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  • 1. Abbasi Hoseini, A.
    et al.
    Lundell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Mekanik, Strömningsfysik. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Andersson, H. I.
    Finite-length effects on dynamical behavior of rod-like particles in wall-bounded turbulent flow2015Inngår i: International Journal of Multiphase Flow, ISSN 0301-9322, E-ISSN 1879-3533, Vol. 76, s. 13-21Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Combined Particle Image Velocimetry (PIV) and Particle Tracking Velocimetry (PTV) measurements have been performed in dilute suspensions of rod-like particles in wall turbulence. PIV results for the turbulence field in the water table flow apparatus compared favorably with data from Direct Numerical Simulations (DNS) of channel flow turbulence and the universality of near-wall turbulence justified comparisons with DNS of fiber-laden channel flow. In order to examine any shape effects on the dynamical behavior of elongated particles in wall-bounded turbulent flow, fibers with three different lengths but the same diameter were used. In the logarithmic part of the wall-layer, the translational fiber velocity was practically unaffected by the fiber length l. In the buffer layer, however, the fiber dynamics turned out to be severely constrained by the distance z to the wall. The short fibers accumulated preferentially in low-speed areas and adhered to the local fluid speed. The longer fibers (l/z > 1) exhibited a bi-modal probability distribution for the fiber velocity, which reflected an almost equal likelihood for a long fiber to reside in an ejection or in a sweep. It was also observed that in the buffer region, high-speed long fibers were almost randomly oriented whereas for all size cases the slowly moving fibers preferentially oriented in the streamwise direction. These phenomena have not been observed in DNS studies of fiber suspension flows and suggested l/z to be an essential parameter in a new generation of wall-collision models to be used in numerical studies.

  • 2.
    Abbasi, Mahmoud
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Synthesis and characterization of magnetic nanocomposite of chitosan/SiO2/carbon nanotubes and its application for dyes removal2017Inngår i: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 145, s. 105-113Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The adsorption characteristics of Direct Blue 71 (DB71) and Reactive Blue 19 (RB19) from aqueous solution onto novel magnetic nanocomposite of Chitosan/SiO2/CNTs (MNCSC) have been investigated. The morphology of MNCSC was characterized by vibrating sample magnetometer (VSM), field-emission scanning electron microscopy (FESEM), X-ray Diffraction (XRD), fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). The effect of initial dye concentration, contact time, adsorbent dosage and initial pH as experimental parameters on the removal of dyes were investigated. The adsorption experiments indicated the maximum adsorption capacity occurred at pH 6.8 for DB71 and pH 2.0 for RB19. The experimental data were analyzed by isotherm models and equilibrium results were fitted well with the Langmuir isotherm model and the maximum adsorption capacity of the MNCSM was determined to be 61.35 mg/g for DB71 (R-2 = 0.996) and 97.08 mg/g for RB19 (R-2 = 0.998). Adsorption data were analyzed with three kinetics models and pseudo second-order equation could best describe for adsorption of dyes. Finally, the thermodynamic parameters were determined. (C) 2017 Elsevier Ltd. All rights reserved.

  • 3.
    Abdi, Sofia
    KTH, Skolan för kemivetenskap (CHE).
    Preparation and process optimization of encapsulating cellulose microspheres2015Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Microspheres are spherically shaped particles within the size range of 1-1000 μm in diameter.

    Due to the their small size and round shape, microspheres show many advantages in various

    applications such as pharmaceuticals, composites and coatings. The microspheres can be

    customized to fit a specific application and are manufactured in various forms such as solid,

    hollow and encapsulating.

    Encapsulating cellulose microspheres have been produced in this project by the emulsionsolvent

    evaporation technique. The purpose of this study was to further investigate the

    possibility of producing encapsulating microspheres with a size range of 10-50 μm that will

    have a high encapsulation. A second purpose of this study was optimizing the emulsifier

    system for the preparation of these spheres. This has been accomplished by varying several

    process parameters such as type of emulsifiers and solvents to study the effect on morphology

    and encapsulation efficiency. The analyses of the spheres were performed with optical

    microscopy, thermal gravimetric analyzer (TGA) and scanning electron microscopy (SEM).

    The emulsifier type and concentration affected the encapsulation and size distribution but had

    no direct effect on the internal and external structure, which was multi-cellular and porous,

    respectively. The highest encapsulation in relation to average size was obtained with 0.1 v/v-

    % of the emulsifier mixture Emulsifier 1 (E1)/Emulsifier 2 (E2) (70/30 %). The solvent used

    to dissolve the polymer had a direct effect on encapsulation, a combination of Solvent 2 (S2)

    and Solvent 1 (S1) proved best for the three tested cellulose derivatives with low, medium and

    high number average molecular weight. The solvent also had an effect on the internal

    structure of the microspheres, becoming more core-shell when using the S1/S2 combination.

  • 4.
    Abdul Hayee, Muhammad
    KTH, Skolan för kemivetenskap (CHE).
    Characterization and utilization of agroforestryresidues as energy source in Brazil2012Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    Brazil is very much rich in agriculture and forestry. The agro industry occupies an area of 28840726 ha. The more important crops are sugarcane (7080920 ha), rice (289030 ha), wheat (1853220 ha), coconut (283205 ha), cassava (1894460 ha), corn (13767400 ha) and grass (140000 ha). These crops generated 597 million tons of residues. Forest plantations in Brazil supplied 102.9 million m3 of industrial roundwood, of which nearly half is for renewable fuelwood and charcoal. Part of this plantation output is destined for the pulp and paper industry:

    The renewable sources are fulfilling 46.4% of the total Brazilian energy demands.

    Energy forestation in Brazil includes mainly Eucalyptus and Bracatingas.

    In this study three biomasses abundant in the Brazil are studied:  i.e. Eucalyptus, Garapeira/Peroba (wood dust) and Sewage Sludge.

    The wood samples (Eucalyptus and Peroba/Garapeira) have higher heating value than the sewage sludge because the wood samples have higher amounts of carbon and hydrogen than the sewage sludge. The sewage sludge has higher ash content and lower amount of volatiles and fixed carbon than the wood samples resulting in a lower heating value.

    The pyrolysis of eucalyptus, garapeira/peroba and sewage sludge has been studied in a thermobalance over a wide range of degradation temperatures. Between 225 °C - 375 °C (for eucalyptus) and 225 °C - 425 °C (for garapeira), the thermal decomposition of the biomass leads to significant weight loss.

    The weight loss for Eucalyptus between 265°C and 350°C is 0.48 % / °C and taking into account a heating rate of 10°C/min, the weight loss is 4.8 % /min. Garapeira has a similar behaviour than eucalyptus. The weight loss for garapeira between 265°C and 365°C is 0.4 % / °C and taking into account a heating rate of 10°C/min, the weight loss is 4 % /min.

    The behaviour of the sewage sludge to the increase of temperature from 25°C to 700 °C in an inert atmosphere do not show such different zones as the behaviour of the woody biomass. Between 150 °C and 235°C the weight loss of the sewage sludge was 0.07 %/°C (0.7 %/min). The highest weight loss takes place between 300 °C and 390 °C (0.15 %/°C or 1.5 %/min). In the third zone, between 500 °C and 600°C, the weight loss was 0.03 %/°C (0.3 %/min).

    The pyrolysis is assumed to be a first order decomposition. The activation energy (E) and the pre exponential factor (A) are calculated for the studied samples.

    The proximate analysis shows differences between the woody biomass and the sewage sludge. The sewage sludge has higher ash content and lower fixed carbon and volatiles. Eucalyptus has lower carbon fixed and higher volatiles than peroba-garapeira.

  • 5.
    ABDULAZIZ, ALI ABDULBASIT
    et al.
    KTH, Skolan för kemivetenskap (CHE).
    GHARIB ALI JALAL, IBRAHIM
    KTH, Skolan för kemivetenskap (CHE).
    GHATTAS, ANGELIKA
    KTH, Skolan för kemivetenskap (CHE).
    SWENSSON, BEATRICE
    KTH, Skolan för kemivetenskap (CHE).
    Utformning av bränslecellssystem för fordon2015Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [sv]

    I detta kandidatexamensarbete var målet att optimera ett bränslecellssystem med avseende på ett antal olika parametrar. Bränslecellssystemet var tänkt att användas i fordonet Sleipner V som är konstruerad i samarbete med andra KTH studenter. En annan bränslecell av företaget Horizon användes för att driva fordonet Sleipner i tävlingen Shell-Eco Marathon eftersom den ursprungliga bränslecellen var i dåligt skick. Sleipner utrustat med bränslecellen från Horizon klarade av att köra två varv i Shell-Eco Marathon.

    I denna rapport tas det upp grundläggande teori om bränsleceller, försökuppställning för experimenten och resultat med tillhörande analys. För att åstadkomma målet med detta arbete så skulle olika parametrar undersökas, men detta kunde inte utföras. På grund av diverse problem med bränslecellen så ändrades fokus till att reparera bränslecellen, vid undersökningen av problemen har vissa resultat uppnåtts.

    Vid körning uppstod spänningsfall och det kan ha berott på masstransportbegränsningar. För att åtgärda dessa problem utfördes en torknings- respektive fuktningsprocess som hade olika påverkan på de individuella cellerna. Efter torkningsprocessen fungerade 18 av 22 celler medan 19 celler fungerade efter fuktningsprocessen.  De icke fungerade cellerna som gav låg spänning kan ha varit för blöta eller för torra.

  • 6.
    Abdullah, Rondek
    KTH, Skolan för kemivetenskap (CHE).
    Study of the Eutrophication of Lake Vallentuna2012Independent thesis Basic level (professional degree), 10 poäng / 15 hpOppgave
    Abstract [en]

    Lake Vallentuna is situated 20 km north of Stockholm, in Täby and Vallentuna municipalities. It is a shallow eutrophicated lake, with a maximum depth of 6, 0 meter and the turnover time of the lake is 1, 6 years. Lake Vallentuna has two inlets, which are Ormstaån in the North and Karbyån in the South. The outlet from Lake Vallentuna is Hagbyån in the South-West. Lake Vallentuna is, due to human activities, influenced by many contaminants, for example phosphorus and nitrogen, which contribute to the eutrophication.

    The natural state of Lake Vallentuna involves a high phosphorus concentration, since it is a lake among fields dominated by clay. The increased phosphorus levels depend on various sources, such as sewage, agriculture, and storm water.

    The aim of this project is to describe the present state of the lake and to predict the future changes. This report will also give phosphorus and calcium levels determined for Lake Vallentunna. By the examination of the chemical and physical parameters we could estimate the contribution of pollutants. To assess the lake condition, an excursion was made to collect samples and perform measurements in the field. The samples were collected from twelve different sites.

    The eight parameters measured in this study are conductivity, temperature, pH, COD, chlorinity, alkalinity, calcium and total phosphorus. The assessment of the lake was based on the guidelines from the Swedish Environmental Protection Agency ”Bedömningsgrunder för miljökvalitet”. We compared the measured values with those in the guidelines. One conclusion is that the Lake is heavily eutrophicated.

    Our measurements indicate that the incoming amount of phosphorus is bigger than the outgoing amount of phosphorus, which means that the amount of phosphorus in the lake increases at the time for the measurements. However, the main source of phosphorus in the lake water is the internal contribution from the sediments, which have been accumulated during many years. The measured values of phosphorus show that the lake is eutrophicated.

    Lake Vallentuna contains big amounts of phosphorus and metal ions (see also Adam Kazi’s diploma work on metal ions in Lake Vallentuna[19] ). The reason is that the lake is situated in a very contaminated area.

  • 7.
    Abid, Fahim
    et al.
    KTH.
    Ghorbani, Hossein
    Pourrahimi, Amir Masoud
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Edin, Hans Ezz
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Differences in morphology and polarization properties of heat-treated XLPE and LDPE insulation2016Inngår i: 2016 IEEE CONFERENCE ON ELECTRICAL INSULATION AND DIELECTRIC PHENOMENA (IEEE CEIDP), IEEE conference proceedings, 2016, s. 113-116Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Cross-linked polyethylene (XLPE) is the most commonly used insulating material for extruded high voltage cable applications. Degassing is a heat-treatment process that is performed to remove methane from XLPE insulation which is formed during the crosslinking reactions as a by-product. Apart from removing methane, heat-treatment influences the electrical properties through changing the morphology due to annealing and also removal of polar crosslinking by-products. Scanning electron microscopy (SEM) is generally used to observe the changes in crystalline structure of the polymer. Frequency domain spectroscopy (FDS) is widely used to study polarization properties of dielectric materials. In this study these two methods are used for a comparative analysis of XLPE and LDPE subjected to different heat-treatment time, with or without a diffusion barrier. Electrical measurements are performed at room temperature. From the SEM imaging conducted after permanganate acid etching, formation of spherulites due to heat-treatment is not obvious in neither LDPE nor in XLPE. However, distinctions between LDPE and XLPE in SEM micrographs are evident. From studies with dielectric polarization spectroscopy, it is found that the LDPE samples are less sensitive to heat-treatment in comparison to the XLPE samples while dissipation factor of XLPE samples are influenced by the choice of pressing film used during sample preparation.

  • 8.
    Abraham, Benjamin
    et al.
    KTH, Skolan för kemivetenskap (CHE).
    Hultgren, Marcus
    KTH, Skolan för kemivetenskap (CHE).
    Ibert, Tommie
    KTH, Skolan för kemivetenskap (CHE).
    Möller, Johan
    KTH, Skolan för kemivetenskap (CHE).
    Termovåtstyrka i oblekt papper2012Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    The wet strength unbleached paper displays after heat treatment is examined in this thesis in which the authors examine the underlying mechanisms of this phenomena by experiments on differently treated paper. Two wet strength mechanism theories are examined; Lignin working as a resin versus carbonyl bonds being the main driving force behind the wet strength after thermal treatment. The authors find that using oxygen bleaching does not increase the wet strength as it would if carbonyl bonds were the main wet strength drivers, the results thus point towards the resin theory but further corroboration is needed before inference can be drawn.

  • 9. Abrahamsson, Christoffer
    et al.
    Nordstierna, Lars
    Nordin, Matias
    Dvinskikh, Sergey V.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi. St. Petersburg State University, Russian Federation.
    Nyden, Magnus
    Magnetic orientation of nontronite clay in aqueous dispersions and its effect on water diffusion2015Inngår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 437, s. 205-210Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The diffusion rate of water in dilute clay dispersions depends on particle concentration, size, shape, aggregation and water-particle interactions. As nontronite clay particles magnetically align parallel to the magnetic field, directional self-diffusion anisotropy can be created within such dispersion. Here we study water diffusion in exfoliated nontronite clay dispersions by diffusion NMR and time-dependant 1H-NMR-imaging profiles. The dispersion clay concentration was varied between 0.3 and 0.7 vol%. After magnetic alignment of the clay particles in these dispersions a maximum difference of 20% was measured between the parallel and perpendicular self-diffusion coefficients in the dispersion with 0.7 vol% clay. A method was developed to measure water diffusion within the dispersion in the absence of a magnetic field (random clay orientation) as this is not possible with standard diffusion NMR. However, no significant difference in self-diffusion coefficient between random and aligned dispersions could be observed.

  • 10.
    Abrahamsson, Sara
    KTH, Skolan för kemivetenskap (CHE).
    Reduktion av organiskt material med MIEX®2012Independent thesis Basic level (professional degree), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Uppsala- och Stockholmsregionerna använder Mälaren och dess tillflöden som dricksvattenkällor. I Mälaren varierar halten organiskt kol från år till år och kan medföra problem såsom oönskad lukt, smak och färg vid dricksvattenrening. Det kan även vara problem med avseende på bildning av desinfektionsbiprodukter (DPB) och transport av toxiska ämnen med dricksvattnet. I takt med den globala uppvärmningen kan dessutom halten av organiskt kol i Mälarens ytvatten och dess tillflöden öka. Det medför att halten av organiskt material även skulle öka i vattenverkens råvatten och det skulle i sin tur uppstå svårigheter att hålla dagens gränsvärden. I takt med hårdare framtida reningskrav borde nuvarande reningsmetoder för organiskt material därför utvecklas. Anjonbytesprocessen MIEX® (Magnetic Ion Exchange resin process) är en lovande alternativ reningsmetod för vatten innehållande löst organiskt material (DOC).

     

    Syftet med examensarbetet var att undersöka reduktion av DOC med hjälp av MIEX® under förhållanden som efterliknar en fullskaleprocess. Målet var att hitta lämplig kontakttid och lämpligt antal bäddvolymer som ska renas i en fullskaleprocess. Selektivitet mot fluorescerande- och UV-absorberande (254 nm) grupper av DOC undersöktes också.

     

    Fastställda slutsatser är att en kontakttid på 15 minuter bör vara lämplig i en fullskaleprocess och att lämpligt antal renade bäddvolymer bör vara 400-1000 BV. MIEX® är selektiv för terrestert DOC, DOC av humifierat material och för aromatiska grupper av DOC.

  • 11.
    Abächerli, A
    et al.
    International lignin institute, Switzerland.
    Gosselink, R
    Agrotechnology & Food Innovations, The Netherlands.
    Jong, E. de
    Agrotechnology & Food Innovations, The Netherlands.
    Baumberger, S
    French National Institute for Agricultural Research.
    Hortling, B
    KCL.
    Bonini, C
    USB.
    D'Auria, M
    USB.
    Zimbardi, F
    ENEA.
    Barisano, D
    ENEA.
    Duarte, J
    INETI.
    Sena-Martins, G
    INETI.
    Ribeiro, B
    INETI.
    Koukios, E
    NTUA.
    Koullas, D
    NTUA.
    Avgerinos, E
    NTUA.
    Vasile, C
    PPI.
    Cazacu, G
    PPI.
    Mathey, R
    Granit.
    Ghidoni, D
    Granit.
    Gellerstedt, Göran
    KTH, Skolan för kemivetenskap (CHE).
    Li, Jiebing
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Quintus-Leino, P
    VTT.
    Piepponen, S
    VTT.
    Laine, A
    VTT.
    Koskinen, P
    VTT.
    Gravitis, J
    LSIWC.
    Suren, J
    Bakelite.
    Fasching, M
    Lenzing.
    Intermediary status of the round Robins in the eurolignin network2005Konferansepaper (Fagfellevurdert)
  • 12. Acciaro, Roberta
    et al.
    Aulin, Christian
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi.
    Lindström, Tom
    Claesson, Per M.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Varga, Imre
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Investigation of the formation, structure and release characteristics of self-assembled composite films of cellulose nanofibrils and temperature responsive microgels2011Inngår i: Soft Matter, ISSN 1744-683X, Vol. 7, nr 4, s. 1369-1377Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The possibility of forming self-organized films using charge-stabilized dispersions of cellulose I nanofibrils and microgel beads of poly-(N-isopropylacrylamide-co-acrylic acid) copolymer is presented. The build-up behavior and the properties of the layer-by-layer (LbL)-constructed films were studied using quartz crystal microbalance with dissipation (QCM-D) and ellipsometry. The morphology of the formed films was also characterized using atomic force microscopy (AFM) imaging. The applied methods clearly demonstrated the successful LbL-assembly of the monodisperse microgels and nanofibrils. The in situ QCM-D measurements also revealed that contrary to the polyelectrolyte bound microgel particles, the nanofibrils-bound gel beads preserve their highly swollen state and do not suffer a partial collapse due to the lack of interdigitation of the oppositely charged components. To probe the accessibility of the gel beads in the formed films, the room temperature (similar to 25 degrees C) loading and release of a fluorescent dye (FITC) was also investigated. The incorporation of the cellulose nanofibrils into the multilayer resulted in an open structure that was found easily penetrable for the dye molecules even at constant room temperature, which is in sharp contrast with previously reported systems based on synthetic polyelectrolytes. The amount of dye released from the multilayer films could be fine-tuned with the number of bilayers. Finally, the thermoresponsivity of the films was also shown by triggering the burst release of the loaded dye when the film was collapsed.

  • 13.
    Acevedo Gomez, Yasna
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Lagergren, Carina
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Reformate from biogas used as fuel in a PEM fuel cell2013Inngår i: EFC 2013 - Proceedings of the 5th European Fuel Cell Piero Lunghi Conference, 2013, s. 163-164Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The performance of a PEM fuel cell can be easily degraded by introducing impurities in the fuel gas. Since reformate of biogas from olive mill wastes will contain at least one third of carbon dioxide, its influence was studied on a PtRu catalyst. A clean reformate gas for the anode (67% H2 and 33% CO2) without any traces of other compounds was used and electrochemical measurements showed that the performance of the fuel cell was hardly affected. However, diluting the hydrogen with higher amounts of CO2 will reduce the performance remarkably.

  • 14. Adamus, Grazyna
    et al.
    Hakkarainen, Minna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Höglund, Anders
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Kowalczuk, Marek
    Albertsson, Ann-Christine
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    MALDI-TOF MS Reveals the Molecular Level Structures of Different Hydrophilic-Hydrophobic Polyether-esters2009Inngår i: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 10, nr 6, s. 1540-1546Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Multi- and triblock copolymers based on 1,5-dioxepan-2-one/epsilon-caprolactone (DXO/CL) were investigated by MALDI-TOF MS to determine the influence of copolymer composition and architecture on the molecular structures at the individual chain level. The copolymer compositions, average block lengths, and molecular weights were determined by H-1 and C-13 NMR and by SEC, respectively. The structures of polyether-ester oligomers (linear, cyclic) as well as the chemical structures of their end groups were established on the basis of their MALDI-TOF mass spectra. The mass spectrum of PDXO homopolymer was relatively simple, however, complex mass spectra were obtained in the case of multi- and triblock copolymers and the mass spectra clearly discerned the molecular level effect of copolymer composition and copolymer type.

  • 15. Adekunle, K. F.
    et al.
    Cho, S. W.
    Patzelt, C.
    Blomfeldt, Thomas
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Skrifvars, M.
    Impact and flexural properties of flax fabrics and lyocell fiber reinforced bio-based thermoset for automotive and structural applications2012Inngår i: ECCM 2012 - Composites at Venice, Proceedings of the 15th European Conference on Composite Materials, European Conference on Composite Materials, ECCM , 2012Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A bio-based thermoset resin was reinforced with flax fabrics and Lyocell fiber. The effect of different weave architecture was studied with four flax fabrics with different architecture: plain, twill (two different types) and dobby. The effect of the outer ply thickness was studied and characterized with flexural and impact testing. Composites manufactured with plain weave reinforcement had the best mechanical properties. The tensile strength, tensile modulus, flexural strength, flexural modulus and impact strength was 280 MPa, 32 GPa, 250 MPa, 25 GPa and 75 kJ/m2 respectively.

  • 16. Adekunle, Kayode
    et al.
    Cho, Sung-Woo
    Patzelt, Christian
    Blomfeldt, Thomas
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Skrifvars, Mikael
    Impact and flexural properties of flax fabrics and Lyocell fiber-reinforced bio-based thermoset2011Inngår i: Journal of reinforced plastics and composites (Print), ISSN 0731-6844, E-ISSN 1530-7964, Vol. 30, nr 8, s. 685-697Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A bio-based thermoset resin was reinforced with flax fabrics and Lyocell fiber. The effect of different weave architectures was studied with four flax fabrics with different architectures: plain, twill (two different types), and dobby. The effect of the outer ply thickness was studied and characterized with flexural and impact testing. Composites manufactured with plain weave reinforcement had the best mechanical properties. The tensile strength, tensile modulus, flexural strength, flexural modulus, and impact strength were 280MPa, 32GPa, 250MPa, 25GPa, and 75 kJ/m (2), respectively. Reinforcements with twill-weave architecture did not impart appreciable flexural strength or flexural modulus even when the outer thickness was increased. Plain- and dobby (basket woven style)-weave architectures gave better reinforcing effects and the flexural properties increased with an increase in outer thickness. Water absorption properties of the composites were studied and it was observed that the hybridization with Lyocell fiber reduced the water uptake. Field-emission scanning electron microscopy was used to study the micro-structural properties of the composites.

  • 17.
    Adhikari, Arindam
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Ytkemi.
    Claesson, Per M.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Ytkemi.
    Pani, Jinshan
    KTH, Skolan för kemivetenskap (CHE), Kemi, Korrosionslära.
    Leygraf, Christofer
    KTH, Skolan för kemivetenskap (CHE), Kemi, Korrosionslära.
    Deidinaitei, Andra
    KTH, Skolan för kemivetenskap (CHE), Kemi, Ytkemi.
    Blomberg, Eva
    KTH, Skolan för kemivetenskap (CHE), Kemi, Ytkemi.
    Electrochemical behavior and anticorrosion properties of modified polyaniline dispersed in polyvinylacetate coating on carbon steel2008Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 53, nr 12, s. 4239-4247Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Conducting polyaniline (Pani) was prepared in the presence of methane sulfonic acid (MeSA) as dopant by chemical oxidative polymerization. The Pani-MeSA polymer was characterized by FT-IR, UV-vis, X-ray diffraction (XRD) and impedance spectroscopy. The polyrner was dispersed in polyvinylacetate and coated oil carbon steel samples by a dipping method. The electrochemical behavior and anticorrosion properties of the coating, oil carbon steel in 3% NaCl were investigated using Open-circuit Potential (OCP) versus time of exposure, and electrochemical techniques including electrochemical impedance spectroscopy (EIS), potentiodynamic polarization and cyclic voltammetry (CV). During initial exposure, the OCP dropped about 0.35 V and the interfacial resistance increased several times, indicating I certain reduction of the polymer and oxidation of the steel surface. Later the OCP shifted to the noble direction and remained at a stable value during the exposure up to 60 days. The EIS monitoring also revealed the initial change and later stabilization of the coating. The stable high OCP and low coating impedance Suggest that the conducting polymer maintains its oxidative state and provides corrosion protection for carbon steel through out the investigated period. The polarization curves and CV show that the conducting polymer coating induces a passive-like behavior and greatly reduces the corrosion of carbon steel.

  • 18.
    Adhikari, Arindam
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Ytkemi.
    Radhakrishnan, S.
    Patil, Rahul
    Influence of dopant ions on properties of conducting polypyrrole and its electrocatalytic activity towards methanol oxidation2009Inngår i: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 159, nr 15-16, s. 1682-1688Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The polypyrrole (PPy) films were deposited on vacuum metallized substrates by electro-oxidation of pyrrole monomer. These electrodes were then modified with a range of metal halides having different electronegativities. The modified polypyrrole electrodes were employed to investigate electrocatalytic activity towards methanol electrochemical oxidation by means of cyclic voltammetry in 0.1 M HClO4 as supporting electrolyte. It was found that the electronegativity of the dopant ion incorporated in the PPy film governs the electrocatalytic activity towards methanol oxidation. Among different dopant anions used in the present work, the PPy doped with zirconium chloride gave the highest anodic current of 10 mA cm(-2) at the oxidation potential of methanol. Electrical property and the charge created due to doping in the polymers were measured using X-ray photoelectron spectroscopy (XPS) and Electron spin resonance spectroscopy (ESR). Electrocatalytic activity of the modified electrodes was correlated with various factors obtained from different polymer characterization experiments. The results were explained on the basis of the charge-transfer efficiency at the electrode I electrolyte interface, which was associated with the acceptor state created by the dopant in the semi-conducting polymer.

  • 19. Adia, Madina Mohamed
    et al.
    Emami, Seyedeh Noushin
    Byamukama, Robert
    Faye, Ingrid
    Borg-Karlson, Anna-Karin
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Antiplasmodial activity and phytochemical analysis of extracts from selected Ugandan medicinal plants2016Inngår i: Journal of Ethnopharmacology, ISSN 0378-8741, E-ISSN 1872-7573, Vol. 186, s. 14-19Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Ethnopharmacological relevance: Resistance of the parasites to known antimalarial drugs has provided the necessity to find new drugs from natural products against malaria. The aim of the study was to evaluate the in vitro antiplasmodial activity of some plants used by Traditional Medical Practitioners (TMPs) of Prometra and Rukararwe in malaria treatment in Uganda to provide scientific proof of the efficacies claimed by these Herbalists. Materials and methods: The air dried samples of Clerodendrum rotundifolium (leaves), Microglossa pyrifolia (leaves), Momordica foetida (leaves) and Zanthoxylum chalybeum (stem bark) used for malaria treatment by TMPs were successively extracted with ethyl acetate, methanol and water to yield twelve extracts. The extracts were tested against the chloroquine-sensitive (NF54) and chloroquine-resistant (FCR3) Plasmodium falciparum strains in vitro using the micro Mark III test which is based on assessing the inhibition of schizont maturation. A compound A was extracted and purified from the stem bark of Z. chalybeum and its structure was identified and confirmed by spectroscopic methods. Results: Most of the extracts tested (92%) showed an antiplasmodial activity with IC50 < 50 mu g/mL. In spite of successive extractions with different solvents, potent anti-plasmodial activity (IC50 < 5 mu g/mL) was observed in the ethyl acetate, methanol and aqueous extracts of M. pyrifolia and C. rotundifolium. Preferential enrichments of activity into water (IC50 < 15 mu g/mL) and Ethyl acetate (IC50 < 5 mu g/mL) were seen in the case of M. foetida and Z chalybeum respectively. The most active extracts were from C rotundifolium and M. pyrifolia with IC50 values less than 2 mu g/mL. Phytochemical analysis of the extracts revealed the presence of saponins, tannins, flavonoids, alkaloids and cardiac glycocides. Fagaramide isolated from Z chalybeum had a higher activity (IC50 2.85 mu g/mL) against the chloroquine-resistant strain than against the chloroquine-senstive (IC50 16.6 mu g/mL) strain used in the study. Conclusion: The plant extracts analysed in this study presented an average antiplasmodial activity (58%). This study revealed for the first time the antiplasmodial activity of the plant C. rotundofolium. It's the first time the compound fagaramide (N-isobutyl-3-(3,4-methylene dioxyphenyl) - 2E-propenamide) has been isolated from Z. chalybeum as one of the compounds that contribute to the activity of this plant against P. falciparum.

  • 20.
    Adler, Jeanette
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Film Formation and Surface Tension Studies of Powder Coatings2005Independent thesis Basic level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    In industrial use of paint systems a swift processing is crucial. Another very important issue is to improve the quality of the final coating. This report investigates the film formation process of powder coatings, specially the spreading of individual powder particles. The obtained results can be used to understand and control the film formation process. In this way the desired levelling can be achieved and thus the desired gloss or other surface characteristics that may be required. This means that the method could be used when evaluating different polymer and additive combinations that could be used to change film formation behaviour or curing time for powder coating systems to suit various substrates. It makes it possible to avoid and minimize different surface defects as orange peel or cratering in the powder coated film.

    We used a reflection optical microscope to better understand the film formation process and especially the spreading of a powder melt on surfaces with various surface energies. The obtained data were: the particle diameter, the area, area ratio and the contact angle of the powder particle as a function of time and temperature. This information can be used to derive the surface tension of any powder melt.

    In this report we evaluate the dependencies of temperature, heat rate and surface energy for powder coatings on different substrates. The method provides information that can be used to optimize the film formation of a specific powder coating/substrate combination. This method can be used to evaluate the powder spreading and levelling on different substrates from a surface tension point of view.

    We found, as expected, that the powder flows out on a hydrophilic surface and is inhibited by a hydrophobic. The increase of the area ratio on a hydrophilic surface was about five times as the initial area coverage and on a hydrophobic surface only two times the initial area coverage. The contact angle between the melted powder particle on the different surface types could be calculated. The melt surface tension could be calculated since three substrates surfaces with various surface energies were used. The melt surface tension was found to be about 18.5 mN/m.

  • 21.
    Adolfsson, Karin
    KTH, Skolan för kemivetenskap (CHE).
    Microwave-assisted synthesis of carbon nanospheres and graphene oxide as by-product of cellulose liquefaction2014Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
  • 22.
    Adolfsson, Karin H.
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Hassanzadeh, Salman
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Hakkarainen, Minna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Valorization of cellulose and waste paper to graphene oxide quantum dots2015Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 5, nr 34, s. 26550-26558Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Biobased graphene oxide quantum dots (GOQD) were derived from cellulose via carbon nanospheres (CN) as intermediate products. Solid CN were synthesized from cellulose through microwave-assisted hydrothermal degradation of alpha-cellulose with H2SO4 as a catalyst at 160 degrees C. The obtained CN were further utilized for the synthesis of GOQD by a two-step reaction including 30 minutes of sonication followed by heating at 90 degrees C under O-rich acidic conditions (HNO3). This process broke down the 3D CN to 2D GOQD. The size of the synthesized GOQD was controlled by the heating time, reaching a dot diameter of 3.3 nm and 1.2 nm after 30 and 60 minutes of heating, respectively. The synthesis process and products were characterized by multiple analytical techniques including FTIR, TGA, SEM, TEM, XPS, XRD, BET, DLS and AFM. Interesting optical properties in aqueous solutions were demonstrated by UV/Vis and fluorescence spectroscopy. Finally we demonstrated that corresponding GOQD can be synthesized from waste paper. This production route thus uses renewable and cheap starting materials and relatively mild synthesis procedures leads to instant nanometric production of 2D dots. In addition it enables recycling of low quality waste to value-added products.

  • 23.
    Adolfsson, Karin H.
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymerteknologi.
    Xie, L.
    Hassanzadeh, Salman
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymerteknologi.
    Pettersson, Torbjörn
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Fiberteknologi.
    Hakkarainen, Minna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymerteknologi.
    Zero-Dimensional and Highly Oxygenated Graphene Oxide for Multifunctional Poly(lactic acid) Bionanocomposites2016Inngår i: ACS Sustainable Chemistry & Engineering, ISSN 2168-0485, Vol. 4, nr 10, s. 5618-5631Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The unique strengths of 2D graphene oxide nanosheets (GONSs) in polymer composites are thwarted by nanosheet agglomeration due to strong intersheet attractions. Here, we reveal that shrinking the planar size to 0D graphene oxide quantum dots (GOQDs), together with the intercalation of rich oxygen functional groups, reduces filler aggregation and enhances interfacial interactions with the host polymer. With poly(lactic acid) (PLA) as a model matrix, atomic force microscopy colloidal probe measurements illustrated that a triple increase in adhesion force to PLA was achieved for GOQDs (234.8 nN) compared to GONSs (80.4 nN), accounting for the excellent exfoliation and dispersion of GOQDs in PLA, in contrast to the notable agglomeration of GONSs. Although present at trace amount (0.05 wt %), GOQDs made a significant contribution to nucleation activity, mechanical strength and ductility, and gas barrier properties of PLA, which contrasted the inferior efficacy of GONSs, accompanied by clear distinction in film transparency (91% and 50%, respectively). Moreover, the GOQDs with higher hydrophilicity accelerated the degradation of PLA by enhancing water erosion, while the GONSs with large sheet surfaces gave a higher hydrolytic resistance. Our findings provide conceptual insights into the importance of the dimensionality and surface chemistry of GO nanostructures in the promising field of bionanocomposites integrating high strength and multifunction (e.g., enhanced transparency, degradation and gas barrier).

  • 24. Afonso, Damien
    et al.
    Valetti, Sabrina
    Fraix, Aurore
    Bascetta, Claudia
    Petralia, Salvatore
    Conoci, Sabrina
    Feiler, Adam
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Sortino, Salvatore
    Multivalent mesoporous silica nanoparticles photo-delivering nitric oxide with carbon dots as fluorescence reporters2017Inngår i: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 9, nr 36, s. 13404-13408Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Amino-terminated mesoporous silica nanoparticles embedding carbon dots (MSCD) formed by calcination were functionalized with a nitric oxide (NO) photodonor (1) to give a robust MSCD-1 conjugate. The intense fluorescence of MSCDs was strongly quenched in MSCD-1 by effective energy transfer. Visible light excitation of MSCD-1 liberates NO, suppresses the energy transfer mechanism and leads to concomitant fluorescence restoration of the MSCD scaffold, which acts as an optical reporter for the released NO. The MSCD-1 hybrid is also able to encapsulate the highly hydrophobic photosensitizer temoporfin, preserving the fluorescence reporting function.

  • 25.
    Agfors, Gunnar
    et al.
    Ledamot av IVA.
    Albertsson, Ann-Christine
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Grenthe, Ingmar
    KTH, Skolan för kemivetenskap (CHE), Kemi, Oorganisk kemi.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Ödberg, Lars
    et, al
    KEMI: den gränslösa vetenskapen2011Bok (Annet (populærvitenskap, debatt, mm))
    Abstract [sv]

    Kemi – handlar inte det bara om farliga ämnen och onödiga tillsatser? Det är kanske bildenmånga har av kemi, men faktum är att utan kemi skulle vi inte ha det höga välstånd vi har i dag.Tack vare kemisk kunskap har vi tillgång till läkemedel som botar sjukdomar och lindrar smärta– med hjälp av syntetiska antibiotika kan infektionssjukdomar som tidigare var dödliga botas,magsår kan behandlas utan dyra och plågsamma operationer och många cancerformer kanframgångsrikt behandlas med syntetiska preparat. Konstgödsel och medel som hindrar skadeinsektergör att skördar kan ökas och svälten i världen därigenom begränsas. Tack vare kemin harvi även tillgång till alla de material vi behöver för att tillverka allt från kläder, rengöringsprodukteroch kosmetika till bilar, TV-apparater och reservdelar till kroppen. Det är genom kemisk syntes vikan framställa dessa och alla de övriga produkter vi behöver för vårt dagliga liv och det är keminsom visar vägen till hållbar produktion som utnyttjar förnybara råvaror och ger minimala mängderavfall. Kemisk kunskap är också oumbärlig för utveckling av nanoteknik och medicinskdiagnostik och andra till kemin angränsande områden. Kemin bidrar alltså till att finna lösningartill många av de komplexa globala problem vi står inför: hälsa, klimat, brist på råvaror, utnyttjandetav nya energikällor och tillgång till livsmedel för att föda jordens ökande befolkning.

    DET ÄR OM ALLT DETTA DEN HÄR BOKEN HANDLAR.

  • 26.
    Aglén, Lina
    KTH, Skolan för kemivetenskap (CHE).
    Qualification of Low Value Fuels for Production of Syngas via the WoodRoll Process2016Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    This master thesis project has, on behalf of Cortus Energy AB, investigated how to increase the

    suitability of so called low value fuels for use in the thermochemical conversion process WoodRoll®.

    The theoretical background of the report includes theory on pyrolysis, gasification and ash chemistry,

    as well as a description of WoodRoll® and a comparison between Woodroll® and more conventional

    technologies. A theoretical and an experimental trial have been conducted to investigate methods

    for potentially increasing the ash fusion temperatures of low value fuels. The theoretical study

    compared published articles on leaching and co-gasification. The experimental study was performed

    using thermogravimetric analysis and investigated if blending was a viable alternative for improving

    behavior. Three new types of industrial wastes were also tested.

    Both the theoretically investigated pretreatment methods and the blending were indicated to

    improve the behavior of low value fuels. When compared, blending was deemed to be economically

    favorable over the investigated pretreatment methods. The most economically favorable alternative

    is if two low value fuels with complementing characteristics can be successfully blended. Blending

    would also be easier to integrate with the current WoodRoll® process design and showed promise of

    high fuel flexibility. The behavior of the blends were influenced by their level of homogeneousness,

    a relationship of interest to investigate further in the future.

  • 27.
    Agrios, Alexander George
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Fysikalisk kemi (stängd 20110630). KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD.
    Cesar, I.
    Comte, P.
    Nazeeruddin, M. K.
    Grätzel, M.
    Nanostructured composite films for dye-sensitized solar cells by electrostatic layer-by-layer deposition2006Inngår i: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 18, nr 23, s. 5395-5397Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The possibilities for making nanocomposite semiconductor films for DSC using the ELBL method was investigated. Coated slides were cut in half vertically giving two strips that can be subjected to different treatments for comparison. The electrode was heated to 450 °C for 30 min and then Cooled to 80 °C. Scanning electron microscopy of a sintered film with 5 cycles of TiO2 nanoparticles shows that the particles are well distributed and completely cover the transparent conducting oxide substrate. Spectroscopic measurements of a dye-coated film in acetonitrile found a dye concentration within the film of 0.15 mM based on an extinction coefficient. The solar cell including a scattering layer had more than double the current of the transparent layer-only cell. It was observed that ELBL method can produce TiO2 films for DSC with high efficiencies at low thickness.

  • 28. Aguirre, Miren
    et al.
    Johansson Salazar-Sandoval, Eric
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik. SP Technical Research Institute of Sweden, Sweden.
    Johansson, Mats
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Ahniyaz, Anwar
    Paulis, Maria
    Ramon Leiza, Jose
    Hybrid acrylic/CeO2 nanocomposites using hydrophilic, spherical and high aspect ratio CeO2 nanoparticles2014Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 2, nr 47, s. 20280-20287Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A dispersion of CeO2 nanoparticles and nanorods stabilized with nitrilotriacetic acid (NTA) and a 4,4'-azobis(4-cyanovaleric acid) (V-501) initiator has been used to initiate the emulsion polymerization of acrylic monomers, yielding stable hybrid CeO2 nanoparticle-nanorod/polyacrylate latexes for the first time. Films cast from these hybrid latexes are transparent due to the very homogenous distribution of the polymer compatibilized CeO2. Furthermore, it has been proven that the UV-Vis absorption capacity of the hybrid latexes is enhanced with the incorporation of the nanorods.

  • 29.
    Ahlawat, Paramvir
    KTH, Skolan för kemivetenskap (CHE).
    Modellering och implementering av simultan dubbel gradient kromatografi2015Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Polypeptides are becoming an important component of the antibiotic therapeutics. The production demand of therapeutic polypeptides is increasing and there is a significant interest in developing more efficient production processes. In pharmaceutical industries, polypeptides are produced as a crude mixture. Reverse phase high performance liquid chromatography (RP HPLC) is used as a typical separation technique to purify the target polypeptide from other impurities. Currently organic modifier gradients are used to elute product peptides separately from impurities. In this work, we add a second, simultaneous counter-ion gradient, in the hope of increasing separation performance and call it double gradient reverse phase chromatography. A general procedure of the model-based optimization of a polypeptide crude mixture purification process was followed to evaluate the effects of the double gradients on industrial chromatographic process. The target polypeptide elution profile was modeled with a bi-Langmuir adsorption equilibrium isotherm. The isotherm parameters of the target polypeptide were estimated by the inverse method. The model parameters of the impurities were regressed from experimental data. The variations of the isotherm parameters with the modifier concentration and counter-ion concentration were taken into account of the adsorption model. After model calibration and validation by comparison with suitable experimental data, Pareto optimization of the process were carried out to analyze the differences between single gradient chromatography and double gradient chromatography. It was observed that the additional linear gradient of counter-ion concentration did not improve the separation process. Conclusively we were able to demonstrate the concept of double gradient reverse phase chromatography within limited time and possible least experimental efforts.

  • 30.
    Ahlberg Tidblad, Annika
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Surface analysis with ESCA and GD-OES of the film formed by cathodic reduction of chromate1991Inngår i: Electrochimica Acta, Vol. 36, nr 10, s. 1605-1610Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In the chlorate process, a small addition of chromate to the electrolyte results in the formation of a cathode film, which inhibits the reduction of the intermediate hypochlorite ions. To enable surface characterization of the chromium film, it was grown by cathodic reduction onto gold and platinum substrates in hydroxide and chlorate solution. Surface analyses of this film by ESCA and GD-OES indicate that it has a distinct and constant chemical composition during growth given by the formula Cr(OH)3·xH2O. The film is thin, less than 50 Å on platinum and 80 Å on gold. It exhibits poor conductivity and covers the entire cathode surface. © 1991.

  • 31.
    Ahmadi, Mozhgan
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Brage, Claes O.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Sjöström, Krister
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Engvall, Klas
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Knoef, H.
    Van De Beld, B.
    Development of an on-line tar measurement method based on photo ionization technique2011Inngår i: Catalysis Today, ISSN 0920-5861, E-ISSN 1873-4308, Vol. 176, nr 1, s. 250-252Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper presents work in progress for development of an on-line method based on PID (Photo Ionization Detector) for quantitative measurement of tar from biomass gasification. To calibrate the method the PID signals are compared to quantitative data of individual tar compounds obtained by an established reference method. The measured response factors for the model tar compounds demonstrated very good linearity. The PID approach was tested on-line with real producer gases from an atmospheric fluidized bed gasifier operated at 800-900 °C. The results suggest that PID can be used for continuous on-line tar measurement of product gases from biomass gasification.

  • 32.
    Ahmadi, Mozhgan
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Knoef, Harrie
    Van De Beld, Bert
    Liliedahl, Truls
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk apparatteknik.
    Engvall, Klaus
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk apparatteknik.
    Development of a PID based on-line tar measurement method: Proof of concept2013Inngår i: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 113, s. 113-121Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this study, a proof of concept was conducted for an on-line tar analyzer based on photo ionization detection (PID). Tar model compounds (naphthalene, acenaphthene, acenaphthylene, fluorene, indane and indene) were used for the initial investigation of the analysis method. It was found that the analysis method has a high sensitivity and a linear behavior was observed between the PID response and the tar concentration over a wide concentration span. The on-line tar analysis method was successfully validated against the solid phase adsorption (SPA) method using a real producer gas.

  • 33.
    Ahmadi, Mozhgan
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Sjöström, Krister
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Brage, Claes
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Engvall, Klas
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Liliedahl, Truls
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Develompent of an online tar measuring method using ionization potential2010Konferansepaper (Fagfellevurdert)
  • 34.
    Ahmadi, Mozhgan
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Sjöström, Krister
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Brage, Claes
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Liliedahl, Truls
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Knoef, Harri A.M.
    Van de Beld, Bert
    Development of an online tar measuring method for quantitative analysis of biomass producer gas2009Konferansepaper (Fagfellevurdert)
  • 35.
    Ahmadi, Mozhgan
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk apparatteknik.
    Svensson, Erik Elm
    Engvall, Klas
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk apparatteknik.
    Application of solid phase microextraction (SPME) as a tar sampling method during real gasificationManuskript (preprint) (Annet vitenskapelig)
  • 36.
    Ahmadi, Mozhgan
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk apparatteknik.
    Svensson, Erik Elm
    Engvall, Klas
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk apparatteknik.
    Application of Solid-Phase Microextraction (SPME) as a Tar Sampling Method2013Inngår i: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 27, nr 7, s. 3853-3860Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper presents the result of an investigation of the potential use of solid-phase microextraction (SPME) as a tar sampling method. The SPME stationary phase used was 50 mu m of polydimethylsiloxane (PDMS) coated on a fused silica fiber. Tar model compounds normally present in a producer gas from gasifiers, benzene, toluene, indane, indene, naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, and pyrene, were used in the investigation. The adsorbed compounds were analyzed by injection into gas chromatography coupled to a flame ionization detector (GC- FID). The amount of adsorbed tar on the SPME fiber determined the detection and quantification limits for the method. The results showed that adsorption of tar model compounds on the SPME fiber increased with decreasing polarity. The adsorption of compounds increased with a decreasing temperature, enabling a possibility to tune the sensitivity of the method by changing the sampling temperature. Conclusively, SPME has a very high potential as a tar sampling method and, in combination with GC- FID trace analysis of tar, is a feasible application.

  • 37.
    Ahmadi Svensson, Mozhgan
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk apparatteknik.
    Sampling and Analysis of Tars by Means of Photo Ionization Detection and Solid Phase Micro Extraction2013Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Gasification of biomass will likely play an important role in the production of energy and chemicals in a future sustainable society. However, during gasification impurities, such as tars, will be formed. Tars may cause fouling and blockages of equipment downstream the gasifier. It is therefore important to minimize the formation of tars, alternatively to remove the formed tars. These processes need to be monitored, which makes it necessary to develop tar analysis methods suitable for this task.

    This work describes the development of two tar analysis methods, an on-line method based on a photoionization detector (PID) and an off-line method based on solid phase microextraction (SPME). Both methods were successfully validated against the established solid phase adsorption (SPA) method.

    The method based on PID was shown to have a very fast response time. Furthermore, the PID method is selective towards tar, but only limited information will be obtained regarding the composition of the tar compounds. The PID method is suitable for applications where it is important to detect fast changes of the tar concentration, i.e. process monitoring.

    The SPME method was shown to be a very sensitive method for qualitative and quantitative tar analysis. The sampling temperature was shown to be crucial for obtaining analysis results with the wanted detection limit. The SPME method is suitable for applications where extremely low detection and quantification limits are needed, i.e. for syngas production.

     

  • 38.
    AHMADZADEH, KARAN
    KTH, Skolan för kemivetenskap (CHE).
    Interaktions potentialla energin mellan ändliga rektangulära disperserade celullosa nanofibriller2015Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    Thermodynamically, native cellulose nano fibrils are more stable in an aggregated state. The aggregated state is however not useful from a material development perspective. Therefore much research has been done to stabilize the dispersal of the fibrils. One method to overcome this instability is by surface substitution of the O6 hydroxyl group with carboxylate groups, to make highly charged fibrils in aqueous solutions. It is therefore of much interest to understand the interaction of highly charged fibrils in aqueous solutions. In this study, we aim to model the interaction potential energy between native and surface modified cellulose nanofibrils in order to understand under what conditions the contribution from the dipole interactions can be neglected. To achieve this we propose to use a continuum electrostatic approach, modeling the electrostatic interactions as a function of the fibrils relative dipole orientation, separation, surface charge as well as ionic strength of the solution, by means of using the Poisson-Boltzmann equation.

  • 39.
    Ajmal Khan, Muhammad
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Raza, Rizwan
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Bohn Lima, Raquel
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik. KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Chaudhry, M. Asharf
    Ahmed, E.
    Abbas, Ghazanfar
    Comparative study of the nano-composite electrolytes based on samaria-doped ceria for low temperature solid oxide fuel cells (LT-SOFCs)2013Inngår i: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 38, nr 36, s. 16524-16531Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Ceria-based electrolyte materials have great potential in low and intermediate temperature solid oxide fuel cell applications. In the present study, three types of ceria-based nanocomposite electrolytes (LNK-SDC, LN-SDC and NK-SDC) were synthesized. One-step co-precipitation method was adopted and different techniques were applied to characterize the obtained ceria-based nano-composite electrolyte materials. TGA, XRD and SEM were used to analyze the thermal effect, crystal structure and morphology of the materials. Cubic fluorite structures have been observed in all composite electrolytes. Furthermore, the crystallite sizes of the LN-SDC, NK-SDC, LNK-SDC were calculated by Scherrer formula and found to be in the range 20 nm, 21 nm and 19 nm, respectively. These values emphasize a good agreement with the SEM results. The ionic conductivities were measured using EIS (Electrochemical Impedance Spectroscopy) with two-probe method and the activation energies were also calculated using Arrhenius plot. The maximum power density was achieved 484 mW/cm(2) of LNK-SDC electrolyte at 570 degrees C using the LiCuZnNi oxide electrodes.

  • 40.
    Akan, Rabia
    KTH, Skolan för kemivetenskap (CHE).
    Oorganiska-organiska nanopartikelbaserade supramolekylära strukturer för biomedicinska applikationer2015Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The possibility to create a multifunctional nanoparticle system via supramolecular chemistry approach with ability to simultaneously target, deliver and diagnose was investigated. Superparamagnetic iron oxide nanoparticles were synthesized by co-precipitation method and surface modified with the cyclic oligosaccharide carboxymethyl-β-cyclodextrin by three different routes. The different routes involved one, two or three reaction steps in order to reach to the final oligosaccharide functionalized nanoparticles. Esterification was performed using the intrinsic hydroxyl functionality of the nanoparticle surfaces or amine functionality was introduced prior to amidization. Further, a polymeric coating was created by incorporation of folic acid functionalized Pluronic® L-35 into carboxymethyl-β-cyclodextrin. The resulting nanoparticle based supramolecular systems were characterized by TEM, TGA, FT-IR, DLS and zeta potential techniques.

     

    The colloidal stabilities of the supramolecular nanoparticle systems were investigated in phosphate buffered saline with pH 7.4 representing body conditions. It was found that a three-step functionalization of iron oxide nanoparticles with citric acid, hexamethylenediamine and finally carboxymethyl-β-cyclodextrin resulted in the most stable ferrofluids. The average size of the resulting carboxymethyl-β-cyclodextrin functionalized nanoparticles was 25 nm prior to, and 50 nm after inclusion of folic acid functionalized Pluronic. The amount of grafted carboxymethyl-β-cyclodextrin on the nanoparticles surfaces was 25 weight %. Thus, the resulting stable ferrofluid creates an efficient platform with potential of multiple uses in biomedicine. This nanoparticle based supramolecular system combines the properties of magnetic targeting and MRI contrast enhancement due to the superparamagnetic iron oxide nanoparticle core, drug delivery of hydrophobic drugs due to the polymer capsule and selective targeting towards tumour cells due to the folic acid.

  • 41.
    AKBARI KHALIL ABAD, HANNANE
    et al.
    KTH, Skolan för kemivetenskap (CHE).
    ARONSSON, JENS
    KTH, Skolan för kemivetenskap (CHE).
    PERSSON, ALEXANDER
    KTH, Skolan för kemivetenskap (CHE).
    REINECK POPA, ERIK
    KTH, Skolan för kemivetenskap (CHE).
    Heterogen katalys för produktion av biodiesel från rester av matolja2015Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Energikonsumtionen inom transportsektor består till störst del av konsumtion av fossila bränslen. Transportsektorn själv står för ca 30 % av världens totala energikonsumtion. Att växla till ett grönt drivmedel skulle bidra till en mer ekologiskt hållbar verksamhet.

    Biodiesel kan vara svaret på transportsektorns problem och kan dessutom framställas av vad man idag anser är avfall. Restmatolja kan med hjälp av katalysatorer transesterifieras till biodiesel som efter inblandning av konventionell diesel kan köras i dagens dieselmotorer.

    För att spara resurser är en process med heterogen katalysator bättre än en homogen process. I rapporten undersöks om MgO, CaO och Li2O kan användas som katalysator för att framställa biodieseln från restmatoljan. Studien undersöker också om SnO eller SnO2 kan tillsättas till katalysatorn för att öka utbytet.

    Försök genomfördes i labbmiljö med restolja från en lokal restaurang. Olika parametrar testades för att optimera utbytet. Parametrarna som ändrades var temperatur, mängd katalysator och molförhållandet mellan alkohol och olja. Varje parameter varierades mellan två värden.

    Resultaten visade att CaO var den enda av de undersökta katalysatorerna som fungerade och gav ett tillräckligt bra utbyte. SnO som användes tillsammans med CaO visade en liten effekt av att öka utbytet, men antalet försök var för få för att kunna dra några säkra slutsatser.

    Resultaten från undersökningen av optimala parametrar visar att utbytet minskar med ökande temperatur. Större andel alkohol jämfört med olja ger ett högre utbyte. Med ökande mängd katalysator finns ett optimalt värde och när det överskrids minskar utbytet igen.

    Vidare studier krävs för att optimera de heterogena katalysatorerna i biodieselframställningen.

  • 42.
    Akhand, Victoria
    KTH, Skolan för kemivetenskap (CHE).
    Mass Balance Model of Impurities for the WoodRoll Process2017Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The depletion time for fossil fuels calculated from 2009 is 35 years for oil, 37 years for gas

    and 107 years for coal. Hence, it has become essential to reduce the dependence on fossil

    fuels by switching over to renewable resources. This in turn will also help in combating the

    negative effects on the environment like global warming. Thermochemical processes such as

    pyrolysis and gasification of biomass are considered the most efficient technology for

    converting biomass to useful energy carriers. Cortus Energy AB is a Swedish company that

    has developed a patented gasification technology called WoodRoll

    ® for gasification of fuels derived from biomass. However, ash in a thermochemical conversion process can cause

    corrosion, sintering, slag and poisoning of catalysts, which leads to operational problems. In

    addition, heavy metals such as Zn, Pb and Cd are environmentally problematic. These metals

    contribute to environmental pollution by contaminating the soil, which in turn can harm

    humans and the ecosystem via the food chain. The undesired elements should therefore be

    identified to minimize their impact on the overall thermochemical process and to reduce the

    emission of these harmful substances.

    The objective of this master thesis project, on behalf of Cortus Energy AB, was to investigate

    possible key numbers that can be used to describe and predict how the ash behaves in their

    patented WoodRoll® process. The key numbers that have been identified are empirically

    developed based on experience of coal combustion. These key numbers are regularly used for

    fuel derived from biomass by companies specializing in analyzing, although knowledge about

    whether they can actually be used on biomass is limited. In order to ensure that the use of

    these for biomass is correct, they must be experimentally verified in the future. In addition, a

    theoretical investigation is conducted to study which species can form and in what phase this

    occurs. The investigation reveals that there are no clear trends for how the inorganic elements

    behave since contradicting results from different studies have been reported. Formation of

    species and their phase depends on several parameters such as temperature, heating rate,

    particle size, volatility, quantity and interaction between the elements in the biomass. The

    thesis project ends with a mass balance model on selected inorganic elements for wood

    residues, as well as for bark. The model could be a tool for Cortus Energy AB to identify

    approximately how much of each element is present in each stream in the WoodRoll® process.

    The models are verified with analysis results. Inorganic elements that affect the

    overall process and its equipment have been selected for modelling. The volume percent of

    H2, CO, CO2 and CH4 in the models agree well with the values obtained by Cortus Energy

    AB. This shows that the thermodynamic equilibrium calculations performed are reasonable.

  • 43.
    Akhand, Victoria
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Celsi, Adrian
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Lagerberg, Tove
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Sångberg, Oscar
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Plastfilm från rapshalm2015Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Projektets syfte är att utvinna hemicellulosa ur rapshalm med hjälp av alkali- och vattenextraktioner, för att sedan tillverka en plastfilm av dessa polymerer. Denna plastfilm är på sikt tänkt att bland annat kunna ersätta dagens syrebarriärer av aluminium i applikationer såsom livsmedelsförpackningar av kartong. Plastfilmen består av hemicellulosan och additiv, endera CMC eller sorbitol. Flertalet analyser av extrakten och plastfilmerna utfördes för att kunna dra slutsatser om struktur och egenskaper. NMR-analysen visade att extrakten innehöll de förväntade sockerarterna och att den främsta deacetyleringen av O-acetylgrupperna skedde vid lågalkaliextraktionen. SEC-analysen gav låga värden på Đ. Dragprovningen gav exceptionella resultat, nämligen en töjningstolerans på 10-60%, beroende på plastfilmernas sammansättning. Två av de mest väsentliga analyserna, jonkromatografi och syrgaspermeabilitetstest, kunde inte genomföras på grund av tekniska fel. Med avseende på miljö, ekonomi samt likvärdiga mekaniska egenskaper är låg alkali som extraktionsmedel att föredra och i plastfilmstillverkningen är en hög tillsats av CMC att föredra eftersom låg CMC och sorbitol gav kladdiga plastfilmer. I framtiden vore det bra om analyser av plastfilmerna kan genomföras med jonkromatografi och syrgaspermeabilitetstester. Vidare vore det önskvärt att finna den optimala tillsatsmängden av CMC.

  • 44.
    Akhlaghi, Shahin
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Degradation of acrylonitrile butadiene rubber and fluoroelastomers in rapeseed biodiesel and hydrogenated vegetable oil2017Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Biodiesel and hydrotreated vegetable oil (HVO) are currently viewed by the transportation sector as the most viable alternative fuels to replace petroleum-based fuels. The use of biodiesel has, however, been limited by the deteriorative effect of biodiesel on rubber parts in automobile fuel systems. This work therefore aimed at investigating the degradation of acrylonitrile butadiene rubber (NBR) and fluoroelastomers (FKM) on exposure to biodiesel and HVO at different temperatures and oxygen concentrations in an automated ageing equipment and a high-pressure autoclave. The oxidation of biodiesel at 80 °C was promoted by an increase in the oxygen partial pressure, resulting in the formation of larger amounts of hydroperoxides and acids in the fuel. The fatty acid methyl esters of the biodiesel oxidized less at 150 °C on autoclave aging, because the termination reactions between alkyl and alkylperoxyl radicals dominated over the initiation reactions. HVO consists of saturated hydrocarbons, and remained intact during the exposure. The NBR absorbed a large amount of biodiesel due to fuel-driven internal cavitation in the rubber, and the uptake increased with increasing oxygen partial pressure due to the increase in concentration of oxidation products of the biodiesel. The absence of a tan δ peak (dynamical mechanical measurements) of the bound rubber and the appearance of carbon black particles devoid of rubber suggested that the cavitation was caused by the detachment of bound rubber from particle surfaces. A significant decrease in the strain-at-break and in the Payne-effect amplitude of NBR exposed to biodiesel was explained as being due to the damage caused by biodiesel to the rubber-carbon-black network. During the high-temperature autoclave ageing, the NBR swelled less in biodiesel, and showed a small decrease in the strain-at-break due to the cleavage of rubber chains. The degradation of NBR in the absence of carbon black was due only to biodiesel-promoted oxidative crosslinking. The zinc cations released by the dissolution of zinc oxide particles in biodiesel promoted reduction reactions in the acrylonitrile part of the NBR. Heat-treated star-shaped ZnO particles dissolved more slowly in biodiesel than the commercial ZnO nanoparticles due to the elimination of inter-particle porosity by heat treatment. The fuel sorption was hindered in HVO-exposed NBR by the steric constraints of the bulky HVO molecules. The extensibility of NBR decreased only slightly after exposure to HVO, due to the migration of plasticizer from the rubber. The bisphenol-cured FKM co- and terpolymer swelled more than the peroxide-cured GFLT-type FKM in biodiesel due to the chain cleavage caused by the attack of biodiesel on the double bonds formed during the bisphenol curing. The FKM rubbers absorbed biodiesel faster, and to a greater extent, with increasing oxygen concentration. It is suggested that the extensive biodiesel uptake and the decrease in the strain-at-break and Young’s modulus of the FKM terpolymer was due to dehydrofluorination of the rubber by the coordination complexes of biodiesel and magnesium oxide and calcium hydroxide particles. An increase in the CH2-concentration of the extracted FKM rubbers suggested that biodiesel was grafted onto the FKM at the unsaturated sites resulting from dehydrofluorination.

  • 45.
    Akhlaghi, Shahin
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Amir Masoud, Pourrahimi
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Christian, Sjöstedt
    Martin, Bellander
    Mikael S., Hedenqvist
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Ulf W., Gedde
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Degradation of fluoroelastomers in rapeseed biodiesel at different oxygen concentrations2017Inngår i: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 136, s. 10-19Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The degradation of fluoroelastomers (FKM) based on different monomers, additives and curing systems was studied after exposure to rapeseed biodiesel at 100 °C and different oxygen partial pressures. The sorption of fuel in the carbon black-filled FKM terpolymer was promoted by the fuel-driven cavitation in the rubber. The bisphenol-cured rubbers swelled more in biodiesel than the peroxide-cured FKM, presumably due to the chain cleavage caused by the attack of biodiesel on the double bonds formed during the bisphenol curing. With any of the selected types of monomer, the FKM rubbers absorbed biodiesel faster and to a greater extent with increasing oxygen partial pressure due to the increase in concentration of the oxidation products of biodiesel. Water-assisted complexation of biodiesel on magnesium oxide and calcium hydroxide particles led to dehydrofluorination of FKM, resulting in an extensive fuel uptake and a decrease in the strain-at-break and the Young's modulus of the rubbers. An increase in the CH2-concentration determined by infrared spectroscopy, and the appearance of biodiesel flakes in scanning electron micrographs of the extracted rubbers, were explained as being due to the presence of insoluble biodiesel grafted onto FKM on the unsaturated sites resulting from dehydrofluorination. The extensibility of the GFLT-type FKM was the least affected on exposure to biodiesel because this rubber contained less unsaturation and metal oxide/hydroxide particles.

  • 46.
    Akhlaghi, Shahin
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material. Scania CV AB, Sweden.
    Gedde, Ulf W.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Hedenqvist, Mikael S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Brana, Maria T. Conde
    Bellander, Martin
    Deterioration of automotive rubbers in liquid biofuels: A review2015Inngår i: Renewable & sustainable energy reviews, ISSN 1364-0321, E-ISSN 1879-0690, Vol. 43, s. 1238-1248Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    Concerns over the fast depletion of fossil fuels, environmental issues and stringent legislation associated with petroleum-based fuels have triggered a shift to bio-based fuels, as an alternative to meet the growing energy demand in the transportation sector. However, since conventional automobile fuel systems are adapted to petroleum-based fuels, switching to biofuels causes a severe deterioration in the performance of currently used rubber components. The degradation of the rubber materials in biofuels is complicated by the presence of different additives in biofuels and rubber compounds, by oxidation of biofuels and by the effects of thermomechanical loadings in the engine. This paper presents a comprehensive review of the effects of different types of biofuels, particularly biodiesel and bioethanol, on the physical, mechanical, morphological and thermal properties of elastomers under different exposure conditions. In addition, the literature data available on the variation of rubbers' resistance to biofuels with the changes in their monomer type and composition, cure system and additives content was also studied. The review essentially focuses on the compatibility of biofuels with acrylonitrile butadiene rubber, fluoroelastomers, polychloroprene rubber and silicon rubber, as the most commonly used automotive rubbers coming into contact with fuels during their service. The knowledge summarized in this study can help to develop a guideline on the selection of rubber for automotive parts designed to withstand biofuels.

  • 47.
    Akhlaghi, Shahin
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Hedenqvist, Mikael S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Brana, M. T. Conde
    Bellander, M.
    Gedde, Ulf W.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Deterioration of acrylonitrile butadiene rubber in rapeseed biodiesel2015Inngår i: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 111, s. 211-222Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The deterioration of acrylonitrile butadiene rubber (NBR) exposed to rapeseed biodiesel at 90 degrees C was studied. The oxidation of biodiesel and NBR during ageing was monitored by H-1 NMR and infrared spectroscopy, HPLC and titration methods. The oxidation of biodiesel was impeded in the presence of NBR, but promoted in biodiesel-exposed rubber. This was explained as being due to the migration of stabilizer from the rubber to biodiesel, the diffusion of dissolved oxygen from biodiesel into NBR and the absorption of oxidation precursors of biodiesel by the rubber. The resemblance between the anomalous sorption kinetics of biodiesel in NBR and the equilibrium benzene uptake by the aged rubbers revealed that biodiesel caused a network defect in NBR, resulting in a gradual increase in the equilibrium swelling. The cleavage of crosslinks was implausible since the Young's modulus of the rubber at low strains, disregarding an initial decrease, increased with increasing exposure time. The appearance of 'naked' carbon black particles in the scanning electron micrographs of the aged rubbers and a drastic decrease in the strain-at-break of NBR after exposure to biodiesel suggests that internal cavitation was caused by the attack of biodiesel on the acrylonitrile units of NBR.

  • 48.
    Akhlaghi, Shahin
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Pourrahimi, A. M.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Christian, Sjöstedt
    Martin, Bellander
    Mikael S., Hedenqvist
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Ulf W., Gedde
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Effects of ageing conditions on degradation of acrylonitrile butadiene rubber filled with heat-treated ZnO star-shaped particles in rapeseed biodiesel2017Inngår i: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The degradation of acrylonitrile butadiene rubber (NBR) after exposure to biodiesel at different oxygen partial pressures in an automated ageing equipment at 80 °C, and in a high-pressure autoclave at 150 °C was studied. The oxidation of biodiesel was promoted by an increase in oxygen concentration, resulting in a larger uptake of fuel in the rubber due to internal cavitation, a greater decrease in the strain-at-break of NBR due to the coalescence of cavity, and a faster increase in the crosslinking density and carbonyl index due to the promotion of the oxidation of NBR. During the high-temperature autoclave ageing, less fuel was absorbed in the rubber, because the formation of hydroperoxides and acids was impeded. The extensibility of NBR aged in the autoclave decreased only slightly due to the cleavage of rubber chains by the biodiesel attack. The degradation of NBR in the absence of carbon black was explained as being due to oxidative crosslinking. The dissolution of ZnO crystals in the acidic components of biodiesel was retarded by removing the inter-particle porosity and surface defects through heat treating star-shaped ZnO particles. The rubber containing heat-treated ZnO particles swelled less in biodiesel than a NBR filled with commercial ZnO nanoparticles, and showed a smaller decrease in the strain-at-break and less oxidative crosslinking.

  • 49.
    Akhlaghi, Shahin
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Pourrahimi, Amir Masoud
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Hedenqvist, Mikael
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Sjöstedt, C.
    Bellander, M.
    Gedde, Ulf
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Degradation of carbon-black-filled acrylonitrile butadiene rubber in alternative fuels: Transesterified and hydrotreated vegetable oils2016Inngår i: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 123, s. 69-79Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The deterioration of acrylonitrile butadiene rubber (NBR), a common sealing material in automobile fuel systems, when exposed to rapeseed biodiesel and hydrotreated vegetable oil (HVO) was studied. The fuel sorption was hindered in HVO-exposed rubber by the steric constraints of bulky HVO molecules, but it was promoted in biodiesel-exposed rubber by fuel-driven cavitation in the NBR and by the increase in diffusivity of biodiesel after oxidation. The absence of a tan δ peak of the bound rubber and the appearance of carbon black particles devoid of rubber suggested that the cavitation was made possible in biodiesel-aged rubber by the detachment of bound rubber from particle surfaces. The HVO-exposed NBR showed a small decrease in strain-at-break due to the migration of plasticizer from the rubber, and a small increase in the Young’s modulus due to oxidative crosslinking. A drastic decrease in extensibility and Payne-effect amplitude of NBR on exposure to biodiesel was explained as being due to the damage caused by biodiesel to the continuous network of bound rubber-carbon black. A decrease in the ZnO crystal size with increasing exposure time suggested that the particles are gradually dissolved in the acidic components of oxidized biodiesel. The Zn2+ cations released from the dissolution of ZnO particles in biodiesel promoted the hydrolysis of the nitrile groups of NBR.

  • 50.
    Alaei, Zahra
    KTH, Skolan för kemivetenskap (CHE).
    Release of Solubilizate from Micelle Triggered by Core Freezing2016Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The present thesis focuses on the release of solubilizate from micelle triggered by core freezing studied using 1H-NMR spectroscopy. The surfactant studied was the nonionic BrijTM S20 with a concentration of 1 wt% in water and hexamethyldisiloxane (HMDSO) was used as the model solubilizate to be loaded in micelle. The solubilizate in the micelle was found be squeezed out by core shrinking of the micelle upon decreasing the temperature. Besides 1H-NMR spectra, self-diffusion coefficients and longitudinal relaxation times                          were also measured upon decreasing the temperature. The temperature-dependent fraction of HMDSO in the micelle was determined together with relevant properties of the micelle, such as core freezing point, internal dynamics and size. The results were compared to corresponding data in the neat micellar system.

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