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  • 51. Carlsson, Daniel O.
    et al.
    Nyström, Gustav
    KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Zhou, Qi
    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.
    Berglund, Lars A.
    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.
    Nyholm, Leif
    Strømme, Maria
    Electroactive nanofibrillated cellulose aerogel composites with tunable structural and electrochemical properties2012In: Journal of Materials Chemistry, ISSN 0959-9428, E-ISSN 1364-5501, Vol. 22, no 36, p. 19014-19024Article in journal (Refereed)
    Abstract [en]

    This work presents conductive aerogel composites of nanofibrillated cellulose (NFC) and polypyrrole (PPy) with tunable structural and electrochemical properties. The conductive composites are prepared by chemically polymerizing pyrrole onto TEMPO-oxidized cellulose nanofibers dispersed in water and the various nanostructures are obtained employing different drying methods. Supercritical CO2 drying is shown to generate high porosity aerogel composites with the largest surface area (246 m(2) g(-1)) reported so far for a conducting polymer-paper based material, whereas composites produced by ambient drying attain high density structures with mechanical properties significantly surpassing earlier reported values for cellulose-conducting polymer composites when normalized with respect to the content of reinforcing cellulose (Young's modulus = 0.51 GPa, tensile strength = 10.93 MPa and strain to failure = 2.5%). Electrochemical measurements clearly show that differences in the porosity give rise to dramatic changes in the voltammetric and chronoamperometric behavior of the composites. This indicates that mass transport rate limitations also should be considered, in addition to the presence of a distribution of PPy redox potentials, as an explanation for the shapes of the voltammetric peaks. A specific charge capacity of similar to 220 C g(-1) is obtained for all composites in voltammetric experiments performed at a scan rate of 1 mV s(-1) and this capacity is retained also at scan rates up to 50 mV s(-1) for the high porosity composites. The composites should be applicable as electrodes in structural batteries and as membranes in ion exchange applications requiring exchange membranes of high mechanical integrity or high porosity.

  • 52.
    Carosio, Federico
    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.
    Cuttica, Fabio
    Medina, Lilian
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Berglund, Lars A.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Clay nanopaper as multifunctional brick and mortar fire protection coating: Wood case study2016In: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 93, p. 357-363Article in journal (Refereed)
    Abstract [en]

    Abstract Wood is one of the most sustainable, esthetically pleasing and environmentally benign engineering materials, and is often used in structures found in buildings. Unfortunately, the fire hazards related to wood are limiting its application. The use of transparent cellulose nanofiber (CNF)/clay nanocomposites, with unique brick-and-mortar structure, is proposed as a sustainable and efficient fire protection coating for wood. Fire performance was assessed by cone calorimetry. When exposed to the typical 35 kW/m2 heat flux of developing fires, the time to ignition of coated wood samples increased up to about 4 1/2 min, while the maximum average rate of heat emission (MARHE) was decreased by 46% thus significantly reducing the potential fire threat from wood structures.

  • 53.
    Carosio, Federico
    et al.
    Politecn Torino, Dipartimento Sci Applicata & Technol, Alessandria, Italy.;KTH Royal Inst Technol, Fibre & Polymer Technol, Stockholm, Sweden..
    Kochumalayil, Joby
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Cuttica, Fabio
    Politecn Torino, Dipartimento Sci Applicata & Technol, Alessandria, Italy..
    Medina, Lilian
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Camino, Giovanni
    Politecn Torino, Dipartimento Sci Applicata & Technol, Alessandria, Italy..
    Berglund, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Nanocellulose/clay thin films and foams: Biobased nanocomposites with superior flame retardant properties2016In: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 252Article in journal (Other academic)
  • 54.
    Carosio, Federico
    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. Politecnico di Torino, Italy.
    Kochumalayil, Joby
    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.
    Fina, A.
    Berglund, Lars A.
    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.
    Extreme Thermal Shielding Effects in Nanopaper Based on Multilayers of Aligned Clay Nanoplatelets in Cellulose Nanofiber Matrix2016In: Advanced Materials Interfaces, ISSN 2196-7350, Vol. 3, no 19, article id 1600551Article in journal (Refereed)
  • 55.
    Carosio, Federico
    et al.
    Politecn Torino, I-15121 Alessandria, Italy.
    Kochumalayil, Jose
    Cuttica, F.
    Camino, G.
    Berglund, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites.
    Oriented Clay Nanopaper from Biobased Components Mechanisms for Superior Fire Protection Properties2015In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 7, no 10, p. 5847-5856Article in journal (Refereed)
    Abstract [en]

    The toxicity of the most efficient fire retardant additives is a major problem for polymeric Materials. Cellulose nanofiber (CNF)/clay nanocomposites, with unique brick-and-mortar structure and prepared by simple filtration, are characterized from the morphological point of view by scanning electron microscopy and X-ray diffraction. These nanocomposites have superior fire protection properties to Other clay nanocomposites and fiber composites. The Corresponding mechanisms are evaluated in terms of flammability (reaction to a flame) and cone calorimetry (exposure to heat flux). These two tests provide a wide spectrum characterization of fire protection properties in CNF/montmorrilonite (MTM) Materials. The morphology of the collected residues after flammability testing is investigated. In addition, thermal and thermo-oxidative stability are evaluated by thermogravimetric analyses performed in inert (nitrogen) and oxidative (air) atmospheres. Physical and chemical mechanisms are identified and related to the unique nanostructure and its low thermal conductivity, high gas barrier properties and CNF/ MTM interactions for char formation.

  • 56. Cataldi, A.
    et al.
    Dorigato, A.
    Deflorian, F.
    Berglund, 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.
    Pegoretti, A.
    Polymer composite with micro- and nanocellulose for artwork protection and restoration2014In: 16th European Conference on Composite Materials, ECCM 2014, 2014Conference paper (Refereed)
    Abstract [en]

    Micro- and nanocomposites were prepared using Aquazol® 500 as a polymeric matrix and a microcrystalline cellulose (MCC), and suspensions of cellulose nanocrystals (CNC), as reinforcing agents. After a preliminary thermo-mechanical characterization that highlighted a stabilizing effect due to the micro- and nanofiller introduction, with an increase of the elastic modulus and a decrease of the thermal expansion coefficient and the creep compliance [1], these materials were applied as canvas lining adhesives. Single-lap shear tests both in quasi-static and creep conditions confirmed the dimensional stability provided by cellulose micro- and nanoparticles, with an important reduction of the adhesives compliance proportional to the filler content. Interestingly, MCC and CNC introduction did not impair the fracture behavior of the neat matrix.

  • 57.
    Chen, Hui
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Baitenov, Adil
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Li, Yuanyuan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Vasileva, Elena
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Popov, Sergei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Photonics.
    Sychugov, Ilya
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Yan, Min
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Berglund, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Thickness Dependence of Optical Transmittance of Transparent Wood: Chemical Modification Effects2019In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 11, no 38, p. 35451-35457Article in journal (Refereed)
    Abstract [en]

    Transparent wood (TW) is an emerging optical material combining high optical transmittance and haze for structural applications. Unlike nonscattering absorbing media, the thickness dependence of light transmittance for TW is complicated because optical losses are also related to increased photon path length from multiple scattering. In the present study, starting from photon diffusion equation, it is found that the angle-integrated total light transmittance of TW has an exponentially decaying dependence on sample thickness. The expression reveals an attenuation coefficient which depends not only on the absorption coefficient but also on the diffusion coefficient. The total transmittance and thickness were measured for a range of TW samples, from both acetylated and nonacetylated balsa wood templates, and were fitted according to the derived relationship. The fitting gives a lower attenuation coefficient for the acetylated TW compared to the nonacetylated one. The lower attenuation coefficient for the acetylated TW is attributed to its lower scattering coefficient or correspondingly lower haze. The attenuation constant resulted from our model hence can serve as a singular material parameter that facilitates cross-comparison of different sample types, at even different thicknesses, when total optical transmittance is concerned. The model was verified with two other TWs (ash and birch) and is in general applicable to other scattering media.

  • 58.
    Chen, Pan
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Terenzi, Camilla
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Berglund, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Wohlert, Jakob
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Molecular dynamics simulation study of moisture effects on chain mobility in hemicellulose-based bio-nanocomposites as observed by 13C CP/MAS NMR relaxometry2017In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 253Article in journal (Other academic)
  • 59.
    Chen, Pan
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Terenzi, Camilla
    Wageningen Univ & Res, Wageningen, Netherlands..
    Furo, Istvan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Berglund, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Wohlert, Jakob
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Heterogeneous dynamics in cellulose from molecular dynamics simulations2019In: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 257Article in journal (Other academic)
  • 60.
    Chen, Pan
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Terenzi, Camilla
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Furo, Istvan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Berglund, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Wohlert, Jakob
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Hydration-Dependent Dynamical Modes in Xyloglucan from Molecular Dynamics Simulation of C-13 NMR Relaxation Times and Their Distributions2018In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 19, no 7, p. 2567-2579Article in journal (Refereed)
    Abstract [en]

    Macromolecular dynamics in biological systems, which play a crucial role for biomolecular function and activity at ambient temperature, depend strongly on moisture content. Yet, a generally accepted quantitative model of hydration-dependent phenomena based on local relaxation and diffusive dynamics of both polymer and its adsorbed water is still missing. In this work, atomistic-scale spatial distributions of motional modes are calculated using molecular dynamics simulations of hydrated xyloglucan (XG). These are shown to reproduce experimental hydration-dependent C-13 NMR longitudinal relaxation times (T-1) at room temperature, and relevant features of their broad distributions, which are indicative of locally heterogeneous polymer reorientational dynamics. At low hydration, the self-diffusion behavior of water shows that water molecules are confined to particular locations in the randomly aggregated XG network while the average polymer segmental mobility remains low. Upon increasing water content, the hydration network becomes mobile and fully accessible for individual water molecules, and the motion of hydrated XG segments becomes faster. Yet, the polymer network retains a heterogeneous gel-like structure even at the highest level of hydration. We show that the observed distribution of relaxations times arises from the spatial heterogeneity of chain mobility that in turn is a result of heterogeneous distribution of water-chain and chain chain interactions. Our findings contribute to the picture of hydration-dependent dynamics in other macromolecules such as proteins, DNA, and synthetic polymers, and hold important implications for the mechanical properties of polysaccharide matrixes in plants and plant-based materials.

  • 61.
    Ciftci, Göksu Cinar
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Larsson, Per
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Riazanova, Anastasia V.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Karppinen, Anni
    Borregaard AS, Sarpsborg, Norway..
    Ovrebo, Hans Henrik
    Borregaard AS, Sarpsborg, Norway..
    Berglund, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Wågberg, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Influence of microfibrillated cellulose fractions on the rheology of water suspensions: Colloidal interactions and viscoelastic properties2018In: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 256Article in journal (Other academic)
  • 62.
    Cobut, Aline
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites.
    Sehaqui, Houssine
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites.
    Berglund, Lars A.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Cellulose Nanocomposites by Melt Compounding of TEMPO-Treated Wood Fibers in Thermoplastic Starch Matrix2014In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 9, no 2, p. 3276-3289Article in journal (Refereed)
    Abstract [en]

    To facilitate melt compounding of cellulose nanofibrils (CNF) based composites, wood pulp fibers were subjected to a chemical treatment whereby the fibers were oxidized using 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO). This treatment introduced negatively charged carboxylate groups to the fibers. TEMPO-treated fibers (TempoF) were added to a mixture of amylopectin starch, glycerol, and water. Granules were prepared from this mixture and processed into CNF composites by extrusion. TempoF were easier to process into composites as compared with non-treated pulp fibers (PF). SEM revealed partial disintegration of TempoF during melt processing. Consequently, TempoF gave composites with much better mechanical properties than those of conventional composites prepared from pulp fibers and TPS. Particularly, at 20 wt% TempoF content in the composite, the modulus and strength were much improved. Such a continuous melt processing route, as an alternative to laboratory solvent casting techniques, may promote large-scale production of CNF-based composites as an environmentally friendly alternative to synthetic plastics/composites.

  • 63.
    Cunha, Ana Gisela
    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.
    Zhou, Qi
    KTH, School of Biotechnology (BIO), Glycoscience. KTH, School of Biotechnology (BIO), Centres, Albanova VinnExcellence Center for Protein Technology, ProNova. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Larsson, Per Tomas
    KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. INNVENTIA AB, Sweden.
    Berglund, Lars A.
    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.
    Topochemical acetylation of cellulose nanopaper structures for biocomposites: mechanisms for reduced water vapour sorption2014In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 21, no 4, p. 2773-2787Article in journal (Refereed)
    Abstract [en]

    Moisture sorption decreases dimensional stability and mechanical properties of polymer matrix biocomposites based on plant fibers. Cellulose nanofiber reinforcement may offer advantages in this respect. Here, wood-based nanofibrillated cellulose (NFC) and bacterial cellulose (BC) nanopaper structures, with different specific surface area (SSA), ranging from 0.03 to 173.3 m(2)/g, were topochemically acetylated and characterized by ATR-FTIR, XRD, solid-state CP/MAS C-13-NMR and moisture sorption studies. Polymer matrix nanocomposites based on NFC were also prepared as demonstrators. The surface degree of substitution (surface-DS) of the acetylated cellulose nanofibers is a key parameter, which increased with increasing SSA. Successful topochemical acetylation was confirmed and significantly reduced the moisture sorption in nanopaper structures, especially at RH = 53 %. BC nanopaper sorbed less moisture than the NFC counterpart, and mechanisms are discussed. Topochemical NFC nanopaper acetylation can be used to prepare moisture-stable nanocellulose biocomposites.

  • 64.
    Cunha, Gisera
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. INRA, Biopolymeres Interact & Assemblages, France.
    Mougel, Jean-Bruno
    Cathala, Bernard
    Berglund, Lars A.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Capron, Isabelle
    Preparation of Double Pickering Emulsions Stabilized by Chemically Tailored Nanocelluloses2014In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 30, no 31, p. 9327-9335Article in journal (Refereed)
    Abstract [en]

    Nanocelluloses are bio-based nanoparticles of interest as stabilizers for oil-in-water (o/w) Pickering emulsions. In this work, the surface chemistry of nanocelluloses of different length, nanofibrillated cellulose (NFC, long) and cellulose nanocrystals (CNC, short), was successfully tailored by chemical modification with lauroyl chloride (C12). The resulting nanofibers were less hydrophilic than the original and able to stabilize water-in-oil (w/o) emulsions. The combination of the two types of nanocelluloses (C12-modified and native) led to new surfactant-free oil-in-water-in-oil (o/w/o) double emulsions stabilized by nanocellulose at both interfaces. Characterization was performed with respect to droplet size distribution, droplet stability over time, and stability after centrifugation. Nanocellulose-based Pickering emulsions can be designed with a substantial degree of control, as demonstrated by the stability of the chemically tailored NFC double emulsions. Furthermore, it was demonstrated that increased nanofiber length leads to increased stability.

  • 65. de Francisco, Raquel
    et al.
    Tiemblo, Pilar
    Hoyos, Mario
    Gonzalez-Arellano, Camino
    Garcia, Nuria
    Berglund, 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.
    Synytska, Alla
    Multipurpose Ultra and Superhydrophobic Surfaces Based on Oligodimethylsiloxane-Modified Nanosilica2014In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 6, no 21, p. 18998-19010Article in journal (Refereed)
    Abstract [en]

    Nonfluorinated hydrophobic surfaces are of interest for reduced cost, toxicity, and environmental problems. Searching for such surfaces together with versatile processing, A200 silica nanoparticles are modified with an oligodimethylsiloxane and used by themselves or with a polymer matrix. The goal of the surface modification is controlled aggregate size and stable suspensions. Characterization is done by NMR, microanalysis, nitrogen adsorption, and dynamic light scattering. The feasibility of the concept is then demonstrated. The silica aggregates are sprayed in a scalable process to form ultrahydrophobic and imperceptible coatings with surface topographies of controlled nanoscale roughness onto different supports, including nanofibrillated cellulose. To improve adhesion and wear properties, the organosilica was mixed with polymers. The resulting composite coatings are characterized by FE-SEM, AFM, and contact angle measurements. Depending on the nature of the polymer, different functionalities can be developed. Poly(methyl methacrylate) leads to almost superhydrophobic and highly transparent coatings. Composites based on commercial acrylic car paint show "pearl-bouncing" droplet behavior. A light-emitting polyfluorene is synthesized to prepare luminescent and water repellent coatings on different supports. The interactions between polymers and the organosilica influence coating roughness and are critical for wetting behavior. In summary, the feasibility of a facile, rapid, and fluorine-free hydrophobization concept was successfully demonstrated in multipurpose antiwetting applications.

  • 66.
    Djahed, Cyrus
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Berglund, Lars A.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Wohlert, Jakob
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Molecular scale deformation mechanisms in cellulose crystals (I and II) by molecular dynamics - synergy between covalent and hydrogen bondsManuscript (preprint) (Other academic)
  • 67. Djahedi, Cyrus
    et al.
    Bergenstrahle-Wohlert, Malin
    Berglund, Lars A.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Wohlert, Jakob
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Role of hydrogen bonding in cellulose deformation: the leverage effect analyzed by molecular modeling2016In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 23, no 4, p. 2315-2323Article in journal (Refereed)
  • 68.
    Djahedi, Cyrus
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Berglund, Lars A.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Wohlert, Jakob
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Molecular deformation mechanisms in cellulose allomorphs and the role of hydrogen bondsManuscript (preprint) (Other academic)
  • 69.
    Djahedi, Cyrus
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Berglund, Lars
    KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Wohlert, Jakob
    KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Molecular deformation mechanisms in cellulose allomorphs and the role of hydrogen bonds2015In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 130, p. 175-182Article in journal (Refereed)
    Abstract [en]

    Differences in tensile properties between cellulose crystal allomorphs cannot be rationalized by simply counting hydrogen bonds. From molecular dynamics computer simulations the cooperative nature of energy contributions to axial cellulose crystal modulus becomes apparent. Using a decomposition of inter and intrarnolecular forces as a function of tensile strain, the three allomorphs show dramatic differences in terms of how the contributions to elastic energy are distributed between covalent bonds, angles, dihedrals, electrostatic forces, dispersion and steric forces.

  • 70. Donius, Amalie E.
    et al.
    Liu, Andong
    KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Berglund, Lars A.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Wegst, Ulrike G. K.
    Superior mechanical performance of highly porous, anisotropic nanocellulose-montmorillonite aerogels prepared by freeze casting2014In: Journal of The Mechanical Behavior of Biomedical Materials, ISSN 1751-6161, E-ISSN 1878-0180, Vol. 37, p. 88-99Article in journal (Refereed)
    Abstract [en]

    Directionally solidified nanofibrillated cellulose (NFC)-sodium-montmorillonite (MMT) composite aerogels with a honeycomb-like pore structure were compared with non-directionally frozen aerogels with equiaxed pore structure and identical composition and found to have superior functionalities. To explore structure-property correlations, three different aerogel compositions of 3 wt% MMT, and 0.4 wt%, 0.8 wt%, and 1.2 wt% NFC, respectively, were tested. Young's modulus, compressive strength and toughness were found to increase with increasing NFC content for both architectures. The modulus increased from 25.8 kPa to 386 kPa for the isotropic and from 2,13 MPa to 3.86 MPa for the anisotropic aerogels, the compressive yield strength increased from 3.3 kPa to 18.0 kPa for the isotropic and from 32.3 kPa to 52.5 kPa for the anisotropic aerogels, and the toughness increased from 6.3 kJ/m(3) to 24.1 kJ/m(3) for the isotropic and from 22.9 kJ/m(3) to 46.2 kJ/m(3) for the anisotropic aerogels. The great range of properties, which can be achieved through compositional as well as architectural variations, makes these aerogels highly attractive for a large range of applications, for which either a specific composition, or a particular pore morphology, or both are required. Finally, because NFC is flammable, gasification experiments were performed, which revealed that the inclusion of MMT increased the heat endurance and shape retention functions of the aerogels dramatically up to 800 degrees C while the mechanical properties were retained up to 300 degrees C.

  • 71.
    Dvinskikh, Sergey V.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Physical Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Industrial NMR Centre.
    Henriksson, Marielle
    KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites.
    Berglund, Lars A.
    KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites.
    Furó, István
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Physical Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Industrial NMR Centre.
    A multinuclear magnetic resonance imaging (MRI) study of wood with adsorbed water: Estimating bound water concentration and local wood density2011In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 65, no 1, p. 103-107Article in journal (Refereed)
    Abstract [en]

    The interaction between moisture and the macromolecular wood tissue is of critical importance to wood properties. In this context, magnetic resonance imaging (MRI) is very promising as this method could deliver molecular information on the submillimeter scale (i.e., along concentration gradients) about both free and adsorbed water and the cell wall polymers. In the present study, it is demonstrated for the first time that wood containing adsorbed heavy water ((H2O)-H-2) can be studied by MRI based on separated images due to water (H-2 MRI) and cell wall polymers (H-1 MRI). Data confirm that in specimens equilibrated at controlled humidity there is a direct correlation between bound water content and relative density of the polymers in wood tissue; there is a strong variation across annual rings.

  • 72. Eichhorn, S. J.
    et al.
    Dufresne, A.
    Aranguren, M.
    Marcovich, N. E.
    Capadona, J. R.
    Rowan, S. J.
    Weder, C.
    Thielemans, W.
    Roman, M.
    Renneckar, S.
    Gindl, W.
    Veigel, S.
    Keckes, J.
    Yano, H.
    Abe, K.
    Nogi, M.
    Nakagaito, A. N.
    Mangalam, A.
    Simonsen, J.
    Benight, A. S.
    Bismarck, A.
    Berglund, Lars A.
    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.
    Peijs, T.
    Review: current international research into cellulose nanofibres and nanocomposites2010In: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 45, no 1, p. 1-33Article, review/survey (Refereed)
    Abstract [en]

    This paper provides an overview of recent progress made in the area of cellulose nanofibre-based nanocomposites. An introduction into the methods used to isolate cellulose nanofibres (nanowhiskers, nanofibrils) is given, with details of their structure. Following this, the article is split into sections dealing with processing and characterisation of cellulose nanocomposites and new developments in the area, with particular emphasis on applications. The types of cellulose nanofibres covered are those extracted from plants by acid hydrolysis (nanowhiskers), mechanical treatment and those that occur naturally (tunicate nanowhiskers) or under culturing conditions (bacterial cellulose nanofibrils). Research highlighted in the article are the use of cellulose nanowhiskers for shape memory nanocomposites, analysis of the interfacial properties of cellulose nanowhisker and nanofibril-based composites using Raman spectroscopy, switchable interfaces that mimic sea cucumbers, polymerisation from the surface of cellulose nanowhiskers by atom transfer radical polymerisation and ring opening polymerisation, and methods to analyse the dispersion of nanowhiskers. The applications and new advances covered in this review are the use of cellulose nanofibres to reinforce adhesives, to make optically transparent paper for electronic displays, to create DNA-hybrid materials, to generate hierarchical composites and for use in foams, aerogels and starch nanocomposites and the use of all-cellulose nanocomposites for enhanced coupling between matrix and fibre. A comprehensive coverage of the literature is given and some suggestions on where the field is likely to advance in the future are discussed.

  • 73. Emami, N.
    et al.
    Soderholm, K. J. M.
    Berglund, Lars A.
    Effect of light power density variations on bulk curing properties of dental composites2003In: Journal of Dentistry, ISSN 0300-5712, E-ISSN 1879-176X, Vol. 31, no 3, p. 189-196Article in journal (Refereed)
    Abstract [en]

    Objective. The hypothesis that low light intensity and long but sufficient curing time can produce composites with volumetric shrinkage, degree of conversion (DC%) and Young's modulus (E-modulus) comparable to those of high light intensity cured composite was tested, when the contraction strain and heat generation were lower with Low Light intensity curing. Methods. Dental composites (Z100 and Z250, 3M ESPE) were investigated. Specimens were cured with Light intensities of 200, 450 and 800 mW/cm(2) for 140, 60 and 35 s from a distance of 7 mm. Strain-gages were used for contraction strain measurements. DC% was measured at the top and the bottom of 4 mm thick samples using FT-Raman spectroscopy. Volumetric polymerization shrinkage was determined using a water displacement method. E-modulus was determined in tension on composite specimens. Results. The results were analyzed using ANOVA and Duncan's multiple range tests and regular t-test. Polymerization stress Level decreased significantly (p < 0.05) when cured with 200 mW/cm(2) rather than with 800 mW/cm(2). Temperature rises were significantly different (p < 0.05) for different composites and light intensity values. Reduction in light intensity did not decrease the DC% values significantly at the top surfaces. The most dramatic differences existed between top and bottom surfaces (p < 0.05) rather than among curing groups. Measured E-modulus and volumetric shrinkage values were not significantly different (p > 0.05) between different light intensity groups. Conclusion. DC%, E-modulus and the volumetric shrinkage values in cured composites were not affected by low Light intensity, however, the contraction strain and polymerization's exotherm were decreased. Thus our results support the proposed hypothesis. Published by Elsevier Science Ltd.

  • 74.
    Ezekiel Mushi, Ngesa
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites.
    Butchosa, Núria
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites.
    Zhou, Qi
    KTH, School of Biotechnology (BIO), Glycoscience. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Berglund, Lars A.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Nanopaper membranes from chitin-protein composite nanofibers: Structure and mechanical properties2014In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 131, no 7, p. 40121-Article in journal (Refereed)
    Abstract [en]

    Chitin nanofibers may be of interest as a component for nanocomposites. Composite nanofibers are therefore isolated from crab shells in order to characterize structure and analyze property potential. The mechanical properties of the porous nanopaper structures are much superior to regenerated chitin membranes. The nanofiber filtration-processing route is much more environmentally friendly than for regenerated chitin. Minerals and extractives are removed using HCl and ethanol, respectively, followed by mild NaOH treatment and mechanical homogenization to maintain chitin-protein structure in the nanofibers produced. Atomic force microscope (AFM) and scanning transmission electron microscope (STEM) reveal the structure of chitin-protein composite nanofibers. The presence of protein is confirmed by colorimetric method. Porous nanopaper membranes are prepared by simple filtration in such a way that different nanofiber volume fractions are obtained: 43%, 52%, 68%, and 78%. Moisture sorption isotherms, structural properties, and mechanical properties of membranes are measured and analyzed. The current material is environmentally friendly, the techniques employed for both individualization and membrane preparation are simple and green, and the results are of interest for development of nanomaterials and biocomposites.

  • 75.
    Ezekiel Mushi, Ngesa
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites.
    Joby Kochumalayil, Jose
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites.
    Cervin, Nicholas
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites.
    Zhou, Qi
    KTH, School of Biotechnology (BIO), Glycoscience. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Berglund, Lars A.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Nanostructured hydrogel based on small diameter native chitin nanofibers: Preparation, structure and propertiesManuscript (preprint) (Other academic)
  • 76.
    Ezekiel Mushi, Ngesa
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites.
    Nurani, Ghasem
    KTH, School of Biotechnology (BIO), Glycoscience.
    Utsel, Simon
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites.
    Brumer, Harry
    KTH, School of Biotechnology (BIO), Glycoscience.
    Zhou, Qi
    KTH, School of Biotechnology (BIO), Glycoscience. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Berglund, Lars A.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Soft, bio-inspired chitin/protein nanocomposites: mechanical behavior and interface interactions between recombinant resilin-like proteins and chitin nanofibersManuscript (preprint) (Other academic)
  • 77.
    Ezekiel Mushi, Ngesa
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites.
    Utsel, Simon
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites.
    Berglund, Lars A.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Nanostructured biocomposite films of high toughness based on native chitin nanofibers and chitosan2015In: Frontiers in Chemistry, E-ISSN 2296-2646, Vol. 18, no 2, article id 99Article in journal (Refereed)
    Abstract [en]

    Chitosan is widely used in films for packaging applications. Chitosan reinforcement by stiff particles or fibers is usually obtained at the expense of lowered ductility and toughness. Here, chitosan film reinforcement by a new type of native chitin nanofibers is reported. Films are prepared by casting from colloidal suspensions of chitin in dissolved chitosan. The nanocomposite films are chitin nanofiber networks in chitosan matrix. Characterization is carried out by dynamic light scattering, quartz crystal microbalance, field emission scanning electron microscopy, tensile tests and dynamic mechanical analysis. The nanostructured biocomposite was produced in volume fractions of 0, 8, 22 and 56% chitin nanofibers. Favorable chitin-chitosan synergy for colloidal dispersion is demonstrated. Also, lowered moisture sorption is observed for the composites, probably due to the favorable chitin-chitosan interface. The highest toughness (area under stress-strain curve) was observed at 8 vol% chitin content. The toughening mechanisms and the need for well-dispersed chitin nanofibers is discussed. Finally, desired structural characteristics of ductile chitin biocomposites are discussed.

  • 78. Fernandes, Susana C. M.
    et al.
    Freire, Carmen S. R.
    Silvestre, Armando J. D.
    Pascoal Neto, Carlos
    Gandini, Alessandro
    Berglund, Lars A.
    KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites.
    Salmén, Lennart
    Transparent chitosan films reinforced with a high content of nanofibrillated cellulose2010In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 81, no 2, p. 394-401Article in journal (Refereed)
    Abstract [en]

    This paper reports the preparation and characterization of nanocomposite films based on different chitosan matrices and nanofibrillated cellulose (NFC) for the purpose of improving strength properties. The nanocomposite films were prepared by a simple procedure of casting a water-based suspension of chitosan and NFC, and were characterized by several techniques: namely SEM, X-ray diffraction, visible spectrophotometry, TGA, tensile and dynamic-mechanical analysis. The films obtained were shown to be highly transparent (transmittance varying between 90 and 20% depending on the type of chitosan and NFC content), flexible, displayed better mechanical properties, with a maximum increment on the Young's modulus of 78% and 150% for high molecular weight (HCH) and water-soluble high molecular weight (WSHCH) filled chitosans, respectively; and of 200% and 320% for low molecular weight (LCH) and water-soluble filled (WSLCH) chitosans, respectively. The filled films also showed increased thermal stability, with, for example, an increase in the initial degradation temperature (Td(i)) from 227 degrees C in the unfilled LCH film up to 271 degrees C in filled LCHNFC50% nanocomposite films, and a maximum degradation temperature (Tdi) raising from 304 degrees C to 313 degrees C for the same materials.

  • 79. Fernberg, S. P.
    et al.
    Berglund, Lars A.
    Bridging law and toughness characterisation of CSM and SMC composites2001In: Composites Science And Technology, ISSN 0266-3538, E-ISSN 1879-1050, Vol. 61, no 16, p. 2445-2454Article in journal (Refereed)
    Abstract [en]

    This work presents an experimental investigation of the fracture properties of three different short-fiber-reinforced composites [one chopped strand mat (CSM) and two sheet molding compound (SMC) materials]. Fracture tests are performed on double-cantilever beam (DCB) specimens loaded with pure bending moments. In this experimental configuration, the bridging law for the material can be derived directly from measurements. No significant dependency on specimen height was observed in our results. The bridging laws determined can, therefore, be considered as material properties. The coupling between microstructure and fracture behaviour is discussed through the measured bridging laws. The beneficial effect (in terms of fracture energy) of increasing tendency for pull-out is confirmed for one SMC, referred to as Flex-SMC, which shows remarkably high fracture energy, J(c) = 56.0 kJ/ml, compared to a standard SMC, termed Std-SMC, J(c)= 25.9 kJ/m(2). This increasing tendency for pull-out is observed to shift the bridging law towards larger crack openings. On the basis of our observations we find the concept of characterising the failure behaviour in terms of bridging laws attractive since it can be used as a tool for the tailoring of the microstructure towards desired fracture behaviour.

  • 80. Fernberg, S. P.
    et al.
    Berglund, Lars A.
    Effects of glass fiber size composition (film-former type) on transverse cracking in cross-ply laminates2000In: Composites. Part A, Applied science and manufacturing, ISSN 1359-835X, E-ISSN 1878-5840, Vol. 31, no 10, p. 1083-1090Article in journal (Refereed)
    Abstract [en]

    Transverse cracking is an important phenomenon in the context of fluid leakage in pipes and pressure vessels. Multiple transverse cracking in [0/90](S) glass-fiber-reinforced vinylester and epoxy laminates with six different fiber surface treatments (size) is examined. Film-former composition is the variable since this component can be easily changed also in commercial size formulations. The influence of the film-former polymer on transverse cracking is significant in epoxy laminates and very strong in vinylester laminates. Both onset of transverse cracking and slope of crack density vs, strain are influenced. Remarkably low crack densities were observed in some vinylester laminates. Micromechanisms of cracking are interpreted. Correlation is established between transverse cracking behavior and interfacial shear strength measured by single fragmentation tests. The strong film-former effect is proposed to be due to a combination of improved interfacial adhesion and the plasticizing effect from the film-former on the interphase region.

  • 81. Fortunati, E.
    et al.
    Armentano, I.
    Zhou, Qi
    KTH, School of Biotechnology (BIO), Glycoscience.
    Iannoni, A.
    Saino, E.
    Visai, L.
    Berglund, Lars A.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites.
    Kenny, J. M.
    Multifunctional bionanocomposite films of poly(lactic acid), cellulose nanocrystals and silver nanoparticles2012In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 87, no 2, p. 1596-1605Article in journal (Refereed)
    Abstract [en]

    Nanocomposite films were prepared by the addition of cellulose nanocrystals (CNCs) eventually surfactant modified (s-CNC) and silver (Ag) nanoparticles in the polylactic acid (PLA) matrix using melt extrusion followed by a film formation process. Multifunctional composite materials were investigated in terms of morphological, mechanical, thermal and antibacterial response. The nanocomposite films maintained the transparency properties of the PLA matrix. Thermal analysis showed increased values of crystallinity in the nanocomposites, more evident in the s-CNC based formulations that had the highest tensile Young modulus. The presence of surfactant favoured the dispersion of cellulose nanocrystals in the polymer matrix and the nucleation effect was remarkably enhanced. Moreover, an antibacterial activity against Staphylococcus aureus and Escherichia coil cells was detected for ternary systems, suggesting that these novel nanocomposites may offer good perspectives for food packaging applications which require an antibacterial effect constant over time. (C) 2011 Elsevier Ltd. All rights reserved.

  • 82. Fortunati, E.
    et al.
    Armentano, I.
    Zhou, Qi
    KTH, School of Biotechnology (BIO), Glycoscience. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Puglia, D.
    Terenzi, A.
    Berglund, Lars A.
    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.
    Kenny, J. M.
    Microstructure and nonisothermal cold crystallization of PLA composites based on silver nanoparticles and nanocrystalline cellulose2012In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 97, no 10, p. 2027-2036Article in journal (Refereed)
    Abstract [en]

    Poly(lactic acid) (PIA) based high performance nanocomposites, were prepared using an innovative combination of nanocrystalline cellulose and silver nanoparticles. Binary and ternary systems were prepared by solvent casting process and their morphological, mechanical and thermal responses were investigated. Pristine (CNC) and surfactant modified cellulose nanocrystals (s-CNC) and silver (Ag) nanoparticles were used, and the effect of cellulose crystal nano-dimension, cellulose modification, and the combination of cellulose nanostructures with silver nanoparticles, was investigated. The important industrial problem of slow crystallization of PIA was addressed by the use of cellulose nanocrystals as biobased nucleating agents and the nonisothermal cold crystallization behaviour of reinforced binary and ternary systems was studied. The presence of surfactant on the nanocrystal surface favoured the dispersion of CNC in the PLA matrix while the thermal investigations and the nonisothermal crystallization studies underlined the ability of s-CNC to act as nucleation agent in both binary and ternary nanocomposites.

  • 83.
    Fu, Qiliang
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Berglund, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Hierarchically structured nanoporous template based on balsa wood2016In: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 251Article in journal (Other academic)
  • 84.
    Fu, Qiliang
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Berglund, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Honeycomb like templates prepared from balsa wood2015In: ICCM International Conferences on Composite Materials, International Committee on Composite Materials , 2015Conference paper (Refereed)
    Abstract [en]

    In the current study, we have used sodium chlorite and sodium hydroxide as extraction solutions, to remove lignin and hemicelluloses from the Balsa (Ochroma Lagopus) wood tissues, without damaging the wood honeycomb architecture. Surface morphologies are studied using scanning electron microscopy (SEM). In addition, sugars analysis of the chemically extracted wood is reported. 

  • 85. Gabilondo, Nagore
    et al.
    Martin, Loli
    Retegi, Alona
    Mondragon, Inaki
    Berglund, Lars A.
    KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Property tailoring of phenol-formaldehyde matrices by control of reactant molar ratio and thermoplastic modification2011In: Polymer international, ISSN 0959-8103, E-ISSN 1097-0126, Vol. 60, no 5, p. 851-858Article in journal (Refereed)
    Abstract [en]

    High modulus, strength and thermal stability make phenol-formaldehyde resins (PFRs) interesting as matrices for nanocomposites. Four PFR matrices synthesized with different formaldehyde (F) to phenol (P) molar ratios were investigated, as well as the influence of thermoplastic modification on their mechanical properties. The effectiveness of a specific curing cycle for obtaining macrovoid- and microvoid-free specimens by controlling the thickness of samples is demonstrated. Fourier transform infrared spectroscopy results reveal that F content increases the presence of oxidized linkages as benzophenones and fully substituted aromatic structures. PFR matrices with highest F content present the highest values of main transition temperature and flexural modulus up to an F/P ratio of 1.8, revealing the achievement of a densely crosslinked and rigid structure. A selected PFR matrix was modified with 5, 10 and 15 wt% of two poly(vinyl butyral) (PVB) thermoplastics of differing molecular weight. Phase separation occurs before gelation in all cases leading to different morphologies, observed using atomic force microscopy and optical microscopy, depending on PVB content: PVB-rich particles in PFR-richmatrix for 5 wt% and co-continuous dual morphology for 10 and 15 wt% for both PVBs. Strength improvement is achieved for PFR matrices modified with 5 wt% of PVB associated with a tailored particulate morphology with a particle size of around 1.2 mu m. Finally, 5 and 10 wt% PVB-modified PFR materials exhibit a very high thermal stability with degradation temperatures very close to those for neat PFR matrix.

  • 86.
    Galland, Sylvain
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Andersson, Richard L.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Ström, Valter
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Engineering Material Physics.
    Olsson, Richard
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Berglund, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites.
    Strong and Moldable Cellulose Magnets with High Ferrite Nanoparticle Content2014In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 6, no 22, p. 20524-20534Article in journal (Refereed)
    Abstract [en]

    A major limitation in the development of highly functional hybrid nanocomposites is brittleness and low tensile strength at high inorganic nanoparticle content. Herein, cellulose nanofibers were extracted from wood and individually decorated with cobalt-ferrite nanoparticles and then for the first time molded at low temperature (<120 degrees C) into magnetic nanocomposites with up to 93 wt % inorganic content. The material structure was characterized by TEM and FE-SEM and mechanically tested as compression molded samples. The obtained porous magnetic sheets were further impregnated with a thermosetting epoxy resin, which improved the load-bearing functions of ferrite and cellulose material. A nanocomposite with 70 wt % ferrite, 20 wt % cellulose nanofibers, and 10 wt % epoxy showed a modulus of 12.6 GPa, a tensile strength of 97 MPa, and a strain at failure of ca. 4%. Magnetic characterization was performed in a vibrating sample magnetometer, which showed that the coercivity was unaffected and that the saturation magnetization was in proportion with the ferrite content. The used ferrite, CoFe2O4 is a magnetically hard material, demonstrated by that the composite material behaved as a traditional permanent magnet. The presented processing route is easily adaptable to prepare millimeter-thick and moldable magnetic objects. This suggests that the processing method has the potential to be scaled-up for industrial use for the preparation of a new subcategory of magnetic, low-cost, and moldable objects based on cellulose nanofibers.

  • 87.
    Galland, Sylvain
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Andersson, Richard
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Salajkova, Michaela
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Ström, Valter
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Engineering Material Physics.
    Olsson, Richard
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Berglund, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Cellulose nanofibers decorated with magnetic nanoparticles: synthesis, structure and use in magnetized high toughness membranes for a prototype loudspeaker2013In: Journal of Materials Chemistry C, ISSN 2050-7526, Vol. 1, no 47, p. 7963-7972Article in journal (Refereed)
    Abstract [en]

    Magnetic nanoparticles are the functional component for magnetic membranes, but they are difficult to disperse and process into tough membranes. Here, cellulose nanofibers are decorated with magnetic ferrite nanoparticles formed in situ which ensures a uniform particle distribution, thereby avoiding the traditional mixing stage with the potential risk of particle agglomeration. The attachment of the particles to the nanofibrils is achieved via aqueous in situ hydrolysis of metal precursors onto the fibrils at temperatures below 100 °C. Metal adsorption and precursor quantification were carried out using Induction Coupled Plasma-Optical Emission Spectroscopy (ICP-OES). FE-SEM was used for high resolution characterization of the decorated nanofibers and hybrid membranes, and TEM was used for nanoparticle size distribution studies. The decorated nanofibers form a hydrocolloid. Large (200 mm diameter) hybrid cellulose/ferrite membranes were prepared by simple filtration and drying of the colloidal suspension. The low-density, flexible and permanently magnetized membranes contain as much as 60 wt% uniformly dispersed nanoparticles (thermogravimetric analysis data). Hysteresis magnetization was measured by a Vibrating Sample Magnetometer; the inorganic phase was characterized by XRD. Membrane mechanical properties were measured in uniaxial tension. An ultrathin prototype loudspeaker was made and its acoustic performance in terms of output sound pressure was characterized. A full spectrum of audible frequencies was resolved.

  • 88.
    Galland, Sylvain
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites.
    Leterrier, Y.
    Nardi, T.
    Plummer, C.J.G.
    Månsson, A. E.
    Berglund, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites.
    UV-cured cellulose nanofiber composites with moisture durable oxygen barrier propertiesManuscript (preprint) (Other academic)
  • 89.
    Galland, Sylvain
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Leterrier, Yves
    Nardi, Tommaso
    Plummer, Christopher J. G.
    Manson, Jan Anders E.
    Berglund, Lars A.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    UV-Cured Cellulose Nanofiber Composites with Moisture Durable Oxygen Barrier Properties2014In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 131, no 16, p. 40604-Article in journal (Refereed)
    Abstract [en]

    Nanocomposites based on 10 to 60 vol % cellulose nanofibers (NFC) in a photopolymerizable hyperbranched acrylate matrix were prepared. Unmodified NFC and NFC chemically modified with a silane coupling agent and with ceric ammonium nitrate for direct polymer grafting from the cellulose surface were used. A homogeneous dispersion of NFC in the matrix was obtained in each case, leading to a marked improvement in oxygen barrier (up to nine times) and thermomechanical properties (storage modulus increased up to seven times). The mechanisms involved in the permeability reduction were investigated, revealing non-monotonic trends in the evolution of the solubility and diffusion coefficients with NFC content. Most significantly, the inherent moisture sensitivity of the oxygen permeability of the NFC was found to be drastically reduced when it was dispersed in the polymer matrix, particularly after chemical modification, underlining the promise of the present approach for the production of robust, high barrier organic films.

  • 90.
    Galland, Sylvain
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites.
    Olsson, Richard T.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Ström, Valter
    Berglund, Lars A.
    KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites.
    Cellulose nanofibrils decorated by inorganic nanoparticles and used in magnetic nanocomposite membranes of high toughnessManuscript (preprint) (Other academic)
  • 91.
    Galland, Sylvian
    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.
    Berthold, Fredrik
    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. Innventia AB, Sweden.
    Prakobna, Kasinee
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Berglund, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Holocellulose nanofibers of high molar mass and small diameter for high-strength nanopaper2015In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 16, no 8, p. 2427-2435Article in journal (Refereed)
    Abstract [en]

    Wood cellulose nanofibers (CNFs) based on bleached pulp are different from the cellulose microfibrils in the plant cell wall in terms of larger diameter, lower cellulose molar mass, and modified cellulose topochemistry. Also, CNF isolation often requires high-energy mechanical disintegration. Here, a new type of CNFs is reported based on a mild peracetic acid delignification process for spruce and aspen fibers, followed by low-energy mechanical disintegration. Resulting CNFs are characterized with respect to geometry (AFM, TEM), molar mass (SEC), and polysaccharide composition. Cellulose nanopaper films are prepared by filtration and characterized by UV-vis spectrometry for optical transparency and uniaxial tensile tests. These CNFs are unique in terms of high molar mass and cellulose-hemicellulose core-shell structure. Furthermore, the corresponding nanopaper structures exhibit exceptionally high optical transparency and the highest mechanical properties reported for comparable CNF nanopaper structures.

  • 92.
    Gioia, Claudio
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH Royal Inst Technol, Fibre & Polymer Technol, Stockholm, Sweden..
    Lo Re, Giada
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites. KTH Royal Inst Technol, Fibre & Polymer Technol, Stockholm, Sweden..
    Lawoko, Martin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH Royal Inst Technol, Stockholm, Sweden..
    Berglund, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH Royal Inst Technol, Fibre & Polymer Technol, Stockholm, Sweden..
    Tunable polymer systems containing well-characterized derivatives from lignin2019In: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 257Article in journal (Other academic)
  • 93.
    Gioia, Claudio
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Lo Re, Giada
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Lawoko, Martin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Berglund, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Tunable thermosetting epoxies based on fractionated and well-characterized lignins2018In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126Article in journal (Refereed)
  • 94. Glauser, T.
    et al.
    Hult, Anders
    KTH, Superseded Departments, Polymer Technology.
    Johansson, Mats K. G.
    KTH, Superseded Departments, Polymer Technology.
    Kornmann, X.
    Berglund, Lars A.
    Toughening of electron-beam cured acrylate resins2000In: Macromolecular materials and engineering (Print), ISSN 1438-7492, E-ISSN 1439-2054, Vol. 280, no 08-jul, p. 20-25Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to improve the toughness of EB-cured acrylate thermost resins by using hyperbranched aliphatic polyesters as additives to obtain a liquid-liquid phase-separated resin. The hyperbranched polyester can be considered as a hydroxyl functional scaffold, on which functional groups were reacted by control phase separation and crosslinking. Alkyl chains of different lengths attached to the scaffold controlled phase separation. The amount of crosslinking within the rubbery particle and between the particles and the matrix was set by the percentage of methacrylate groups. A good phase separation was obtained; therefore, T-g decreased only slightly compared to the pure acrylate. The K-IC value of the cured resins was increased by 30%. The phase-separated resins showed stability with time and no significant increase in particle size was noticed after 18 months.

  • 95.
    Hajian, Alireza
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Berglund, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Conductive and strong nanocomposites based on cellulose nanofibrils and carbon nanotubes2015In: ICCM International Conferences on Composite Materials, International Committee on Composite Materials , 2015Conference paper (Refereed)
    Abstract [en]

    Single-wall carbon nanotubes (SWNTs) can be dispersed with the aid of cellulose nanofibrils (CNF) in aqueous medium. The dispersions have high stability and quality that can be utilized into self-assembly of functional composites having high electrical conductivity and strength. The composites were then carefully analyzed in terms of their mechanical and electrical properties as well as dispersion quality. 

  • 96.
    Hajian, Alireza
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Fu, Qiliang
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Berglund, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Recyclable and superelastic aerogels based on carbon nanotubes and carboxymethyl cellulose2018In: Composites Science And Technology, ISSN 0266-3538, E-ISSN 1879-1050, Vol. 159, p. 1-10Article in journal (Refereed)
    Abstract [en]

    Deformation mechanisms are largely unknown for superelastic carbon nanotube (CNT) aerogels, and this hampers materials design efforts. The CNT network in the cell walls is typically crosslinked or connected by a thermoset polymer phase. In order to create a recyclable superelastic aerogel, unmodified single or multi-walled CNTs were dispersed in water by adding to aqueous carboxymethyl cellulose (CMC) solution. Directional freeze-drying was used to form honeycombs with cell walls of random-in-the-plane CNTs in CMC matrix. Cell wall morphology and porosity were studied and related to CNT type and content, as well as elastic or plastic buckling of the cell walls under deformation. CMC acts as a physical crosslinker for the CNTs in a porous cell wall. Aerogel structure and properties were characterized before and after recycling. The conductivity of the composite aerogel with a density of 10 kg/m3, 99% porosity and 50 wt % single-walled CNT exceeds 0.5 S/cm. The potential of these superelastic and conductive aerogels for applications such as mechanoresponsive materials was examined in cyclic conductivity tests at different strains. This opens a new route for recyclable superelastic CNT composite aerogels, avoiding material loss, chemical treatment or addition of other components.

  • 97.
    Hajian, Alireza
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Lindstrom, Stefan
    Linkoping Univ, Div Solid Mech, Dept Management & Engn, Linkoping, Sweden..
    Berglund, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Nanocellulose as dispersant for carbon nanotube suspensions2016In: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 251Article in journal (Other academic)
  • 98.
    Hajian, Alireza
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Wang, Zhen
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
    Berglund, Lars. A
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Hamedi, Mahiar M.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Cellulose Nanopaper with Monolithically Integrated Conductive Micropatterns2019In: Advanced Electronic Materials, ISSN 2199-160X, Vol. 5, no 3, article id 1800924Article in journal (Refereed)
    Abstract [en]

    This work presents a route to fabricate micropatterned conductive structures where the conductors are monolithically integrated with nanocellulose-based paper. To fabricate conductive features, microstructures are patterned on filter papers using wax-printing, followed by vacuum filtration of carbon nanotubes (CNTs) or silver nanowires (AgNWs) dispersed in aqueous cellulose nanofibrils (CNFs). These patterns are then laminated onto a pure CNF substrate (both in gel-state) and dried to form cellulose nanopapers with integrated conductive micropatterns. Resolutions of the conductive features are shown down to 400 µm wide, 250 nm thick, and with conductivity values of 115 ± 5 S cm −1 for the CNF–CNT and 3770 ± 230 S cm −1 for the CNF–AgNW micropatterns. The nanopaper and the conductive patterns both constitute random fibrous networks, and they display similar ductility and swelling behavior in water. Thus, the integrated conductive micropatterns can withstand folding, as well as wetting cycles. This stability of the micropatterns makes them useful in various devices based on nanocellulose substrates. As an example, an electroanalytical nanopaper device that operates in wet conditions is demonstrated.

  • 99.
    Hamedi, Mahiar M.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Hajian, Alireza
    KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Fall, Andreas B.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Håkansson, Karl
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Salajkova, Michaela
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Lundell, Fredrik
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Berglund, Lars A.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Highly Conducting, Strong Nanocomposites Based on Nanocellulose-Assisted Aqueous Dispersions of Single-Wall Carbon Nanotubes2014In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 8, no 3, p. 2467-2476Article in journal (Refereed)
    Abstract [en]

    It is challenging to obtain high-quality dispersions of single-wall nanotubes (SWNTs) in composite matrix materials, in order to reach the full potential of mechanical and electronic properties. The most widely used matrix materials are polymers, and the route to achieving high quality dispersions of SWNT is mainly chemical functionalization of the SWNT. This leads to increased cost, a loss of strength and lower conductivity. In addition full potential of colloidal self-assembly cannot be fully exploited in a polymer matrix. This may limit the possibilities for assembly of highly ordered structural nanocomposites. Here we show that nanofibrillated cellulose (NFC) can act as an excellent aqueous dispersion agent for as-prepared SWNTs, making possible low-cost exfoliation and purification of SWNTs with dispersion limits exceeding 40 wt %. The NFC:SWNT dispersion may also offer a cheap and sustainable alternative for molecular self-assembly of advanced composites. We demonstrate semitransparent conductive films, aerogels and anisotropic microscale fibers with nanoscale composite structure. The NFC:SWNT nanopaper shows increased strength at 3 wt % SWNT, reaching a modulus of 133 GPa, and a strength of 307 MPa. The anisotropic microfiber composites have maximum conductivities above 200 S cm(-1) and current densities reaching 1400 A cm(-2).

  • 100. Hassel, B. I.
    et al.
    Modén, Carl S.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Berard, P.
    Berglund, Lars A.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Single cube apparatus - Shear properties determination and shear strain variation in natural density gradient materials2009In: ICCM-17 17th International Conference on Composite Materials, 2009Conference paper (Refereed)
    Abstract [en]

    Transversal shear of softwoods was studied with the single cube apparatus (SCA). Full field strain data and FEA were used to validate the device. Once a close to pure shear strain region was confirmed, the relationship between shear strain and radial density gradient was obtained; finally an improved FE model was created.

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