of van der Waals and electrostatic interactions. Clearly, the forces acting near cellulose surfaces are very dependent on the way the cellulose surface has been prepared.

  • 324.
    Nyström, Gustav
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Fall, Andreas
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Carlsson, Linn
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Aligned Cellulose Nanocrystals and Directed Nanoscale Deposition of Colloidal Spheres2014Ingår i: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 21, nr 3, s. 1591-1599Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Cellulose nanocrystals are aligned in wrinkled polydimethylsiloxane templates and transferred to polyethyleneimine-coated silica surfaces in a printing process similar to microcontact printing. The highly aligned nanorods were deposited onto the surfaces with a line-to-line distance of 225-600 nm without loss of alignment. It was also possible to repeat the transfer process on the same surface at a 90-degree angle to create a network structure. This demonstrates the versatility of the technique and creates more options for advanced multilayering of materials. To demonstrate that the surface properties of the anionic cellulose nanorods were unaffected by the transfer process and to prove the concept of functionalizing transferred particles, cationic latex particles were electrostatically self-assembled onto the cellulose nanorods. The directed deposition of these particles resulted in excellent site specificity and the highest resolution to date for controlled deposition of colloids on an electrostatically patterned surface.

  • 325.
    Nyström, Gustav
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Marais, Andrew
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Karabulut, Erdem
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Cui, Yi
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Hamedi, Mahiar
    Self-assembled three-dimensional and compressible interdigitated thin-film supercapacitors and batteries2015Ingår i: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 6, s. 7259-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Traditional thin-film energy-storage devices consist of stacked layers of active films on two-dimensional substrates and do not exploit the third dimension. Fully three-dimensional thin-film devices would allow energy storage in bulk materials with arbitrary form factors and with mechanical properties unique to bulk materials such as compressibility. Here we show three-dimensional energy-storage devices based on layer-by-layer self-assembly of interdigitated thin films on the surface of an open-cell aerogel substrate. We demonstrate a reversibly compressible three-dimensional supercapacitor with carbon nanotube electrodes and a three-dimensional hybrid battery with a copper hexacyanoferrate ion intercalating cathode and a carbon nanotube anode. The three-dimensional supercapacitor shows stable operation over 400 cycles with a capacitance of 25â €‰Fâ €‰g â '1 and is fully functional even at compressions up to 75%. Our results demonstrate that layer-by-layer self-assembly inside aerogels is a rapid, precise and scalable route for building high-surface-area 3D thin-film devices.

  • 326.
    Olin, Pontus Hans
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Fiberteknologi.
    Pettersson, Torbjörn
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Fiberteknologi.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Fiberteknologi.
    Influence of tilt angle and droplet size on the sliding rate of water droplets on superhydrophobic surfaces2012Konferensbidrag (Övrigt vetenskapligt)
  • 327.
    Olin, Pontus
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi.
    Hill, Caroline
    Ovaskainen, Louise
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi.
    Ruda, Marcus
    Schimidt, Oskar
    Turner, Charlotta
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi.
    Development of a semi-continuous spray process for production of superhydrophobic coatings from supercritical carbon dioxide solutionsManuskript (preprint) (Övrigt vetenskapligt)
  • 328.
    Olin, Pontus
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Fiberteknologi.
    Hyll, Caroline
    KTH, Skolan för industriell teknik och management (ITM), Industriell produktion, Mätteknik och optik.
    Ovaskainen, Louise
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Fiberteknologi.
    Ruda, Marcus
    Schmidt, Oskar
    Turner, Charlotta
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Fiberteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Development of a Semicontinuous Spray Process for the Production of Superhydrophobic Coatings from Supercritical Carbon Dioxide Solutions2015Ingår i: Industrial & Engineering Chemistry Research, ISSN 0888-5885, E-ISSN 1520-5045, Vol. 54, nr 3, s. 1059-1067Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Superhydrophobic surfaces have been fabricated in a continuous spray process, where an alkyl ketene dimer (AKD) wax is dissolved in supercritical carbon dioxide (scCO(2)) and sprayed onto the substrate. The mass of extracted AKD from scCO2 has been investigated as well as the pressure, temperature, and flow of CO2 at the steady-state spray conditions. Several different substrates such as glass, aluminum, paper, poly(ethylene terephthalate) (PET), and polytetrafluoroethylene (PTFE) have been successfully coated, and the superhydrophobic properties have been evaluated by measurement of water contact angle, water drop friction, scanning electron microscopy (SEM), and surface topography. The most efficient spray process, considering surface properties and mass of extracted AKD, is obtained at the lowest temperature investigated, 67 degrees C, and the highest pressure evaluated in this study, 25 MPa. We also show that the influence of preexpansion conditions (p, T) on the surface temperature at the selected spray distance (3 cm) is negligible by measurement with an infrared camera during spraying.

  • 329.
    Olin, Pontus
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi.
    Lindström, Stefan B.
    Pettersson, Torbjörn
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Water Drop Friction on Superhydrophobic Surfaces2013Ingår i: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 29, nr 29, s. 9079-9089Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    To investigate water drop friction on superhydrophobic surfaces, the motion of water drops on three different superhydrophobic surfaces has been studied by allowing drops to slide down an incline and capturing their motion using high-speed video. Two surfaces were prepared using crystallization of an alkyl ketene dimer (AKD) wax, and the third surface was the leaf of a Lotus (Nelumbo Nucifera). The acceleration of the water droplets on these superhydrophobic surfaces was measured as a function of droplet size and inclination of the surface. For small capillary numbers, we propose that the energy dissipation is dominated by intermittent pinning-depinning transitions at microscopic pinning sites along the trailing contact line of the drop, while at capillary numbers exceeding a critical value, energy dissipation is dominated by circulatory flow in the vicinity of the contacting disc between the droplet and the surface. By combining the results of the droplet acceleration with a theoretical model based on energy dissipation, we have introduced a material-specific coefficient called the superhydrophobic sliding resistance, b(sh). Once determined, this parameter is sufficient for predicting the motion of water drops on superhydrophobic surfaces of a general macroscopic topography. This theory also infers the existence of an equilibrium sliding angle, beta(eq), at which the drop acceleration is zero. This angle is decreasing with the radius of the drop and is in quantitative agreement with the measured tilt angles required for a stationary drop to start sliding down an incline.

  • 330.
    Olin, Pontus
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi.
    Lindström, Stefan B.
    Solid Mechanics , Department of Management and Engineering, the Institute of Technology, Linköping University.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Trapping of Water Drops by Defects on Superhydrophobic SurfacesManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    In this work the effect of line‑shaped defects on the motion of water drops on superhydrophobic surfaces have been investigated using high‑speed video. The defects were introduced on superhydrophobic wax surfaces by a simple scratching method. It is shown that the motion of the drop in the vicinity of the defect can be approximated by a damped harmonic oscillator. Whether a drop gets trapped or not while traversing the defect is determined by the incident speed and the characteristics of the oscillator, more specifically by the damping ratio z and the nondimensional forcing constant â. We also show that it is possible to predict the trapping speed as well as the exit speed using a simple work‑energy consideration in systems with negligible viscous dissipation.

  • 331.
    Olin, Pontus
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Lindström, Stefan B.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Trapping of Water Drops by Line-Shaped Defects on Superhydrophobic Surfaces2015Ingår i: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 31, nr 23, s. 6367-6374Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We have investigated the effect of line-shaped topographical defects on the motion of water drops across superhydrophobic wax surfaces using a high-speed video camera. The defects are introduced onto the superhydrophobic wax surfaces by a scratching procedure. It is demonstrated that the motion of a drop interacting with the defect can be approximated by a damped harmonic oscillator. Whether a drop passes or gets trapped by the defect is determined by the incident speed and the properties of the oscillator, specifically by the damping ratio and a nondimensional forcing constant representing the effects of gravity and pinning forces. We also show that it is possible to predict a critical trapping speed as well as an exit speed in systems with negligible viscous dissipation using a simple work energy consideration.

  • 332.
    Oliveira de Castro, Danielle
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Karim, Zoheb
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Medina, Lilian
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Biokompositer.
    Svedberg, A.
    Wågberg, Lars
    Söderberg, Daniel
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Berglund, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Scale up of nanocellulose/hybrid inorganic films using a pilot web former2017Ingår i: International Conference on Nanotechnology for Renewable Materials 2017, TAPPI Press , 2017, s. 408-418Konferensbidrag (Refereegranskat)
  • 333. Ondaral, Sedat
    et al.
    Ankerfors, Caroline
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Fiberteknologi.
    Ödberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Fiberteknologi.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Fiberteknologi.
    Surface-Induced Rearrangement of Polyelectrolyte Complexes: Influence of Complex Composition on Adsorbed Layer Properties2010Ingår i: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 26, nr 18, s. 14606-14614Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The adsorption characteristics of two different types of polyelectrolyte complexes (PECs). prepared by mixing poly(allylamine hydrochloride) and poly(acrylic acid) in a confined impinging jet (CIJ) mixer, have been investigated with the aid of stagnation point adsorption reflectometry (SPAR), a quartz crystal microbalance with dissipation (QCM-D), and atomic force microscopy (A FM) using SiO2 surfaces The two sets of PEC were prepared by combining high molecular mass PAH/FAA (PEC-A) and low molt:cubit mass PAH/PAA (PEC-B) The PEC-A showed a higher adsorption to the SiO2 surfaces than the PEC-B The adsorption of the PEC-A also showed a larger change in the dissipation (AD), according to the QCM-D measurements, suggesting that the adsorbed layer of these complexes had a relatively lower viscosity and a lower shear modulus Complementary investigations of the adsorbed layer using A FM imaging showed that the adsorbed layer of PEC-A was significantly different from that of PEC-B and that the changes in properties with adsorption time were very different for the two types of PECs The PEC-A complexes showed a coalescence into larger block of complexes on the SiO2 surface, but this was not detected with the PEC-B The size determinations of the complexes in solution showed that they were very stable over time, and it was therefore concluded that the coalescence of the complexes was induced I the interaction between the complexes and the surface The results also indicated that polyelectrolytes can migrate between the different complexes adsorbed to the surface The results also give indications that the preparation of PEC-B leads to the formation of two different types of polyelectrolyte complexes differing in the amount of polymer in the complexes: i.e., two populations of complexes were formed with similar sizes but with totally different adsorption structures at the solid-liquid interface.

  • 334. Ondaral, Sedat
    et al.
    Usta, Mustafa
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Gumusderelioglu, Menemse
    Ondaral, Meryem
    FIXATION OF DISSOLVED AND COLLOIDAL SUBSTANCES ON FIBERS AND SILICON OXIDE SURFACES USING WATER SOLUBLE CROSSLINKED CATIONIC POLYMERS2008Ingår i: Cellulose Chemistry and Technology, ISSN 0576-9787, Vol. 42, nr 1-3, s. 61-69Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The efficiency of water soluble crosslinked cationic polymers (CCP) in the fixation of dissolved and colloidal substances (DCS) onto fibers was investigated. Two different types of CCP were synthesized by dispersion polymerization of acrylamide (AAm) and diallyldimethylammonium chloride (DADMAC), with N,N'-methylene-bis-acrylamide (MBA) as a crosslinker. Relative turbidity, zeta potential and average diameter of the colloidal particles were determined to monitor their performance in DCS fixation. The results indicated that both polymers were able to fix a maximum amount of DCS particles onto fibers around a zero zeta potential, most probably clue to a patch-type flocculation mechanism. The conclusion reached was that flocculation was significant while the particles still had a negative zeta potential. The aggregation mechanism of a fiber-free DCS suspension occurred as Charge neutralisation, changed, by the addition of 10 mM NaCl to a patch-type mechanism. The CCPI consumption necessary to attain a maximum DCS removal was lower than the CCP2 consumption, as ascribed to the higher charge density and higher molecular mass of this polymer. The experiments performed on a quartz crystal microbalance equipment with dissipation (QCM-D) showed that the adsorbed charge and layer thickness of the polymers significantly affected fixation of the DCS particles onto the pre-adsorbed polymer layers on the SiO2 surface.

  • 335.
    Ondaral, Sedat
    et al.
    Karadeniz Tech Univ, Fac Forestry, Dept Pulp & Paper Technol.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Enarsson, Lars-Erik
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    The adsorption of hyperbranched polymers on silicon oxide surfaces2006Ingår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 301, nr 1, s. 32-39Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The electrostatic interaction between quarternised hyperbranched polymers (polyesteramides) and a silicon oxide (SiO2) surface has been studied via adsorption studies with quartz crystal microbalance instrument with dissipation (QCM-D). Frequency shift (Delta f) results show that the increase in both pH and salt concentration positively affect the adsorbed amount of these polymers, calculated by Sauerbrey equation, on the QCM crystal. The adsorbed amount of HA1 (with lower molecular weight and higher charge density) was lower than that of HA2 (with higher molecular weight and lower charge density) in all experiments. It was also observed that there are no significant changes in the dissipation after adsorption of these polymers. This indicated that both hyperbranched polymers formed rigid adsorbed layers on the negative SiO2 surface. Additionally, the results were compared with adsorption of poly-DADMAC and the results showed that the hyperbranched polymers formed thicker and more rigid layers as compared with the poly-DADMAC.

  • 336.
    Ovaskainen, Louise
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi.
    Chigome, S.
    Birkin, Natasha A.
    Howdle, Steven M.
    Torto, N.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi.
    Turner, Charlotta
    Superphydrophobic polymeric coatings produced by rapid expansion of supercritical solutions combined with electrostatic deposition (RESS-ED)Manuskript (preprint) (Övrigt vetenskapligt)
  • 337.
    Ovaskainen, Louise
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi.
    Chigome, Samuel
    Birkin, Natasha A.
    Howdle, Steven M.
    Torte, Nelson
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Turner, Charlotta
    Superhydrophobic polymeric coatings produced by rapid expansion of supercritical solutions combined with electrostatic depostion (RESS-ED)2014Ingår i: Journal of Supercritical Fluids, ISSN 0896-8446, E-ISSN 1872-8162, Vol. 95, s. 610-617Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper we present a method to produce superhydrophobic polymeric coatings by combining the rapid expansion of supercritical solutions (RESS) with electrostatic deposition (ED). A copolymer, poly(vinyl acetate)-poly(vinyl pivalate) was dissolved in a mixture of supercritical carbon dioxide and acetone and sprayed through a nozzle with an applied voltage of 8 kV onto a surface placed on a earthed collector. Spray distance and polymer concentration were altered to find the most suitable spraying conditions. Superhydrophobic surfaces were produced when spraying both with and without a voltage, although the water repellent surfaces could be produced at a larger variety of processing parameters using the RESS-ED technique. The greatest improvement of using the RESS-ED process was that larger and thinner coatings were produced with a more even surface coverage of the created polymer particles compared to spraying without the applied voltage.

  • 338.
    Ovaskainen, Louise
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi.
    Meizoso, Irene Rodriguez
    Turner, Charlotta
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Preparation of polymeric surface coatings by using supercritical carbon dioxide2013Ingår i: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 245Artikel i tidskrift (Övrigt vetenskapligt)
  • 339.
    Ovaskainen, Louise
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi.
    Olin, Pontus
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi.
    Pettersson, Torbjörn
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Wear studies of superhydrophobic coatings of wax and polymers sprayed from rapid expansion of supercritical solutions (RESS)Manuskript (preprint) (Övrigt vetenskapligt)
  • 340.
    Ovaskainen, Louise
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Olin, Pontus
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Tuominen, Mikko
    Pettersson, Torbjörn
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    The effect of different wear on superhydrophobic wax coatings2017Ingår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 32, nr 2, s. 195-203Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Wear resistance of superhydrophobic coatings made by spraying a crystallizing wax from supercritical carbon dioxide solutions was evaluated using several methods. Scratch tests were performed using a tip in contact with the surface using atomic force microscope (AFM). Compression tests were performed by applying different loads on a rubber stamp placed on the surface. Frictional wear was evaluated by stroking an index finger over the surfaces while measuring applied load and friction. The wetting properties of the coatings were subsequently evaluated as advancing and receding water contact angles, superhydrophobic sliding resistance according to a recently developed method and surface roughness, coating morphology was studied using scanning electron microscopy and optical profilometry. Scratching with tip of an AFM cantilever with a force of 12 nN removed major fraction of the wax coating from underlying silica substrate whereas subjecting the surfaces to a compressive load up to 59 kPa did not significantly influence the superhydrophobicity of the coatings. Frictional wear measurements indicate that superhydrophobic properties were immediately lost after pressing and moving a finger over the coating, as movement of the finger destroyed the fine surface structure. Nevertheless, the surfaces could withstand up to 200000 falling water drops without losing their superhydrophobicity.

  • 341.
    Ovaskainen, Louise
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Fiberteknologi.
    Olin, Pontus
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Fiberteknologi.
    Tuominen, Mikko
    SP Kemi, Material och Ytor, Drottning Kristinas väg 45, SE-114 86 Stockholm.
    Pettersson, Torbjörn
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Fiberteknologi.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Fiberteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Wear studies of superhydrophobic coatings of wax sprayed from rapid expansion of supercritical solutions (RESS)Manuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    The wear resistance of superhydrophobic coatings made by spraying a wax from supercritical carbon dioxide solutions have been evaluated by different methods. Scratch tests were performed by using the tip of the cantilever in an atomic force microscope (AFM) by applying an increasing load force on the tip during the measurement. Compression tests were also performed by applying different loads onto a rubber stamp that was placed on the surfaces. In addition to this, frictional wear was evaluated by moving an index finger over the surface using a device that measured the applied load and frictional forces. The wetting properties of the exposed coatings were subsequently evaluated in terms of advancing and receding water contact angles, the superhydrophobic sliding resistance parameter and the surface roughness (RMS). The morphology of the coatings was studied by scanning electron microscopy and optical profilometry. Scratching, with the AFM, at load forces of 12 nN was enough to fully remove the coating from the underlying silica substrate. Results also show that the surfaces remained superhydrophobic after being exposed to compression loads up to 59 kPa. The frictional wear measurments showed that the superhydrophobic properties were immediately lost after pressing and moving a finger over the coating since the lateral movement destroyed the fine surface structure.  Finally it was found that the surfaces could stand up to 200 000 falling water drops without losing its superhydrophobicity.

  • 342.
    Ovaskainen, Louise
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi.
    Rodriguez-Meizoso, Irene
    Birkin, Natasha A.
    Howdle, Steven M.
    Gedde, Ulf
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi.
    Turner, Charlotta
    Towards superhydrophobic coatings made by non-fluorinated polymers sprayed from a supercritical solution2013Ingår i: Journal of Supercritical Fluids, ISSN 0896-8446, E-ISSN 1872-8162, Vol. 77, s. 134-141Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The objective of this study was to create a superhydrophobic surface using polymers that are non-fluorinated and applying them to a surface via rapid expansion of a supercritical solution (RESS). Solubility studies of poly(epsilon-caprolactone) (PCL) and a statistical copolymer of vinyl acetate and vinyl pivalate (P(VAc-VPi))in supercritical carbon dioxide (scCO(2)) were carried out using an extraction procedure. It was found that the most suitable process parameters for spraying these polymers using the RESS technique were 30 MPa, 40 degrees C and 10% (v/v) acetone as a co-solvent. The surfaces produced were characterized in terms of their morphology and hydrophobic properties by scanning electron microscopy and contact angle measurements, respectively. The most hydrophobic surfaces were obtained by spraying the P(VAc-VPi) copolymers, giving advancing water contact angles in the range of 120-155 degrees due to the hydrophobic character of the polymer and the microstructure formed with the RESS technique. These results show great promise for the creation of superhydrophobic surfaces using non-fluorinated polymers applied to surfaces via RESS technique.

  • 343. Pelton, R.
    et al.
    Zhang, J.
    Wågberg, Lars
    Rundlof, M.
    The role of surface polymer compability in the formation of fiber/fiber bonds in paper2000Ingår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 15, nr 5, s. 400-406Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The tensile strength of unbeaten kraft pulp handsheets was measured as a function of the compatibility of polymers adsorbed on the fibers. Two types of fibers were prepared, one was treated with slightly cationic dextran and the second was treated with slightly hydrophobic cationic dextran. The dextrans were chosen because both are paper strength enhancing polymers and yet they are incompatible with each other. Either dextran alone significantly enhanced paper strength whereas sheets made with mixtures were weaker. The results are interpreted in terms of the polymer compatibility. When a fiber/fiber bond forms between two surfaces bearing incompatible adsorbed polymers, the polymers will not interdiffuse during sheet consolidation thus giving a relatively weak interfiber bond.

  • 344.
    Pendergraph, Sam
    et al.
    Fibre & Polymer Technol, Arlington Hts, IL USA..
    Carrick, Christopher
    KTH.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Carlmark, Anna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Johansson, Mats
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. Royal Inst Tech, Stockholm, Sweden..
    Klein, Gregor
    KTH.
    Träger, Andrea
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Macroscopic cellulose probes for contact adhesion2015Ingår i: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 249Artikel i tidskrift (Övrigt vetenskapligt)
  • 345.
    Petrou, Georgia
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Glykovetenskap.
    Jansson, Ronnie
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Proteinvetenskap, Protein Engineering.
    Hogqvist, Mark
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH).
    Erlandsson, Johan
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Wågberg, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Hedhammar, My
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Proteinvetenskap, Proteinteknologi.
    Crouzier, Thomas
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Glykovetenskap.
    Genetically Engineered Mucoadhesive Spider Silk2018Ingår i: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 19, nr 8, s. 3268-3279Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Mucoadhesion is defined as the adhesion of a material to the mucus gel covering the mucous membranes. The mechanisms controlling mucoadhesion include nonspecific electrostatic interactions and specific interactions between the materials and the mucins, the heavily glycosylated proteins that form the mucus gel. Mucoadhesive materials can be used to develop mucosal wound dressings and noninvasive transmucosal drug delivery systems. Spider silk, which is strong, biocompatible, biodegradable, nontoxic, and lightweight would serve as an excellent base for the development of such materials. Here, we investigated two variants of the partial spider silk protein 4RepCT genetically engineered in order to functionalize them with mucoadhesive properties. The pLys-4RepCT variant was functionalized with six cationically charged lysines, aiming to provide nonspecific adhesion from electrostatic interactions with the anionically charged mucins, while the hGal3-4RepCT variant was genetically fused with the Human Galectin-3 Carbohydrate Recognition Domain which specifically binds the mucin glycans Gal beta 1-3GlcNAc and Gal beta 1-4GlcNAc. First, we demonstrated that coatings, fibers, meshes, and foams can be readily made from both silk variants. Measured by the adsorption of both bovine submaxillary mucin and pig gastric mucin, the newly produced silk materials showed enhanced mucin binding properties compared with materials of wild-type (4RepCT) silk. Moreover, we showed that pLys-4RepCT silk coatings bind mucins through electrostatic interactions, while hGal3-4RepCT silk coatings bind mucins through specific glycan-protein interactions. We envision that the two new mucoadhesive silk variants pLys-4RepCT and hGal3-4RepCT, alone or combined with other biofunctional silk proteins, constitute useful new building blocks for a range of silk protein-based materials for mucosal treatments.

  • 346. Pettersson, G.
    et al.
    Hoglund, H.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    The use of polyelectrolyte multilayers of cationic starch and CMC to enhance strength properties of papers formed from mixtures of unbleached chemical pulp and CTMP. Part I2006Ingår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 21, nr 1, s. 115-121Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The construction of alternating multilayers of cationic potato starch and anionic carboxymethylcellulose (CMC) was investigated in two parts. In the first part, stagnation point adsorption reflectometry (SPAR) showed that the chosen chemicals formed polyelectrolyte multilayers (PEM) upon adsorption to the silicon oxide surface. This was in accordance with earlier work. The chosen polyelectrolytes adsorbed to similar extents on the silicon oxide surface and recharged the surface enough to allow for adsorption of a consecutive layer. In the second part, the multilayer concept was tested on 80/20, 20/80% of total in Mixture of mixed spruce CTMP and bleached chemical Pulp in order to enhance the sheet strength properties of a typical packaging board furnish.. The multilayers yielded a significant improvement in Scott Bond values and tensile index and a marginal improvement in tensile stiffness index. The Scott Bond values were improved more than 150% for papers prepared from a furnish consisting of 80% spruce CTMP and 20% chemical pulp. Polyelectrolyte inultilayers treatment also led to a slight densification of the sheets, but the polyelectrolyte multilayers treatment resulted in a more favourable density/strength relationship than that achieved with a change in the amount of chemical pulp.

  • 347. Pettersson, G.
    et al.
    Hoglund, H.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    The use of polyelectrolyte multilayers of cationic starch and CMC to enhance strength properties of papers formed from mixtures of unbleached chemical pulp and CTMP. Part II Influence of addition strategy, fibre treatment and fibre type2006Ingår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 21, nr 1, s. 122-128Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Polyelectrolyte multilayers (PEM) consisting of cationic starch and anionic carboxymethylcellulose (CMC) have been applied to different pulp fibres in order to enhance the out-of-plane sheet strength properties of a typical packaging board furnish. An unbleached softwood chemical pulp was treated with multilayers consisting of two layers of cationic starch and one layer of CIVIC, and then mixed with different mechanical and chemimechanical pulps. Hand sheets were prepared with the aid of the Rapid Kothen sheet former from stocks consisting of 20% treated chemical pulp and 80% mechanical or chemimechanical pulp, which was either PGW from spruce, HT-CTMP from spruce or birch, or a standard spruce CTMP. Multilayer treatment significantly improved Scott Bond values and in some cases improved the tensile index, with the achieved effects being significantly larger than the effects of applying starch alone. Positive effects were obtained by treating only 20% of the furnish, showing a very high efficiency of the adsorbed multilayers. Compared to earlier work, one important finding was that the PEM treatment should preferably be applied only to the chemical pulp and not on the entire stock. It was possible to increase the out-of-plane strength properties, measured as Scott Bond values, with just a very small increase in density of the sheets. Multilayer treatment of the chemical pulp improved the joint strength between the fibres while maintaining the high bulk of the sheets prepared from the stiff mechanical and chemimechanical fibres.

  • 348. Pettersson, Gunilla
    et al.
    Sjoberg, Jessica C.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Hoglund, Hans
    Averheim, Andreas
    Increased joint-forming ability of ductile kraft pulp fibres by polyelectrolyte multilayer treatment - Influence of refining and drying strategies2007Ingår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 22, nr 2, s. 228-235Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this study a sack paper furnish was used. It consisted of a high-consistency kraft pulp refined in either an atmospheric pressure or a pressurized system. The pulps were subsequently low-consistency refined in an Escher-Wyss laboratory refiner to 17.5-20.5 SR. Ordinary ISO sheets and freely dried sheets were manufactured from these pulp samples to serve as reference sheets. The laboratory sheets made of pulp from the pressurized system had a higher strain at break and tensile energy adsorption index but a lower tensile index than sheets made of pulp from a conventional atmospheric high-consistency refiner. These sheets were subject to a polyelectrolyte multilayer treatment to increase the interaction between the fibres, thus enhancing the paper strength properties. The polyelectrolyte multilayers (PEM) were applied by sequentially treating fibres from an unbleached kraft pulp for sack paper production with cationic starch and anionic carboxymethyl cellulose. The multilayer treatment was only applied to 50% of the stock and both ordinary ISO sheets and freely dried sheets were prepared with one and three layers of polyelectrolyte. Evaluation of the strength properties of the sheets showed that the addition of only one layer of starch increased strain at break, tensile index, tensile energy adsorption index, and out-of-plane properties measured as Scott-bond values. Using the multilayer technique created large increases in Scott-bond, a measure of the internal bonding of the sheets. The achieved effects were significantly larger than those usually achieved by applying starch alone to enhance the out-of plane strength properties. Also, the density increased considerably when the third layer was applied, for both ISO and freely dried sheets, though the tensile strength was enhanced significantly only in the freely dried sheets.

  • 349.
    Pettersson, Torbjörn
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Erlandsson, Johan
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Larsson, Per
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Wågberg, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    On the mechanism of freeze-induced crosslinking of aerogels made from periodate-oxidised cellulose nanofibrils2018Ingår i: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 255Artikel i tidskrift (Övrigt vetenskapligt)
  • 350.
    Pettersson, Torbjörn
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi.
    Gustafsson, Emil
    KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Johansson, Erik
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi.
    JKR approach to study joint formation2010Ingår i: ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY: volume 239, 2010, s. CELL-144-Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    To gain a more fundamental understanding of the mechanism for joint formation between pulp fibres, we have utilized the JKR approach to study the adhesion properties of multilayers formed using anionic and cationic MFC (microfibrillar cellulose). The effect of using anionic or cationic MFC in the outermost layer has been elucidated and compared with measurements performed on other types of cellulosic model surfaces. Furthermore, our JKR instrument has been modified to enable measurements of the drying process, by comparing the adhesion interaction between PVAm (poly[vinylamine]) coated surfaces that have been dried in contact, or dried before being brought into contact. The typical contact area in the JKR experiments are in the micrometre range and our measurements have been compared with nanoscale adhesion measurements by colloidal probe AFM (atomic force microscopy).

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