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  • 201.
    Ek, Monica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Axegård, Peter
    Modern hydrogen peroxide bleaching.1994Conference paper (Refereed)
  • 202.
    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)
  • 203.
    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)
  • 204.
    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)
  • 205.
    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.
    On the formation of oxalic acid in bleaching.1996Conference paper (Refereed)
    Abstract [en]

    In modern pulp mills with prodn. of bleached chem. pulp the increased closure of the bleach plant effluent water system will lead to increased concns. of a variety of dissolved org. substances.  Among these oxalic acid is one of the most detrimental due to the facile formation of insol. calcium oxalate once the pH-value is low enough to liberate calcium ions from the pulp.  The ppt. may cause severe prodn. problems.  Therefore, the formation of oxalic acid from the bleaching of kraft pulps with a variety of bleaching agents have been analyzed.  Two methods of anal. have been employed, viz. ion chromatog. and enzymic oxidn. to hydrogen peroxide.  The former is a std. method requiring a certain sample treatment whereas the latter may be used on line.  Anal. of the aq. phase after each bleaching stage in a O D EO D sequence reveals that oxalic acid can be formed in all stages with the oxygen stage being the predominant contributor.  A comparison between different bleaching agents applied to the same pulp again reveals oxygen as a major producer of oxalic acid.  The oxalic acid can be formed from both lignin and polysaccharides but expts. with isolated lignin indicates that the predominant part of the oxalic acid is formed from carbohydrates.       

  • 206.
    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.

  • 207.
    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)
  • 208.
    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)
  • 209.
    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)
  • 210.
    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.

  • 211.
    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.

  • 212.
    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)
  • 213.
    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.

  • 214.
    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)
  • 215.
    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)
  • 216.
    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.

  • 217.
    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)
  • 218.
    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)
  • 219.
    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.

  • 220.
    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)
  • 221.
    Ekman, Fredrik
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics.
    Development and Evaluation of Textile Actuators2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Existing actuators in robotics are noisy, rigid and not very lifelike in their movements. There is a need for actuators in especially limb prosthetics and exoskeletons that are silent, softly moving and preferably operating on low currents. One such solution is the conducting polymers.

    Textiles are well researched and there is a wide variety of patterning. Even more important is their reproducibility and how easily they are mass-produced.

    This thesis work combines conducting polymers with textiles to achieve linear textile actuators. The textiles are coated with the conducting polymer Polypyrrole which has the property of volume change, when a voltage is applied and there is a reservoir of ions accessible. The volume change, expansion and contraction, results in a linear actuation. The force and strain are measured while changing different parameters and the results are evaluated in this thesis.

  • 222. Eldsäter, C.
    et al.
    Albertsson, A-C.
    Karlsson, S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Impact of degradation mechanisms on poly(3-hydroxybutyrate-co-3-hydroxyvalerate) during composting1997In: Acta Polymerica, ISSN 0323-7648, E-ISSN 1521-4044, Vol. 48, no 11, p. 478-483Article in journal (Refereed)
  • 223. Eldsäter, C.
    et al.
    Erlandsson, B.
    Renstad, R.
    Albertsson, A-C.
    Karlsson, S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    The biodegradation of amorphous and crystalline regions in film-blown poly(ε-caprolactone)2000In: Polymer, ISSN 0032-3861, E-ISSN 1873-2291, Vol. 41, no 4, p. 1297-1304Article in journal (Refereed)
  • 224. Eldsäter, Carina
    et al.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Albertsson, Ann-Christine
    Effect of abiotic factors on the degradation of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) in simulated and natural composting environments1999In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 64, no 2, p. 177-183Article in journal (Refereed)
  • 225. 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.

  • 226.
    Engström, Joakim
    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. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Hatton, Fiona
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    D'Agosto, F.
    Université de Lyon, Univ Lyon 1, CPE Lyon, CNRS, UMR 5265, C2P2 (Chemistry, Catalysis, Polymers & Processes), Team LCPP Bat 308F, 43 Bd du 11 Novembre 1918, 69616 Villeurbanne, France .
    Lansalot, M.
    Université de Lyon, Univ Lyon 1, CPE Lyon, CNRS, UMR 5265, C2P2 (Chemistry, Catalysis, Polymers & Processes), Team LCPP Bat 308F, 43 Bd du 11 Novembre 1918, 69616 Villeurbanne, France .
    Malmström, Eva
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Carlmark, Anna
    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.
    Soft and rigid core latex nanoparticles prepared by RAFT-mediated surfactant-free emulsion polymerization for cellulose modification-a comparative study2017In: Polymer Chemistry, ISSN 1759-9954, E-ISSN 1759-9962, Vol. 8, no 6, p. 1061-1073Article in journal (Refereed)
    Abstract [en]

    Latex nanoparticles comprising cationically charged coronas and hydrophobic cores with different glass transition temperatures (Tg) have been prepared by surfactant-free, RAFT-mediated emulsion polymerization, where the particles form through a polymerization-induced self-assembly (PISA) type mechanism. Poly(2-dimethylaminoethyl methacrylate-co-methacrylic acid) (P(DMAEMA-co-MAA)) was utilized as a hydrophilic macroRAFT agent for the polymerization of methyl methacrylate (MMA) or n-butyl methacrylate (nBMA), respectively, resulting in two different latexes, with either a core of high (PMMA) or low (PnBMA) Tg polymer. By varying the molar mass of the hydrophobic block, latexes of different sizes were obtained (DHca. 40-120 nm). The adsorption of the latexes to cellulose model surfaces and cellulose nanofibrils (CNF) was studied using quartz crystal microbalance with dissipation monitoring (QCM-D). The surfaces with adsorbed PnBMA latexes yielded hydrophobic surfaces both before and after annealing, whereas surfaces with adsorbed PMMA latex became hydrophobic only after annealing, clearly showing the influence of the Tg of the core. The latexes were also used to modify macroscopic cellulose in the form of filter papers. Similar to the CNF surfaces, no annealing was required to achieve hydrophobic surfaces with PnBMA latexes. Finally, nanocomposites of CNF and the polymer nanoparticles were prepared through a one-pot mixing procedure. It was found that the largest synthesized PMMA latex (120 nm) facilitated a more strainable CNF network at 50% relative humidity, with a nearly 200% increase in strain at break compared to the neat CNF reference film as well as to the composite films with PnBMA latexes or to the smaller sized PMMA latexes. This difference was attributed to the spherical shape and rigidity of the large PMMA latex nanoparticles during composite formation. This highly interesting result should indeed be considered in the future design of novel biocomposites.

  • 227.
    Erdal, Nejla
    KTH, School of Chemical Science and Engineering (CHE).
    Uptake and Release of Active Ingredients in Pharmaceutical Eye Drops from Silicone Hydrogel Bandage Contact Lenses2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 228.
    Erdal, Nejla B.
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Adolfsson, Karin H.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    De Lima, Sara
    Karolinska Inst, St Erik Eye Hosp, Div Ophthalmol & Vis, Dept Clin Neurosci, Stockholm, Sweden..
    Hakkarainen, Minna
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.
    In vitro and in vivo effects of ophthalmic solutions on silicone hydrogel bandage lens material Senofilcon A2018In: Clinical and experimental optometry, ISSN 0816-4622, E-ISSN 1444-0938, Vol. 101, no 3, p. 354-362Article in journal (Refereed)
    Abstract [en]

    Background: Acuvue Oasys silicone hydrogel contact lenses (Senofilcon A) are used as bandage lenses and often combined with ophthalmic solutions in the treatment of ocular diseases. Concerns have been raised regarding the compatibility and effect of eye-drop solutions on the bandage lenses, which have led to frequent replacement of lenses causing clinical problems. Some patients experience pain or discomfort during treatments and the accumulation of drugs and preservatives in lenses has been suggested as a possible reason. The aim with this study was to investigate the effect of ophthalmic solutions on silicone hydrogel bandage lens material Senofilcon A in vitro and in vivo. Methods: The effect of three common ophthalmic solutions Isopto-Maxidex, Timosan and Oftaquix on Acuvue Oasys (Senofilcon A) bandage lenses was evaluated. An in vitro model method was developed where drug and preservative uptake by Acuvue Oasys was monitored with ultraviolet-visible spectroscopy and laser desorption ionisation mass spectrometry. Surface morphology changes of the lenses were evaluated using scanning electron microscopy. The method was then implemented for the in vivo pilot study evaluating lenses worn by patients. Results: In vitro model study monitoring the drug and preservatives uptake showed that the active ingredients from all the eye drops together with preservatives were taken up by the lenses in significant amounts. For the in vivo study no traces of active ingredients or preservatives could be found on the worn and treated lenses regardless of time being worn or dosage profiles. The surface morphology changes in the in vivo study were also minor in contrast to the changes observed in the in vitro scanning electron microscopy images. Conclusion: The in vivo results demonstrate minor effects of the ophthalmic solutions on the worn lenses. These results do not support the building up of preservatives and drugs on the contact lenses as the cause of pain or discomfort experienced by some patients, which is encouraging for the use of bandage lenses in combination with ophthalmic solutions.

  • 229.
    Erdal, Nejla B.
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.
    Hakkarainen, Minna
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.
    Construction of Bioactive and Reinforced Bioresorbable Nanocomposites by Reduced Nano-Graphene Oxide Carbon Dots2018In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 19, no 3, p. 1074-1081Article in journal (Refereed)
    Abstract [en]

    Bioactive and reinforced poly(ϵ-caprolactone) (PCL) films were constructed by incorporation of cellulose derived reduced nanographene oxide (r-nGO) carbon nanodots. Two different microwave-assisted reduction routes in superheated water were utilized to obtain r-nGO and r-nGO-CA. For the latter, a green reducing agent caffeic acid (CA), was incorporated in the reduction process. The materials were extruded and compression molded to obtain proper dispersion of the carbon nanodots in the polymer matrix. FTIR results revealed favorable interactions between r-nGO-CA and PCL that improved the dispersion of r-nGO-CA. r-nGO, and r-nGO-CA endorsed PCL with several advantageous functionalities including improved storage modulus and creep resistance. The considerable increase in storage modulus demonstrated that the carbon nanodots had a significant reinforcing effect on PCL. The PCL films with r-nGO-CA were also evaluated for their osteobioactivity and cytocompatibility. Bioactivity was demonstrated by formation of hydroxyapatite (HA) minerals on the surface of r-nGO-CA loaded nanocomposites. At the same time, the good cytocompatibility of PCL was retained as illustrated by the good cell viability to MG63 osteoblast-like cells giving promise for bone tissue engineering applications.

  • 230.
    Erdtman, Edvin
    et al.
    Akademin för textil, teknik och ekonomi, Högskolan i Borås, Borås, Sverige.
    Bohlén, Martin
    Akademin för textil, teknik och ekonomi, Högskolan i Borås, Borås, Sverige.
    Ahlström, Peter
    Akademin för textil, teknik och ekonomi, Högskolan i Borås, Borås, Sverige.
    Gkourmpis, Thomas
    Innovation & Technology, Borealis AB, Stenungsund, Sweden.
    Berlin, Mikael
    Tetra Pak Packaging Solutions AB, Ruben Rausings Gata, Lund, Sweden.
    Andersson, Thorbjörn
    Tetra Pak Packaging Solutions AB, Ruben Rausings Gata, Lund, Sweden.
    Bolton, Kim
    Akademin för textil, teknik och ekonomi, Högskolan i Borås, Borås, Sverige.
    A molecular-level computational study of the diffusion and solubility of water and oxygen in carbonaceous polyethylene nanocomposites2016In: Journal of Polymer Science Part B: Polymer Physics, ISSN 0887-6266, E-ISSN 1099-0488, Vol. 54, no 5, p. 589-602Article in journal (Refereed)
    Abstract [en]

    Monte Carlo and molecular dynamics simulations were performed to investigate the effect on the solubility, diffusion, and permeability of water and oxygen when adding graphene or single-walled carbon nanotubes (SWCNTs) to polyethylene (PE). When compared with pure PE, addition of graphene lowered the solubility of water, whereas at lower temperatures, the oxygen solubility increased because of the oxygen–graphene interaction. Addition of SWCNTs lowered the solubility of both water and oxygen when compared with pure PE. A detailed analysis showed that an ordered structure of PE is induced near the additive surface, which leads to a decrease in the diffusion coefficient of both penetrants in this region. The addition of graphene does not change the permeation coefficient of oxygen (in the direction parallel to the filler) and, in fact, may even increase this coefficient when compared with pure PE. In contrast, the water permeability is decreased when graphene is added to PE. The addition of SWCNTs decreases the permeability of both penetrants. Graphene can consequently be added to selectively increase the solubility and permeation of oxygen over water, at least at lower temperatures. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 589–602

  • 231. Erlandsson, Bengt
    et al.
    Albertsson, Ann-Christine
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Molecular weight determination in degraded oxidizable and hydrolyzable polymers giving deviation from accurate using calibration and the Mark-Houwink-Sakaruda (MHS) equation1997In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 57, no 1, p. 15-23Article in journal (Refereed)
  • 232. Erlandsson, Bengt
    et al.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Albertsson, Ann-Christine
    Correlation between molecular weight changes and 14CO2 evolution from biodegraded 14C-labelled ethylene-vinyl alcohol copolymer and ethylene polymer1998In: Acta Polymerica, ISSN 0323-7648, E-ISSN 1521-4044, Vol. 49, p. 363-Article in journal (Refereed)
  • 233. Erlandsson, Bengt
    et al.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Albertsson, Ann-Christine
    The mode of action of corn starch and a pro-oxidant system in LDPE: influence of thermooxidation and UV-irradiation on the molecular weight changes1997In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 55, no 2, p. 237-245Article in journal (Refereed)
  • 234.
    Erlandsson, Johan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    CONTROLLED ASSEMBLY AND FUNCTIONALISATION OF CELLULOSE-BASED MATERIALS2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The environmental effects caused by the use of fossil-based resources have intensified and driven society and research towards new materials and processes that utilise renewable resources. Within the development of new materials, wood has been identified as a raw-material from which high performing materials can be derived. One such material is cellulose nanofibrils (CNFs) which are capable of replacing several currently used fossil-based materials. However, for CNFs to exhibit the required material properties they need to be chemically or physically modified. This means that the properties of the CNFs can be specifically adapted to fit the demand in particular areas, for example electrical energy storage. In these applications it is the mechanical properties; the large, easily functionalised surface and ability to be moulded into 3D shapes that make CNFs a highly interesting raw material.

    This thesis explores the formation and functionalisation of CNF- and fibre-based materials and their novel use in applications such as energy storage. The wet stability of the materials was achieved by crosslinking and ice templating the fibrils by a novel freezing procedure, which makes it possible to avoid the use of freeze-drying and subsequent crosslinking. Using colloidal probe atomic force microscopy adhesion measurements, hemiacetals were shown to be formed between the aldehyde-containing fibrils when they are brought into molecular contact, for example during ice templating. Hemiacetal crosslinked aerogels have been shaped and functionalised to demonstrate their application as biomimetic structural composites, electrical circuits and electrical cells. In addition, crosslinked, light-weight 3D fibre networks were prepared with á similar chemistry by a self-assembly process of pulp fibres. These networks could be dried under ambient conditions and the materials formed were wet-stable due to the hemiacetal crosslinks formed in the fibre–fibre contacts, which provided the networks with excellent mechanical properties and shape recovery capacity in water.

    Finally, using a newly developed polyampholyte and mixing it with CNFs, heterofunctional composite films and aerogels could be prepared. By activating crosslinkable groups in these composite materials, they were able to undergo further water based chemical functionalisation. In this highly dispersed state, the composite could be irreversibly crosslinked by a hydrothermal treatment to create transparent, low solid content hydrogels.

    The full text will be freely available from 2020-10-11 10:00
  • 235.
    Erlandsson, Johan
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
    Pettersson, Torbjörn
    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.
    Ingverud, Tobias
    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.
    Granberg, H.
    Larsson, Per A.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Malkoch, Michael
    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. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    On the mechanism behind freezing-induced chemical crosslinking in ice-templated cellulose nanofibril aerogels2018In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 6, no 40, p. 19371-19380Article in journal (Refereed)
    Abstract [en]

    The underlying mechanism related to freezing-induced crosslinking of aldehyde-containing cellulose nanofibrils (CNFs) has been investigated, and the critical parameters behind this process have been identified. The aldehydes introduced by periodate oxidation allows for formation of hemiacetal bonds between the CNFs provided the fibrils are in sufficiently close contact before the water is removed. This is achieved during the freezing process where the cellulose components are initially separated, and the growth of ice crystals forces the CNFs to come into contact in the thin lamellae between the ice crystals. The crosslinked 3-D structure of the CNFs can subsequently be dried under ambient conditions after solvent exchange and still maintain a remarkably low density of 35 kg m-3, i.e. a porosity greater than 98%. A lower critical amount of aldehydes, 0.6 mmol g-1, was found necessary in order to generate a crosslinked 3-D CNF structure of sufficient strength not to collapse during the ambient drying. The chemical stability of the 3-D structure can be further enhanced by converting the hemiacetals to acetals by treatment with an alcohol under acidic conditions.

  • 236. Escalante, Alfredo
    et al.
    Goncalves, Ana
    Bodin, Aase
    Stepan, Agnes
    Sandstrom, Corine
    Toriz, Guillermo
    Gatenholm, Paul
    Wallenberg Wood Sci Ctr, Chalmers, Sweden.
    Flexible oxygen barrier films from spruce xylan2012In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 87, no 4, p. 2381-2387Article in journal (Refereed)
    Abstract [en]

    Arabinoglucuronoxylan was extracted from Norway spruce and films prepared by casting from aqueous solution. The sugar analysis and NMR confirmed that the spruce xylan was composed of arabinose, 4-O-methyl-glucuronic acid and xylose in a ratio of 1:2:11 respectively. Substitutions of 4-O-methyl-alpha-D-GlcpA at O-2 and of alpha-L-Araf at O-3 on the xylose backbone were found by NOE analysis. NOE cross-peaks indicated as well that there is at least one free xylose on the main chain present between two substitutions. Whether the distribution of side chains was random or in blocks was uncertain. The average molecular weight of the sample was determined by size exclusion chromatography to be 12,780 g/mol. Arabinoglucoronoxylan casting yielded transparent flexible films with an average stress at break of 55 MPa, strain at break of 2.7% and a Young's Modulus 2735 MPa. Wide-angle X-ray scattering analysis showed that the arabinoglucuronoxylan films were totally amorphous. Addition of sorbitol as plasticizer resulted in less strong but more flexible films (strain at break of 5%). Peaks of crystallinity could be seen in X-ray which corresponds to sorbitol crystallizing in distinct phases. The dynamic mechanical analysis showed that the arabinoglucuronoxylan film softened at a later relative humidity (80% RH) in comparison with plasticized films (60% RH). The films showed low oxygen permeability and thus have a potential application in food packaging.

  • 237.
    España, J. M.
    et al.
    Instituto de Tecnología de Materiales (ITM), Universitat Politècnica de València (UPV), Alcoy (Alicante), Spain.
    Fages, E.
    Textile Research Institute (AITEX), Alcoy (Alicante), Spain.
    Moriana, Rosana
    Textile Research Institute (AITEX), Alcoy (Alicante), Spain.
    Boronat, T.
    Instituto de Tecnología de Materiales (ITM), Universitat Politècnica de València (UPV), Alcoy (Alicante), Spain.
    Balart, R.
    Instituto de Tecnología de Materiales (ITM), Universitat Politècnica de València (UPV), Alcoy (Alicante), Spain.
    Antioxidant and antibacterial effects of natural phenolic compounds on green composite materials2012In: Polymer Composites, ISSN 0272-8397, E-ISSN 1548-0569, Vol. 33, no 8, p. 1288-1294Article in journal (Refereed)
    Abstract [en]

    The aim of this study is to establish the thermal performance of a biocomposite (Arbofill kokos®), stabilized with different natural phenolic additives, to check the antioxidant capacity of the resulting compounds. Different phenolic compounds (thymol, carvacrol, α-tocopherol, and tannic acid) were used as biobased additives and the concentrations ranged between 0.5 wt% and 2 wt%. The results obtained were compared with formulations containing a typical industrial petroleum-based antioxidant agent (octadecyl-3-(3,5-di-tert- butyl-4-hydroxyphenyl) propionate). Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used to characterize the antioxidant performance of the selected natural additives. The antimicrobial effect of these natural phenolic compounds was also studied by analyzing the growth of bacterial colonies. The comparison between the natural phenolic compounds and the petroleum-based antioxidant compound showed good antioxidant action for natural phenolic compounds; in all the mixtures of biocomposite and antioxidant agent the oxidation onset temperature (OOT) increased in a remarkable way, but the highest stabilization effect was achieved with α-tocopherol with provides a % increase on OOT of about 45%. With regard to antibacterial activity of the different natural phenolic compounds, thymol, and carvacrol showed interesting antibacterial properties against Staphylococcus aureus. Copyright © 2012 Society of Plastics Engineers.

  • 238.
    Eta, Valerie
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Laboratory of Industrial Chemistry and Reaction Engineering, Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Åbo-Turku, Finland.
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Laboratory of Industrial Chemistry and Reaction Engineering, Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Åbo-Turku, Finland.
    Deconstruction of Nordic hardwood in switchable ionic liquids and acylation of the dissolved cellulose2016In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 136, p. 459-465Article in journal (Refereed)
    Abstract [en]

    Nordic hardwood (Betula pendula) was fractionated in a batch autoclave equipped with a custom-made SpinChem® rotating bed reactor, at 120°C using CO2 and CS2-based switchable ionic liquids systems. Analyses of the non-dissolved wood after treatment showed that 64 wt% of hemicelluloses and 70 wt% of lignin were removed from the native wood. Long processing periods or successive short-time treatments using fresh SILs further decreased the amount of hemicelluloses and lignin in the non-dissolved fraction to 12 and 15 wt%, respectively. The cellulose-rich fraction was partially dissolved in an organic superbase and an ionic liquid system for further derivatization. Homogeneous acylation of the dissolved cellulose in the presence or absence of catalyst resulted in cellulose acetates with variable degree of substitution (DS), depending on the treatment conditions. By varying the reaction conditions, the cellulose acetate with the desired DS could be obtained under mild conditions.

  • 239.
    Evangelopoulos, Panagiotis
    KTH, School of Industrial Engineering and Management (ITM).
    Pyrolysis and Detoxification of Waste Electrical and Electronic Equipment (WEEE) for Feedstock Recycling2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The trends in waste electrical and electronic equipment (WEEE) generation shows that their volume constantly increases, while the current waste management technologies have proven to be insufficient in order to meet the strict criteria and the new legislations of the European Union. Pyrolysis and thermal treatment in general could be a valuable solution for closing the loop of materials and could contribute to the energy demands of modern society.

    Pyrolysis as a process and combination of other pre-treatment techniques was investigated with a focus on energy production, metal separation and feedstock recycling. In this work, several fractions of real WEEE have been tested based on the process requirements and the focus of each individual study.

    Firstly, the investigation was focused on the primary products of the process, revealing most of the environmental pollutants as well as the valuable monomers that can enhance feedstock recycling. A correlation of the process’ final temperature with the evolution of the major products was performed. Moreover, a conceptual reaction mechanism of Bisphenol A decomposition was suggested based on the process products.

    Then, a reduction of the bromine content of the initial WEEE fraction was achieved by solvent extraction pre-treatment. Isopropanol and toluene were tested as solvents capable of removing one of the main flame retardants at WEEE fractions, Tetrabromobisphenol A. The results indicate that the reduction of bromine was successfully performed even at ~37%. This result was further confirmed by the reduction or total removal of brominated species in the pyrolysis products. The toluene seems to be a valuable option for the pre-treatment, since it can be provided by the pyrolysis process itself, making the entire treatment more sustainable and in accordance with the concept of circular economy.

    Density separators used in the sorting of WEEE materials usually produced high moisture content fractions. As soon as those fractions follow thermal treatment, the moisture will eventually become steam, which influences the process. Therefore, WEEE materials were pyrolysed in nitrogen and steam atmospheres and their decomposition was evaluated. Steam had a negative impact on the products, since several high molecular weight products were detected, revealing that steam limits secondary cracking reactions. Additionally, the results show that the presence of steam complicates the separation of oils and favours the migration of antimony to the gas phase. Therefore, a drying step before using pyrolysis for this fraction is necessary.

    Low temperature pyrolysis was also investigated for making the WEEE more fragile to enhance metal separation from the carbonised solid residue while the fate of bromine was also monitored. The results indicate that the separation is possible at low temperatures for minimising the energy consumption of the process but it should be at least 40 ° higher than the onset temperature of the selected material. The separation was also evaluated with fractionation of the solid residue, revealing that the produced bromine-free solid carbonised material can be further utilised for energy production.

    Finally, the entire process was tested in a continuous screw reactor for overall process evaluation. The results indicate that the liquid products of pyrolysis can be used for feedstock recycling, producing necessary organic compounds that can be used for manufacturing new plastics or can be used as liquid fuel. The brominated compounds tend to migrate to the gas phase, as the temperature of the process increases, making the recycling of metals from the solid residue easier. The process in general can be self-sustained since the energy needed for the system to heat up can be covered from its gas production.

  • 240.
    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.

  • 241.
    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.

  • 242.
    Fagerland, Jenny
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Synthesis of degradable aliphatic polyesters: strategies to tailor the polymer microstructure2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Key factors for successful tissue engineering are the synthesis and design of the scaffold materials. Aliphatic polyesters have been studied and often used as scaffold materials for tissue engineering. However, their lack of biological cues and degradation under high-temperature processing (e.g., 3D printing) are a limitation. In this thesis, different synthesis strategies are presented which has the potential to improve the performance of aliphatic polyesters as scaffolds for tissue regeneration.

    To stimulate interactions between exogenous materials and the surrounding tissue, two different strategies were applied. Either, by designing a two component system in which the different degradation profiles of the polymers allow for sequential release of growth factors. Or, by peptide functionalization of an aliphatic polyester chain using template-assisted chemo-enzymatic synthesis. The results from the studies were successful. A hierarchical system was obtained in which the poly(L-lactide-co-glycolide)-graft-poly(ethylene glycol) methyl ether (PLGA-g-MPEG), hydroxyapatite solution formed a gel around and within the pores of the poly(L-lactide-co-ε-caprolactone) scaffold at 37 ºC, within 1 min, that was stable for 3 weeks. The peptide functionalization was also successful where an aliphatic polyester of L-lactide was functionalized with different oligopeptides using a grafter (ethyl hept-6-enoylalaninate) and chemo-enzymatic synthesis.

    The thermal properties of poly(L-lactide-co-hydroxybutyrate) were tailored (by modification of the microstructure) to potentially improve the processability of the aliphatic polyester.  The results showed that the yttrium salan catalyst was the most successful, yielding high molecular weight copolymers in shorter time. They also showed that the Tg could be tailored by varying the amount of rac-β-butyrolactone in the copolymer to better suit thermal processing techniques, such as 3D printing.

  • 243.
    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.
    Mapping the synthesis and the impact of low molecular weight PLGA-g-PEG on sol-gel properties to design hierarchical porous scaffolds2013In: Journal of polymer research, ISSN 1022-9760, E-ISSN 1572-8935, Vol. 21, no 1, p. 337-Article in journal (Refereed)
    Abstract [en]

    Bone morphogenetic protein 2 (BMP-2)-functionalized poly(l-lactide-co-epsilon-caprolactone) (PLCL) porous scaffolds have shown promising results in bone tissue regeneration studies. It is believed that even better results are achieved by hierarchical porous scaffolds and a designed sequential release of growth factors. We therefore synthesized (l-lactide-co-glycolide)-g-poly(ethylene glycol) (PLGA-g-PEG) oligomers which could be injected into PLCL porous scaffolds. They were synthesized by ring-opening polymerization and carefully characterized by nuclear magnetic resonance spectroscopy (NMR), matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS), and size exclusion chromatography (SEC). The sol-gel transition temperature, pH, and functional life were determined and correlated with the molecular structure of PLGA-g-PEG. We found that low molecular weight PLGA-g-PEG was obtained and poly(l-lactide-co-glycolide-co-poly(ethylene glycol) methyl ether) (PLGA-MPEG) appeared to contribute to gelation. It was possible to design a system that formed a hydrogel within 1 min at 37 A degrees C with a pH between 6 and 7 and with a functional life of around 1 month. These low molecular weight thermosensitive PLGA-g-PEG oligomers, which can be injected into PLCL scaffolds, appear promising for bone tissue engineering applications.

  • 244.
    Fagerland, Jenny
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Pappalardo, Daniela
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology. University of Sannio, Italy.
    Schmidt, Björn
    KTH, School of Biotechnology (BIO), Protein Technology.
    Syrén, Per-Olof
    KTH, School of Biotechnology (BIO), Protein Technology.
    Finne-Wistrand, Anna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Template-assisted enzymatic synthesis of oligopeptides from a polylactide chain2017In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 18, no 12, p. 4271-4280Article in journal (Refereed)
    Abstract [en]

    Peptides are often attached to polymer materials, as bioactive components, for the control of interactions between the material and its surrounding proteins and cells. However, synthesizing peptides and attaching them to polymers can be challenging and laborious. Herein, we describe the grafting of oligopeptides to an aliphatic polyester, using a one-step chemo-enzymatic synthesis with papain as the biocatalySt. To enable enzyme-mediated functionalization of the polyester, ethyl hept-6-enoylalaninate (grafter) was synthesized and attached to polylactide chains using thiol-ene click reactions. The oligopeptides were grafted onto the polylactide chains using two different synthetic routes: the grafting from strategy, in which the grafter was attached to the polyester prior to oligopeptide synthesis, or the grafting to strategy, in which oligopeptides were synthesized on the grafter first, then attached to the polymer chain. The final products were analyzed and their structures were confirmed using nuclear magnetic resonance (NMR). The peptide attachment was evaluated using size exclusion chromatography (SEC), contact angle measurement and energy-dispersive X-ray spectroscopy scanning electron microscopy (EDS-SEM). Furthermore, the mechanistic aspects of the synthesis of the oligopeptides on the grafter were studied using molecular dynamics (MD) simulations. The simulation revealed that hydrogen bonding (between the P1 amide nitrogen of the grafter backbone and the carbonyl oxygen of D158 in the papain) maintain the grafter in a productive conformation to stabilize the transition state of nitrogen inversion, a key step of the biocatalytic mechanism. Apart from being biologically relevant, both experimental and computational results suggest that the designed grafter is a good template for initiating chemo-enzymatic synthesis. The results also showed that the grafting to strategy was more successful compared to the grafting from strategy. Overall, a successful synthesis of predefined peptide functionalized polylactide was prepared, where the oligopeptides were grafted in an easy, time efficient, and environmentally friendly way.

  • 245.
    Fagerland, Karin
    KTH, School of Chemical Science and Engineering (CHE).
    Stabilizer Migration in Polyolefins determined by FTIR2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The purpose of this study was to develop a method for analyzing the distribution of stabilizers, containing hindered phenols, in polyolefins with Fourier Transform Infrared Spectroscopy (FTIR). The peak from the hindered phenol is weak and difficult to detect with FTIR, but trough reaction chlorine dioxide (ClO2) a quinone structure is formed that binds water which gives a much stronger signal in the spectrum. The aim was to  investigate whether or not it is possible to relate the absorbed amount of water to the concentration of stabiliser in the polymer.

     

    The results were that the stabilizers in a material can be related to the water absorption within a material, but not between different materials. This is based on the result from FTIR line scan that shows how the water absorption peak of a ClO2 exposed PP follows the same pattern as the ester peak of an unexposed PP over a cross section. The water absorption could not be related to the amount of stabilizers when different materials were compared since the materials absorbed unequal amounts of water.

     

    The water absorption peak increases with time until it stabilizes after 6 days (144 hours), thus when all hindered phenols have reacted with chlorine dioxide. The concentration of chlorine dioxide was of less importance for the water absorption as long as ClO2 was in excess relative the hindered phenols, for this study, 0,1 g/L was enough.  It was also concluded that reaction with ClO2 was more effective in 50°C than in room temperature since a larger water absorption peak was obtained at this temperature. The method can also be considered repeatable within a specific material since similar values ​​of the water absorption peak was obtained at separate experiments.

     

    Irganox 1330 was identified with HPLC in all of the polyolefins. There were also other hindered phenols present in most of the other polymers but they could not be identified due to overlaps. Because of the similar molecular structure of Irganox 1010 and Irganox 1076, it was impossible to achieve separation with an isocratic HPLC since they were affected in the same way by the solid and mobile phase.

     

  • 246. Fatarella, Enrico
    et al.
    Corsi, Leopoldo
    Nesti, Solitario
    Mylläri, Ville
    Järvelä, Pentti
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Syrjala, Seppo
    Polymeric composition comprising functionalized PEEK2014Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    The present invention relates to a polymeric composition comprising functionalized polyetheretherketone (PEEK) of formula (II), in admixture with a co-polymer having a melting point lower than the melting point of the non-functionalized PEEK of formula (I). The invention further relates to the use of said composition for the preparation of fibers having antibacterial, decontaminant and self-cleaning properties, useful, for example, for making sanitary garments, such as sanitary coats and masks and for making, for example, filters for ventilation systems and filters for kitchen hoods.

  • 247.
    Fatarella, Enrico
    et al.
    Next Technology Tecnotessile Società Nazionale di Ricerca s.r.l.
    Mylläri, Ville
    Tampere University of Technology.
    Ruzzante, Marco
    Next Technology Tecnotessile Società Nazionale di Ricerca s.r.l.
    Pogni, Rebecca
    Department of Biotechnology, Chemistry and Pharmacy, University of Siena.
    Baratto, Maria
    Department of Biotechnology, Chemistry and Pharmacy, University of Siena.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Syrjälä, Seppo
    Tampere University of Technology.
    Järvelä, Pentti
    Tampere University of Technology.
    Sulfonated polyetheretherketone/polypropylene polymer blends for the production of photoactive materials2015In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 132, no 8Article in journal (Refereed)
  • 248.
    Fateh-Alavi, Kamyar
    et al.
    KTH, Superseded Departments, Polymer Technology.
    Gedde, Ulf W.
    KTH, Superseded Departments, Polymer Technology.
    Effect of stabilizers on surface oxidation of silicone rubber by corona discharge2004In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 84, no 3, p. 469-474Article in journal (Refereed)
    Abstract [en]

    Crosslinked polydimethylsiloxane (PDMS) containing Irganox(R) 1076, Tinuvin(R) 770 or lrganox(R) 565, prepared by swelling PDMS in a solution of one of these stabilizers in n-hexane, was exposed to a corona discharge and the corona exposure time (tau(crit)) to form a brittle, silica-like layer was determined by optical microscopy. The critical corona exposure time showed a linear increase with increasing stabilizer concentration; Tinuvin 770 showed the highest efficiency and Irganox 1076 the lowest. The increase in tau(crit) on corona exposure of the stabilized samples with reference to the value for unstabilized PDMS was similar to that reported earlier for air plasma exposed samples. The efficiency of the stabilizers towards corona-induced surface oxidation of PDMS was also confirmed by X-ray photoelectron spectroscopy.

  • 249.
    Fateh-Alavi, Kamyar
    et al.
    KTH, Superseded Departments, Fibre and Polymer Technology.
    Karlsson, Sigbritt
    KTH, Superseded Departments, Fibre and Polymer Technology.
    Gedde, Ulf W.
    KTH, Superseded Departments, Polymer Technology.
    A rapid microwave-assisted solvent extraction method for assessment of stabilizer concentration in crosslinked polydimethylsiloxane2004In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 93, no 5, p. 2185-2192Article in journal (Refereed)
    Abstract [en]

    Crosslinked polyclimethylsiloxanes were prepared containing 0.05 to 0.2 wt % of either a phenolic antioxidant (Irganox(R) 1010) or a hindered amine stabilizer (Tinuvin(R) 144). The stabilizer concentration was assessed by HPLC and UV-Vis spectroscopy of Soxhlet and microwave-assisted solvent extracts. Almost complete recovery of stabilizer was achieved with Soxhlet extraction. High stabilizer recovery was achieved when acetone was used as the solvent in the microwave-assisted extraction. HPLC was shown to be an efficient method for determining the concentration of Irganox 1010. For Tinuvin 144 the selectivity of both UV-Vis spectroscopy and HPLC was poor, leading to imprecise evaluation of the antioxidant concentration. The loss of stabilizer by migration from polymer to hot water (75 and 95degreesC) was monitored for the systems stabilized with Irganox 1010 and the diffusion coefficient of the antioxidant in the polymer was determined.

  • 250.
    Fazelinejad, Samaneh
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Åkesson, Dan
    University of Borås, Faculty of Textiles, Engineering and Business.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Repeated mechanical recycling of polylactic acid filled with chalk2017In: Progress in Rubber, Plastics and Recycling Technology, ISSN 0266-7320, E-ISSN 1478-2413, p. 1-16Article in journal (Refereed)
    Abstract [en]

    Polylactic acid (PLA) was compounded with 30 wt% chalk and 5 wt% of a biobased plasticiser on a twin screw extruder. Mechanical recycling of the obtained compound was studied by multiple extrusions up to six cycles. The degradation was monitored by mechanical and thermal tests. Tensile and flexural tests did not reveal any major degradation after six cycles of processing. Characterising the material with differential scanning calorimetry (DSC) did not detect any significant change of the thermal properties. The material was also characterised by FTIR and, again, no significant change was detected. The material was finally characterised by melt flow index and by proton nuclear magnetic resonance (1H-NMR). Both tests revealed that some degradation had occurred. The 1H-NMR clearly showed that the chain length had been reduced. Also, the MFI test showed that degradation had occurred. However, the study reveals that PLA filled with chalk can be recycled by repeated extrusion for up to 6 cycles, without severe degradation. This should be of relevance when considering the end-of-life treatment of polymer products made from PLA.

2345678 201 - 250 of 925
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