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  • 51. Albertsson, A-C.
    et al.
    Barenstedt, C.
    Karlsson, S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Degradation of enhanced environmentally degradable polyethylene in biological aqueous media: mechanisms during the first stages1994In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 51, no 6, p. 1097-1105Article in journal (Refereed)
  • 52. Albertsson, A-C.
    et al.
    Barenstedt, C.
    Karlsson, S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Increased biodegradation of a low-density polyethylene (LDPE) matrix in starch-filled LDPE materials1993In: Journal of environmental polymer degradation, ISSN 1064-7546, E-ISSN 1572-8900, Vol. 1, no 4, p. 241-245Article in journal (Refereed)
  • 53. Albertsson, A-C.
    et al.
    Barenstedt, C.
    Karlsson, S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Solid-phase extraction and gas chromatographic-mass spectrometric identification of degradation products from enhanced environmentally degradable polyethylene1995In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 690, no 2, p. 207-217Article in journal (Refereed)
  • 54. Albertsson, A-C.
    et al.
    Barenstedt, C.
    Karlsson, S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Susceptibility of enhanced environmentally degradable polyethylene to thermal and photo-oxidation1992In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 37, no 2, p. 163-171Article in journal (Refereed)
  • 55. Albertsson, A-C.
    et al.
    Barenstedt, C.
    Karlsson, S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Lindberg, T.
    Degradation product pattern and morphology changes as means to differentiate abiotically and biotically aged degradable polyethylene1995In: Polymer, ISSN 0032-3861, E-ISSN 1873-2291, Vol. 36, no 16, p. 3075-83Article in journal (Refereed)
  • 56. Albertsson, A-C.
    et al.
    Griffin, G. J. L.
    Karlsson, S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Nishimoto, K.
    Watanabe, Y.
    Spectroscopic and mechanical changes in irradiated starch-filled LDPE1994In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 45, no 2, p. 173-178Article in journal (Refereed)
  • 57. Albertsson, A-C.
    et al.
    Karlsson, S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Abiotic degradation products from enhanced environmentally degradable polyethylene1994In: Acta Polymerica, ISSN 0323-7648, E-ISSN 1521-4044, Vol. 45, no 2, p. 97-103Article in journal (Refereed)
  • 58. Albertsson, A-C.
    et al.
    Karlsson, S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Aspects of biodeterioration of inert and degradable polymers1993In: International Biodeterioration & Biodegradation, ISSN 0964-8305, E-ISSN 1879-0208, Vol. 31, no 3, p. 161-170Article in journal (Refereed)
  • 59. Albertsson, A-C.
    et al.
    Karlsson, S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Biodegradable polymers1992In: Comprehensive Polymer Science, Supplement Series, Midland, Michigan: Pergamon Press, 1992, p. 285-Chapter in book (Refereed)
  • 60. Albertsson, A-C.
    et al.
    Karlsson, S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Biodegradation and testmethods for environmental and biomedical applications of polymers1990In: Degradable Materials, Boca Raton: CRC Press, 1990, p. 263-Chapter in book (Refereed)
  • 61. Albertsson, A-C.
    et al.
    Karlsson, S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Chemistry and biochemistry of polymer biodegradation1994In: Chemistry and Technology of Biodegradable Polymers / [ed] G.J.L. Griffin, London, England: Blackie Academic & Professional , 1994, p. 7-17Chapter in book (Refereed)
  • 62. Albertsson, A-C.
    et al.
    Karlsson, S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Chromatographic fingerprinting as a means to predict degradation mechanisms1996In: Journal of environmental polymer degradation, ISSN 1064-7546, E-ISSN 1572-8900, Vol. 4, no 1, p. 51-3Article in journal (Refereed)
  • 63. Albertsson, A-C.
    et al.
    Karlsson, S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Controlled degradation by artificial and biological processes1996In: Macromol. Design of Polymeric Materials, Marcel Dekker, 1996, p. 54-Chapter in book (Refereed)
  • 64. Albertsson, A-C.
    et al.
    Karlsson, S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Degradable polyethylene-starch complex1991In: Makromolekulare Chemie, Macromolecular Symposia, Vol. 48-49, no Eur. Polym. Fed. Symp. Polym. Mater., 3rd, 1990, p. 395-402Article in journal (Refereed)
  • 65. Albertsson, A-C.
    et al.
    Karlsson, S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Degradable Polymers1996In: The Polymeric Materials Encyclopedia: Synthesis, Properties and Applications / [ed] J. C. Salamone, Boca Raton, USA: CRC Press, 1996, p. 150-Chapter in book (Refereed)
  • 66. Albertsson, A-C.
    et al.
    Karlsson, S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Degradable polymers for the future1995In: Acta Polymerica, ISSN 0323-7648, E-ISSN 1521-4044, Vol. 46, no 2, p. 114-123Article in journal (Refereed)
  • 67. Albertsson, A-C.
    et al.
    Karlsson, S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Environment-adaptable polymers1993In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 41, no 3, p. 345-349Article in journal (Refereed)
  • 68. Albertsson, A-C.
    et al.
    Karlsson, S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Increased biodegradation of LDPE-matrix in starch-filled LDPE materials1992In: Materials Science and Engineering, Vol. 67, p. 296-297Article in journal (Refereed)
  • 69. Albertsson, A-C.
    et al.
    Karlsson, S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Macromolecular architecture-nature as model for degradable polymers1996In: Journal of Macromolecular Science, Part A: Pure and Applied Chemistry, Vol. 33, no 10, p. 1565-1570Article in journal (Refereed)
  • 70. Albertsson, A-C.
    et al.
    Karlsson, S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    New tools for analyzing degradation1995In: Macromolecular Symposia, ISSN 1022-1360, E-ISSN 1521-3900, Vol. 98, no 35th IUPAC International Symposium on Macromolecules, 1995, p. 797-801Article in journal (Refereed)
  • 71. Albertsson, A-C.
    et al.
    Karlsson, S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Polyethylene degradation and degradation products1990In: Agricultural and Synthetic Polymers: Biodegradability and Utilization, American Chemical Society (ACS), 1990, Vol. 433, no Agricultural & Synthetic Polymers, p. 60-64Chapter in book (Refereed)
  • 72. Albertsson, A-C.
    et al.
    Karlsson, S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    The Influence of Biotic and Abiotic Environments on the Degradation of Polyethylene.1990In: Progress in polymer science, ISSN 0079-6700, E-ISSN 1873-1619, Vol. 15, no 2, p. 177-192Article in journal (Refereed)
  • 73. Albertsson, A-C.
    et al.
    Sares, C.
    Karlsson, S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Increased biodegradation of low-density polyethylene (LDPE) with nonionic surfactant1993In: Acta Polymerica, ISSN 0323-7648, E-ISSN 1521-4044, Vol. 44, no 5, p. 243-246Article in journal (Refereed)
  • 74.
    Albertsson, Ann-Christine
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Frontiers in Biomacromolecules: Functional Materials from Nature2012In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 13, no 12, p. 3901-3901Article in journal (Other academic)
  • 75.
    Albertsson, Ann-Christine
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Edlund, Ulrica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Barrier layers for packaging laminates and packaging laminates comprising such barrier layers2009Patent (Other (popular science, discussion, etc.))
  • 76.
    Albertsson, Ann-Christine
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Erlandsson, Bengt
    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.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Molecular weight changes and polymeric matrix changes correlated with the formation of degradation products in biodegraded polyethylene1999In: Journal of environmental polymer degradation, ISSN 1064-7546, E-ISSN 1572-8900, Vol. 64, p. 91-99Article in journal (Refereed)
    Abstract [en]

    The molecular weight changes in abiotically and biotically degraded LDPE and LDPE modified with starch and/or prooxidant were compared with the formation of degradation products, The samples were thermooxidized for 6 days at 100 degrees C to initiate degradation and then either inoculated with Arthobacter paraffineus or kept sterile. After 3.5 years homologous series of mono- and dicarboxylic acids and ketoacids were identified by GC-MS in abiotic samples, while complete disappearance of these acids was observed in biotic environments. The molecular weights of the biotically aged samples were slightly higher than the molecular weights of the corresponding abiotically aged samples, which is exemplified by the increase in (M) over bar(n) from 5200 g/mol for a sterile sample with the highest amount of prooxidant to 6000 g/mol for the corresponding biodegraded sample. The higher molecular weight in the biotic environment is explained by the assimilation of carboxylic acids and low molecular weight polyethylene chains by microorganisms. Assimilation of the low molecular weight products is further confirmed by the absence of carboxylic acids in the biotic samples. Fewer carbonyls and more double bonds were seen by FTIR in the biodegraded samples, which is in agreement with the biodegradation mechanism of polyethylene.

  • 77.
    Albertsson, Ann-Christine
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Groning, M.
    Hakkarainen, Minna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Emission of volatiles from polymers - A new approach for understanding polymer degradation2006In: Journal of polymers and the environment, ISSN 1064-7546, E-ISSN 1572-8900, Vol. 14, no 1, p. 8-13Article in journal (Refereed)
    Abstract [en]

    Emission of low molar mass compounds from different polymeric materials was determined and the results from the volatile analysis were applied to predict the degree of degradation and long-term properties, to determine degradation rates and mechanisms, to differentiate between biotic and abiotic degradation and for quality control work. Solid-phase microextraction and solid-phase extraction together with GC-MS were applied to identify and quantify the low molar mass compounds. Volatiles were released and monitored at early stages of degradation before any matrix changes were observed by e.g. SEC, DSC and tensile testing. The analysis of volatiles can thus also be applied to detect small differences between polymeric materials and their susceptibility to degradation. The formation of certain degradation products correlated with the changes taking place in the polymer matrix, these indicator products could, thus, be analysed to rapidly predict the degree of degradation in the polymer matrix and further to predict the long-term properties and remaining lifetime of the product.

  • 78.
    Albertsson, Ann-Christine
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Gröning, Mikael
    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.
    Chromatographic analysis as a tool for predicting material performance2005In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, p. 247-248Article in journal (Other academic)
  • 79.
    Albertsson, Ann-Christine
    et al.
    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.
    Degradable polymers and their interaction with the environment2007In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 223, p. 566-567Article in journal (Other academic)
  • 80.
    Albertsson, Ann-Christine
    et al.
    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.
    Designed to degrade Suitably designed degradable polymers can play a role in reducing plastic waste2017In: Science, ISSN 0036-8075, E-ISSN 1095-9203, Vol. 358, no 6365, p. 872-873Article in journal (Refereed)
  • 81.
    Albertsson, Ann-Christine
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    The three stages in the degradation of polymers- polyethylene as a model substance1988In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 35, p. 1289-1302Article in journal (Refereed)
  • 82. Albertsson, Ann-Christine
    et al.
    Renstad, Rasmus
    Erlandsson, Bengt
    Eldsäter, Carina
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Effect of processing additives on (bio)degradability of film-blown poly(ε-caprolactone)1998In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 70, no 1, p. 61-74Article in journal (Refereed)
  • 83.
    Albán Reyes, Diana Carolina
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Skoglund, Nils
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Department of Engineering Sciences and Mathematics, Luleå University of Technology, Luleå, Sweden .
    Svedberg, Anna
    Eliasson, Bertil
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Sundman, Ola
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    The influence of different parameters on the mercerisation of cellulose for viscose production2016In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 23, no 2, p. 1061-1072Article in journal (Refereed)
    Abstract [en]

    A quantitative analysis of degree of transformation from a softwood sulphite dissolving pulp to alkalised material and the yield of this transformation as a function of the simultaneous variation of the NaOH concentration, denoted [NaOH], reaction time and temperature was performed. Samples were analysed with Raman spectroscopy in combination with multivariate data analysis and these results were confirmed by X-ray diffraction. Gravimetry was used to measure the yield. The resulting data were related to the processing conditions in a Partial Least Square regression model, which made it possible to explore the relevance of the three studied variables on the responses. The detailed predictions for the interactive effects of the measured parameters made it possible to determine optimal conditions for both yield and degree of transformation in viscose manufacturing. The yield was positively correlated to the temperature from room temperature up to 45 A degrees C, after which the relation was negative. Temperature was found to be important for the degree of transformation and yield. The time to reach a certain degree of transformation (i.e. mercerisation) depended on both temperature and [NaOH]. At low temperatures and high [NaOH], mercerisation was instantaneous. It was concluded that the size of fibre particles (mesh range 0.25-1 mm) had no influence on degree of transformation in viscose processing conditions, apparently due to the quick reaction with the excess of NaOH.

  • 84.
    Aldaeus, F.
    et al.
    RISE, Innventia.
    Schweinebarth, H.
    RISE, Innventia.
    Törngren, P.
    RISE, Innventia.
    Jacobs, A.
    RISE, Innventia.
    Simplified determination of total lignin content in kraft lignin samples and black liquors2011In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, no 4, p. 601-604Article in journal (Refereed)
  • 85. Aldea, Steliana
    et al.
    Snåre, Mathias
    Eränen, Kari
    Grenman, Henrik
    Rautio, Anne-Riika
    Kordás, Krisztian
    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, Biskopsgatan 8, 20500 Åbo-Turku, Finland.
    Salmi, Tapio
    Murzin, Dmitry Y.
    Crystallization of Nano-Calcium Carbonate: The Influence of Process Parameters2016In: Chemie Ingenieur Technik, ISSN 0009-286X, E-ISSN 1522-2640, Vol. 88, no 11, p. 1609-1616Article in journal (Refereed)
    Abstract [en]

    Precipitated calcium carbonate was synthesized by carbonation of calcium hydroxide in the presence and absence of ultrasound (conventional stirring) at atmospheric as well as at elevated pressures and different initial concentrations of Ca(OH)2. Spherical morphology of the formed calcite was favored at high Ca(OH)2 concentrations and low CO2 pressures. The presence of ultrasound did not show any influence on the reaction rate in case of efficient mixing. A small increase of the reaction rate was observed at lower CO2 pressures. Elevated pressures in combination with ultrasound did not lead to notable changes of reaction rate or particle morphology.

  • 86.
    Aldujaili, Aya
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Berndtson, Emma
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Hedström, Tom
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Piccolo, Sofia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Rahmani, Zakaria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Åhlén, Michelle
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Hur partikelstorleksfördelning påverkar kritiska parametrar för medicinska enheter2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Projektet har inriktning på Galdermas produkter Deflux och Solesta, de ämnen som produkterna är uppbyggda av (dextran och hyaluronsyra) har studerats laborativt. Ändringar av parametrar såsom koncentration av dextran men även i siktningsmetod (dubbel- respektive enkelsiktningar samt olika filterstorlekar) har genomförts. Resultatet av dessa ändringar har erhållits med hjälp av mikroskop, laserdiffraktometer samt dragprovare. De slutsatser som har kunnat dras från resultaten är att med ökad partikeldiameter erhålls en lägre extruderingskraft, oavsett om använd siktningsmetod var enkel- eller dubbelsiktning. Vidare så erhålls en större extruderingskraft med ökad koncentration av dextran.

  • 87.
    Alemrajabi, Mahmood
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Rasmuson, Åke
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Korkmaz, Kivanc
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Forsberg, Kerstin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Upgrading of a rare earth phosphate concentrate within the nitrophosphate process2018In: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786Article in journal (Refereed)
  • 88.
    Alevanau, Aliaksandr
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Study of pyrolysis and gasification of biomass from the self-organization perspective2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis focuses on the analysis of kinetics of i) low-temperature pyrolysis of gaseous hydrocarbons, ii) high-temperature steam gasification of char of wood pellets (>700oC), iii) high temperature pyrolysis of straw pellets in an atmosphere of argon and steam, and iv) high temperature pyrolysis of slices of transversally cut wooden sticks. The results of the kinetic measurements in the high-temperature cases are approximated using a least-square based optimization software, which was specially developed to analyse kinetics prone for deviation from the Arrhenius law.In the thesis a general analysis of the researched materials and kinetics of their pyrolysis and gasification is presented from the self-organization perspective. The energy transfer phenomena in both the pyrolysis and gasification processes of biomass are discussed with an emphasis on an analysis of basic phenomena involving the self-organized dynamics on fractal structures in the chosen biomass samples.

  • 89.
    Alexiadis, Alessio
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Cornell, Ann
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Dudukovic, M. P.
    Comparison between CFD calculations of the flow in a rotating disk cell and the Cochran/Levich equations2012In: Journal of Electroanalytical Chemistry, ISSN 1572-6657, Vol. 669, p. 55-66Article in journal (Refereed)
    Abstract [en]

    Three CFD (Computational Fluid Dynamics) models (single-phase. VOF and Euler-Euler) are employed to simulate the flow in a finite, rotating electrode cell under different operative conditions. The main dimensionless groups are derived and their effect on the flow is investigated. Except very close to the rotating electrode (i.e. in the hydrodynamic layer), the results show a flow pattern considerably different from Cochran's approximate analytical solution often used in electrochemistry. Historically, the Cochran equation was used to derive the Levich equation, which permits the calculation of the limiting current density on a rotating electrode. Despite the general inadequacy of Cochran's analytical solution, however, we show that the Levich equation often retains its validity because, in many practical situations, the concentration boundary layer is considerably smaller than the hydrodynamic boundary layer. When bubbles are generated on the electrode and a certain critical void fraction is exceeded, however, the Levich equation also becomes inaccurate. We propose, therefore, an amended version of this equation, which provides results closer to the CFD calculations.

  • 90.
    Alexiadis, Alessio
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Dudukovic, M. P.
    Ramachandran, P.
    Cornell, Ann
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    On the stability of the flow in multi-channel electrochemical systems2012In: Journal of Applied Electrochemistry, ISSN 0021-891X, E-ISSN 1572-8838, Vol. 42, no 9, p. 679-687Article in journal (Refereed)
    Abstract [en]

    The importance of the fluid dynamics in the modelling of electrochemical systems is often underestimated. The knowledge of the flow velocity pattern in an electrochemical cell, in fact, can allow us to associate certain electrochemical reactions with specific fluid patterns to maximize the yield of some reaction and, conversely, to minimize unwanted or side reactions. The correct evaluation of the convective term in the Nernst-Planck equation, however, requires the solution of the so-called Navier-Stokes equations, and computational fluid dynamics (CFD) is today the established method to numerically solve these equations. In this work, a CFD model is employed to show that the gas-liquid flow pattern can be remarkably different in a single channel or in a multi-channel gas-evolving electrochemical system. In the single channel, in fact, under certain conditions, vortices and recirculation regions can appear in the flow, which does not appear in the multi-channel case. The reason of this difference is found in the uneven distribution of the small bubbles in the two cases. Additionally, a second, simplified, model of the flow is discussed to show how a higher concentration of small bubbles in the single channel system can destabilize the flow.

  • 91.
    Alexiadis, Alessio
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Dudukovic, M. P.
    Ramachandran, P.
    Cornell, Ann
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Wanngård, J.
    Bokkers, A.
    The flow pattern in single and multiple submerged channels with gas evolution at the electrodes2012In: International Journal of Chemical Engineering, ISSN 1687-806X, E-ISSN 1687-8078, Vol. 2012, p. 392613-Article in journal (Refereed)
    Abstract [en]

    We show that the gas-liquid flow pattern in a single gas-evolving electrochemical channel can be remarkably different from the flow pattern in multiple submerged gas-evolving electrochemical channels. This is due to the fact that in a single channel there is a higher accumulation of small bubbles and these can considerably affect the liquid velocity pattern which in turn may affect the performance of a cell. Since experimental work is often carried out in single channels, while industrial applications almost always involve multiple channels, this study provides insight into the factors that affect the flow pattern in each situation and establishes the basis for relating the behavior of single-and multiple-channel devices.

  • 92.
    Alexiadis, Alessio
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Dudukovic, M. P.
    Ramachandran, P.
    Cornell, Ann
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Wanngård, J.
    Bokkers, A.
    Transition to pseudo-turbulence in a narrow gas-evolving channel2012In: Theoretical and Computational Fluid Dynamics, ISSN 0935-4964, E-ISSN 1432-2250, Vol. 26, no 6, p. 551-564Article in journal (Refereed)
    Abstract [en]

    Different flow regimes have been observed, both experimentally and in CFD simulations, in narrow channels with gas evolution. In this manuscript, we examine, using the Euler-Euler model, the flow in a narrow channel, where gas is evolved from a vertical wall. We find some pseudo-turbulent features at conditions described in this manuscript. The transition to this pseudo-turbulent regime is associated with the value of a specific dimensionless group.

  • 93.
    Alfthan, Johan
    KTH, Superseded Departments, Solid Mechanics.
    A simplified network model for mechano-sorptive creep in paper2003In: Journal of Pulp and Paper Science (JPPS), ISSN 0826-6220, Vol. 29, no 7, p. 228-234Article in journal (Refereed)
    Abstract [en]

    A simplified network model for mechanosorptive creep is presented. The model resembles Cox's model for fibrous materials, but creep and the influence of bonds are included in addition to the elastic behaviour of the fibres. Three different creep laws describing the creep of individual fibres are applied in the simulations of creep of the network. Results from simulations using the model are presented. The influence of the amplitude of moisture content changes is discussed. It is shown that the model may produce macroscopic strains that are linear in stress, even though the creep of the fibres is nonlinear This may explain why both regular creep and mechanosorptive creep at small loads appear to be linear in stress.

  • 94.
    Alfthan, Johan
    KTH, Superseded Departments, Solid Mechanics.
    The effect of humidity cycle amplitude on accelerated tensile creep of paper2004In: Mechanics of time-dependant materials, ISSN 1385-2000, E-ISSN 1573-2738, Vol. 8, no 4, p. 289-302Article in journal (Refereed)
    Abstract [en]

    The creep of paper is accelerated by moisture cycling, an effect known as mechanosorptive creep. In this paper, the effect of different amplitudes of the moisture content is investigated experimentally and numerically. Tensile creep tests were made in a climate chamber. Low basis weight isotropic sheets were used in the tests. The moisture content history was measured during each creep test using a balance placed in the climate chamber. The experimental results are compared to predictions using a theoretical network model. A brief description of the model is given. In the model it is assumed that the anisotropic hygroexpansion of the fibres produces large stresses at the fibre-fibre bonds when moisture changes. The resulting stress state will accelerate creep if the material obeys creep laws that are nonlinear in stress. A quite good fit between the theoretical model and the experimental creep curves is obtained.

  • 95.
    Ali, Fuade
    KTH, School of Chemical Science and Engineering (CHE).
    Förändringar av Vallentunasjöns kemi under olika årstider2011Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
  • 96.
    Ali, Sharafat
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Berastegui, Pedro
    Stockholm University.
    Esmaeilzadeh, Saeid
    Stockholm University.
    Eriksson, Lars
    Stockholm University.
    Jekabs, Grins
    Stockholm University.
    A cubic calcium oxynitrido-silicate, Ca2.89Si2N1.76O4.242011In: Acta Crystallographica Section E: Structure Reports Online, ISSN 1600-5368, E-ISSN 1600-5368, Vol. 67, article id i66Article in journal (Refereed)
    Abstract [en]

    The title compound, tricalcium oxynitride silicate, withcomposition Ca3-xSi2N2-2xO4+2x (x ’ 0.12), is a perovskiterelatedcalcium oxynitrido silicate containing isolated oxynitridosilicate 12-rings. The N atoms are statistically disorderedwith O atoms (occupancy ratio N:O = 0.88:0.12) and occupythe bridging positions in the 12 ring oxynitrido silicate anion,while the remaining O atoms are located at the terminalpositions of the Si(O,N)4 tetrahedra. The majority of the Ca2+cations fill the channels along [100] in the packing of the 12-ring anions. The rest of these cations are located at severalpositions, with partial occupancy, in channels along the bodydiagonals.

  • 97.
    Ali Soomro, Razium
    et al.
    University of Bristol, England; University of Sindh, Pakistan.
    Richard Hallam, Keith
    University of Bristol, England.
    Hussain Ibupoto, Zafar
    University of Sindh, Pakistan.
    Tahira, Aneela
    University of Sindh, Pakistan.
    Jawaid, Sana
    University of Sindh, Pakistan.
    Tufail Hussain Sherazi, Syed
    University of Sindh, Pakistan.
    Sirajjuddin,
    Univ Sindh, Natl Ctr Excellence Analyt Chem, Jamshoro 76080, Pakistan.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    A highly selective and sensitive electrochemical determination of melamine based on succinic acid functionalized copper oxide nanostructures2015In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 5, no 127, p. 105090-105097Article in journal (Refereed)
    Abstract [en]

    This study presents the development of a highly selective and sensitive electrochemical sensor for the determination of melamine from aqueous environments. The sensor system is based on functionalised marigold-like CuO nanostructures fabricated using a controlled hydrothermal process, where the utilised succinic acid is considered to play a dual role as a functionalising and growth controlling agent (modifier). The fabricated nanostructures exhibit sharp and well-ordered structural features with dimensions (thickness) in the range of 10-50 nm. The sensor system exhibits strong linearity within the concentration range of 0.1 x 10(-9) to 5.6 x 10(-9) M and demonstrates an excellent limit of detection up to 0.1 x 10(-10) M. The extreme selectivity and sensing capability of the developed sensor is attributed to the synergy of selective interaction between succinic acid and melamine moieties, and the high surface area of marigold-like CuO nanostructures. In addition to this, the developed sensor was also utilised for the determination of melamine from real milk samples collected from different regions of Hyderabad, Pakistan. The obtained excellent recoveries proved the feasibility of the sensor for real life applications. The sensor system offers an operative measure for detecting extremely low melamine content with high selectivity in food contents.

  • 98.
    Alin, Jonas
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Analytical tools for identification and quantification of migrants from food packaging2011Conference paper (Other academic)
    Abstract [en]

    Polymers are frequently used as packaging material for food and therefore it is of concern that migrating substances such as additives or degradation products could contaminate the food. Sometimes also processing or microwave heating of food is performed directly inside the food package, which could lead to increased migration. Chromatographic and mass spectrometric analysis techniques can be used to detect, identify and quantify compounds that are released from polymers during such scenarios and, with suitable extraction and analysis techniques for example solid phase micro extraction coupled to gas chromatography – mass spectrometry (SPME-GC-MS), the migrating substances can be identified and quantified. We have previously detected the emission of low molecular weight substances from polymers using SPME-GC-MS [1,2]. With these analysis techniques we have shown that significant antioxidant degradation takes place during microwave heating of the polypropylene (PP) packages in the fatty food simulants, which further led to increased migration of potentially toxic degradation products into the food [3]. No antioxidant degradation was observed in aqueous food simulants or during conventional heating at the same temperature. Electrospray ionization-mass spectrometry (ESI-MS) was shown to be a valuable tool for studying the less volatile migrants. Antioxidant migration rates from three PP materials to fatty food simulants differed largely with respect to the PP type and increased with decreasing degree of crystallinity in the materials, as determined by high performance liquid chromatography (HPLC) [4]. The extraction efficiency of a headspace - solid phase microextraction (HS-SPME) method could be predicted from the analyte properties using a partial least squares (PLS) regression model [5].

     

    References

    [1] M Gröning, M Hakkarainen, Journal of Chromatography, (2001) 932, 1-11

    [2] M Hakkarainen, Journal of Chromatography, (2003)  1010, 9-16

    [3] J. Alin and M. Hakkarainen, Journal of Agricultural and Food Chemistry, (2011) DOI: 10.1021/jf1048639

    [4] J. Alin and M. Hakkarainen, Journal of Applied Polymer Science, (2010) 118, 1084-1093

    [5] J. Alin and M. Hakkarainen, manuscript

  • 99.
    Alin, Jonas
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Quality control of polymeric packaging and recycled materials by chromatographic and mass spectrometric techniques2011Conference paper (Other academic)
    Abstract [en]

    During the lifetime polymers can emit degradation products and additives to the surrounding environment. The development of analytical techniques to identify and quantify migrated compounds is essential to assess the safety of the plastic products. This is especially important when plastic materials are used in demanding or otherwise sensitive applications such as toys, medical products, food packaging or water pipes as well as when new types of polymeric materials such as nanocomposites, degradable materials, functional materials or recycled materials are developed. We have in several studies applied chromatographic and mass spectrometric techniques for analysis of emissions from different polymeric materials. As an example we have shown that microwave heating can lead to accelerated degradation of additives incorporated in the polypropylene (PP)packages, which further led to increased migration of potentially toxic degradation products into the food [1]. Significant antioxidant degradation was shown to take place during microwave heating of the packages in the fatty food simulants, while no degradation of antioxidants was detected during conventional heating of the packages in the fatty food simulants. No antioxidant degradation was observed in aqueous food simulants. Antioxidant migration rates from three PPmaterials to fatty food simulants differed largely with respect to the PP type and increased with decreasing degree of crystallinity in the materials [2]. Stereocomplexation improved the migration resistance of novel polylactide based packaging materials in contact with food simulants [3]. When polymeric materials are recycled one point of concern is the presence of unknown low molecular weight products in the materials. In addition the recycled materials could be more susceptible for further degradation even when further stabilized. We have shown that increasing amounts of degradation products are formed during aging of in-plant recycling of polyamide 6.6[4]. The amount of degradation products could also be correlated to deterioration of material properties such as mechanical properties. The odor coming polypropylene materials containing recycled milled phenol-formaldehyde glass-fiber scrap was shown to be caused by the presence of phenol in the materials [5].

    1. J. Alin and M. Hakkarainen, Journal of Agricultural and Food Chemistry (2011) 59(10), 5418-5427

    2. J. Alin and M. Hakkarainen, Journal of Applied Polymer Science (2010) 118(2), 1084-1093.

    3. Y. Bor, J. Alin and M. Hakkarainen, Packaging Technology and Science, DOI: 10.1002/pts.990.

    4. M. Gröning and M. Hakkarainen, Journal of Applied Polymer Science, (2002) 86, 3396-3407

    5. M. Gröning, H. Eriksson, M. Hakkarainen and A.-C. Albertsson, Polymer Degradation andStability, (2006) 91, 1815-1823

  • 100.
    Alin, Jonas
    et al.
    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.
    Microwave heating causes rapid degradation of antioxidants in polypropylene packaging leading to greatly increased specific migration to food simulants as shown by ESI-MS and GC-MS2011In: Journal of Agricultural and Food Chemistry, ISSN 0021-8561, E-ISSN 1520-5118, Vol. 59, no 10, p. 5418-5427Article in journal (Refereed)
    Abstract [en]

    Microwave heating of commercial microwavable polypropylene packaging in contact with fatty food simulants caused significant antioxidant degradation and increased specific migration as shown by electrospray ionization-mass spectrometry (ESI-MS) and gas chromatography-mass spectrometry (GC-MS). Degradation of the antioxidants Irgafos 168 and Irganox 1010 was not detected during conventional heating of polypropylene packaging at the same temperature. The migration into aqueous food simulants was primarily restricted by the water solubility of the migrants. Using isooctane as fatty food simulant caused significant swelling and greatly enhanced overall migration values compared to the other fatty food simulant, 99.9% ethanol, or the aqueous food simulants 10% ethanol, 3% acetic acid, or water. ESI-MS spectra clearly reflected the overall migration values, and the number and amount of compounds detected decreased as the hydrophilicity of the food simulant increased. ESI-MS was shown to be an excellent tool for the analysis of semivolatile migrants and a good complement to GC-MS analysis of volatile migrants.

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