Change search
Refine search result
567891011 351 - 400 of 2472
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 351. Camacho, W.
    et al.
    Karlsson, S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Quality assessment of co-mingled recycled resins by fourier transform raman spectroscopy and multivariate calibration2001In: Polymer Recycling, Vol. 6, no 2/3, p. 89-98Article in journal (Refereed)
  • 352. Camacho, Walker
    et al.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Quality determination of recycled plastic packaging waste by identification of contaminants by GC-MS after microwave assisted extraction (MAE)2001In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 71, no 1, p. 123-134Article in journal (Refereed)
  • 353. Camacho, Walker
    et al.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Simultaneous determination of molecular weight and crystallinity of recycled HDPE by infrared spectroscopy and multivariate calibration2002In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 85, no 2, p. 321-327Article in journal (Refereed)
  • 354.
    Cameli, Fabio
    KTH, School of Chemical Science and Engineering (CHE).
    Microbial Fuel Cell for Waste Water Treatment2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Microbial Fuel Cell is a novel technology that can be used for a waste water treatment in order to simultaneously remove carbonaceous matter and nitrogen while producing electrical power.

    Even if it is not an established technology so far, MFC could be a cost effective option for waste water treatment and the major challenge of this process will be the device scale-up. Exoelectrogenic bacteria are capable of converting the chemical energy of organic matter into electrical energy by transferring the electrons produced in the oxidation to the anode electrode.

    This project focused on developing a single device for nitrification, denitrification and carbon removal. Two double air-cathode single chamber MFCs are used to test the feasibility of this process that could replace the biological unit in a waste water treatment train.

    The cells tested in this study were manufactured with the purpose of achieving a high surface area on both the anode electrode (vitreous carbon foam) and the air-cathode electrodes (metallic mesh with diffusion layer and active layer) with different catalysts for the reduction reaction (cobalt and platinum). The bacterial biofilm growth is a fundamental step and the cells Open Circuit Potential was monitored during all the start-up period to determine the microorganism acclimation: a three days lag period was observed in both cells before the potential rise. The second cell was forced to reach higher voltage through an anode polarization and that seems to positively affect the biofilm stability at lower voltages transferring a greater amount of electrons and hence obtaining a higher current and power generation. For this reason after three weeks of inoculation the second cell reached an open circuit potential of 0.76 V which is a promising value for such a system.

    Electrochemical and biological tests were conduced in order to test the power production of the cell and the substrate removal from the waste water. Polarization curves were used to evaluate power generation (and the maximum production under a specific external load) and the cell voltage trend which is characterized by activation and ohmic losses: 32 mW/ and 41 mW/  are the power density normalized by cathode surface (72 ) reached by respectively first and second cell. The experimental conditions were varied from low to high temperature and from low to high inlet flow rate but the most affecting phenomenon seems to be the biofilm formation since significant voltage drops were noticed after long closed circuit operation. Higher cell voltage characterized the second cell thanks to more active cathode (platinum catalyst used) and more negative bacterial biofilm but a bigger drop in current generation over time affects the system performance and the most reliable reason is the shorter acclimation time compared to the first cell.

    Cyclic voltammetry tests were carried out on both electrodes to study the potential range of activity and determine an optimal operational voltage despite of mass transport or kinetic limitations.

    Substrate removal tests at different retention times in power generation conditions (external load 100 Ω) showed a relatively high total nitrogen consumption (maximum 72.2 %) for the first cell while lower values were achieved by the second system meaning that a longer acclimation period is beneficial for nitrifying and denitrifying bacteria to thrive on the cathode biofilm.

    Effluent pH level are almost similar to the initial values probably because of nitrification and denitrification protons offset.

  • 355. Canton, S. E.
    et al.
    Zhang, X.
    Liu, Y.
    Zhang, J.
    Papai, M.
    Corani, A.
    Smeigh, A. L.
    Smolentsev, G.
    Attenkofer, K.
    Jennings, G.
    Kurtz, C. A.
    Li, F.
    Harlang, T.
    Vithanage, D.
    Chabera, P.
    Bordage, A.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ott, S.
    Warnmark, K.
    Sundstrom, V.
    Watching the dynamics of electrons and atoms at work in solar energy conversion2015In: Faraday discussions (Online), ISSN 1359-6640, E-ISSN 1364-5498, Vol. 185, p. 51-68Article in journal (Refereed)
    Abstract [en]

    The photochemical reactions performed by transition metal complexes have been proposed as viable routes towards solar energy conversion and storage into other forms that can be conveniently used in our everyday applications. In order to develop efficient materials, it is necessary to identify, characterize and optimize the elementary steps of the entire process on the atomic scale. To this end, we have studied the photoinduced electronic and structural dynamics in two heterobimetallic ruthenium-cobalt dyads, which belong to the large family of donor-bridge-acceptor systems. Using a combination of ultrafast optical and X-ray absorption spectroscopies, we can clock the light-driven electron transfer processes with element and spin sensitivity. In addition, the changes in local structure around the two metal centers are monitored. These experiments show that the nature of the connecting bridge is decisive for controlling the forward and the backward electron transfer rates, a result supported by quantum chemistry calculations. More generally, this work illustrates how ultrafast optical and X-ray

  • 356. Cardoso, Marcos R.
    et al.
    Martins, Renato J.
    Dev, Apurba
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Voss, Tobias
    Mendonca, Cleber R.
    Highly hydrophobic hierarchical nanomicro roughness polymer surface created by stamping and laser micromachining2015In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 132, no 24, article id 42082Article in journal (Refereed)
    Abstract [en]

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

  • 357.
    Carlborg, Carl Fredrik
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Haraldsson, Tommy
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Wijngaart, Wouter van der
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    RELIABLE BATCH MANUFACTURING OF MINIATURIZED VERTICAL VIAS IN SOFT POLYMER REPLICA MOLDING2007In: 11th International Conference on Miniaturized Systems for Chemistry and Life Sciences (microTAS 2007), 2007, p. 527-529Conference paper (Refereed)
    Abstract [en]

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

  • 358.
    Carlborg, Carl Fredrik
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Haraldsson, Tommy
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Öberg, Kim
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Malkoch, Michael
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    van der Wijngaart, Wouter
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    BEYOND PDMS:: OFF-STOCHIOMETRY THIOL-ENE BASED SOFT LITHOGRAPHY FOR RAPID PROTOTYPING OF MICROFLUIDIC DEVICES2010In: 14th International Conference on Miniaturized Systems for Chemistry and Life Sciences (micro TAS 2010), 2010, p. 70-72Conference paper (Refereed)
    Abstract [en]

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

  • 359.
    Carlborg, Carl Fredrik
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Saharil, Farizah
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Haraldsson, Tommy
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Wijngaart, Wouter van der
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    LOW TEMPERATURE “CLICK” WAFER BONDING OF OFF-STOICHIOMETRY THIOL-ENE (OSTE) POLYMERS TO SILICON2011In: 15th International Conference on Miniaturized Systems for Chemistry and Life Sciences (microTAS 2011), 2011, p. 1143-1145Conference paper (Refereed)
    Abstract [en]

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

  • 360.
    Carlborg, Carl Fredrik
    et al.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Vastesson, Alexander
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Liu, Yitong
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    van der Wijngaart, Wouter
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Johansson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Haraldsson, Tommy
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Functional Off-Stoichiometry Thiol-ene-epoxy Thermosets Featuring Temporally Controlled Curing Stages via an UV/UV Dual Cure Process2014In: Journal of Polymer Science Part A: Polymer Chemistry, ISSN 0887-624X, E-ISSN 1099-0518, Vol. 52, no 18, p. 2604-2615Article in journal (Refereed)
    Abstract [en]

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

  • 361.
    Carlmark, Anna
    KTH, Superseded Departments, Fibre and Polymer Technology.
    Complex Macromolecular Architectures by Atom Transfer Radical Polymerization2004Doctoral thesis, comprehensive summary (Other scientific)
    Abstract [en]

    Controlled radical polymerization has proven to be a viableroute to obtain polymers with narrow polydispersities (PDI's)and controlled molecular weights under simple reactionconditions. It also offers control over the chain-]ends of thesynthesized polymer. Atom transfer radical polymerization(ATRP) is the most studied and utilized of these techniques. Inthis study ATRP has been utilized as a tool to obtain differentcomplex macromolecular structures.

    In order to elaborate a system for which a multitude ofchains can polymerize in a controlled manner and in closeproximity to one another, a multifunctional initiator based onpoly(3-ethyl-3-(hydroxymethyl)oxetane was synthesized. Themacroinitiator was used to initiate ATRP of methyl acrylate(MA). The resulting dendritic-]linear copolymer hybrids hadcontrolled molecular weights and low PDI's. Essentially thesame system was used for the grafting of MA from a solidsubstrate, cellulose. A filter paper was used as cellulosesubstrate and the hydroxyl groups on the cellulose weremodified into bromo-]ester groups, known to initiate ATRP.Subsequent grafting of MA by ATRP on the cellulose made thesurface hydrophobic. The amount of polymer that was attached tothe cellulose could be tailored. In order to control that thesurface polymerization was -eliving-f and hence that thechain-]end functionality was intact, a second layer of ahydrophilic monomer, 2-hydroxyethyl methacrylate, was graftedonto the PMA- grafted cellulose. This dramatically changed thehydrophilicity of the cellulose.

    Dendronized polymers of generation one, two and three weresynthesized by ATRP of acrylic macromonomers based on2,2-bis(hydroxymethyl)propionic acid. In the macromonomerroute, macromonomers of each generation were polymerized byATRP. The polymerizations resulted in polymers with low PDI's.The kinetics of the reactions were investigated, and thepolymerizations followed first-order kinetics when ethyl2-bromopropionate was used as the initiator. In the-egraft-]onto-f route dendrons were divergently attached to adendronized polymer of generation one, that had been obtainedby ATRP.

  • 362.
    Carlmark, Anna
    et al.
    KTH, Superseded Departments, Fibre and Polymer Technology.
    Malmström, Eva E
    KTH, Superseded Departments, Fibre and Polymer Technology.
    ATRP of dendronized aliphatic macromonomers of generation one, two, and three2004In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 37, no 20, p. 7491-7496Article in journal (Refereed)
    Abstract [en]

    Atom transfer radical polymerization (ATRP) of dendritic, aliphatic macromonomers has been investigated. The macromonomers were based on acrylate functionalized 2,2-bis(methylol)propionic acid (bis-MPA) dendrons, with a flexible spacer of 10 carbons incorporated in the structure in between the polymerizable group and the dendritic wedge. Dendronized polymers of generation one, two, and three were successfully synthesized by ATRP. The polymerizations proceeded until over 80% conversion was reached, while maintaining control over polydispersity index (PDI). Plots of ln([M](0)/[M]) vs time for the polymerization of all three macromonomers showed a linear dependence, indicating that the number of propagating radicals in the reaction solution was constant throughout the reaction, when ethyl 2-bromopropionate (EBrP) was used as an initiator (i.e., radical termination was negligible). All of the resulting polymers had low PDI values and molecular weight close to the theoretical ones. The products were analyzed by H-1 and C-13 NMR spectroscopies, size exclusion chromatography (SEC), differential scanning calorimetry (DSC), and matrix-assisted laser desorption-ionization time-of-flight (MALDI-TOF).

  • 363.
    Carlson, Annika
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry.
    Electrochemical properties of alternative polymer electrolytes in fuel cells2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Fuel cells, using hydrogen as energy carrier, allow chemically‑stored energy to be utilized for many applications, including balancing the electrical grid and the propulsion of vehicles. To make the fuel cell technology more accessible and promote a sustainable energy society, this thesis focuses on alternative polymer electrolytes, as they can potentially lead to a lower cost and a more environmentally‑friendly fuel cell. The main subject is anion exchange membrane fuel cells (AEMFCs), for which the importance of gas diffusion electrode morphology and platinum electrode reactions are investigated. Properties of the membrane such as water flux during operation are evaluated. Furthermore, novel polymer electrolytes are studied: variations of poly(phenylene oxide)‑based membranes in AEMFCs; and cellulose‑based membranes in a proton exchange membrane fuel cell (PEMFC).

     

    The AEMFC results show that the performance is dependent on the electrode morphology. Electrochemical experiments in a hydrogen/hydrogen cell combined with modelling show that the hydrogen oxidation reaction proceeds through the Tafel‑Volmer reaction pathway on platinum. Application of the model in a hydrogen/oxygen cell shows that the cathode has the slowest reaction rate. During operation, the water flux through the membrane is directed from the anode where water is produced to the cathode where it is consumed. This leads to an increase in water content at both electrodes, which implies that electrode flooding is more likely than dry‑out during operation. The effect of membrane thickness on water flux is shown to be larger than the effect of polymer structure for several different types of poly(phenylene oxide)‑based membranes. The comparison of these polymers also indicates that a high conductivity, for the relative humidity achieved in a fuel cell, promotes increased performance. Finally, the study of cellulose-based membranes in a PEMFC shows that cellulose as a renewable, natural polymer has promising properties, such as stable conductivity for relative humidities above 65 % and a low gas permeability.

  • 364.
    Carlson, Annika
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry.
    Ekström, Henrik
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry. COMSOL.
    Grimler, Henrik
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry.
    Lagergren, Carina
    KTH, Superseded Departments (pre-2005), Chemical Engineering and Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry.
    Wreland Lindström, Rakel
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry.
    Lindbergh, Göran
    KTH, Superseded Departments (pre-2005), Chemical Engineering and Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry.
    An Electrochemical Impedance Study of the Hydrogen Electrode Reaction in the Anion Exchange Membrane Fuel CellManuscript (preprint) (Other academic)
  • 365.
    Carlson, Annika
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry.
    Eriksson, Björn
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry.
    Olsson, Joel
    Lund University.
    Lindbergh, Göran
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry.
    Lagergren, Carina
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry.
    Jannasch, Patric
    Lund University.
    Wreland Lindström, Rakel
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry.
    Fuel cell evaluation of anion exchange membranes based on PPO with different cation placementManuscript (preprint) (Other academic)
  • 366.
    Carlson, Annika
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry.
    Shapturenka, Pavel
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry.
    Eriksson, Björn
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry.
    Lindbergh, Göran
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry.
    Lagergren, Carina
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry.
    Wreland Lindström, Rakel
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry.
    Electrode parameters and operating conditions influencing the performance of anion exchange membrane fuel cells2018In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 277, p. 151-160Article in journal (Refereed)
    Abstract [en]

    A deeper understanding of porous electrode preparation and performance losses is necessary to advance the anion exchange membrane fuel cell (AEMFC) technology. This study has investigated the performance losses at 50 °C for varied: Tokuyama AS-4 ionomer content in the catalyst layer, Pt/C loading and catalyst layer thickness at the anode and cathode, relative humidity, and anode catalyst. The prepared gas diffusion electrodes in the interval of ionomer-to-Pt/C weight ratio of 0.4–0.8 or 29–44 wt% ionomer content show the highest performance. Varying the loading and catalyst layer thickness simultaneously shows that both the cathode and the anode influence the cell performance. The effects of the two electrodes are shown to vary with current density and this is assumed to be due to non-uniform current distribution throughout the electrodes. Further, lowering the relative humidity at the anode and cathode separately shows small performance losses for both electrodes that could be related to lowered ionomer conductivity. Continued studies are needed to optimize, and understand limitations of, each of the two electrodes to obtain improved cell performance.

  • 367. Carlsson, L. A.
    et al.
    Lindström, Tom
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    A shear-lag approach to the tensile strength of paper2005In: Composites Science And Technology, ISSN 0266-3538, E-ISSN 1879-1050, Vol. 65, no 2, p. 183-189Article in journal (Refereed)
    Abstract [en]

    A shear-lag approach to the prediction of the tensile strength of paper is outlined and examined. It is demonstrated that transition of fiber strength to paper strength requires long fibers for sheets with weak fiber-fiber bonds, or low relative bonded area. Fiber pull-out is encountered even for highly bonded sheets. Predictions of tensile strength for papers of the same fiber length, but with different beating degrees, and for papers with different fiber lengths and beating degrees, are in quantitative agreement with previously published data.

  • 368.
    Carlsson, Linn
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Surface Modification of Cellulose by Covalent Grafting and Physical Adsorption2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The interest in new environmentally friendly cellulose‐based productshas increased tremendously over the last years. At the same time theSwedish forest industry faces new challenges in its strive to increase the utilization of cellulose fibers in high‐value end‐products. The aim of this study was to expand the toolbox for surface modification of cellulose byemploying covalent surface‐initiated (SI) polymerizations or by physicaladsorption of polymers. SI‐ring‐opening polymerization (ROP) of ε‐caprolactone (ε‐CL) was performed from filter paper (FP) and high surface area nanopaper (NP).Larger amounts of polycaprolactone (PCL) were grafted from NP, compared to FP, owing to the higher amount of available initiating hydroxyl groups. Furthermore, the mechanical properties of PCL were improved by the grafting of FP and NP, as compared to pure PCL.It is challenging to characterize a polymer grafted from a surface. Hence, quartz crystal microbalance with dissipation (QCM‐D) was employed to investigate SI‐ROP in real time from a cellulose model surface. Furthermore, it was shown by colloidal probe AFM that increased lengthof grafted PCL, from cellulose microspheres, improved the interfacialadhesion to a pure PCL surface, suggesting that chain entanglements havea significant impact on the interfacial properties. Increased temperatureand time in contact also improved the adhesion.In order to investigate the degree of substitution (DS) and the degree of polymerization (DP), PCL‐grafted hydrolyzed cellulose cotton linters (HCCL) were studied by solid state NMR. It was found that despite a DS of only a few percent, the surface character changed considerably; furthermore, the DS was virtually independent of the DP. To increase theamount of grafted polymer, ring‐opening metathesis polymerization (ROMP) of norbornene was performed from FP. Short polymerizationtimes and low temperatures resulted in highly grafted surfaces. Alternatively, physical adsorption by electrostatic interactions was employed to modify a cellulose model surface in the QCM‐D. Cationic latex nanoparticles of poly(dimetylaminoethyl methacrylate‐co‐methacrylicacid)‐block‐poly(methyl methacrylate) were produced by reversible addition‐fragmentation chain‐transfer (RAFT)‐mediated surfactant‐freeemulsion polymerization by polymerization‐induced self‐assembly (PISA).This strategy does not require any organic solvents and could potentiallybe introduced in industrial processes.

  • 369.
    Carlsson, Linn
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Utsel, Simon
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Malmström, Eva
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Carlmark, Anna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Surface-initiated ring-opening polymerization from cellulose model surfaces monitored by a Quartz Crystal Microbalance2012In: Soft Matter, ISSN 1744-683X, E-ISSN 1744-6848, Vol. 8, no 2, p. 512-517Article in journal (Refereed)
    Abstract [en]

    Polymer surface-grafting is an excellent method to modify the properties of a surface. However, surface-initiated polymerization is still relatively poorly understood due to the lack of appropriate characterization methods and tools to monitor the polymerizations. Herein, we report the in situ, surface-initiated ring-opening polymerization (SI-ROP) investigated in real time by the Quartz Crystal Microbalance (QCM) technique. The polymerization was performed from a cellulose model surface and the polymerization was initiated directly from the available hydroxyl groups on the cellulose. The cyclic monomer 3-caprolactone and an organic catalyst, 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), were used, and the reaction was performed in bulk at room temperature. Since a free polymer was formed in bulk in parallel to the grafting from the surface, the reaction was performed in three cycles with rinsing steps in between to measure only the effect of the surface grafting. The change in frequency showed that the grafted amount of polymer increased after each cycle indicating that most of the chain ends remained active. After polymer grafting, the cellulose model surface showed a more hydrophobic character, and the surface roughness of the cellulose model surface was reduced. This study clearly shows that QCM is a viable method to monitor SI-ROP in situ from cellulose surfaces. We believe this is an important step towards a deeper understanding of how to tailor the interface between polymer-modified cellulose and a polymer matrix in biocomposites.

  • 370.
    Carlsson, Magnus
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Nuclear Chemistry.
    Stenman, David
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Nuclear Chemistry.
    Merényi, Gabor
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Nuclear Chemistry.
    Reitberger, Torbjörn
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Nuclear Chemistry.
    A comparative study on the degradation of cotton linters induced by carbonate and hydroxyl radicals generated from peroxynitrite2005In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 59, no 2, p. 132-142Article in journal (Refereed)
    Abstract [en]

    Carbonate (CO3.(-)) and hydroxyl (HO.) radicals were chemically produced in cotton linter suspensions using peroxynitrite as a radical precursor. Both radicals could degrade cotton linters, as shown by viscosity and GPC-SEC measurements. As evidenced by the viscosity measurements, the presence of oxygen during the cotton linter treatments slightly increased cellulose degradation by both radicals. For the carbonate radical, more than 90% of the viscosity losses could be recovered by reductive NaBH4 treatment before measuring the viscosity, whereas only approximately 40% of the viscosity was recovered after hydroxyl radical degradation and subsequent NaBH4 treatment. This indicates that carbonate radicals mainly abstract H-atoms adjacent to hydroxyl groups, i.e., at C-2, C-3 and C-6. This intramolecular selectivity may reflect a polar effect, whereby hydrogen atom abstractions from these positions are favoured. In addition, abstraction at C-6 would be sterically and statistically favoured.

  • 371.
    Carrick, Christopher
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Macro-, Micro- and Nanospheres from Cellulose: Their Preparation, Characterization and Utilization2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The structure of a polymeric material has a great influence in many fundamental scientific areas as well as in more applied science, since it affects the diffusion, permeability, mechanical strength, elasticity, and colloidal properties of the materials. The results in this thesis demonstrate that it is possible to fabricate solid and hollow cellulose spheres with a cellulose shell and encapsulated gas, liquid or solid particles and with a sphere size ranging from a few hundreds of nanometres to several millimetres, all with a tailored design and purpose.

    The sizes of the different spheres have been controlled by three different preparation methods: large cellulose macrospheres by a solution solidification procedure, hollow micrometre-sized cellulose spheres by a liquid flow-focusing technique in microchannels, and nanometre-sized cellulose spheres by a membrane emulsification technique. 

    The spheres were then modified in different ways in order to functionalize them into more advanced materials. This thesis demonstrates how to control the cellulose sphere dimensions and the wall-to-void volume ratio, the elasticity and the functionality of the spheres as such, where they were prepared to be pH-responsive, surface specific and X-ray active. These modifications are interesting in several different types of final materials such as packaging materials, drug release devices or advanced in vivo diagnostic applications.

    In the more fundamental science approach, surface-smooth solid cellulose spheres were prepared for characterization of the macroscopic work of adhesion when a cellulose surface is separated from another material. Using these ultra-smooth macroscopic cellulose probes, it is possible to measure the compatibility and the surface interactions between cellulose and other materials which provide an important tool for incorporating cellulose into different composite materials. 

  • 372.
    Carrick, Christopher
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Pendergraph, Samuel A.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Nanometer Smooth, Macroscopic Spherical Cellulose Probes for Contact Adhesion Measurements2014In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 6, no 23, p. 20928-20935Article in journal (Refereed)
    Abstract [en]

    Cellulose spheres were prepared by dissolving cellulose fibers and subsequently solidifying the solution in a nonsolvent. Three different solution concentrations were tested and several nonsolvents were evaluated for their effect on the formation of spheres. Conditions were highlighted to create cellulose spheres with a diameter of similar to 1 mm and a root-mean-square surface roughness of similar to 1 nm. These solid spheres were shown to be easily chemically modified without changing the mechanical properties significantly. Contact adhesion measurements were then implemented with these spheres against a poly(dimethylsiloxane) (PDMS) elastomer in order to quantify the adhesion. Using Johnson-Kendall-Roberts (JKR) theory, we quantified the adhesion for unmodified cellulose and hydrophobic cellulose spheres. We highlight the ability of these spheres to report more accurate adhesion information, compared to spin-coated thin films. The application of these new cellulose probes also opens up new possibilities for direct, accurate measurement of adhesion between cellulose and other materials instead of using uncertain surface energy determinations to calculate the theoretical work of adhesion between cellulose and different solid materials.

  • 373.
    Carvalho, Danila
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Study on the structure and properties of xylan extracted from eucalyptus, sugarcane bagasse and sugarcane straw2015Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Lignocellulosic biomasses are an important source of chemical components such as cellulose, lignin and hemicelluloses, and can be used for a variety of purposes in both the pulp and paper and chemical conversion industries. Xylan, the main hemicellulose found in hardwood and grass plants, plays an important role during the pulping/pretreatment process reactions, including those used in 2nd generation bioethanol production. It may also play an important role in the production of certain novel materials.

    This thesis evaluates the composition of eucalyptus (Eucalyptus urophylla x Eucalyptus grandis), sugarcane bagasse and sugarcane straw, with a specific focus on the structure and properties of xylan. The chemical characterization of biomasses showed that sugarcane bagasse and straw contain larger amounts of extractives, ash and silica than eucalyptus. The large amount of silica leads to an overestimation of the Klason lignin content, if not corrected. By using a complete mass balance approach, sugarcane bagasse and straw were shown to contain smaller amounts of lignin (18.0% and 13.9%, respectively) than previously reported for these raw materials, and certainly a much smaller amount of lignin than was found in eucalyptus (27.4%). The hemicellulose content in sugarcane bagasse (28.7%) and straw (29.8%) was much higher than that in eucalyptus (20.3%).

    In order to investigate the structure of the xylan in greater detail, it was extracted with dimethyl sulfoxide from holocellulose, obtained by either peracetic acid or sodium chlorite delignification. The structure of the isolated xylans was confirmed by FTIR and 1H NMR analysis. In eucalyptus, the O-acetyl-(4-O-methylglucurono)xylan (MGX) was identified. This had a molar ratio of xylose units to branches of 4-O-methylglucuronic acid of 10:1.1 and a degree of acetylation of 0.39. All 4-O- methylglucuronic acid groups were attached to position O-2 of the xylose units, which had an acetyl group in position O-3. The acetyl groups were distributed in positions O-3 (64%), O-2 (26%) and O-2,3 (10%). The MGX had a molecular weight (Mw) of about 42 kDa.

    In bagasse and straw, arabinoxylan (AX) was identified. This had a molar ratio of xylose units to arabinosyl substitutions of 10:0.5 for bagasse and 10:0.6 for straw. A degree of acetylation was 0.29 and 0.08 for bagasse and straw, respectively. The arabinose units were attached preferentially to position O-3 in AX. In the xylan from bagasse, the acetyl groups were found in positions O-3 (60%), O-2 (13%) and O-2,3 (27%), while in the xylan from straw, the acetyl groups were distributed between positions O-3 (67%) and O-2 (33%). The AX had a molecular weight (Mw) of about 38 kDa and 30 kDa for bagasse and straw, respectively.

    The differences in the structure of xylan present in the various biomasses played an important role during hydrothermal pretreatment, which is often used as the first step in 2nd generation ethanol production. The varying amounts of uronic acid and acetyl groups resulted in different starting pH levels of liquor and, thus, affected the chemical transformation in the biomasses in different ways. The hydrothermal pretreatment resulted mostly in the removal and/or transformation of hemicelluloses, but also in the formation of a significant number of pseudo-lignin structures. In addition, in eucalyptus, pseudo-extractives structures were generated. The sugarcane straw showed the highest mass loss during the investigated pretreatment.

  • 374. Castro, A.
    et al.
    Vilaplana, Francisco
    KTH, School of Biotechnology (BIO), Glycoscience.
    Nilsson, L.
    Characterization of a water soluble, hyperbranched arabinogalactan from yacon (Smallanthus sonchifolius) roots2017In: Food Chemistry, ISSN 0308-8146, E-ISSN 1873-7072, Vol. 223, p. 76-81Article in journal (Refereed)
    Abstract [en]

    Yacon (Smallanthus sonchifolius Poepp. &amp; Endl.) roots are largely grown in Andean countries and have attracted recent interest due to their antioxidant and prebiotic effects. Yacon is typically consumed as a fruit due to its sweet taste and juiciness. The macromolecular properties of an aqueous extract of yacon are investigated using asymmetric flow field-flow fractionation (AF4) coupled to UV, multiangle light scattering (MALS) and differential refractive index (dRI) detection. The method allows for determination of molar mass and size over the size distribution. Three major populations were found of which one strongly dominates in concentration. Through collection of fractions from AF4, carbohydrate composition and glycosidic linkage analysis for the dominating population was performed. The results show that the dominating population consists of a highly branched arabinogalactan (type 2) with a molar mass of approximately 1–2 · 105 g/mol, a hydrodynamic radius of approximately 6–10 nm and a relatively high apparent density (approx. 70–150 kg/m3).

  • 375.
    Castro, O.
    et al.
    University of Costa Rica, San José, Costa Rica.
    Rodríguez, T.
    University of Costa Rica, San José, Costa Rica.
    Setterwall, Fredrik
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Martínez, Joaquín
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Optimization Variables Affecting the Manufacture of New Sulfated Amides based on Palm Kernel Oil1996In: Chemistry and Technology and Soap Detergent Industry Conference: Proceedings of the 1996 PORIM International Palm Oil Congress / [ed] Muhammad, B., Kuala Lumpur, Malaysia: Universiti Teknologi Malaysia , 1996, p. 314-315Conference paper (Refereed)
  • 376. Cataldi, A.
    et al.
    Dorigato, A.
    Deflorian, F.
    Berglund, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Pegoretti, A.
    Polymer composite with micro- and nanocellulose for artwork protection and restoration2014In: 16th European Conference on Composite Materials, ECCM 2014, 2014Conference paper (Refereed)
    Abstract [en]

    Micro- and nanocomposites were prepared using Aquazol® 500 as a polymeric matrix and a microcrystalline cellulose (MCC), and suspensions of cellulose nanocrystals (CNC), as reinforcing agents. After a preliminary thermo-mechanical characterization that highlighted a stabilizing effect due to the micro- and nanofiller introduction, with an increase of the elastic modulus and a decrease of the thermal expansion coefficient and the creep compliance [1], these materials were applied as canvas lining adhesives. Single-lap shear tests both in quasi-static and creep conditions confirmed the dimensional stability provided by cellulose micro- and nanoparticles, with an important reduction of the adhesives compliance proportional to the filler content. Interestingly, MCC and CNC introduction did not impair the fracture behavior of the neat matrix.

  • 377. Cavalli, Alessandro
    et al.
    Wang, Jia
    Zadeh, Iman Esmaeil
    Reimer, Michael E.
    Verheijen, Marcel A.
    Soini, Martin
    Plissard, Sebastien R.
    Zwiller, Val
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Haverkort, Jos E. M.
    Bakkers, Erik P. A. M.
    High-Yield Growth and Characterization of < 100 > InP p-n Diode Nanowires2016In: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 16, no 5, p. 3071-3077Article in journal (Refereed)
    Abstract [en]

    Semiconductor nanowires are nanoscale structures holding promise in many fields such as optoelectronics, quantum computing, and thermoelectrics. Nanowires are usually grown vertically on (111)-oriented substrates, while (100) is the standard in semiconductor technology. The ability to grow and to control impurity doping of (100) nanowires is crucial for integration. Here, we discuss doping of single-crystalline < 100 > nanowires, and the structural and optoelectronic properties of p-n junctions based on < 100 > InP nanowires. We describe a novel approach to achieve low resistance electrical contacts to nanowires via a gradual interface based on p-doped InAsP. As a first demonstration in optoelectronic devices, we realize a single nanowire light emitting diode in a < 100 >-oriented InP nanowire p-n junction. To obtain high vertical yield, which is necessary for future applications, we investigate the effect of the introduction of dopants on the nanowire growth.

  • 378.
    Cazot, Mathilde
    KTH, School of Chemical Science and Engineering (CHE).
    Empirical Modeling of a full-iron redox flow battery2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The need for energy storage is growing to reduce the carbon footprint of electricity

    production. Among the conceivable storage solutions, the redox flow battery (RFB) is

    one of the most promising. The best-researched type is the vanadium flow battery, but

    extensive research is underway to develop a cheaper and more compact system. The full-

    iron redox flow battery is an attractive alternative. A testing module has been developed,

    in order to study the influence of different operating parameters on the system output.

    The experiments highlight that the electrode compression, the stacking of single cells and

    the charge and discharge rates are design key factors and need a precise optimization. A

    35% electrode compression is a good trade-off between pump power losses and low contact

    resistances inside the cell. Single cells undergo a higher self-discharge when they are piled

    up; it is the direct effect of a power leakage called shunt current. The stack design must

    be thought with caution to lessen this power loss. The cycling profile also influence the

    battery performance. The findings confirm that optimizing the charge and discharge rates

    can prolong the system lifespan.

  • 379.
    Celander, Martin
    KTH, School of Chemical Science and Engineering (CHE).
    En undersökning av Ullnasjön2016Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
  • 380.
    Celsi, Adrian
    KTH, School of Chemical Science and Engineering (CHE).
    Developmental lignocellulose mapping in crop stems2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    With current techniques there is no rapid, one-step alternative to investigate plant composition and anatomy. In this study we present the use of luminescent

    conjugated oligothiophene (LCO), as a carbohydrate marker in unused cash crop stems. Stem samples were analyzed between day 0-75 using FTIR, gas

    chromatography, confocal laser scanning microscopy and spectral imaging analysis. Carbohydrate composition analysis confirmed cellulose presence in all

    time points tested and that fractions of monosaccharaides stay constant in the stem during growth. Using confocal and fluorescence microscopy, emission from

    LCO bound to cellulose was detected and stem composition and anatomy visualized.

    Overall, we demonstrate that LCOs can be utilized for compositional analyzes in plant tissues as a non-destructive and one-step alternative to today’s techniques.

    This method shows high applicability for structure and anatomy studies in plant tissues, but also as a compliment for current composition analysis techniques.

     

  • 381.
    Cervin, Nicholas
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Porous Cellulose Materials from Nano Fibrillated Cellulose2012Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    In the first part of this work a novel type of low-density, sponge-like material for the separation of mixtures of oil and water has been prepared by vapour deposition of hydrophobic silanes on ultra-porous nanocellulose aerogels. To achieve this, a highly porous (> 99 %) nanocellulose aerogel with high structural flexibility and robustness is first formed by freeze-drying an aqueous dispersion of the nanocellulose. The density, pore size distribution and wetting properties of the aerogel can be tuned by selecting the concentration of the nanocellulose dispersion before freeze-drying. The hydrophobic light-weight aerogels are almost instantly filled with the oil phase when they selectively absorb oil from water, with a capacity to absorb up to 45 times their own weight. The oil can also be drained from the aerogel and the aerogel can then be subjected to a second absorption cycle.In the second part of the work a novel, lightweight and strong porous cellulose material has been prepared by drying aqueous foams stabilized with surface-modified NanoFibrillated Cellulose (NFC). Confocal microscopy and high-speed video imaging show that the long-term stability of the wet foams can be attributed to the octylamine-coated, rod-shaped NFC nanoparticles residing at the air-liquid interface which prevent the air bubbles from collapsing or coalescing. Careful removal of the water yields a porous cellulose-based material with a porosity of 98 % and a density of 30 mg cm-3. These porous cellulose materials have a higher Young’s modulus than other cellulose materials made by freeze drying and a compressive energy absorption of 56 kJ m-3 at 80 % strain. Measurements with an autoporosimeter reveal that most pores are in the range of 300 to 500 μm.

  • 382.
    Cervin, Nicholas Tchang
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Johansson, E.
    Benjamins, J. -W
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Mechanisms behind the Stabilizing Action of Cellulose Nanofibrils in Wet-Stable Cellulose Foams2015In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 16, no 3, p. 822-831Article in journal (Refereed)
    Abstract [en]

    The principal purpose of the investigation was to clarify the mechanisms behind the stabilizing action of cellulose nanofibrils (CNFs) in wet-stable cellulose foams. Following the basic theories for particle-stabilized foams, the investigation was focused on how the surface energy of the stabilizing CNF particles, their aspect ratio and charge density, and the concentration of CNF particles at the air-water interface affect the foam stability and the mechanical properties of a particle-stabilized air-liquid interface. The foam stability was evaluated from how the foam height changed over time, and the mechanical properties of the interface were evaluated as the complex viscoelastic modulus of the interface using the pendant drop method. The most important results and conclusions are that CNFs can be used as stabilizing particles for aqueous foams already at a concentration as low as 5 g/L. The major reasons for this were the small dimensions of the CNF and their high aspect ratio, which is important for gel-formation and the complex viscoelastic modulus of the particle-filled air-water interface. The influence of the aspect ratio was also demonstrated by a much higher foam stability of foams stabilized with CNFs than of foams stabilized by cellulose nanocrystals (CNC) with the same chemical composition. The charge density of the CNFs affects the level of liberation within larger aggregates and hence also the number of contact points at the interface and the gel formation and complex viscoelastic modulus of the air-water interface. The charges also result in a disjoining pressure related to the long-range repulsive electrostatic pressure between particle-stabilized bubbles and hence contribute to foam stability. (Figure Presented).

  • 383.
    Cevér, Patrik
    KTH, School of Chemical Science and Engineering (CHE).
    Klimatavtryck för mikrobiellt producerat proteinfoder baserat på livsmedelsavfall kontra konventionellt proteinfoder till fisk: En fallstudie från Uppsala- och Stockholmsregionen2015Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
  • 384.
    Chamoun, Ninus
    et al.
    KTH, School of Chemical Science and Engineering (CHE).
    Kjellvertz, Viktor
    KTH, School of Chemical Science and Engineering (CHE).
    Mahajan, William
    KTH, School of Chemical Science and Engineering (CHE).
    Song, Yuanchao
    KTH, School of Chemical Science and Engineering (CHE).
    Fate of Heavy Metals in Waste to Energy (WtE) Processes2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This study was made to increase the understanding of how heavy metals in the aqueous phase are removed at low initial concentrations in different pH and Eh values. The reaction that has been studied is mainly hydroxide precipitation and adsorption in a condensate treatment. In the study, data from one of Vattenfalls waste incinerators was analysed and the results from the data were then compared to previous studies. To increase the understanding, modelling of the heavy metals behaviour in the given concentrations was then made with Medusa and PHREEQC. The heavy metals that were analysed were Sb, As, Pb, Zn, Cr, and Cd. The low initial concentration that vary between 36.1-23600 μg/l complicates the removal process because it corresponds in a low driving force and the results are hard to compare to other studies since the initial concentrations vary between 10-100 mg/l.

    From the modelling and the measurement data it can be seen that Pb, Zn, Cr, and Cd was removed by hydroxide precipitation at pH 10. According to the speciation calculations, the dominant species at this pH are Pb(OH)

    2 , Cd(OH)2, Zn(OH)2 and Cr(OH)3. For arsenic a clear conclusion could not be drawn from the modelling and the measurement data because of low precision. Due to the limited thermodynamic parameters of antimony in comparison with other heavy metals in the database of Medusa and PHREEQC, the modelling of antimony behaviour in condensate treatment has relatively larger uncertainty is low. The modelling results show that the main species in acidic solutions for antimony is Sb(OH)3 and in basic solutions Sb(OH)-6. Further investigation for antimony in needed for a clear conclusions to be drawn

  • 385. Champ, Simon
    et al.
    Koch, Oliver
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Westman, Eva-Helena
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Feuerhake, Robert
    Haehnle, Hans-Joachim
    Biocidal coatings2006Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    Biocidal multilayered system, characterized in that it comprises at least the following layers: - an anionic or cationic carrier, preferably cellulose as anionic carrier, - on this carrier alternating polymeric cationic and anionic layers starting with a layer having a charge opposite to that of the carrier, - wherein at least one layer is hydrophobically modified.

  • 386. Chang, B.
    et al.
    Schneider, K.
    Patil, N.
    Roth, Stephan V.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. DESY, Hamburg, Germany.
    Heinrich, G.
    Microstructure characterization in a single isotactic polypropylene spherulite by synchrotron microfocus wide angle X-ray scattering2018In: Polymer, ISSN 0032-3861, E-ISSN 1873-2291, Vol. 142, p. 387-393Article in journal (Refereed)
    Abstract [en]

    Position-resolved microstructure in a single spherulite of iPP is quantitatively studied by synchrotron microfocus wide angle X-ray scattering. The results show that the normal of mother lamellae in a spherulite is aligned mainly perpendicular to the radius, and the subsidiary daughter lamellae are inclined 80.75° with respect to that of the dominant mother lamellae. The crystallinity in the spherulite is in the range of 46%–56%, which is rarely influenced by the crystallization temperature. The ratio between the daughter lamellae and the mother lamellae is 0.18 when iPP crystallizes at 138 °C and it decreases to 0.11 as the crystallization temperature is decreased to 130 °C. The b-axis and c-axis in the mother lamellae tend to orient perpendicular to the radius direction, and the a-axis prefers to align in the radius direction.

  • 387.
    Chang, Tingru
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Atmospheric corrosion of copper and copper-based alloys in architecture: from native surface oxides to fully developed patinas2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Copper and copper-based alloys are commonly used in both ancient and modern architecture. This requires an in-depth fundamental and applied understanding on their atmospheric corrosion behavior at different climatic, environmental and pollutant levels and how these parameters influence e.g. corrosion initiation, patina characteristics, aesthetic appearances, corrosion rates, and runoff rates. This doctoral thesis elucidates the role of native surface oxides on the corrosion performance, corrosion initiation, formation and evolution of corrosion products from hours to months, years and even centuries, to diffuse dispersion of metals from Cu metal/Cu alloy surfaces focusing on the roles of alloying elements, microstructure, and deposition of chlorides. In-depth investigations have been performed at both laboratory and field conditions on commercial Cu metal and copper-based alloys of a golden alloy (Cu5Zn5Al1Sn) and Sn-bronzes (Cu4Sn, Cu6Sn). Patina characteristics and relations to the presence of microstructural inclusions have in addition been investigated for historic patinas of Cu metal roofing of different age and origin, highlighted with data for a 400 years old Cu patina exposed at urban conditions.

    A multi-analytical approach comprising microscopic, spectroscopic and electrochemical methods was employed for in-depth investigations of surface characteristics and bulk properties. Electron backscattered diffraction (EBSD) was utilized to characterize the microstructure. Auger electron spectroscopy (scanning-AES), X-ray photoelectron spectroscopy (XPS), glow discharge optical emission spectroscopy (GDOES) were employed for surface chemical compositional analysis, and atomic absorption spectroscopy (AAS) to assess the amount of metal release from the patinas. Cathodic reduction (CR) and electrochemical impedance spectroscopy (EIS) were used to assess the amount and corrosion resistance of corrosion products formed at laboratory conditions. Confocal Raman micro-spectroscopy (CRM), infrared reflection absorption spectroscopy (IRAS) and grazing incidence X-ray diffraction (GIXRD) were used to identify the phases of corrosion products. Colorimetry was used to assess surface appearances.

    Cu5Zn5Al1Sn and Cu4Sn/Cu6Sn exhibit favorable bulk properties with respect to corrosion in terms of smaller grain size compared with Cu metal and show non-significant surface compositional variations. The presence of multi-component native oxides predominantly composed of Cu2O enriched with Sn-oxides on Cu4Sn/Cu6Sn, and with ZnO, SnO2 and Al2O3 on Cu5Zn5Al1Sn, improves the barrier properties of the native surface oxides and the overall corrosion resistance of Cu4Sn/Cu6Sn and Cu5Zn5Al1Sn. The formation of Zn/Al/Sn-containing corrosion products (e.g. Zn5(CO3)2(OH)6 and Zn6Al2(OH)16CO3·4H2O) significantly reduces the corrosion rate of Cu5Zn5Al1Sn in chloride-rich environments. Alloying with Sn reduces the corrosion rate of Sn-bronze at urban environments of low chloride levels but results in enhanced corrosion rates at chloride-rich marine conditions.

    A clear dual-layer structure patina was observed for centuries-old naturally patinated copper metal with an origin from the roof of Queen Anne's Summer Palace in Prague, the Czech Republic. The patina comprises an inner sub-layer of Cu2O and an outer sub-layer of Cu4SO4(OH)6/Cu3SO4(OH)4. Abundant relatively noble inclusions (mainly rosiaite (PbSb2O6)) were observed and incorporated in both the copper matrix and the patina. The largest inclusions of higher nobility than the surrounding material create significant micro-galvanic effects that result in a fragmentized patina and large thickness ratios between the Cu4SO4(OH)6/Cu3SO4(OH)4 and the Cu2O sub-layer, investigated via a statistical analysis of inclusions and patina characteristics of eight different historic urban copper patinas.

  • 388.
    Chang, Tingru
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Odnevall Wallinder, Inger
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    de la Fuente, D.
    Chico, B.
    Morcillo, M.
    Welter, J. -M
    Leygraf, Christopher
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Analysis of historic copper patinas. Influence of inclusions on patina uniformity2017In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 10, no 3, article id 298Article in journal (Refereed)
    Abstract [en]

    The morphology and elemental composition of cross sections of eight historic copper materials have been explored. The materials were taken from copper roofs installed in different middle and northern European environments from the 16th to the 19th century. All copper substrates contain inclusions of varying size, number and composition, reflecting different copper ores and production methods. The largest inclusions have a size of up to 40 μm, with most inclusions in the size ranging between 2 and 10 μm. The most common element in the inclusions is O, followed by Pb, Sb and As. Minor elements include Ni, Sn and Fe. All historic patinas exhibit quite fragmentized bilayer structures, with a thin inner layer of cuprite (Cu2O) and a thicker outer one consisting mainly of brochantite (Cu4SO4(OH)6). The extent of patina fragmentation seems to depend on the size of the inclusions, rather than on their number and elemental composition. The larger inclusions are electrochemically nobler than the surrounding copper matrix. This creates micro-galvanic effects resulting both in a profound influence on the homogeneity and morphology of historic copper patinas and in a significantly increased ratio of the thicknesses of the brochantite and cuprite layers. The results suggest that copper patinas formed during different centuries exhibit variations in uniformity and corrosion protection ability.

  • 389.
    Chavez Varela, Camila
    KTH, School of Chemical Science and Engineering (CHE).
    Elektrokemisk sensor för styrning av bränslecell2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Telecommunication stations for surveillance, wireless communication nodes, and other applications require a main energy source, energy storage unit and a back-up energy system. In the last years, fuel cells have become a good replacement for diesel generators in remote and off-grid applications. Fuel cells provide several advantages like high energy efficiency, no moving parts, silent, scaling is a function of their surface area instead of volume, and reliability. Among the disadvantages there are equipment cost, and difficulties in hydrogen storage. Simplifying the control system of the hydrogen feed control will lower the equipment costs and allow the use of this technology for remote applications where the system is mainly fed by renewable sources, like solar panels, and constant maintenance represents an issue.

    For this purpose the present work investigates the use of a single air-breathing micro fuel cell, used as a sensor cell that can serve to control a fuel cell energy backup system. First the sensor cell was tested under different conditions of temperature, hydrogen humidity, flooding, and hydrogen inlet flow in order to determine optimum operation conditions. Then the sensor cell was connected to the hydrogen outlet of a single cell or stack, receiving the remaining hydrogen that was not consumed by the stack. Further tests were performed by modifying the hydrogen flow, resistance value, and stack current output. During the experiments the sensor cell voltage was monitored. The results show that the micro fuel cell delivers a cell voltage signal sensible to the hydrogen inlet flow, which means it can be used to control the operation of a fuel cell stack. The sensibility of the voltage signal can be modified by means of the resistance connected to its circuit. The stability in time of the voltage signal was achieved by setting the sensor cell to 45 °C or higher.

  • 390. Chen, Bin
    et al.
    Sun, Xi
    Li, Xin
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Xie, Yongshu
    TICT based fluorescence "turn-on" hydrazine probes2014In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 199, p. 93-100Article in journal (Refereed)
    Abstract [en]

    Fluorescence "turn-on" probes PC3 and C3 with weak background emissions were developed for hydrazine sensing. The aldehyde and dicyanovinyl groups were used as the recognition units for PD and C3, respectively. Because of low reactivity of the aldehyde group, the fluorescence of PC3 was enhanced by only ca. 93 folds upon addition of a large amount of 1646 eq. hydrazine. In contrast, 0 exhibited fluorescence enhancement by ca. 239 folds upon addition of only 1.3 eq. hydrazine, and thus it showed high sensitivity towards hydrazine, with the detection limit of 7 ppb. In aqueous systems, it also works well with improved selectivity for hydrazine over CN-. The weak fluorescence of PC3 and 0 can be ascribed to twisted intramolecular charge transfer (TICT) processes by the combination of the bulky diphenylamino and 9-anthryl units, which were well demonstrated by theoretical calculations, viscosity dependent fluorescence, and fluorescence decay behaviour. Addition of hydrazine induced the disappearance of the TICT deactivation pathway, resulting in the observed fluorescence enhancement. It can be concluded that the combination of the bulky diphenylamino and 9-anthryl units is an effective approach for developing fluorescence turn-on hydrazine probes based on the TICT mechanism.

  • 391.
    Chen, Chao
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.
    Development of Non-leaching Antibacterial Approaches on Cellulose-based Substrates and Their Mechanisms2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The layer-by-layer (LbL) technique is becoming a powerful tool that has been applied in many surface coatings and functionalizations in recent years. It has many advantages including a fast and mild process, the flexibility of choice of substrate, and the easiness to scale-up. Novel antibacterial materials can be achieved using this technique, by immobilizing selected antibacterial agents on surfaces of desired substrates. An ideal antibacterial agent, a cationic polyelectrolyte, can be LbL-deposited onto the surfaces in mono or multi layers, make the surfaces lethal to the bacteria due to their positive charge. This approach is able not only to effectively control the spreading of bacteria but also to minimize bacterial resistance as well as the environmental impact.

    Cellulose fibres modified by different cationic polyelectrolytes including PDADMAC, PAH, PVAm as either monolayer or multilayer assembled with PAA using LbL deposition have shown more than 99.99 % bacterial removal as well as the inhibition of bacterial growth. Among these modifications, two layers of PVAm assembled with one layer of PAA have shown the highest antibacterial efficiency due to the highest adsorbed amount and charge density. Secondly, PAA was replaced by a bio-based cellulose nano-fibril (CNF), as a middle layer between two layers of PVAm, which decreases the carbon-footprint and expands the possibility of using LbL technique in antibacterial applications, since the LbL technique can be used long as the alternate layers are oppositely charged. The fibres modified with this approach have shown similar and even better antibacterial properties than those of PAA.

    To develop the antibacterial approach using LbL on cellulose fibres, it is also essential to understand the antibacterial mechanism. It was found that the charge density and surface structures are two important factors affecting bacterial adhesion and the bactericidal effect. To study this, different charged cellulose model surfaces were made by coating oxidized, regenerated cellulose followed by PVAm/CNF/PVAm LbL deposition, and a better antibacterial effect was observed on the higher charged surface. By calculating the force between the bacteria and charged surface, it was suggested that a higher interaction due to the higher surface charge causes a large stress on the bacterial cell wall which leads to the disruption of the bacteria. To further improve the bactericidal effect, the flat surfaces were patterned with micro and nano structures using a femtosecond laser technique. The weakening of the bacterial cell wall caused by the charged surface makes the bacteria more vulnerable and easier to disrupt. This approach has been shown to be valid on both Gram-positive S. aureus, and Gram-negative E. coli. The effect was greater on E. coli with a weaker membrane structure and higher surface potential, which shows that the antibacterial mechanism is a physical disrupt of the bacterial cell.

    The full text will be freely available from 2019-12-13 23:54
  • 392.
    Chen, Chao
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.
    Illergård, Josefin
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Effect of cationic polyelectrolytes in contact-active antibacterial layer-by-layer functionalization2017In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 71, no 7-8, p. 649-658Article in journal (Refereed)
    Abstract [en]

    Contact-active surfaces have been created by means of the layer-by-layer (LbL) modification technique, which is based on previous observations that cellulose fibers treated with polyelectrolyte multilayers with polyvinylamine (PVAm) are perfectly protected against bacteria. Several different cationic polyelectrolytes were applied, including PVAm, two different poly(diallyl dimethyl ammonium chloride) polymers and two different poly(allylamine hydrochloride) polymers. The polyelectrolytes were self-organized in one or three layers on cellulosic fibers in combination with polyacrylic acid by the LbL method, and their antibacterial activities were evaluated. The modified cellulose fibers showed remarkable bacterial removal activities and inhibited bacterial growth. It was shown that the interaction between bacteria and modified fibers is not merely a charge interaction because a certain degree of bacterial cell deformation was observed on the modified fiber surfaces. Charge properties of the modified fibers were determined based on polyelectrolyte titration and zeta potential measurements, and a correlation between high charge density and antibacterial efficiency was observed for the PVAm and PDADMAC samples. It was demonstrated that it is possible to achieve antibacterial effects by the surface modification of cellulosic fibers via the LbL technique with different cationic polyelectrolytes.

  • 393.
    Chen, Fei
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Monnier, Xavier
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Gällstedt, Mikael
    Innventia, Sweden.
    Gedde, Ulf W.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Hedenqvist, Mikael S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Wheat gluten/chitosan blends: A new biobased material2014In: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 60, p. 186-197Article in journal (Refereed)
    Abstract [en]

    Wheat gluten and chitosan are renewable materials that suffer from some poor properties that limit their use as a potential replacement of petroleum-based polymers. However, polymer blends based on wheat gluten and chitosan surprisingly reduced these shortcomings. Films were cast from acidic aqueous or water/ethanol solutions of wheat gluten and chitosan. Wheat gluten was the discontinuous phase in the 30-70 wt.% wheat gluten interval investigated. The most homogeneous films were obtained when reducing agents were used (alone or together with urea or glycerol). They consisted mainly of 1-2 mu m wheat gluten particles uniformly distributed in the continuous chitosan phase. Slightly smaller particles were also observed in the water/ethanol solvent system, but together with significantly larger particles (as large as 200 mu m). Both small and large particles were observed, albeit in different sizes and contents, when surfactants (both with and without a reducing agent) or urea (without a reducing agent) were used. The particles were often elongated, and preferably along the film, the most extreme case being observed when the glyoxal crosslinker was used together with sodium sulfite (reducing agent), showing particles with an average thickness of 0.6 mu m and an aspect ratio of 4.2. This film showed the highest transparency of all the blend films studied. For one of the most promising systems (with sodium sulfite), having good film homogeneity and small particles, the mechanical and moisture solubility/diffusivity properties were studied as a function of chitosan content. The extensibility, toughness and moisture solubility increased with increasing chitosan content, and the moisture diffusivity was highest for the pristine chitosan material. It is noteworthy that the addition of 30 wt.% wheat gluten to chitosan reduced the moisture uptake, while the extensibility/toughness remained unchanged.

  • 394.
    Chen, Fei
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Nilsson, Fritjof
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Gällstedt, M.
    Hedenqvist, Mikael S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Chitosan extrusion at high solids content: An orthogonal experimental design study2014In: Polymers from Renewable Resources, ISSN 2041-2479, Vol. 5, no 1, p. 1-12Article in journal (Refereed)
    Abstract [en]

    For economic reasons and to save time there is a need to shorten the drying operation associated with the production of chitosan materials. Hence it is of interest to extrude chitosan at as high a solids content as possible. This is, to our knowledge, the first systematic study of the extrusion of chitosan at high solids content (60 wt%). An orthogonal experimental design was used to evaluate the effect of processing conditions and material factors on the extrudability of chitosan. This, together with the examination of the evenness and surface finish of the extrudate, made it possible to determine the best conditions for obtaining a readily extrudable high quality material. It was observed that a 1/1 ratio of chitosans with molar masses of 12 and 133 kDa, a process liquid containing 30 wt% acetic acid and 70 wt% water, and extrusion at 50 rpm and 50°C were the optimal material and processing conditions. Materials processed under these conditions were evaluated mechanically at different times after extrusion (stored at 50% RH) in order to see when the properties stabilized. Most mass loss occurred within the first three days after extrusion and this governed the mechanical properties (stiffness and extensibility), which also exhibited the largest changes within these three days (an increase in modulus from 18 to 830 MPa and a decrease in elongation at break from 17 to 3%).

  • 395. Chen, S.
    et al.
    Li, W.
    Li, Xin
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Zhu, W. -H
    Aggregation-controlled photochromism based on a dithienylethene derivative with aggregation-induced emission2017In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 5, no 10, p. 2717-2722Article in journal (Refereed)
    Abstract [en]

    We report novel aggregation-induced emission (AIE) characteristics involving aggregation-controlled photochromism properties of a dithienylethene derivative, BTE-EQ, where two quinolinemalononitrile (EQ) units are covalently attached to a dithienylethene core. The typical AIE effect of BTE-EQ has been found to originate from the AIE character of the EQ units with respect to the reference compound BTE, which does not contain an EQ unit. The photochromism study, together with density functional theory calculations, reveals that the photochromic activity of BTE-EQ can be reversibly switched off and on by controlling the aggregation state during the AIE process, which provides a novel route to controlling the photochromism of diarylethenes.

  • 396.
    Chen, Song
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Resource recovery.
    Abdel-Magied, Ahmed F.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Resource recovery.
    Fu, Le
    Uppsala Universitet, Department of Engineering Sciences.
    Jonsson, Mats
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry.
    Forsberg, Kerstin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Resource recovery.
    Incorporation of strontium and europium in crystals of α-calcium isosaccharinate2019In: Journal of Hazardous Materials, ISSN 0304-3894, E-ISSN 1873-3336, Vol. 364, p. 309-316Article in journal (Refereed)
    Abstract [en]

    The final repository for short-lived, low and intermediate level radioactive waste in Sweden is built to act as a passive repository. Already within a few years after closure water will penetrate the repository and conditions of high alkalinity (pH 10.5―13.5) and low temperature (< 7 °C) will prevail. The mobility of radionuclides in the repository is dependent on the radionuclides distribution between solid and liquid phases. In the present work the incorporation of strontium (II) and europium (III) in α-calcium isosaccharinate (ISA) under alkaline conditions (pH ~10) at 5 °C and 50 °C have been studied. The results show that strontium and europium are incorporated into α-Ca(ISA)2 when crystallized both at 5 °C and 50 °C. Europium is incorporated to a greater extent than strontium. The highest incorporation of europium and strontium at 5 °C rendered the phase compositions Ca0.986Eu0.014(ISA)2 (2.4% of Eu(ISA)3 by mass) and Ca0.98Sr0.02(ISA)2 (2.2% of Sr(ISA)2 by mass). XPS spectra show that both trivalent and divalent Eu coexist in the Eu incorporated samples. Strontium ions were found to retard the elongated growth of the Ca(ISA)2crystals. The incorporation of Sr2+ and Eu3+ into the solid phase of Ca(ISA)2 is expected to contribute to a decreased mobility of these ions in the repository.

  • 397. Chen, Y.
    et al.
    Nielsen, Jens
    KTH, Centres, Science for Life Laboratory, SciLifeLab. Novo Nordisk Foundation Center for Biosustainability.
    Advances in metabolic pathway and strain engineering paving the way for sustainable production of chemical building blocks2013In: Current Opinion in Biotechnology, ISSN 0958-1669, E-ISSN 1879-0429, Vol. 24, no 6, p. 965-972Article, review/survey (Refereed)
    Abstract [en]

    Bio-based production of chemical building blocks from renewable resources is an attractive alternative to petroleum-based platform chemicals. Metabolic pathway and strain engineering is the key element in constructing robust microbial chemical factories within the constraints of cost effective production. Here we discuss how the development of computational algorithms, novel modules and methods, omics-based techniques combined with modeling refinement are enabling reduction in development time and thus advance the field of industrial biotechnology. We further discuss how recent technological developments contribute to the development of novel cell factories for the production of the building block chemicals: adipic acid, succinic acid and 3-hydroxypropionic acid.

  • 398.
    Cheng, Jie
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. Tsinghua University, Beijing, China.
    Pan, J.
    Wang, T.
    Lu, X.
    Micro-galvanic corrosion of Cu/Ru couple in potassium periodate (KIO4) solution2018In: Corrosion Science, ISSN 0010-938X, E-ISSN 1879-0496, Vol. 137, p. 184-193Article in journal (Refereed)
    Abstract [en]

    This paper focuses on the study of micro-galvanic corrosion of the Cu/Ru couple in KIO4 solution. Practical nobility across the Cu/Ru interface was evaluated by Volta potential mapping, and the morphological changes were monitored by in-situ atomic force microscopy measurements during exposure in a KIO4 solution. Chemical composition of precipitated corrosion product was analyzed by Confocal Raman spectroscopy immediately after the exposure. The results show that Cu is the anode of the Cu/Ru couple, and accelerated dissolution of Cu preferentially occurs near the Cu/Ru interface. However, subsequent formation of insoluble Cu(IO3)2·nH2O leads to precipitation, which impedes further Cu corrosion.

  • 399.
    Chernyshev, Alexander
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Resource recovery.
    Forsberg, Kerstin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Resource recovery.
    Jonsson, Mats
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry.
    Impact of organic cement additives on the mobility of radionuclides in a radioactive waste repository2017Conference paper (Refereed)
  • 400.
    Chernyshev, Alexander N.
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Resource recovery.
    Jonsson, Mats
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry.
    Forsberg, Kerstin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Resource recovery.
    Characterization and degradation of a polyaryl ether based superplasticizer for use in concrete barriers in deep geological repositories2018In: Applied Geochemistry, ISSN 0883-2927, E-ISSN 1872-9134, Vol. 95, p. 172-181Article in journal (Refereed)
    Abstract [en]

    Superplasticizers are important additives used in concrete barriers in geological waste repositories. Superplasticizers have been a major concern in the long-term assessments of safe geological disposal for radioactive waste since superplasticizers and their degradation products can act as complexing ligands and thereby increase the mobility of radionuclides. In this work a new type of superplasticizer, based on a polyaryl ether polymer, has been characterized. It was found that the superplasticizer combines the structural features of polycarboxylate ether based superplasticizers and sulfonated naphthalene-formaldehyde based superplasticizers and that it contains organophosphatecharged groups. A novel method for evaluating the rate of degradation of the superplasticizer under alkaline conditions was elaborated and the degradation products and rate constant of the process was determined. The results demonstrate that degradation occurs rapidly compared to the typical lifetime of a repository.

567891011 351 - 400 of 2472
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf