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  • 101. Badia, J.D.
    et al.
    Strömberg, Emma
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Ribes-Greus, A.
    Material valorisation of amorphous polylactide. Influence of thermo-mechanical degradation on the morphology, segmental dynamics, thermal and mechanical performance2012In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 97, no 4, p. 670-678Article in journal (Refereed)
    Abstract [en]

    This paper reports the effects of multiple mechanical recycling on the structure and properties of amorphous polylactide (PIA). The influence of the thermo-mechanical degradation induced by means of five successive injection cycles was initially addressed in terms of macroscopic mechanical properties and surface modification. A deeper inspection on the structure and morphology of PLA was associated to the thermal properties and viscoelastic behaviour. Although FT-IR analysis did not show significant changes in functional groups, a remarkable reduction in molar mass was found by viscometry. PIA remained amorphous throughout the reprocessing cycles, but the occurrence of a cold-crystallization during DSC and DMTA measurements, which enthalpy increased with each reprocessing step, suggested chain scission due to thermo-mechanical degradation. The effect of chain shortening on the glass-rubber relaxation studied by DMTA showed an increase in free volume affecting the segmental dynamics of PLA, particularly after the application of the second reprocessing step, in connection to the overall loss of performance showed by the remaining properties.

  • 102. Badia, J.D.
    et al.
    Strömberg, Emma
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Ribes-Greus, A
    The role of crystalline, mobile amorphous and rigid amorphous fractions on the performance of recycled poly (ethylene terephthalate) (PET)2012In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 97, no 1, p. 98-107Article in journal (Refereed)
    Abstract [en]

    The action of thermo-mechanical degradation induced by mechanical recycling of poly(ethylene terephthalate) was simulated by successive injection moulding cycles. Degradation reactions provoked chain scissions and a reduction in molar mass mainly driven by the reduction of diethyleneglycol to ethylene glycol units in the flexible domain of the PET backbone, and the formation ofeOH terminated species with shorter chain length. The consequent microstructural changes were quantified taking into account a three-fraction model involving crystalline, mobile amorphous (MAF) and rigid amorphous fractions (RAF). A remarkable increase of RAF, to a detriment of MAF was observed, while the percentage of crystalline fraction remained nearly constant. A deeper analysis of the melting behaviour, the segmental dynamics around the glass-rubber relaxation, and the macroscopic mechanical performance, showed the role of each fraction leading to a loss of thermal, viscoelastic and mechanical features, particularly remarkable after the first processing cycle.

  • 103. Badia, J.D.
    et al.
    Strömberg, Emma
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Ribes-Greus, Amparo
    Characterization of Induced Thermo-mechanical Degradation on Poly (ethylene terephthalate)2011Conference paper (Refereed)
  • 104. Badia, J.D.
    et al.
    Strömberg, Emma
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Ribes-Greus, Amparo
    STUDY OF THERMO-MECHANICAL AND THERMO-OXIDATIVE DEGRADATION OF POLYLACTIDE BYMALDI-TOF MS. A STATISTICAL DESIGN OF EXPERIMENTS TO OPTIMIZE THE SAMPLE PREPARATIONPROCEDURES2011Conference paper (Refereed)
  • 105.
    Badía, J. D.
    et al.
    Universidad Politécnica de Valencia, Spain.
    Moriana, Rosana
    Universidad Politécnica de Valencia, Spain.
    Santonja-Blasco, L.
    Universidad Politécnica de Valencia, Spain.
    Ribes-Greus, A.
    Universidad Politécnica de Valencia, Spain.
    A thermogravimetric approach to study the influence of a biodegradation in soil test to a Poly(lactic acid)2008In: Macromolecular Symposia, ISSN 1022-1360, E-ISSN 1521-3900, Vol. 272, no 1, p. 93-99Article in journal (Refereed)
    Abstract [en]

    An amorphous grade Poly (lactic acid) (PLA) was selected for an accelerated burial in soil test during 450 days. Thermogravimetric analyses were carried out to study the effects of degradation in soil on the thermal stability and the thermal decomposition kinetics. A single stage decomposition process is observed for all degradation times. It is shown that the thermal stability of PLA is slightly affected by degradation in soil. Concerning the study of the thermal decomposition kinetics, Criado master curves were plotted from experimental data to focus the study of the thermodegradation kinetic model.The kinetic methods proposed by Broido and Chang were used to calculate the apparent activation energies (Ea) of the degradation mechanism. These results were compared to the Ea values obtained by the method developed by Coats and Redfern in order to prove the applicability of the former methods to the kinetic study. As expected, non-linear tendency is found out for Ea variation along the degradation times, which can be explained as an evolution by stages. Copyright © 2008 WILEY-VCH Verlag GmbH & Co. KGaA.

  • 106.
    Badía, José David
    et al.
    Instituto de Investigación en Tecnología de Materiales, Universidad Politécnica de Valencia, Spain.
    Santonja-Blasco, Laura
    Instituto de Investigación en Tecnología de Materiales, Universidad Politécnica de Valencia, Spain.
    Moriana, Rosana
    Instituto de Investigación en Tecnología de Materiales, Universidad Politécnica de Valencia, Spain.
    Ribes-Greus, Amparo
    Instituto de Investigación en Tecnología de Materiales, Universidad Politécnica de Valencia, Spain.
    Thermal analysis applied to the characterization of degradation in soil of polylactide: II. on the thermal stability and thermal decomposition kinetics2010In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 95, no 11, p. 2192-2199Article in journal (Refereed)
    Abstract [en]

    The disposal stage of polylactide (PLA) was assessed by burying it in active soil following an international standard. Degradation in soil promotes physical and chemical changes in the polylactide properties. The characterization of the extent of degradation underwent by PLA was carried out by using Thermal Analysis techniques. In this paper, studies on the thermal stability and the thermal decomposition kinetics were performed in order to assess the degradation process of a commercial PLA submitted to an accelerated soil burial test by means of multi-linear-non-isothermal thermogravimetric analyses. Results have been correlated to changes in molecular weight, showing the same evolution as that described by the parameters of thermal stability temperatures and apparent activation energies. The decomposition reactions can be described by two competitive different mechanisms: Nucleation model (A2) and Reaction Contracting Volume model (R3). The changes in the kinetic parameters and kinetic models are in agreement with the calorimetric and dynamic-mechanical-thermal results, presented in the Part I of the study [1]. © 2010 Elsevier Ltd. All rights reserved.

  • 107.
    Bakare, Fatimat O.
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Ramamoorthy, Sunil Kumar
    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.
    Thermomechanical properties of bio-based composites made from a lactic acid thermoset resin and flax and flax/basalt fibre reinforcements2016In: Composites. Part A, Applied science and manufacturing, ISSN 1359-835X, E-ISSN 1878-5840, Vol. 83, p. 176-184Article in journal (Refereed)
    Abstract [en]

    Low viscosity thermoset bio-based resin was synthesised from lactic acid, allyl alcohol and pentaerythritol. The resin was impregnated into cellulosic fibre reinforcement from flax and basalt and then compression moulded at elevated temperature to produce thermoset composites. The mechanical properties of composites were characterised by flexural, tensile and Charpy impact testing whereas the thermal properties were analysed by dynamic mechanical thermal analysis (DMTA) and thermogravimetric analysis (TGA). The results showed a decrease in mechanical properties with increase in fibre load after 40 wt.% for the neat flax composite due to insufficient fibre wetting and an increase in mechanical properties with increase fibre load up to 60 wt.% for the flax/basalt composite. The results of the ageing test showed that the mechanical properties of the composites deteriorate with ageing; however, the flax/basalt composite had better mechanical properties after ageing than the flax composite before ageing.

  • 108. Bedo, Daniel
    et al.
    Imre, Balazs
    KTH, School of Biotechnology (BIO), Glycoscience. Hungarian Academy of Sciences, Hungary; Budapest University of Technology and Economics, Hungary.
    Domjan, Attila
    Schoen, Peter
    Vancso, G. Julius
    Pukanszky, Bela
    Coupling of poly(lactic acid) with a polyurethane elastomer by reactive processing2017In: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 97, p. 409-417Article in journal (Refereed)
    Abstract [en]

    A segmented polyurethane elastomer (PU) was synthesized in poly(lactic acid) (PLA) melt by reactive processing. The isocyanate component was anticipated to react with the end-groups of PLA resulting in the formation of block-copolymers. The stoichiometry of the functional groups was optimized in the preliminary experiments. Two different processing methods were compared in the further experiments: conventional mixing of PU with PLA (PLA/PU), and reactive blending (PLA-b-PU). The comparison of the structure and properties of compatibilized reactive blends and conventional physical blends clearly shows the benefits of reactive processing. Coupling resulted in a finer dispersion of the particles in the matrix leading to better mechanical properties in the reactive blend. The successful synthesis of PEA-b-PU block copolymers was confirmed by NMR spectroscopy. The isocyanate component was found to react only with the hydroxyl end-groups of PLA, while the formation of amide and acylurea groups was not detected on the carboxyl end.

  • 109.
    Benselfelt, Tobias
    et al.
    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.
    Cranston, Emily D.
    Department of Chemical Engineering, McMaster University.
    Ondaral, Sedat
    Department of Pulp and Paper Technology, Karadeniz Technical University.
    Johansson, Erik
    Cellutech AB.
    Brumer, Harry
    The Michael Smith Laboratories and the Department of Chemistry, The University of British Columbia.
    Rutland, Mark W.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Adsorption of Xyloglucan onto Cellulose Surfaces of Different Morphologies: An Entropy-Driven Process2016In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 17, no 9, p. 2801-2811Article in journal (Refereed)
    Abstract [en]

    The temperature-dependence of xyloglucan (XG) adsorption onto smooth cellulose model films regenerated from N-methylmorpholine N-oxide (NMMO) was investigated using surface plasmon resonance spectroscopy, and it was found that the adsorbed amount increased with increasing temperature. This implies that the adsorption of XG to NMMO-regenerated cellulose is endothermic and supports the hypothesis that the adsorption of XG onto cellulose is an entropy-driven process. We suggest that XG adsorption is mainly driven by the release of water molecules from the highly hydrated cellulose surfaces and from the XG molecules, rather than through hydrogen bonding and van der Waals forces as previously suggested. To test this hypothesis, the adsorption of XG onto cellulose was studied using cellulose films with different morphologies prepared from cellulose nanocrystals (CNC), semicrystalline NMMO-regenerated cellulose, and amorphous cellulose regenerated from lithium chloride/dimethylacetamide. The total amount of high molecular weight xyloglucan (XGHMW) adsorbed was studied by quartz crystal microbalance and reflectometry measurements, and it was found that the adsorption was greatest on the amorphous cellulose followed by the CNC and NMMO-regenerated cellulose films. There was a significant correlation between the cellulose dry film thickness and the adsorbed XG amount, indicating that XG penetrated into the films. There was also a correlation between the swelling of the films and the adsorbed amounts and conformation of XG, which further strengthened the conclusion that the water content and the subsequent release of the water upon adsorption are important components of the adsorption process.

  • 110.
    Benyahia Erdal, Nejla
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.
    Adolfsson, Karin H.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Pettersson, Torbjörn
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Hakkarainen, Minna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Green Strategy to Reduced Nanographene Oxide through Microwave Assisted Transformation of Cellulose2018In: ACS Sustainable Chemistry and Engineering, ISSN 2168-0485, Vol. 6, no 1, p. 1245-1255Article in journal (Refereed)
    Abstract [en]

    A green strategy for fabrication of biobased reduced nanographene oxide (r-nGO) was developed. Cellulose derived nanographene oxide (nGO) type carbon nanodots were reduced by microwave assisted hydrothermal treatment with superheated water alone or in the presence of caffeic acid (CA), a green reducing agent. The carbon nanodots, r-nGO and r-nGO-CA, obtained through the two different reaction routes without or with the added reducing agent, were characterized by multiple analytical techniques including FTIR, XPS, Raman, XRD, TGA, TEM, AFM, UV-vis, and DLS to confirm and evaluate the efficiency of the reduction reactions. A significant decrease in oxygen content accompanied by increased number of sp2 hybridized functional groups was confirmed in both cases. The synergistic effect of superheated water and reducing agent resulted in the highest C/O ratio and thermal stability, which also supported a more efficient reduction. Interesting optical properties were detected by fluorescence spectroscopy where nGO, r-nGO, and r-nGO-CA all displayed excitation dependent fluorescence behavior. r-nGO-CA and its precursor nGO were evaluated toward osteoblastic cells MG-63 and exhibited nontoxic behavior up to 200 μg mL-1, which gives promise for utilization in biomedical applications.

  • 111.
    Bergenstrahle-Wohlert, Malin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    d'Ortoli, Thibault Angles
    Sjoberg, Nils A.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Widmalm, Goran
    Wohlert, Jakob
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    On the anomalous temperature dependence of cellulose aqueous solubility2016In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 23, no 4, p. 2375-2387Article in journal (Refereed)
  • 112.
    Berggren, Frida
    KTH, School of Chemical Science and Engineering (CHE).
    Development of an Expancel Product through Optimisation of Polymer Composition and the Suspension Stabilising System2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Thermally expandable microspheres are spherical particles around 5-­‐40 µm in size, consisting of a polymeric shell in which a blowing agent has been encapsulated. The microspheres are expanded upon heating, resulting in a particularly low density. Microspheres are therefore suitable to use as light weight filler or as foaming agent.

    AkzoNobel is world leading in the production of expandable microspheres, which are commercialised under the name Expancel. Sustainability is a great focus at AkzoNobel and two issues that AkzoNobel works with today is to develop products free from chlorine and Me1. The aim with this thesis has been to investigate whether it is possible to produce microspheres free from these chemicals and to see if they can be a more sustainable alternative to one of the existing Expancel grades.

    In this study, the microspheres have been produced through free radical suspension polymerisation and analysed by measuring mainly the particle size and expansion properties. The polymeric shell was composed of the monomers acrylonitrile, methacrylonitrile, and methyl acrylate. The main focus has been to evaluate the silica-­‐based stabilisation system, which stabilise the monomer droplets during the suspension polymerisation. The stabilisation is possible due to the formation of silica flocs that is adsorbed on the surface of the droplets. It has been investigating how different parameters, e.g. amount of stabiliser or mixing procedure, affects the formation of silica flocs and the stabilisation of monomer droplets.

    For the silica-­‐based system, it was found that the mixing order, stirring rate, and amount of stabilisers affect the formation of flocs. It was also seen that the amount of stabiliser affect the stabilisation of droplets, and that some stabilisers is more significant than others.

    Microspheres without chlorine and Me1 have successfully been produced in laboratory scale (50 mL and 1 L). The expansion and size of the microspheres produced in this study was relatively similar to one of the existing Expancel grades. However, the reproducibility of polymerisations in 1 litre reactors has been poor.

  • 113.
    Berglund, Jennie
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Azhar, Shoaib
    Lawoko, Martin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Lindström, Mikael
    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.
    Vilaplana, Francisco
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Glycoscience. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Wohlert, Jakob
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Henriksson, Gunnar
    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.
    The structure of galactoglucomannan impacts the degradation under alkaline conditions2018In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882XArticle in journal (Refereed)
    Abstract [en]

    Galactoglucomannan (GGM) from sprucewas studied with respect to the degradation behavior inalkaline solution. Three reference systems includinggalactomannan from locust bean gum, glucomannanfrom konjac and the linear water-soluble carboxymethylcellulose were studied with focus onmolecular weight, sugar composition, degradationproducts, as well as formed oligomers, to identifyrelative structural changes in GGM. Initially allmannan polysaccharides showed a fast decrease inthe molecular weight, which became stable in the laterstage. The degradation of the mannan polysaccharidescould be described by a function corresponding to thesum of two first order reactions; one slow that wasascribed to peeling, and one fast that was connectedwith hydrolysis. The galactose side group wasstable under conditions used in this study (150 min,90 C, 0.5 M NaOH). This could suggest that, apartfrom the covalent connection to C6 in mannose, thegalactose substitutions also interact non-covalentlywith the backbone to stabilize the structure againstdegradation. Additionally, the combination of differentbackbone sugars seems to affect the stability of thepolysaccharides. For carboxymethyl cellulose thedegradation was linear over time which furthersuggests that the structure and sugar composition playan important role for the alkaline degradation. Moleculardynamics simulations gave details about theconformational behavior of GGM oligomers in watersolution, as well as interaction between the oligomersand hydroxide ions.

  • 114. Bergnor, Elisabeth
    et al.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Johansson, E
    The role of metal ions in TCF-bleaching.1994In: Proceedings 3rd European Workshop on Lignocellulosics and Pulp, 1994, p. 284-289Conference paper (Refereed)
  • 115.
    Bergström, L. Magnus
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Aratono, Makoto
    Synergistic effects in mixtures of two identically charged ionic surfactants with different critical micelle concentrations2011In: Soft Matter, ISSN 1744-683X, E-ISSN 1744-6848, Vol. 7, no 19, p. 8870-8879Article in journal (Refereed)
    Abstract [en]

    Expressions for the critical micelle concentration (cmc) and activity coefficients as functions of surfactant composition in mixtures of two identically charged monovalent ionic surfactants are derived from the nonlinear Poisson-Boltzmann (PB) theory. For the special case of no added salt, the simple expression cmc(alpha) = xcmc(1)(alpha) + (1 - x)cmc(2)(alpha) is deduced, where the exponential parameter alpha > 1 depends on the number of ionic species in a surfactant molecule as well as the curvature of the self-assembled interface. Theoretical predictions are compared with cmc values obtained with some different experimental techniques for mixtures of the two cationic surfactants didodecyldimethylammonium bromide (DDAB) and dodecyltrimethylammonium bromide (DTAB) in water and in the absence of added salt. It is demonstrated that the PB theory generates significantly better agreement with experimental data than predicted by ideal behaviour or the regular mixture theory. We find that maximum synergistic effects occur at a DDAB mole fraction in solution y = 0.005. According to the PB theory, this very low value of y corresponds to a mole fraction of DDAB in the self-assembled interfacial aggregates equal to x = 0.995. Moreover, our calculations of the surfactant composition in the self-assembled interfacial aggregates above cmc demonstrate that the transition from small micelles to large bilayer aggregates is found to consistently occur at a mole fraction of DDAB equal to about x = 0.41-0.42, irrespective of the surfactant molar ratio in solution. Experimental observations strongly support the fact that concentrations of free surfactant, as well as the surfactant composition in the self-assembled interfacial aggregates, may be accurately calculated from the non-linear Poison-Boltzmann theory. On the other hand, a micelle-to-bilayer transition induced by changes in surfactant mole fraction in the self-assembled interfacial aggregates is consistent with neither ideal surfactant behaviour nor synergistic behaviour according to the regular mixture theory.

  • 116.
    Berts, Ida
    et al.
    Uppsala University, Science for Life Laboratory, SciLifeLab. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry.
    Fragneto, Giovanna
    Institut Laue-Langevin.
    Hilborn, Jöns
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Rennie, Adrian R.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Tuning the density profile of surface-grafted hyaluronan and the effect of counter-ions2013In: European Physical Journal E, ISSN 1292-8941, Vol. 36, no 7, p. 70-Article in journal (Refereed)
    Abstract [en]

    The present paper investigates the structure and composition of grafted sodium hyaluronanat a solid-liquid interface using neutron reflection. The solvated polymer at the surface could be described with a density profile that decays exponentially towards the bulk solution. The density profileof the polymer varied depending on the deposition protocol. A single-stage deposition resulted in denser polymer layers, while layers created with a two-stage deposition process were more diffuse and had an overall lower density. Despite the diffuse density profile, two-stage deposition leads to a highersurface excess. Addition of calcium ions causes a strong collapse of the sodium hyaluronan chains, increasing the polymer density near the surface. This effect is more pronounced on the sample prepared by two-stage deposition due to the initial less dense profile. This study provides an understanding at a molecular level of how surface functionalization alters the structure and howsurface layers respond to changes in calcium ions in the solvent.

  • 117.
    Berts, Ida
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Ossipov, Dmitri
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Fragneto, Giovanna
    Institut Laue-Langevin.
    Frisk, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Rennie, Adrian. R
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Polymeric Smart Coating Strategy for Titanium Implants2014In: Advanced Engineering Materials, ISSN 1438-1656, E-ISSN 1527-2648, Vol. 16, no 11, p. 1340-1350Article in journal (Refereed)
    Abstract [en]

    Hyaluronan based hydrogel coatings can mimic extracellular matrix components and incorporate growth factors that can be released during a progressive degradation while new tissue regenerates. This paper describes a structural characterization of a hydrogel coating made of modified hyaluronan polymers and how these coatings interact with bone morphogenetic protein-2 (BMP-2). Quartz crystal microbalance and neutron reflectivity measurements were used for in-situ, real-time measurements of the adsorption properties of polymers and proteins on smooth titanium oxide surfaces that mimic implant products in orthopedics. The adsorption of BMP-2 on a bare titanium oxide surface is compared to that on titanium oxide coated with different chemically modified hyaluronan, the most important being hyaluronan with bisphosphonate groups (HA-BP). The subsequent release of the BMP-2 from these hydrogel coatings could be triggered by calcium ions. The amount of adsorbed protein on the surfaces as well as the amount of released protein both depend on the type of hyaluronan coating. We conclude that HA-BP coated titanium oxide surfaces provide an excellent material for growth factor delivery in-vivo.

  • 118.
    Bi, Ran
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Lignocellulose Degradation by Soil Micro-organisms2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Lignocellulosic biomass is a sustainable resource with abundant reserves. Compared to petroleum ‐ based products, the biomass ‐ derived polymers and chemicals give better environmental profiles. A lot of research interest is focused on understanding the lignocellulose structures.

    Lignin, among the three major wood components, represents most difficulty for microbial degradation because of its complex structure and because cross ‐ linking to hemicellulose makes wood such a compact structure. Nevertheless, wood is naturally degraded by wood ‐ degrading micro ‐ organisms and modified and partly degraded residual of lignin goes into soil. Therefore soil serves as a good environment in which to search for special lignin ‐ degraders. In this thesis, different types of lignin have been used as sole carbon sources to screen for lignin ‐ degrading soil micro ‐ organisms. Eleven aerobic and three anaerobic microbe strains have been isolated and identified as able to grow on lignin. The lignin degradation patterns of selected strains have been studied and these partly include an endwise cleavage of  β‐ O ‐ 4 bonds in lignin and is more complex than simple hydrolytic degradation.

    As lignin exists in wood covalently bonded to hemicellulose, one isolated microbe strain, Phoma herbarum, has also been studied with regards to its ability to degrade covalent lignin polysaccharide networks (LCC). The results show that its culture filtrate can attack lignin ‐ polysaccharide networks in a manner different from that of the commercial enzyme product, Gammanase, possibly by selective cleavage of phenyl glucoside bonds. The effects on LCC of Phoma herbarum also enhance polymer extractability. Hot ‐ water extraction of a culture filtrate of Phoma herbarum ‐ treated fiberized spruce wood material gave an amount of extracted galactoglucomannan more than that given by the Gammanase ‐ treated material and non ‐ enzyme ‐ treated material.

    Over millions of years of natural evolution, micro ‐ organisms on the one hand develop so that they can degrade all wood components to get energy for growth, while plants on the other hand also continuously develop to defend from microbial attack. Compared with lignin and cellulose, hemicelluloses as major components of plant cell walls, are much more easily degraded, but hemicelluloses differ from cellulose in that they are acetylated to different extents. The biological functions of acetylation are not completely understood, but it is suggested is that one function is to decrease the microbial degradability of cell walls. By cultivation of soil micro ‐ organisms using mannans acetylated to deffernent degrees as sole carbon source on agar plates, we were able to see significant trends where the resistance towards microbial degradation of glucomannan and galactomannan increased with increasing degree of acetylation. Possible mechanisms and the technological significance of this are discussed. Tailoring the degree of acetylation of polysaccharide materials might slow down the biodegradation, making it possible to design a material with a degradation rate suited to its application.

  • 119.
    Bi, Ran
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Azhar, Shoaib
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Mckee, Lauren
    KTH, School of Biotechnology (BIO), Glycoscience. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Henriksson, Gunnar
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Culture Filtrates from a Soil Organism Enhances Extractability of Polymers from Fiberised Spruce WoodManuscript (preprint) (Other academic)
  • 120.
    Bi, Ran
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Berglund, Jennie
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Vilaplana, Francisco
    KTH, School of Biotechnology (BIO), Glycoscience. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    McKee, Lauren
    KTH, School of Biotechnology (BIO), Glycoscience. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Henriksson, Gunnar
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    The Degree Of Acetylation Affects The Microbial Degradability Of HemicellulosesManuscript (preprint) (Other academic)
  • 121.
    Bi, Ran
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Huang, Shan
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology. Linnaus University, Sweden.
    Henriksson, Gunnar
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Isolation of exceedingly low oxygen consuming fungal strains able to utilize lignin as carbon sourceIn: Cellulose Chemistry and Technology, ISSN 0576-9787Article in journal (Refereed)
  • 122.
    Bi, Ran
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Lawoko, Martin
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Henriksson, Gunnar
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Phoma herbarum, a soil fungus able to grow on natural lignin and synthetic lignin (DHP) as sole carbon source and cause lignin degradationManuscript (preprint) (Other academic)
  • 123.
    Bi, Ran
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Oinonen, Petri
    Ecohelix AB, Teknikringen 38, 10044 Stockholm, Sweden.
    Wang, Yan
    Henriksson, Gunnar
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    A Method for Studying Effects on Lignin-Polysaccharide Networks during Biological Degradation and Technical Processes of Wood2016In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 11, no 1, p. 1307-1318Article in journal (Refereed)
    Abstract [en]

    Woody tissues consist primarily of a mixture of cellulose, hemicelluloses, and lignin. Covalent bonds between lignin and polysaccharides likely play a central role in determining the mechanical and physical properties of wood. Intact and defined lignin-polysaccharide networks have not been isolated in large quantities because of the recalcitrance of lignin, which demands harsh chemical treatments that alter its structure. This report presents a method for preparing large quantities of lignin-polysaccharide networks similar to those naturally present in wood based on the enzymatic oxidation of hemicellulose from Norway spruce. Fungal enzymes produced from various carbon sources were used to depolymerize these networks. The method was used for simulating "enzyme mining" - a concept in biorefineries, giving a possible explanation for its mechanisms.

  • 124.
    Bladholm, Viktor
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    Organic Fillers for Solid Rocket Fuel2018Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Liquid propellant and solid propellant rockets are the most commonly used rockets

    Liquid propellant rockets have the advantage of being manoeuvrable with a high specific performance while they exhibit problems with storage and a complex design. Solid propellant rockets offer simplicity and are storable while they have a large environmental impact and could be difficult to handle. A third type of rocket, hybrid propellant rocket has the potential to combine the simplicity of solid propellant rocket with the manoeuvrability of liquid propellant rockets. While the hybrid propellant rocket offers advantages over liquid propellant and solid propellant rocket it have problems with its fuel which have a low regression rate and low density. Organic fillers were evaluated since they may increase in the regression rate and the density of the solid fuel. 50 organic fillers were assessed with regards to their specific impulse, density, cost and handling properties. The organic fillers with the most promising properties were then experimentally evaluated. Thermogravimetric analysis (TGA), isothermal weight loss test, compatibility test and differential scanning calorimetry analysis were conducted. The results indicate that hexamine, fluorene, anthracene and 1,4-dicyanobenzene are the most suitable organic fillers of those evaluated..

  • 125.
    Blinkovskaja, Irina
    KTH, School of Chemical Science and Engineering (CHE).
    Lanasol på bomull, ylle och fleece2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A new type of natural, antimicrobial, biocompatible agent is presented. Lanasol--a brominated cyclic compound that can be extracted from red sea algae and occurs naturally was applied onto the three most commonly available fabrics: cotton, wool and fleece. Samples of the fabrics were tested for a series of properties such Antibacterial effectiveness, durability to laundering and flammability.

     

    The treated fabric surface and the Lanasol percentage present at the surface of the fabric were evaluated by performing SEM, IR and Density Archimedes. The antimicrobial activity of the coated fibres against fungi Fussarium, was assessed using qualitative Agar diffusion test.

     

    The Lanasol treated samples displayed very good antimicrobial properties compared to the untreated control samples.  It was observes that antibacterial effectives increased significantly with higher Lanasols solutions of 10% compared to 2,5%. Antibacterial properties remained effective after 10 washes but decreased visibly after 20 washes.  Anti-flammability properties were strongest in unwashed samples with considerable ignition time differences to the untreated control samples.

     

    The results obtained from the current study demonstrate that Lanasol, which has previously not been tested for textile durability, has significant potential as a new antibacterial agent. This concept opens the door to further research into the increasing the antimicrobials properties as well as enhancing the success of commercial application of Lanasol for textile treatment.

  • 126.
    Blomfeldt, Thomas
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Freeze-Dried Wheat Gluten-Based Foams2012Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis presents wheat gluten foams as an alternative to the available commercialfoams. Polymeric foams, like all plastics, are mostly made from petroleum, and this isaffecting the environment negatively with the emission of greenhouse gases and generation oflandfills. During the past decades, there has been a drive to replace petroleum-based plasticswith alternatives made from renewable resources. Wheat gluten has interesting and promisingproperties as an alternative resource. As a large by-product in Europe from the biofuelindustry it is largely available and at a low price.In order to develop an insulation material based on this renewable resource, foammaterials have been made by freeze-drying frozen mixtures consisting of either acommercially available wheat gluten powder or various protein rich fractions of gliadins orglutenins extracted from the commercial powder. Some of the foams were further modifiedwith the addition of glycerol as plasticizer or bacterial cellulose as a reinforcing fiber. Theresulting cellular structure was shown to depend on the initial gluten concentration, and thefraction and type of additive used. The wheat gluten foam materials contained mainly an openpore structure with average pore diameters ranging from 20 to 70 μm.The addition of glycerol and/or bacterial cellulose changed the foam structure, theprotein structure and the mechanical properties. The addition of 20 wt.% glycerol wassufficient to plasticize the foam and to achieve a low modulus and a high strain recovery, butwith glycerol the average pores size increased due to the difference in freezing conditions.The bacterial cellulose gave a small and insignificant increase in stiffness and also a moreuniform cell structure. In addition, the glycerol-containing samples had a more polymerizedprotein structure, whereas the foams containing fibers had a lower degree of polymerization.Foams made from a glutenin rich fraction were much stiffer and stronger than gliadinrich foams. The glutenin rich foams had a higher degree of polymerization than the latter,foam the relatively mild heat treatment.The gluten foams were promising as insulation materials. The thermal conductivityvalues were 0.04-0.05 (W/m⋅°C), and were close to that of commercially available closed cellpolystyrene and polyurethane foams, that both have values at ca. 0.03 (W/m⋅°C).The wheat gluten foams showed also promising combustion properties with longignition times, no material dripping and a large content of residual char. The glycerolcontainingfoam however, exhibited a more rigorous bubbling and a larger flame.

  • 127.
    Bolakhrif, Sabah
    KTH, School of Chemical Science and Engineering (CHE).
    Synthesis and application of PLA and PLA/GO fibers through thermo-responsive transformation of PLA particles2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    PLA nanofibers were successively produced by thermo-responsive transformation of PLA particles in water. The morphological structure of the nanofibers could be optimized by the heat treatment as well as the incorporation of GO to the fiber surface. PLA/GO fiber demonstrated a more stable morphology and GO provided good compatibility between PLA and starch. Both PLA and PLA/GO fibers incorporated in starch films resulted in increased thermal stability and mechanical properties. However, the most favorable properties were assigned starch films containing high concentration of PLA/GO fibers. These films with completely green components could possibly be utilized in biodegradable packaging applications.

                                                                                                                               

  • 128.
    Bor, Yasemin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Alin, Jonas
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Hakkarainen, Minna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Polylactide stereocomplexation leads to reduced migration during microwave heating in contact with food simulants2014In: Journal of Food Engineering, ISSN 0260-8774, E-ISSN 1873-5770, Vol. 134, p. 1-4Article in journal (Refereed)
    Abstract [en]

    The effect of stereocomplexation on the stability and migration resistance of polylactide during microwave and conventional heating in contact with different food simulants was evaluated. The heating effects were followed through mass loss measurements, molecular weight measurements and identification of the individual migrants by electrospray ionization-mass spectrometry (ESI-MS). Increased mass losses were observed as a function of time and temperature, but approximately 50% smaller mass losses were always measured for PLA stereocomplex as compared to the corresponding regular PLEA material. The stability of the stereocomplex material was, thus, significantly higher. Microwave heating increased the mass loss as compared to the conventional heating at the same time and temperature. This effect was especially significant when 10% ethanol was used as food simulant instead of water. The amount of water-soluble migrants was in most cases under the detection limits, but when heating temperature was increased to 95 C, ESI-MS revealed the formation of homologous series of linear lactic acid oligomers. Results indicate that PEA stereocomplex materials could have potential in single-use microwave applications.

  • 129. Bose, Indranil
    et al.
    Ohlander, Anna
    Stich, Matthias I. J.
    Kiesl, Christian
    Hemmetzberger, Dieter
    Klink, Gerhard
    Trupp, Sabine
    Bock, Karlheinz
    Polymer opto-chemical-electronic based module as a detection system for volatile analytes on a foil substrate2012In: Proceedings of SPIE - The International Society for Optical Engineering, SPIE - International Society for Optical Engineering, 2012, Vol. 8479Conference paper (Other academic)
    Abstract [en]

    In this paper, we report on a novel device that addresses the needs for an efficient, field deployable and disposable system in the field of bio-chemical sensors using organic semiconductors. The Fraunhofer Institute has enabled a complete roll-to-roll manufactured polymer-opto-chemical-electronic module on a foil substrate, wherein an electroluminescent light source has been hetero-integrated together with an organic TFT, working as a photo detector. A chemically sensitive, colour changing film is sandwiched in between the two elements to form an optical detection system for volatile analytes such as amines. The setup, henceforth referred to as the “PolyOpto” module, comprises of a dye coated layer that can detect specific chemical reactions by colour change inserted in between the EL light source and the OTFT photo-detector. A hole is laser cut through the system to allow the sensor layer to come in contact with the gases, which then through a chemical reaction, changes colour and initiates a different response in the output of the organic transistor. Hence, this allows for a disposable chemo-analytical system that can be used in various application fields. As compared to conventional systems, the advantage here lies in the direct integration of the different functionalities without any advanced assembly steps, simultaneous use of coatings for both components (transparent electrode and wiring layer) and roll-to-roll compatibility, thus rendering a disposable system. We believe that it aptly demonstrates the capabilities of polytronics in functional integration for low-cost bio-sensor manufacturing

  • 130.
    Boujemaoui, Assya
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. 831220-7585.
    Polycaprolactone  Nanocomposites Reinforced  with   Cellulose Nanocrystals  Surface - modified  via  Covalent  Grafting  or  Physical Adsorption - a Comparative studyManuscript (preprint) (Other academic)
  • 131.
    Boujemaoui, Assya
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. 831220-7585.
    RAFT/MADIX Polymerization of Vinyl Acetate on Cellulose Nanocrystals for Nanocomposite ApplicationsManuscript (preprint) (Other academic)
  • 132.
    Boujemaoui, Assya
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology. 831220-7585.
    Surface Modification of Nanocellulose towards Composite Applications2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Nanocelluloses have attracted great interest during recent decades owing to their renewability, abundancy and remarkable physical and mechanical properties. The aim of this work was to investigate new strategies for surface modification and functionalization of nanocelluloses and their subsequent incorporation in polymer-host matrices.

    Nanocomposites of cellulose nanofibrils (CNF) and polycaprolactone (PCL) were produced by employing CNF nanopaper (NP) as a template and surface-initiated ring-opening polymerization (SI-ROP) of ε-caprolactone (ε-CL). SI-ROP of ε-CL from filter paper (FP) was also carried out for comparison. A larger amount of PCL was grafted from NP than from FP. The grafted NP had stronger mechanical properties than neat PCL.

    Cellulose nanocrystal (CNC)-reinforced polyvinyl acetate (PVAc) nanocomposites were also investigated. CNC were modified via “SI-reversible addition-fragmentation chain transfer and macromolecular design via the interchange of xanthate” (SI-RAFT/MADIX) polymerization of vinyl acetate (VAc). The resulting nanocomposites exhibited improved mechanical performance than the unmodified CNC.

    It is generally agreed that covalent grafting is superior to physical adsorption for the modification of a reinforcing agent. However, this hypothesis has never been thoroughly investigated. CNC was modified either through covalent grafting or through physical adsorption of poly(butyl methacrylate) (PBMA). Both methods resulted in improved mechanical performance than that of pure PCL or PCL containing unmodified CNC. However, covalent grafting gave the best mechanical performance even at high relative humidity.

    Functionalized CNC (F-CNC) were obtained through a versatile methodology employing organic acids bearing a functional group were employed for the simultaneous acid hydrolysis and esterification of cellulose fibers. This provided a facile route for the preparation of F-CNC.

  • 133.
    Boujemaoui, Assya
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Mazieres, Stephane
    Malmström, Eva
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Destarac, Mathias
    Carlmark, Anna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    SI-RAFT/MADIX polymerization of vinyl acetate on cellulose nanocrystals for nanocomposite applications2016In: Polymer, ISSN 0032-3861, E-ISSN 1873-2291, Vol. 99, p. 240-249Article in journal (Refereed)
    Abstract [en]

    In the present work, poly(vinyl acetate) grafted cellulose nanocrystals (CNC-g-PVAc) were prepared via surface initiated reversible addition-fragmentation chain transfer and macromolecular design via the interchange of xanthates (SI-RAFT/MADIX) polymerization. Successful grafting of PVAc from CNC was confirmed by FT-IR and TGA analysis. PVAc nanocomposites reinforced with CNC-g-PVAc, as well as pristine CNC for comparison, of different weight percentages (0.5, 1, 3 and 5 wt%) of CNC were prepared via solvent casting. The PVAc reinforced with CNC-g-PVAc resulted in higher transparency and improved mechanical properties compared with unmodified CNC nanocomposites. The addition of 5 wt% CNC-g-PVAc increased the modulus of neat PVAc with as much as 154%. The proposed SI-RAFT/MADIX on CNC could be applied to wide range of monomers, and it is believed to be an efficient and robust method for CNC functionalization, thus expanding the potential applicability of CNC.

  • 134.
    Boujemaoui, Assya
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Mongkhontreerat, Surinthra
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    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.
    Preparation and characterization of functionalized cellulose nanocrystals2015In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 115, p. 457-464Article in journal (Refereed)
    Abstract [en]

    In this work, a series of functional nanocrystals (F-CNCs) was successfully produced by an efficient preparation method, combining acid hydrolysis and Fischer esterification with various organic acids. Functionalities such as ATRP initiators, double bonds, triple bonds, and thiols could be incorporated on CNCs. Surface modification was confirmed by FT-IR, XPS, and elemental analysis. Physical properties of FC-NCs were assessed by AFM, XRD and TGA. Moreover, ATRP initiator functionalized CNCs were utilized to graft poly(methyl methacrylate) via ATRP, thiol functionalized CNCs were reacted with Ellman's reagent to determine the thiol content and dye disperse red 13 was attached to alkyne functionalized CNCs to estimate the propiolate content. The herein presented method is a highly versatile and straightforward procedure for the preparation of F-CNCs which is believed to be a better alternative for the commonly utilized, extensive, multistep, and time consuming post functionalization methods.

  • 135.
    Bruce, Carl
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Surface Modification of Cellulose by Covalent Grafting and Physical Adsorption for Biocomposite Applications2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    There is an increasing interest to replace fossil-based materials with renewable alternatives. Cellulose fibers/nanofibrils (CNF) are sustainable options since they are biobased and biodegradable. In addition, they combine low weight with high strength; making them suitable to, for example, reinforce composites. However, to be able to use them as such, modifications are often necessary. This study therefore aimed at modifying cellulose fibers, model surfaces of cellulose and CNF. Cellulose fibers and CNF were thereafter incorporated into composite materials and evaluated.

    Surface-initiated ring-opening polymerization (SI-ROP) was performed to graft ε-caprolactone (ε-CL) from cellulose fibers. From these fibers, paper-sheet biocomposites were produced that could form laminate structures without the need for any addition of matrix polymer.

    By combining ROP and atom transfer radical polymerization (ATRP), diblock copolymers of poly(2-dimethylaminoethyl methacrylate) (PDMAEMA) and PCL were prepared. Quaternized (cationic) PDMAEMA, allowed physical adsorption of block copolymers onto anionic surfaces, and, thereby, alteration of surface energy and adhesion to a potential matrix. Furthermore, the architecture of block copolymers of PCL and PDMAEMA was varied to investigate effects on morphology/crystallinity and adsorption behavior. In addition, poly(butadiene) was also evaluated as the hydrophobic block in the form of cationic and anionic triblock copolymers.

    Polystyrene (PS) was covalently grafted from CNF and used as reinforcement in PS-based composites. In an attempt to determine stress transfer from matrix to CNF, a method based on Raman spectroscopy was utilized.

    Covalent grafting and physical adsorption of PCL from/onto CNF were compared by incorporating modified CNF in PCL matrices. Both approaches resulted in improved mechanical properties compared to unmodified CNF, but even at low amounts of modified CNF, covalent grafting gave tougher materials and indicated higher interfacial adhesion.

  • 136.
    BRÄNNSTRÖM, SARA
    KTH, School of Chemical Science and Engineering (CHE).
    En studie om hur koncentrerad saltsyra vid hög temperatur påverkar PP, PVC och CPVC2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Hydrochloric acid is commonly used in pickling plants where temperatures may be up to 90 °C. In such corrosive environments, pipes or containers of metals cannot be used and the use of plastic materials is therefore a more suitable option. For example it may be possible to use polypropylene (PP), polyvinyl chloride (PVC) and chlorinated PVC (CPVC) for these applications. Plastics are not standardized materials; therefore the chemical resistances of commercially available plastics need to be tested individually.

    The effect of hydrochloric acid (HCl) at high temperatures on commercially available materials from different manufacturers was studied. Totally five PP, five PVC and two CPVC materials were investigated. The materials were exposed to concentrated HCl at 60 °C for up to 8 weeks. The chemical changes were analyzed with Fourier Transfer Infrared Spectroscopy (FTIR). Differential Scanning Calorimetry (DSC) was used to measure the Oxidative Induction Time (OIT). The mechanical properties were studied with Charpy impact testing and tensile testing. An indicator technique was used to measure the diffusion of HCl in the materials. Quantification of how much HCl the materials absorb was performed with Ion chromatography (IC).

    The results showed that the PP samples lost antioxidants as seen in both FTIR spectra and changes in OIT. The PVC materials had a decrease in filler content where the acid had penetrated. The mechanical properties seemed to be unchanged after exposure for 8 weeks. Only two PVC materials seemed to have a decrease in stress at yield. Concluding, most of the tested PVC and CPVC materials are suitable for the use in contact with concentrated HCl. All PP, PVC and CPVC materials can be used in contact with concentrated HCl in 60 oC up to 8 weeks.

  • 137. Buchert, Johanna
    et al.
    Bergnor, Elisabeth
    Lindblad, Gunnar
    Viikari, Liisa
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Significance of xylan and glucomannan in the brightness reversion of kraft pulps1997In: TAPPI Journal, ISSN 0734-1415, Vol. 80, no 6, p. 165-171Article in journal (Refereed)
    Abstract [en]

    The brightness reversion of kraft pulps is caused by the presence of residual lignin, chlorinated extractives, or oxidized carbohydrates. The effect of hemicellulose content, i.e., xylan (I) and glucomannan (II), on the thermal stability of modern bleached kraft pulps was investigated. Different O-delignified hard- and softwood kraft pulps were bleached with different bleaching sequences contg. ClO2, H2O2, or O3. Hemicellulose-degrading enzymes, i.e., xylanase or mannanase, were used for selective removal of the resp. hemicellulose from the pulps, and the role of partially removed I and II on the brightness stability of these pulps was studied. Because of the structure of kraft I, enzymic removal of I also resulted in a decreased carboxyl group content in the pulps, whereas II removal did not affect the carboxyl group content. By decreasing the carboxyl groups in the pulps in conjunction with I removal, the thermal aging of the pulps was significantly decreased. The role of II was less significant. Thus, the uronic acids present in the pulp participate in the brightness reversion of kraft pulps.

  • 138. Buchert, Johanna
    et al.
    Bergnor, Elisabeth
    Lindblad, Gunnar
    Viikari, Liisa
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    The role of xylan and glucomannan in yellowing of kraft pulps.1995In: Proceedings 8th Int. Symp. Wood Pulp. Chem., 1995, p. 43-48Conference paper (Refereed)
    Abstract [en]

    The effects of xylan and glucomannan on the thermal stability of unbleached, partially bleached, and fully bleached pine and birch kraft pulps were studied.  The choice of bleaching chems. strongly affected the brightness reversion.  Compared with hydrogen peroxide or chlorine dioxide, bleaching with ozone reduced the amt. of carboxyl groups and subsequently the pc-nos. of oxygen-delignified pulps.  Xylan removal reduced also the amt. of carboxyl groups in the pulps and this was reflected in improved brightness stability whereas glucomannan removal had no effect.  Thus, the uronic acids bound to pulp xylan were found to participate in the brightness reversion of kraft pulps.

  • 139. Buchert, Johanna
    et al.
    Tenkanen, Maija
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Teleman, Anita
    Vuorinen, Tapani
    Effect of pulping and bleaching on pulp carbohydrates and technical properties.1996In: Proceedings Int. Pulp Bleaching, 1996, p. 39-42Conference paper (Refereed)
    Abstract [en]

    Pulping and bleaching have a profound effect on the carbohydrate chem. of kraft pulps.  The chem. structure of xylan is modified due to the conversion of methylglucuronic acid side groups to hexenuronic acid side groups.  Pulping conditions strongly affect the amt. of hexenuronic acid present in the pulp and subsequently modified kraft pulps have different carboxyl group profiles as compared with conventionally cooked pulps.  Due to its reactivity, hexenuronic acid is readily degraded when chlorine dioxide or ozone are used as bleaching chems.  However, TCF-pulps bleached with peroxide and oxygen contain high amts. of hexenuronic acid.  Thus, depending on the pulping and bleaching method, the quality and quantity of carboxylic acids in different types of pulps varies significantly.  The differences in the uronic acid content are in turn reflected in the macroscale properties of the pulps, such as brightness stability.       

  • 140.
    Burman, Lina
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Albertsson, Ann-Christine
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Hakkarainen, Minna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Indicator products and chromatographic fingerprinting: New tools for degradation state and lifetime estimation2008In: CHROMATOGRAPHY FOR SUSTAINABLE POLYMERIC MATERIALS: RENEWABLE, DEGRADABLE AND RECYCLABLE, Berlin: Springer Verlag , 2008, Vol. 211, p. 1-22Chapter in book (Refereed)
    Abstract [en]

    The demands on polymeric products are growing both with respect to their function and purity. There is a need for new high-throughput characterisation tools for rapid quality control and evaluation of materials. Precise control over degradation rate and service-life are also prerequisites for successful use of degradable polymers in an increasing number of applications. The chromatographic fingerprinting and indicator product concepts, presented in the current paper, are novel and attractive alternatives for rapid evaluation of the product quality, degradability, durability and service-life. The sensitivity of these techniques allows for detection of small initial changes in the materials and signs of early degradation. The possible applications include evaluation of different pro-oxidants or antioxidants, optimisation of processing parameters, evaluation of long-term properties or storage stability and lifetime prediction. The same principal could also be applied to process control and monitoring, acceptance or rejection of raw materials, intermediate and final products. The usefulness of indicator products and chromatographic fingerprinting is shown for estimation of the degradation state of degradable polyethylene. in addition, chromatographic fingerprinting together with multivariate data analysis is utilised to classify degradable polyethylene materials based on their incorporated pro-oxidant systems.

  • 141.
    Butchosa Robles, Núria
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites.
    Tailoring Cellulose Nanofibrils for Advanced Materials2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Cellulose nanofibrils (CNFs) are nanoscale fibers of high aspect ratio that can be isolated from a wide variety of cellulosic sources, including wood and bacterial cellulose. With high strength despite of their low density, CNFs are a promising renewable building block for the preparation of nanostructured materials and composites. To fabricate CNF-based materials with improved inherent rheological and mechanical properties and additional new functionalities, it is essential to tailor the surface properties of individual CNFs. The surface structures control the interactions between CNFs and ultimately dictate the structure and macroscale properties of the bulk material. In this thesis we have demonstrated different approaches, ranging from non-covalent adsorption and covalent chemical modification to modification of cellulose biosynthesis, to tailor the structure and surface functionalities of CNFs for the fabrication of advanced materials. These materials possess enhanced properties such as water-redispersibility, water absorbency, dye adsorption capacity, antibacterial activity, and mechanical properties.

    In Paper I, CNFs were modified via the irreversible adsorption of carboxymethyl cellulose (CMC). The adsorption of small amounts of CMC onto the surface of CNFs prevented agglomeration and co-crystallization of the nanofibrils upon drying, and allowed the recovery of rheological and mechanical properties after redispersion of dried CNF samples.

    In Paper II, CNFs bearing permanent cationic charges were prepared through quaternization of wood pulp fibers followed by mechanical disintegration. The activation of the hydroxyl groups on pulp fibers by alkaline treatment was optimized prior to quaternization. This optimization resulted in individual CNFs with uniform width and tunable cationic charge densities. These cationic CNFs demonstrated ultrahigh water absorbency and high adsorption capacity for anionic dyes.

    In Paper III, via a similar approach as in Paper II, CNFs bearing polyethylene glycol (PEG) were prepared by covalently grafting PEG to carboxylated pulp fibers prior to mechanical disintegration. CNFs with a high surface chain density of PEG and a uniform width were oriented to produce macroscopic ribbons simply by mechanical stretching of the CNF hydrogel network before drying. The uniform grafted thin monolayer of PEG on the surface of individual CNFs prevented the agglomeration of CNFs and facilitated their alignment upon mechanical stretching, thus resulted in ribbons with ultrahigh tensile strength and modulus. These optically transparent ribbons also demonstrated interesting biaxial light scattering behavior.

    In Paper IV, bacterial cellulose (BC) was modified by the addition of chitin nanocrystals (ChNCs) into the growing culture medium of the bacteria Acetobacter aceti which secretes cellulose in the form of entangled nanofibers. This led to the in situ incorporation of ChNCs into the BC nanofibers network and resulted in BC/ChNC nanocomposites exhibiting bactericidal activity. Further, blending of BC nanofibers with ChNCs produced nanocomposite films with relatively lower tensile strength and modulus compared to the in situ cultivated ones. The bactericidal activity increased significantly with increasing amount of ChNCs for nanocomposites prepared by direct mixing of BC nanofibers and ChNCs.

    In Paper V, CNFs were isolated from suspension-cultured wild-type (WT) and cellulose-binding module (CBM) transformed tobacco BY-2 (Nicotiana tabacum L. cv bright yellow) cells. Results from strong sulfuric acid hydrolysis indicated that CNFs from transgenic cells overexpressing CBM consisted of longer cellulose nanocrystals compared to CNFs from WT cells. Nanopapers prepared from CNFs of transgenic cells demonstrated significantly enhanced toughness compared to CNFs of WT cells.

  • 142.
    Bäckström, Eva
    KTH, School of Chemical Science and Engineering (CHE).
    Covalently modified starch with novel graphene oxide as biomaterial2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Today there is a large interest to develop new biomedical material to treat medical conditions. These materials need to be biocompatible and preferably bioresorbable. One option is the common biopolymer starch. Typically it needs reinforcement to allow usage. Nano-sized Graphene Oxide (GO) is promising reinforcing filler since it is nontoxic and strong. A method to produce starch-based hydrogels reinforced with nano-sized graphene oxide was demonstrated in this work. Graphene Oxide was derived from starch by microwave irradiation followed by oxidation. In turn the produced GO were covalently attached to starch by an esterification reaction using DCC and DMAP in DMSO to get the reinforced starch (STGO). Both GO and STGO were carefully investigated by TEM, SEM, DLS, AFM, NMR, FTIR, TGA and XRD. Starch hydrogels containing GO and STGO were produced in the presence of glycerol. Mineralization test on the gel proved that the carboxyl group present in GO functions as an anchoring site for the mineral Hydroxyapatite that is fundamental for enamel. Higher concentration of reinforced starch in the hydrogels showed better results with a higher density of mineral growth and a stoichiometric mineral. The STGO starch hydrogels thus show great potential to be utilized in dental applications to regenerate the demineralized teeth.

  • 143. Camacho, W.
    et al.
    Karlsson, S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Quality assessment of co-mingled recycled resins by fourier transform raman spectroscopy and multivariate calibration2001In: Polymer Recycling, Vol. 6, no 2/3, p. 89-98Article in journal (Refereed)
  • 144. Camacho, Walker
    et al.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Quality determination of recycled plastic packaging waste by identification of contaminants by GC-MS after microwave assisted extraction (MAE)2001In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 71, no 1, p. 123-134Article in journal (Refereed)
  • 145. Camacho, Walker
    et al.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Simultaneous determination of molecular weight and crystallinity of recycled HDPE by infrared spectroscopy and multivariate calibration2002In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 85, no 2, p. 321-327Article in journal (Refereed)
  • 146. Cardoso, Marcos R.
    et al.
    Martins, Renato J.
    Dev, Apurba
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Voss, Tobias
    Mendonca, Cleber R.
    Highly hydrophobic hierarchical nanomicro roughness polymer surface created by stamping and laser micromachining2015In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 132, no 24, article id 42082Article in journal (Refereed)
    Abstract [en]

    This article describes the design and fabrication of hierarchical nanomicrostructured polymer surfaces with high hydrophobicity. The nanoscale roughness is achieved by stamping a ZnO nanowire film into PDMS. Subsequently, microstructures with different periodicities are created in the stamped PDMS sample by direct laser writing using femtosecond pulses. With this approach, we were able to produce hierarchical surface morphologies, composed of nano and microscale structures that exhibit water contact angles larger than 160 degrees.

  • 147.
    Carlborg, Carl Fredrik
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Haraldsson, Tommy
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Wijngaart, Wouter van der
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    RELIABLE BATCH MANUFACTURING OF MINIATURIZED VERTICAL VIAS IN SOFT POLYMER REPLICA MOLDING2007In: 11th International Conference on Miniaturized Systems for Chemistry and Life Sciences (microTAS 2007), 2007, p. 527-529Conference paper (Refereed)
    Abstract [en]

    We introduce and have successfully tested an uncomplicated polydimethylsiloxane (PDMS) compatible method for batch manufacturing vertical microfluidic interconnects via a surface inhibition of cationic photopolymerization. The yield of the maskless method is 100%. Moreover, the method enhances bond strength with subsequently laminated polymer layers.

  • 148.
    Carlborg, Carl Fredrik
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Haraldsson, Tommy
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Öberg, Kim
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Malkoch, Michael
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    van der Wijngaart, Wouter
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    BEYOND PDMS:: OFF-STOCHIOMETRY THIOL-ENE BASED SOFT LITHOGRAPHY FOR RAPID PROTOTYPING OF MICROFLUIDIC DEVICES2010In: 14th International Conference on Miniaturized Systems for Chemistry and Life Sciences (micro TAS 2010), 2010, p. 70-72Conference paper (Refereed)
    Abstract [en]

    We present an easy to use, rapid fabrication platform for microfluidic systems, based on micro-molding of novel thiolene based polymer formulations. The novel fabrication platform addresses major drawbacks of PDMS by allowing large freedom in material and surface properties, including: (photo)patterning of stable surface modifications, bonding without plasma treatment, rapid UV or thermal curing, variable E-modulus, minimized leaching of uncured components [1] and suppressed non-specific binding of biomolecules [2]. This process is potentially suited for both rapid prototyping in the laboratory and medium-scale commercial production, bridging the “development gap”.

  • 149.
    Carlborg, Carl Fredrik
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Saharil, Farizah
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Haraldsson, Tommy
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Wijngaart, Wouter van der
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    LOW TEMPERATURE “CLICK” WAFER BONDING OF OFF-STOICHIOMETRY THIOL-ENE (OSTE) POLYMERS TO SILICON2011In: 15th International Conference on Miniaturized Systems for Chemistry and Life Sciences (microTAS 2011), 2011, p. 1143-1145Conference paper (Refereed)
    Abstract [en]

    We present a low temperature (< 37°C) wafer-scale microfluidic batch packaging process using covalent, dry bonding of offstoichiometry thiol-ene polymers (OSTE), enabling rapid, bio-compatible integration of fluidics on wafer-scale in combination with excellent polymer properties.

  • 150.
    Carlborg, Carl Fredrik
    et al.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Vastesson, Alexander
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Liu, Yitong
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    van der Wijngaart, Wouter
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Johansson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Haraldsson, Tommy
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Functional Off-Stoichiometry Thiol-ene-epoxy Thermosets Featuring Temporally Controlled Curing Stages via an UV/UV Dual Cure Process2014In: Journal of Polymer Science Part A: Polymer Chemistry, ISSN 0887-624X, E-ISSN 1099-0518, Vol. 52, no 18, p. 2604-2615Article in journal (Refereed)
    Abstract [en]

    We present a facile two-stage UV/UV activation method for the polymerization of off-stoichiometry thiol-ene-epoxy, OSTE+, networks. We show that the handling and processing of these epoxy-based resins is made easier by introducing a material with a controlled curing technique based on two steps, where the first step offers excellent processing capabilities, and the second step yields a polymer with suitable end-properties. We investigate the sequential thiol-ene and thiol-epoxy reactions during these steps by studying the mechanical properties, functional group conversion, water absorption, hydrolytic stability, and thermal stability in several different thiol-ene-epoxy formulations. Finally, we conclude that the curing stages can be separated for up to 24 h, which is promising for the usefulness of this technique in industrial applications.

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