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  • 201.
    Edlund, Ulrica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Zhu Ryberg, Yingzhi
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Albertsson, Ann-Christine
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Barrier Films from Renewable Forestry Waste2010In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 11, no 9, p. 2532-2538Article in journal (Refereed)
    Abstract [en]

    Biobased free-standing films and coatings with low oxygen permeability were designed from a wood hydrolysate according to a recovery and formulation procedure that provides added value to wood converting industrial processes. Wood components released to the wastewater in the hydrothermal treatment of spruce wood were recovered and converted to an oligo- and polysaccharide-rich, noncellulosic fraction that was utilized in film formulations in a range of concentrations and compositions. Free-standing smooth and transparent films as well as coatings on thin PET were prepared and characterized with respect to oxygen permeability, tensile properties, structure, and water vapor transmission. With oxygen permeabilities as low as below I cm(3) mu m m(-2) day(-1) kPa(-1) and with adequate mechanical properties, the films and coatings show promising property profiles for renewable packaging applications.

  • 202. Eguees, Itziar
    et al.
    Stepan, Agnes M.
    Eceiza, Arantxa
    Toriz, Guillermo
    Gatenholm, Paul
    Wallenberg Wood Sci Ctr, Gothenburg, Sweden.
    Labidi, Jalel
    Corncob arabinoxylan for new materials2014In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 102, p. 12-20Article in journal (Refereed)
    Abstract [en]

    Corncob agricultural waste was used as a source of arabinoxylan for preparation of films. Three arabinoxylan samples were prepared: crude extract (CCAX), purified by a washing step, and purified by bleaching CCAX. Films prepared with untreated CCAX were water soluble, yellowish in color and had poor mechanical properties. After the purification processes the Young's modulus increased from similar to 293 MPa to similar to 1400-1600 MPa, and strength was improved from similar to 9 MPa to around 53 MPa, while the strain at break was kept at similar to 8% both in untreated and purified CCAX. The contact angle was increased from similar to 21.3 degrees to 67-74 degrees after washing or bleaching CCAX. Acetylation of bleached CCAX showed the highest thermal resistance (325 degrees C), had low T-g (125 degrees C) and a high contact angle (80 degrees), and its films were stronger (strength similar to 67 MPa; Young's modulus similar to 2241 MPa) and more flexible (similar to 13%). These characteristics make purified CCAX a suitable material to be used as a matrix for film applications.

  • 203.
    Eita, Mohamed
    et al.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Wagberg, 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.
    Muhammed, Mamoun
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Thin Films of Zinc Oxide Nanoparticles and Poly(acrylic acid) Fabricated by the Layer-by-Layer Technique: a Facile Platform for Outstanding Properties2012In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 116, no 7, p. 4621-4627Article in journal (Refereed)
    Abstract [en]

    The incorporation of nanoparticles into polyelectrolytes thin films opens the way to a broad range of applications depending on the functionality of the nanoparticles. In this work, thin films of ZnO nanoparticles and poly(acrylic acid) (PAA) were built up using the layer-by-layer technique. The thickness of a 20-bilayer film is about 120 nm with a surface roughness of 22.9 nm as measured by atomic force microscopy (AFM). Thin ZnO/PAA films block UV radiation starting at a wavelength of 361 nm due to absorption by ZnO although the films are highly transparent. Due to their high porosity, these thin films show a broadband antireflection in the visible region, and thus they provide selective opacity in the UV region and enhanced transmittance in the visible region up to the near-infrared region. They are also superhydrophilic due to their high porosity and surface roughness.

  • 204.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Cellulose, cellulose regenerates and derivatives2009Conference paper (Refereed)
  • 205.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Delignification and bleaching of the future pulp mill2002Conference paper (Refereed)
  • 206.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    New Cell. Innovative Biopolymers2006Conference paper (Refereed)
  • 207.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    New Cellulose Derivatives from Wood for High Value Products2007Conference paper (Refereed)
  • 208.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    The Pulp Mill biorefinery2006Conference paper (Refereed)
  • 209.
    Ek, Monica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Engström, Ann-Charlott
    Henriksson, Gunnar
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Increase Reactivity of Dissolving Pulps by different pretreatments2006Conference paper (Refereed)
  • 210.
    Ek, Monica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Engström, Ann-Christine
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Henriksson, Gunnar
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Vehviläinen, M
    Tamperere University.
    Heikkilä, S
    Temperere University.
    Agnemo, Roland
    Domsjö Fabriker.
    Cellulose derivatives: improved accessibility and reactivity2005In: 13th ISWFPC: Vol 2, 2005, p. 121-126Conference paper (Refereed)
  • 211.
    Ek, Monica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Freiholtz, Anna
    Gellerstedt, Göran
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Formation of oxalic acid during bleaching1996Conference paper (Refereed)
  • 212.
    Ek, Monica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Gellerstedt, GöranKTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.Henriksson, GunnarKTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Paper products physics and technology2009Collection (editor) (Refereed)
  • 213.
    Ek, Monica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Gellerstedt, GöranKTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.Henriksson, GunnarKTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Pulping chemistry and technology2009Collection (editor) (Refereed)
    Abstract [en]

    The production of forestry products is based on a complex chain of knowledge in which the biological material wood with all its natural variability is converted into a variety of fiber-based products, each one with its detailed and specific quality requirements. This four volume set covers the entire spectrum of pulp and paper chemistry and technology from starting material to processes and products including market demands. Supported by a grant from the Ljungberg Foundation, the Editors at the Royal Institute of Technology, Stockholm, Sweden coordinated over 30 authors from university and industry to create this comprehensive overview. This work is essential for all students of wood science and a useful reference for those working in the pulp and paper industry or on the chemistry of renewable resources.

  • 214.
    Ek, Monica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Gierer, Josef
    Jansbo, Kerstin
    Study on the Selectivity of Bleaching with Oxygen-Containing Species1989In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 43, no 6, p. 391-396Article in journal (Refereed)
    Abstract [en]

    In the bleaching of pulp, the term Selectivity is widely used but poorly defined.This work is an attempt to quantify the selectivity of bleaching with Oxygen-containing species by generating hydroxil radicals and measuring their reaction rates with some lignin and carbohydrate models. Results of this investigation show that the selectivity factor defined as the ratio of the rate constants for a given pair of lignin and carbohydrate models, lies between 5 and 6.

  • 215.
    Ek, Monica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Gierer, Josef
    Jansbo, Kerstin
    Reitberger, Torbjoern
    Chemiluminescences as a means of observing hydroxyl radicals in bleaching processes.1987In: Proc. 4th int. Symp. Wood Pulp chem., Paris, France, 1987, p. 283-284Conference paper (Refereed)
  • 216.
    Ek, Monica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Gierer, Josef
    Reitberger, Torbjoern
    Hydroxyl radicals in oxygen bleaching1985In: Proc. 3rd Int. Symp. Wood Pulp. Chem., 1985, p. 209-210Conference paper (Refereed)
  • 217.
    Ek, Monica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Gustavsson, Catrin
    Kadiric, Jasmin
    Teder, Ants
    Formation and dissolution/degradation of hexenuronic acids during kraft pulping of Eucalyptus Globulus.2001Conference paper (Refereed)
  • 218.
    Ek, Monica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Ibarra, David
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Köpcke, Viviana
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Larsson, Per Tomas
    Jääskeläinen, Anna-Stiina
    Production of dissolving grade pulps from non-wood paper grade pulps using enzymatic and chemical pre-treatments for the viscose process2010Conference paper (Refereed)
    Abstract [en]

    Cellulose is the most abundant biorenewable material, constitutes an important polymer since it is used as raw material for several products, e.g.  Paper and board but also cellulose-based products which have many important applications in the pharmaceutical, textile, food and paint industries.  A raw material with high cellulose content and low content of hemicelluloses, residual lignin, extractives and minerals is required for the prodn. of these products, e.g.  Cotton and dissolving grade pulp are used.  However, the high cost prodn. of dissolving grade pulps has aroused the possibility of upgrading paper grade pulps into dissolving pulps by selective removal of hemicelluloses and subsequent activation of the pulps.  This study reports the feasibility to produce dissolving grade pulps from different pulps, i.e.  Non-wood paper grade pulps and conventional hardwood kraft pulps, employing enzymic and chem. pretreatments.  A monocomponent endoglucanase and a xylanase followed by alk. extn. were tested in order to increase the accessibility and reactivity of the cellulose pulp and decrease the hemicellulose content, resp.  An optimization of these treatments in terms of enzyme dosage, incubation time and a possible combination of them was investigated.  The treatment effects on reactivity according to Fock's method, viscosity, hemicellulose content and mol. wt. distribution, using size exclusion chromatog. (SEC), were analyzed.  The characterization of cellulose structure after the enzymic and chem. treatments was investigated by different techniques.

  • 219.
    Ek, Monica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Illergård, Josefin
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Biointeractive fibres: A sustainable way of fighting bacteria by using antibacterial cellulosic fibres2010Conference paper (Refereed)
    Abstract [en]

    Bacterial growth is a risk of infection.  Antibiotics did long time seem to be a soln. to the problem, but now the consequences are seen, as antibiotic-resistant strains are evolving.  The substances are also eventually released into the environment, where they often are harmful to living organisms.  Antibacterial surfaces state another option.  However, a majority of the now existing surfaces are of leaching type i.e. assocd. with the same problems as the antibiotics.  The non-leaching are a safer option, but until now the fabrication has been a problem with use of e.g. org. solvents.  We present a sustainable way of forming an antibacterial material onto cellulose by using the polyelectrolyte multilayer technique.  By step-wise adsorbing oppositely charged polyelectrolytes in an aq. soln. contg. fibers, at room-temp., the surface of the fibers are modified.  The result is a non-leaching material with bacteria inhibiting properties.  Also the fabrication is quite safe, as polymers have shown lower toxicity to humans than their monomeric counterparts.  Cellulose is an excellent substrate for antibacterial surfaces.  It is easy to modify with the present technique and is in itself a sustainable materials, with multiple applications.  Combined this gives us in total a new, antibacterial material which also opens up for sustainable cellulose-based products.

  • 220.
    Ek, Monica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    From Cellulose Accessibility to Polymer and Product Properties of Cellulose Derivatives2009Conference paper (Refereed)
  • 221.
    Ek, Monica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Fardim, Pedro
    Maunu, Sirkka Liisa
    University of Helsinki.
    Nousiainen, Pertti
    Siika-Aho5, Matti
    Walkenström, Pernilla
    New cellulose derivatives from wood for high value products2008In: TAPPSA: Technical Association of the Pulp and Paper Industry of Southern Africa, ISSN 1029-0109, no September 2008Article in journal (Refereed)
    Abstract [en]

    Various pre-treatment methods to increase the accessibility of cellulose materials to swelling and reactive agents at different hierarchical levels, has been developed. It was demonstrated that enzymes are very efficient at increasing the cellulose reactivity. A new method to measure the reactivity and accessibility of the hydroxyl groups on cellulose was developed. Reversible addition-fragmentation chain transfer (RAFT) agents were synthesized and used further in esterification reactions with cellulose samples to prepare cellulose based graft-copolymers. MALDI-TOFMS was evaluated for characterization of cellulose derivatives. Methods to prepare electrospun fibres, casings, sponges and beads, were developed with target applications in pharmaceuticals and foods.

  • 222.
    Ek, Monica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Köpcke, Viviana
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Ibarra, David
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Larsson, Per Tomas
    Characterization of dissolving pulps produced from Kraft pulps2009Conference paper (Refereed)
  • 223.
    Ek, Monica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Lennholm, Helena
    A studies on the mechanism of the photo-yellowing of partially acetylated ground wood pulps.1991Conference paper (Refereed)
  • 224.
    Ek, Monica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Lennholm, Helena
    Iversen, Tommy
    A comment on the effect of carbonyl groups on the light-induced reversion of groundwood pulp1990In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 5, no 4, p. 159-160Article in journal (Refereed)
    Abstract [en]

    Sodium borohydride redn. of stone groundwood pulp from spruce (Picea abies) had no dramatic effect on the light-induced brightness reversion.  This indicates that the direct scission of phenacyl aryl ether linkages is not an important step in the initial chromophore formation.

  • 225.
    Ek, Monica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Lennholm, Helena
    Lindblad, Gunnar
    Iversen, Tommy
    A study of the photochromic behaviour of UV-irradiated mechanical pulps.1992In: Proc. 2nd European Workshop Lignocellulosic Pulp (EWLP), 1992, p. 183-186Conference paper (Refereed)
  • 226.
    Ek, Monica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Lennholm, Helena
    Lindblad, Gunnar
    Iversen, Tommy
    The light-induced colour reversion of groundwood pulps1991In: Proc 6th Int. Symp. Wood Pulp Chem., Melbourne, Australia, 1991, p. 439-442Conference paper (Refereed)
  • 227.
    Ek, Monica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Westman, Eva-Helena
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Karlsson, Josefin
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    CELL 28-Biointeractive fibers with antibacterial properties2008In: ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY: Volume: 235, 2008, p. 28-CELL-Conference paper (Refereed)
    Abstract [en]

    Growth of bacteria on various surfaces may cause major concern if encountered in the wrong environment.  The ability to impart antimicrobial properties onto surfaces is therefore desirable.  Modification of both glass surfaces and cellulose membranes using weak polyelectrolytes as antimicrobial agent is presented.  The aim was to incorporate a known carrier of antimicrobial activity into a multilayer structure of adsorbed polyelectolytes at different surfaces and evaluate the antibacterial activities.  The approach involved screening for antimicrobial activity in soln. of modified and unmodified polymers.  The polymers were evaluated against gram-neg. E. coli and gram-pos. B. subtilis. In order to elucidate the mode of action of the polymers, the charge was detd.  This is done since earlier studies have shown that both charge and degree of hydrophobicity are of importance in terms of exerted activity.  Results show that the chosen polymers exert activity in the immobilized state.  Different techniques have been used to evaluate the mechanisms.

  • 228.
    Ek, Monica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Westman, Eva-Helena
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Cellulose films and fibres with antibacterial properties2007Conference paper (Refereed)
  • 229.
    Ekelund, Maria
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Long-term performance of poly(vinyl chloride) cables: mechanical and electrical performances and the effect of plasticizer migration2007Licentiate thesis, comprehensive summary (Other scientific)
    Abstract [en]

    Cables insulated with plasticized poly(vinyl chloride) were aged at temperatures between 80 and 180 °C in air and their conditions were assessed by indenter modulus measurements, tensile testing, infrared (IR) spectroscopy, differential scanning calorimetry (DSC) and liquid chromatography (HPLC). Electrical testing of oven-aged cable samples was performed in order to relate the electrical functionality during a high-energy line break accident to the mechanical properties and to establish a lifetime criterion. The mechanical data taken at room temperature after ageing could be superimposed with regard to ageing time and temperature. The ageing-temperature shift factor showed Arrhenius temperature dependence. The jacketing material showed an immediate increase in stiffness (indenter and Young’s modulus) and a decrease in the strain at break on ageing; these changes were dominated by loss of plasticizer by migration also confirmed by IR spectroscopy, DSC and HPLC. The core insulation showed smaller and also delayed changes in these mechanical parameters; the loss of plasticizer by migration was retarded by the closed environment and the changes in the mechanical parameters were due to chemical degradation (dehydrochlorination). Comparison with data obtained from this study and from other studies indicates that extrapolation of data for the jacketing insulation can be performed according to the Arrhenius equation even down to service temperatures (20-40 °C). Extraction of plasticizer of samples from cables that have been exposed to service for 25 years showed a minor decrease (within the margin of error) in plasticizer content with reference to that of unexposed cable samples. The low temperature deterioration of the jacketing is according to this scheme dominated by loss of plasticizer by migration.

    Numerical analysis were performed on desorption data obtained by liquid chromatography. The fitting of the data to Fick’s law showed a transition between 100 and 120 ºC. This was interpreted as a change from evaporation-control of migration at low temperatures to a diffusion-control of migration at the higher temperatures.

  • 230.
    Ekelund, Maria
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Azhdar, Bruska
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Gedde, Ulf W.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Evaporative loss kinetics of di(2-ethylhexyl)phthalate (DEHP) from pristine DEHP and plasticized PVC2010In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 95, no 9, p. 1789-1793Article in journal (Refereed)
    Abstract [en]

    The migration of di(2-ethylhexyl)phthalate (DEHP) from poly(vinyl chloride) (PVC) to a surrounding gas phase at temperatures below 120 degrees C kinetically is controlled by evaporation. The effects on the DEHP loss rate of nitrogen flow rate, relative humidity and degradation of the plasticizer at 100 degrees C was assessed. The sample mass decreased linearly with time for both pristine DEHP and plasticized PVC at comparable rates, suggesting that a thin film of DEHP was present on the jacketing insulation during desorption. The latter hypothesis was supported by infrared spectroscopy and by the fact that DEHP is an amphiphilic molecule that will tend to aggregate at the surface with the hydrophobic 2-ethylhexyl units at the air interface. The effect on the migration rate of moisture present in the gas phase was negligible. The DEHP loss rate increased in a retarding non-linear fashion with increasing gas flow rate. In one of the experiments, DEHP was accidently degraded as revealed by discoloration, the presence of low molar mass degradation products (liquid chromatography) containing additional carbonyl groups (infrared spectroscopy) and an increase in the evaporation rate at temperatures between 100 and 130 degrees C. (C) 2010 Elsevier Ltd. All rights reserved.

  • 231.
    Ekevåg, Per
    et al.
    KTH, Superseded Departments, Fibre and Polymer Technology.
    Lindström, Tom
    KTH, Superseded Departments, Fibre and Polymer Technology.
    Gellerstedt, Göran
    KTH, Superseded Departments, Fibre and Polymer Technology.
    Lindström, Mikael
    KTH, Superseded Departments, Fibre and Polymer Technology.
    Addition of carboxymethylcellulose to the kraft cook2004In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 19, no 2, p. 200-207Article in journal (Refereed)
    Abstract [en]

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

  • 232. El Ghaoui, Hanane
    et al.
    Raihane, Mustapha
    Rhouta, Benaissa
    Bitinis, Natacha
    Carlmark, Anna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Arroyo, Miguel
    Verdejo, Raquel
    Lopez-Manchado, Miguel A.
    Lahcini, Mohammed
    Bismuth complex catalysts for the in situ preparation of polycaprolactone/silicate bionanocomposites2014In: Polymer international, ISSN 0959-8103, E-ISSN 1097-0126, Vol. 63, no 4, p. 709-717Article in journal (Refereed)
    Abstract [en]

    Solvent-free, bismuth-catalysed in situ polymerization of caprolactone in the presence of layered silicates enables the formulation of a series of polycaprolactone/silicate bionanocomposites. Three organophilic montmorillonites obtained by cationic exchange reaction with tetrabutylammonium iodide, benzyltriethylammonium chloride and vinylbenzyltriphenylphosphonium chloride salts, respectively, were used as reinforcing reagents for these materials. The effects of clay and bismuth catalyst type (bismuth(III) acetate and triphenylbismuth) are discussed on the basis of composite morphologies and molecular weights of resulting polymers.

  • 233. Elsander, Anna
    et al.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Gellerstedt, Göran
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Oxalic acid formation during ECF and TCF bleaching of kraft pulp1997In: Proceedings Minimum Effluent Mills Symposium, 1997, p. 63-66Conference paper (Refereed)
    Abstract [en]

    The formation of oxalic acid (I) during bleaching of softwood kraft pulp was studied.  Bleaching agents used were O, H2O2, ClO2, peracetic acid (II), and O3.  The formation of I acid increased linearly with the decrease in kappa no.  II bleaching gave less I than the other bleaching agents.  In O3 bleaching ∼1/3 of the formed I was adsorbed on the pulp and not released until a later stage.

  • 234.
    Enebro, Jonas
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    New Mass Spectrometric Methods for Structure Analysis of Carboxymethyl Cellulose2008Doctoral thesis, comprehensive summary (Other scientific)
    Abstract [en]

    Carboxymethyl cellulose (CMC) is a cellulose derivative, made from cellulose by introduction of carboxymethyl groups along the molecules. The properties of CMC are affected by several parameters where the molar mass and molar mass distribution, degree of substitution (DS) and the distribution pattern along, and between, the cellulose molecules are the most prominent.

    In the present thesis we have investigated the use of various mass spectrometric techniques, such as matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) and electrospray ionization MS (ESI-MS), for characterization of the chemical structure of CMC. We here present a refined sample preparation procedure for MALDI that greatly facilitates the spectrum acquisition and improves the quality of the mass spectrum when analyzing partially hydrolyzed CMC. The refined method allows for estimation of the DS in CMC samples as a complement to more expensive and laborious methods. We also show that by combining MALDI-TOFMS with selective hydrolysis, by purified endoglucanase, and size-exclusion chromatography (SEC) it is possible to differentiate between CMCs of similar monomer composition but differences in the substitution pattern. Our findings show that the CMC containing longer non-substituted cellulose segments along the polymer backbone also displayed the highest intermolecular interactions in solution, as measured by rheometry.

    In order to take full advantage of the selective hydrolysis, provided by purified endoglucanases, more information regarding their selectivity on CMC must be investigated. We therefore present methods where chemical sample preparation of the oligomeric enzyme products is performed in order to facilitate the chemical structure characterization by ESI-MS/MS and liquid chromatography MS (LC-MS). These methods provides valuable information regarding the substituent distribution along the oligomeric enzyme products, and thereby gives indications regarding the selectivity of the endoglucanases on CMC substrates. From our finding we are able to present interesting information regarding the selectivity of four endoglucanases (Cel7B, Cel5A, Cel45A and Cel74A) from the filamentous fungus Trichoderma reesei and provide plausible explanations to their apparent differences in selectivity on CMC.

  • 235.
    Engström, Joakim
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology.
    Tailored adhesion of PISA-latexes for cellulose modification and new materials2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis is focused on applying modification chemistry to already known cellulosic substrates from wood (i.e. cellulose nanofibrils, CNFs, and cellulose nanocrystals, CNCs). The modification is needed to overcome the drawbacks with the nanocellulosics alone, such as sensitivity to water (hydrophilicity) and the brittle material properties (however great stiffness). The first aim is to incorporate nanocellulosics into hydrophobic degradable materials of poly(ε-caprolactone) (PCL), resulting in aggregation if not modified. The challenge is to reach high fraction of nanocellulosics, whilst maintaining the flexibility of PCL and improving the properties of the resulting nanocomposite with the corresponding stiffness of the nanocellulosics. The second aim is to increase toughness and strain-at-break for nanocomposite materials of CNF-networks, to increase the plastic deformation equivalent of fossil-based polymeric materials such as polypropylene (PP). Aiming to achieve these goals, the thesis also includes new synthetic strategies of tailored-made set of block copolymers as modifying components. The modifying components, were synthesised by surfactant-free emulsion polymerisation and polymerisation induced self-assembly (PISA), so called PISA-latexes.

    Two types of cationic polyelectrolytes, (poly(2-dimethylaminoethy methacrylate) (PDMAEMA) and poly(N-[3-(dimethylamino)propyl] methacrylamide (PDMAPMA)), being the corona of the latex, were synthesised. Followed by chain-extension with different hydrophobic monomers such as methyl methacrylate and butyl methacrylate, making up the core polymer of the resulting PISA-latex. The cationic PISA-latexes show narrow size distributions and the glass transition (Tg) of the core polymer can be varied between -40 °C to 150 °C. The PISA-latexes show strong adhesion to silica and cellulose surfaces as assessed by quartz crystal microbalance (QCM-D). Results also indicate that latexes with Tg below room temperature, considered soft, behave different in the wet state than latexes with Tg above room temperature, considered rigid. The softer latexes form clusters (visualised by imaging with microscopy and atomic force measurements (AFM)) and undergo film formation in the wet state. The latter, shown by colloidal probe measurements using AFM resulting in very large work of adhesion and pull-off forces.

    The PISA-latexes compatibilize CNCs and different CNFs with PCL as a matrix polymer, observed by a small increase in stiffness for the final nanocomposites, however not at a level expected by rule-of-mixtures. The promising wet feeding technique results in large increase in stiffness but maintain PCL’s flexibility, above 200% strain-at-break, which is rarely observed for CNF-reinforced nanocomposites. The, in this case, rigid latex facilitate the dispersion of CNFs in the matrix without aggregation, until finally coalescing after processing and possibly giving rise to improved adhesion between CNF and the latex in the matrix, indicated by rheology measurements. Lastly, new nanocomposite films consisting of 75wt% CNF and 25wt% of PISA-latexes were produced and evaluated. The results show that CNF and rigid 100 nm sized PISA-latex, with PMMA core, gives a very tough double network, with strain-at-break above 28%, stiffness of 3.5 GPa and a strength of 110 MPa. These are impressive properties compared to commonly used fossil-based plastic materials.

    The full text will be freely available from 2020-02-01 15:00
  • 236.
    Engström, Joakim
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Asem, Heba
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology.
    Brismar, Hjalmar
    KTH, Superseded Departments (pre-2005), Physics. KTH, Centres, Science for Life Laboratory, SciLifeLab. KTH, School of Engineering Sciences (SCI), Applied Physics.
    Zhang, Yuning
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Malkoch, Michael
    KTH, Superseded Departments (pre-2005), Fibre and Polymer Technology. KTH, Superseded Departments (pre-2005), Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology.
    Malmström, Eva
    KTH, Superseded Departments (pre-2005), Fibre and Polymer Technology.
    In situ encapsulation of Nile red or Doxorubicinduring RAFT‐mediated emulsion polymerizationvia PISAManuscript (preprint) (Other academic)
  • 237.
    Engström, Joakim
    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, Coating Technology.
    Benselfelt, Tobias
    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, Coating Technology.
    Wågberg, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    D'Agosto, Franck
    Université de Lyon, Univ Lyon 1, CPE Lyon, CNRS UMR 5265, C2P2 (Chemistry, Catalysis, Polymers & Processes), LCPP, 69616 Villeurbanne, France .
    Lansalot, Muriel
    Université de Lyon, Univ Lyon 1, CPE Lyon, CNRS UMR 5265, C2P2 (Chemistry, Catalysis, Polymers & Processes), LCPP, 69616 Villeurbanne, France .
    Carlmark, Anna
    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, Coating Technology. RISE.
    Malmström, Eva
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology.
    Tailoring adhesion of anionic surfaces using cationic PISA-latexes – towards tough nanocellulose materials in the wet state2019In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 11, p. 4287-4302Article in journal (Refereed)
    Abstract [en]

    Cationic latexes with Tgs ranging between −40 °C and 120 °C were synthesised using n-butyl acrylate (BA) and/or methyl methacrylate (MMA) as the core polymers. Reversible addition–fragmentation chain transfer (RAFT) combined with polymerisation-induced self-assembly (PISA) allowed for in situ chain-extension of a cationic macromolecular RAFT agent (macroRAFT) of poly(N-[3-(dimethylamino)propyl] methacrylamide) (PDMAPMA), used as stabiliser in so-called surfactant-free emulsion polymerisation. The resulting narrowly distributed nanosized latexes adsorbed readily onto silica surfaces and to model surfaces of cellulose nanofibrils, as demonstrated by quartz crystal microbalance with dissipation monitoring (QCM-D) measurements. Adsorption to anionic surfaces increased when increasing ionic strength to 10 mM, indicating the influence of the polyelectrolyte effect exerted by the corona. The polyelectrolyte corona affected the interactions in the wet state, the stability of the latex and re-dispersibility after drying. The QCM-D measurements showed that a lower Tg of the core results in a more strongly interacting adsorbed layer at the solid–liquid interface, despite a comparable adsorbed mass, indicating structural differences of the investigated latexes in the wet state. The two latexes with Tg below room temperature (i.e. PBATg-40 and P(BA-co-MMA)Tg3) exhibited film formation in the wet state, as shown by AFM colloidal probe measurements. It was observed that P(BA-co-MMA)Tg3 latex resulted in the largest pull-off force, above 200 m Nm−1 after 120 s in contact. The strongest wet adhesion was achieved with PDMAPMA-stabilized latexes soft enough to allow for interparticle diffusion of polymer chains, and stiff enough to create a strong adhesive joint. Fundamental understanding of interfacial properties of latexes and cellulose enables controlled and predictive strategies to produce strong and tough materials with high nanocellulose content, both in the wet and dry state.

  • 238.
    Engström, Joakim
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Stamm, Arne
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology.
    Tengdelius, Mattias
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology.
    Syrén, Per-Olof
    KTH, Centres, Science for Life Laboratory, SciLifeLab. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology.
    Fogelström, Linda
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology.
    Malmström, Eva
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Cationic latexes of bio‐based hydrophobicmonomer Sobrerol methacrylate (SobMA)Manuscript (preprint) (Other academic)
  • 239.
    Erdal, Nejla
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Hakkarainen, Minna
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology. KTH, Superseded Departments (pre-2005), Fibre and Polymer Technology. KTH, Superseded Departments (pre-2005), Polymer Technology.
    Blomqvist, Anders
    Vetenskapens Hus.
    Polymer, giant molecules with properties: An entertaining activity introducing polymers to young students2019In: Journal of Chemical Education, ISSN 0021-9584, E-ISSN 1938-1328, Vol. 96, no 8, p. 1691-1695Article in journal (Refereed)
    Abstract [en]

    In this activity, polymer materials are introduced to 13–16 year old students. The activity is aimed at students with no or little knowledge of polymers. An engaging lecture covering the basics of polymer technology and sustainable development in the plastics field is presented. Important polymers such as polyethylene (PE), cellulose, and polylactide (PLA) are presented, and examples of their everyday use are shown. Quiz questions are employed in the introductory lecture to engage the students, to start discussions, and to evaluate the learning progress. The students are then engaged in two entertaining activities involving a natural polymer alginate and superabsorbent polymers. Alginate spaghetti is produced using different salt solutions enabling the students to create and destroy materials just by playing around with the chemistry, which helps them understand the polymeric material. The second activity has an application-based approach where the ability of superabsorbent polymers in diapers to retain water is investigated. The overall quiz results and discussions after the activities show an improved understanding of polymers and their applications and properties, making this activity useful for teaching polymers to young students.

  • 240.
    Eriksson, Magnus
    et al.
    KTH, School of Biotechnology (BIO), Biochemistry (closed 20130101).
    Boyer, Antoine
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Sinigoi, Loris
    KTH, School of Biotechnology (BIO), Biochemistry (closed 20130101).
    Johansson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Malmström, Eva
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Hult, Karl
    KTH, School of Biotechnology (BIO), Biochemistry (closed 20130101).
    Trey, Stacy
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Martinelle, Mats
    KTH, School of Biotechnology (BIO), Biochemistry (closed 20130101).
    One-Pot Enzymatic Route to Tetraallyl Ether Functional Oligoesters: Synthesis, UV Curing, and Characterization2010In: Journal of Polymer Science Part A: Polymer Chemistry, ISSN 0887-624X, E-ISSN 1099-0518, Vol. 48, no 23, p. 5289-5297Article in journal (Refereed)
    Abstract [en]

    An enzymatic one-pot route in bulk was used to synthesize tetraallyl ether (tAE) functional oligomers based on divinyl adipate, 1,4-butanediol and trimethylolpropane diallyl ether. By using lipase B from Candida antarctica as catalyst and varying the stoichiometric ratio of monomers, it was possible to reach targeted molecular weights (from 1300 to 3300 g mol(-1)) of allyl-ether functional polyesters. The enzyme catalyzed reaction reached completion (>98% conversion based on all monomers) within 24 h at 60 degrees C, under reduced pressure (72 mbar) resulting in similar to 90% yield after filtration. The tAE-functional oligoesters were photopolymerized, without any purification other than removal of the enzyme by filtration, with thiol functional monomers (dithiol, tetrathiol) in a 1: 1 ratio thiol-ene reaction. The photo-initiator, 2,2-dimethoxy-2-phenylacetophenone, was used to improve the rate of reaction under UV light. High conversions (96-99% within detection limits) were found for all thiol-ene films as determined by FT-Raman spectroscopy. The tAE-functional oligoesters were characterized by NMR, MALDI, and SEC. The UV-cured homopolymerized films and the thiol-ene films properties were characterized utilizing DSC and DMTA.

  • 241.
    Eshete Asrat, Tesfaye
    KTH, School of Chemical Science and Engineering (CHE).
    Functionalization of Biomedical Surfaces:  2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Under this project, functionalization of Poly (L-lactic acid) (PLLA) and Poly (ε-caprolactone) (PCL) substrate surfaces with DL- and L- forms of Asparagine and Cysteine is performed.  Poly (L-lactic acid) (PLLA) and Poly (ε-caprolactone) (PCL) substrate surfaces were prepared by solvent casting method from their corresponding pellets. Vapor phase photo grafting technique is implemented to introduce reactive sites. Acrylic acid is a monomer used in presence of Benzophenone initiator. Coupling of DL- and L- forms Asparagine and Cysteine were performed at different reaction conditions. Grafted and coupled surfaces were analyzed for the change in surface chemical composition. Different surface analysis techniques were applied to verify the change in surface properties relative to the bare substrate surfaces. ATR-FTIR was extensively used to analysis functional groups from grafted and coupled surfaces. A change in absorption bands is observed from functionalized surfaces. A reduction in contact angle from ~72° to ~45° for PLLA surfaces and from ~89° to ~55° for PCL surfaces is obtained. The specimens have been sent to department of materials chemistry, Uppsala University, Sweden for XPS analysis and the results are pending. Based on the results obtained from performed tests, functionalization of the substrate surfaces with DL- and L- forms of Asparagine and Cysteine is made possible.

  • 242.
    Fagerland, Jenny
    KTH, School of Chemical Science and Engineering (CHE).
    Identification of Swelling cause on Rubber Gaskets2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The aim of this master thesis was to develop an analysis method which identifies the swelling cause of EPDM rubber gaskets. The method shall facilitate failure investigation of rubber gaskets used in plate heat exchangers which require both determinations of volatile and involatile compounds as well as polar and non-polar compounds. To achieve this goal a combination analysis method of Headspace Gas chromatography Mass spectrometry (GC-MS) and liquid-liquid extraction Fourier Transform Infrared spectroscopy (FT-IR) was chosen. Three extraction fluids were tested to extract the compounds from the EPDM rubber: tetrahydrofuran, 2-propanol and supercritical carbon dioxide. The analysis method was first tested on EPDM rubber samples swelled in four known solvents with different volatility and polarity (hexane, acetic acid, 1-octanol and pentadecane). Then it was tested on EPDM rubber samples swelled in three different mixtures of these four solvents and finally on two EPDM gaskets, swelled by unknown media, that were being assessed in an actual failure investigations.

    The analysis method was successful in identifying compounds which caused EPDM rubber gaskets to swell but not in a way as it was supposed to. The FT-IR analysis could not be used to identify compounds in a mixture because the spectra of mixtures are very difficult to analyze. However the FT-IR results complimented the results from the GC-MS analysis which due to a poor search database was not good enough to determine the exact composition of the swelling agents by itself. The liquid extraction also gave useful information about how much swelling agents that were absorbed by the EPDM gasket. Tetrahydrofuran and 2-propanol were the most effective for extraction of the solvents. However, supercritical carbon dioxide was very good for selective extraction of non-polar compounds.

    The method detected both polar and non-polar compounds but non-polar compounds with low boiling point were not detected. It did not interact strongly enough with the GC-column used in this trials, because the polarity of the column was not sufficient. The method detects both volatile and involatile compounds. But to be sure that all volatile swelling agents were detected a special sample handling technique must be developed.

    To improve the analysis method it is suggested that the method is developed so that only GC-MS analysis is needed. This is accomplished by further GC-MS analysis with other GC-columns and better search databases. It is also suggested that the method is developed so that it is not only a qualitative analysis method but also a quantitative analysis method.  In that way it can be used as a much more effective tool during failure investigations.

  • 243.
    Fagerland, Jenny
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Synthesis and Characterization of Self-Assembling Low Molecular Weight Copolymers for Bioengineering Applications2013Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The constant need for improved biomedical materials and the interest in producing materials with similar properties to the extracellular matrix in different tissues has resulted in increasing interest in research on hydrogels. Over the last decade self-assembling copolymers have been of particular interest since they form hydrogels in response to external stimuli such as temperature. In this thesis, two self-assembling low molecular weight copolymers; poly(L-lactide-co-glycolide) grafted with poly(ethylene glycol) methyl ether (PLGA-g-MPEG) and poly(L-lysine-co-L-alanine) (poly(Lys-co-Ala)) were synthesized for possible bioengineering applications. Their chemical structure and composition was analysed by nuclear magnetic resonance spectroscopy (NMR) and matrix assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF-MS). The results showed that low molecular weight PLGA-g-MPEG and poly(Lys-co-Ala) were successfully obtained.

    PLGA-g-MPEG hydrogels were formed at 37°C, within 1 minute, at a pH between 6-7 and had a functional life of one month. The block cooligopeptides of L-lysine and L-alanine formed cubic, hexagonal and hollow crystals in low pH and irregularly shaped crystals in at pH 7, while plate-like crystals were formed at both pH 3 and 7 form the random cooligopeptides. Evaluation of the properties of the low molecular weight copolymers, such as pH, functional life and crystalline morphology, revealed that the chemical composition and solvent composition strongly affects their self-assembling properties.

    These synthesized low molecular weight copolymers showed promise results for use as material in biomedical applications. Areas of potential use for these materials include bioengineered hierarchical scaffold material facilitating sequential release of growth factors, for example in bone tissue engineering, and as materials for encapsulated drug delivery.

  • 244.
    Fagerland, Jenny
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Finne-Wistrand, Anna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Numata, Keiji
    Short One-Pot Chemo-Enzymatic Synthesis of L-Lysine and L-Alanine Diblock Co-Oligopeptides2014In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 15, no 3, p. 735-743Article in journal (Refereed)
    Abstract [en]

    Amphiphilic diblock co-oligopeptides are interesting and functional macromolecular materials for biomedical applications because of their self-assembling properties. Here, we developed a synthesis method for diblock co-oligopeptides by using chemo-enzymatic polymerization, which was a relatively short (30 min) and efficient reaction (over 40% yield). Block and random oligo(L-lysine-co-L-alanine) [oligo(Lys-co-Ala)] were synthesized using activated papain as enzymatic catalyst. The reaction time was optimized according to kinetic studies of oligo(L-alanine) and oligo(L-lysine). Using H-1 NMR spectroscopy and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, we confirmed that diblock and random co-oligopeptides were synthesized. Optical microscopy further revealed differences in the crystalline morphology between random and block co-oligopeptides. Plate-like, hexagonal, and hollow crystals were formed due to the strong impact of the monomer distribution and pH of the solution. The different crystalline structures open up interesting possibilities to form materials for both tissue engineering and controlled drug/gene delivery systems.

  • 245.
    Fagerland, Jenny
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Finne-Wistrand, Anna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Pappalardo, Daniela
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. University of Sannio, Italy.
    Modulating the thermal properties of poly(hydroxybutyrate) by the copolymerization of rac-beta-butyrolactone with lactide2016In: New Journal of Chemistry, ISSN 1144-0546, E-ISSN 1369-9261, Vol. 40, no 9, p. 7671-7679Article in journal (Refereed)
    Abstract [en]

    Biobased poly(hydroxybutyrate) is produced by microorganisms under controlled conditions. It is a linear, high molecular weight, fully isotactic and highly crystalline polymer. However, it has poor mechanical and thermal properties. We have modulated the thermal properties of this material by ring-opening co-polymerization of rac-beta-butyrolactone (BL) with lactide (LA) in the presence of salan-based yttrium and aluminum catalysts. The prepared poly(hydroxybutyrate-co-lactide) copolymers were characterized by proton and carbon nuclear magnetic resonance (H-1 and C-13 NMR), size exclusion chromatography (SEC) and differential scanning calorimetry (DSC) analyses. The salan-yttrium compound was a more effective catalyst compared to the aluminum compound, affording high molecular weight copolymers with higher monomer conversion and a monomodal distribution of the molecular weights. The kinetic experiments showed a higher rate of polymerization for the LA with respect to the BL. The copolymers were amorphous and DSC showed unique transition temperatures for all of the samples. The formation of a gradient copolymer is proposed.

  • 246.
    Fang, Dong
    KTH, School of Industrial Engineering and Management (ITM), Industrial Ecology.
    Mechano-Sorptive Creep – Structural Origin on the Single Fiber Level2009Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The consuming of paper and fibrous products is nowadays tremendous in our daily life. The raw material used in the paper industry is mainly wood fibers. A better understanding of properties of these fibers will help to improve the performance of the paper industry. Fiber deforms with time when subjected to a load, which has to be compensated for in packaging materials by the use of thicker papers thus more material. This deformation increases in the variable climate. This well-known complex phenomenon is called mechano-sorptive creep and leads to large losses in the paper industry every year.

     In order to understand the influence on the creep phenomenon of different fiber morphology, and how and to what extent the fibril angle affects the mechano-sorptive creep, the creep behavior of four series of fibers from spruce were measured by DMA (Dynamic Mechanical Analyzer) at a constant humidity climate followed by an immediately cyclic humidity. The fibers used were mature latewood fibers, mature earlywood fibers, juvenile latewood fibers and juvenile earlywood fibers. The CLSM (Confocal Laser Scanning Microscopy) was used to determine the microfibril angle of the fibers. The results of the tests show a higher creep rate at cyclic humidity than that at constant humidity. The comparisons among fibers show that latewood fibers have higher mechano-sorptive creep ratio (creep rate at cyclic humidity/ creep rate at constant humidity) than earlywood fibers and that juvenile wood fibers have higher creep ratio than mature wood fibers. One of the main conclusions drawn in this study was that the higher the fibril angle, the lower was the mechano-sorptive creep ratio.

  • 247.
    Farbod, Kambiz
    KTH, School of Chemical Science and Engineering (CHE).
    Uv and spontaneously cured polyethylene glycol-based hydrogels for soft and hard tissue scaffolds2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    UV-curing is one of the most commonly used methods for producing hydrogels for soft and hard tissue scaffolds. Spontaneous curing is an alternative method which possesses some advantages in comparison to the conventional UV-curing methods; for example, in situ crosslinking and excluding initiators. The main objective of this study was to investigate promising materials for producing UV and spontaneously cured hydrogels, and subsequently to perform a comparison between the produced hydrogels with regard to their different mechanical and physical properties.Seventeen different hydrogels including five UV-cured and twelve spontaneously cured hydrogels were produced by applying thiol-ene chemistry and by varying precursor materials. Hydrogel systems including di- and tetra- functional PEGs of different lengths (2 kDa and 6 kDa) and two different thiol-crosslinkers (ETTMP 1300 Da and DTT) were subsequently characterized and evaluated. The evaluation tests applied in this study were Raman spectroscopy, weight and volumetric swelling test, leaching test, tensile test, and rheology test. Between all the systems, tetra-acrylated PEG (6 kDa) BisMPA was found to be the most promising system. The pH level of the applied solvent (PBS) for spontaneously cured hydrogels was varied from the physiologically relevant level of 7.4 to 7.0 and 7.8 in order to investigate the dependency of physical and mechanical properties of the hydrogels to this parameter.Spontaneous curing of tetra-acrylated PEG (6 kDa) BisMPA with ETTMP 1300 Da as the thiol-crosslinker, was accomplished within 3½ min in PBS with a pH level of 7.4; and it came out to be the fastest spontaneously cured system between all the tested hydrogels. Increasing the PBS pH level resulted in a faster curing process (accomplished in 1½ min). Spontaneously cured hydrogels generally showed decreased mechanical properties, but improved swelling behavior compared to UV-cured hydrogels. Nevertheless, the discussed system still possessed 50% of the elastic modulus in the tensile test in comparison to the UV-cured state; and showed the highest elastic modulus in comparison to other spontaneously cured systems. The storage modulus of the mentioned hydrogel in the spontaneously cured state was very close to the same parameter in the UV-cured hydrogel based on the same precursors. It also possessed the highest storage modulus between all the spontaneously cured hydrogels. Although the obtained swelling properties of this system were not the highest between all the tested hydrogels, these parameters were still in an acceptable range as for a hydrogel proposed for tissue scaffold application (swelling ratio: 9.72, water content: 89.71%, volumetric swelling ratio: 9.05). Furthermore, the system had the lowest weight loss ratio between all the acrylate-based hydrogels (including both UV and spontaneously cured systems), which along with the Raman spectroscopy results shows the high crosslinking efficiency of the system.

  • 248.
    Farhat, Wissam
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Stamm, Arne
    KTH, Centres, Science for Life Laboratory, SciLifeLab. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology.
    Robert-Monpate, Maxime
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology. KTH, Centres, Science for Life Laboratory, SciLifeLab. Ecole Super Chim Organ & Minerale, 1 Allee Reseau Jean Marie Buckmaster, F-60200 Compiegne, France.
    Biundo, Antonino
    KTH, Centres, Science for Life Laboratory, SciLifeLab. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology.
    Syrén, Per-Olof
    KTH, Centres, Science for Life Laboratory, SciLifeLab. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology.
    Biocatalysis for terpene-based polymers2019In: Zeitschrift für Naturforschung C - A Journal of Biosciences, ISSN 0939-5075, E-ISSN 1865-7125, Vol. 74, no 3-4, p. 90-99Article in journal (Refereed)
    Abstract [en]

    Accelerated generation of bio-based materials is vital to replace current synthetic polymers obtained from petroleum with more sustainable options. However, many building blocks available from renewable resources mainly contain unreactive carbon-carbon bonds, which obstructs their efficient polymerization. Herein, we highlight the potential of applying biocatalysis to afford tailored functionalization of the inert carbocyclic core of multicyclic terpenes toward advanced materials. As a showcase, we unlock the inherent monomer reactivity of norcamphor, a bicyclic ketone used as a monoterpene model system in this study, to afford polyesters with unprecedented backbones. The efficiencies of the chemical and enzymatic Baeyer-Villiger transformation in generating key lactone intermediates are compared. The concepts discussed herein are widely applicable for the valorization of terpenes and other cyclic building blocks using chemoenzymatic strategies.

  • 249. Feliu, Neus
    et al.
    Walter, Marie Valérie
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Montañez, Maria I.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Kunzmann, Andrea
    Hult, Anders
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Nyström, Andreas
    Malkoch, Michael
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Fadeel, Bengt
    Stability and biocompatibility of a library of polyester dendrimers in comparison to polyamidoamine dendrimers2012In: Biomaterials, ISSN 0142-9612, E-ISSN 1878-5905, Vol. 33, no 7, p. 1970-1981Article in journal (Refereed)
    Abstract [en]

    Dendrimers can be designed for several biomedical applications due to their well-defined structure, functionality and dimensions. The present study focused on the in vitro biocompatibility evaluation of a library of aliphatic polyester dendrimers based on 2,2-bis(methylol)propionic acid (bis-MPA) with an overall diameter of 0.5-2 nm. In addition, dendrimers with two different chemical surfaces (neutral with hydroxyl end group and anionic with carboxylic end group) and dendrons corresponding to the structural fragments of the dendrimers were evaluated. Commercial polyamidoamine dendrimers (PAMAM) with cationic (amine) or neutral (hydroxyl) end group were also included for comparison. Cell viability studies were conducted in human cervical cancer (HeLa) and acute monocytic leukemia cells (THP.1) differentiated into macrophage-like cells as well as in primary human monocyte-derived macrophages. Excellent biocompatibility was observed for the entire hydroxyl functional bis-MPA dendrimer library, whereas the cationic, but not the neutral PAMAM exerted dose-dependent cytotoxicity in cell lines and primary macrophages. Studies to evaluate material stability as a function of pH, temperature, and time, demonstrated that the stability of the 4th generation hydroxyl functional bis-MPA dendrimer increased at acidic pH. Taken together, bis-MPA dendrimers are degradable and non-cytotoxic to human cell lines and primary cells.

  • 250. Feng, Nianjie
    et al.
    Ma, Qingzhi
    Yuan, Meiting
    Zhai, Huamin
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Improving Degradation Ability Toward Wheat Straw Chemical Composition by Co-Cultivation of Pycnoporus sanguineus with Candida tropicalis2015In: Journal of Biobased Materials and Bioenergy, ISSN 1556-6560, E-ISSN 1556-6579, Vol. 9, no 6, p. 567-571Article in journal (Refereed)
    Abstract [en]

    It is important for lignocellulosic bioconversion of wheat straw to be intensified by co-cultivation of Pycnoporus sanguineus with Candida tropicalis. The biodegradation properties, involving the enzymes composition and their activities, fibrous tissue morphologies, and chemical composition of co-cultivation, were studied. The co-cultivation obviously improved enzymes composition and enhanced carboxymethyl cellulase, xylanase and laccase activities. The co-cultivation increased the porosity of fibrous tissue in wheat straw. The co-cultivation is presented an advantageous performance in the aspects of lignin and carbohydrate degradation than the cultivation of P. sanguineus alone. The degradation process of the chemical composition in wheat straw by the co-cultivation can be divided into the first rapid phase and the following slow degradation one. The co-cultivation of P sanguineus with C. tropicalis increased the delignification by 15.2% in the rapid phase and the carbohydrate degradation ratio by 61.5% in the slow phase. The above intensifying degradation ability were resulted from the combination improvement of enzymes composition, their activities and fibrous tissue morphologies.

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