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  • 2451.
    Zhou, Mi
    et al.
    Chalmers Univ Technol, Dept Chem & Chem Engn, SE-41296 Gothenburg, Sweden.;Chalmers Univ Technol, Wallenberg Wood Sci Ctr, SE-41296 Gothenburg, Sweden..
    Sandstrom, Hilda
    Chalmers Univ Technol, Dept Chem & Chem Engn, SE-41296 Gothenburg, Sweden..
    Belioka, Maria-Paraskeui
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Pettersson, Torbjörn
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Mattsson, Tuve
    Chalmers Univ Technol, Dept Chem & Chem Engn, SE-41296 Gothenburg, Sweden.;Chalmers Univ Technol, Wallenberg Wood Sci Ctr, SE-41296 Gothenburg, Sweden..
    Investigation of the cohesive strength of membrane fouling layers formed during cross-flow microfiltration: The effects of pH adjustment on the properties and fouling characteristics of microcrystalline cellulose2019Ingår i: Chemical engineering research & design, ISSN 0263-8762, E-ISSN 1744-3563, Vol. 149, s. 52-64Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Fluid dynamic gauging was used to investigate the cohesive strength of the membrane fouling layer formed during cross-flow microfiltration of microcrystalline cellulose. Fouling behaviour was compared at two pH levels (i.e. different surface charges of the particles and membranes) with two membranes (i.e. regenerated cellulose and polyethersulphone). It was found that a suspension at low pH, where the surface charge of the particles is close to zero, resulted in thicker and stronger surface fouling layers (668 +/- 66 mu m thick at a shear stress of 36 Pa for the regenerated cellulose membrane). The permeate flux was reduced by 62% during the first 1000 s. For close-to-neutral pH, where the particles are negatively charged, the fouling layers were thinner and less resistant to shear stress (290 +/- 77 mu m thick at a shear stress of 36 Pa) and the decline of the flux was faster: a 90% decrease was recorded during the initial 1000 s. The differences in flux decline behaviour suggest a more pronounced blocking of the pore openings for the membranes at the higher pH. Similar fouling behaviour was observed for the two membranes. An atomic force microscope equipped with a colloid probe was used to evaluate particle/particle and particle/membrane interactions. Elsevier B.V. All rights reserved.

  • 2452.
    Zhou, Nian
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Influence of grinding operations on surface integrity and chloride induced stress corrosion cracking of stainless steels2016Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Stainless steels were developed in the early 20th century and are used where both the mechanical properties of steels and corrosion resistance are required. There is continuous research to allow stainless steel components to be produced in a more economical way and be used in more harsh environments. A necessary component in this effort is to correlate the service performance with the production processes.

    The central theme of this thesis is the mechanical grinding process.  This is commonly used for producing stainless steel components, and results in varied surface properties that will strongly affect their service life. The influence of grinding parameters including abrasive grit size, machine power and grinding lubricant were studied for 304L austenitic stainless steel (Paper II) and 2304 duplex stainless steel (Paper I). Surface integrity was proved to vary significantly with different grinding parameters. Abrasive grit size was found to have the largest influence. Surface defects (deep grooves, smearing, adhesive/cold welding chips and indentations), a highly deformed surface layer up to a few microns in thickness and the generation of high level tensile residual stresses in the surface layer along the grinding direction were observed as the main types of damage when grinding stainless steels. A large degree of residual stress anisotropy is interpreted as being due to mechanical effects dominating over thermal effects.

    The effect of grinding on stress corrosion cracking behaviour of 304L austenitic stainless steel in a chloride environment was also investigated (Paper III). Depending on the surface conditions, the actual loading by four-point bend was found to deviate from the calculated value using the formula according to ASTM G39 by different amounts. Grinding-induced surface tensile residual stress was suggested as the main factor to cause micro-cracks initiation on the ground surfaces. Grinding along the loading direction was proved to increase the susceptibility to chloride-induced SCC, while grinding perpendicular to the loading direction improved SCC resistance.

    The knowledge obtained from this work can provide a reference for choosing appropriate grinding parameters when fabricating stainless steel components; and can also be used to help understanding the failure mechanism of ground stainless steel components during service.

  • 2453.
    Zhou, Qi
    et al.
    Wuhan University, China .
    Zhang, L. N.
    Wuhan University, China .
    Minoda, M.
    Wuhan University, China .
    Miyamoto, T.
    Wuhan University, China .
    Phase transition of thermosensitive amphiphilic cellulose esters bearing olig(oxyethylene)s2000Ingår i: Polymer Bulletin, ISSN 0170-0839, E-ISSN 1436-2449, Vol. 45, nr 05-apr, s. 381-388Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A series of cellulose esters bearing olig(oxyethylene)s with different degree of substitution (DS) and different length of the oxyethylene chain were synthesized by a homogeneous reaction of cellulose with corresponding monofunctional acid chloride in a 10% LiCl-dimethyl acetoamide (DMAc) solution. The effect of total DS value on the solubility of the derivatives in aqueous solution was investigated. It was found that the lower limit DS value for both water-soluble and amphiphilic derivatives decreases with increasing length of oxyethylene chains. The amphiphilic derivatives, which are soluble in both water and chloroform, precipitate out of aqueous solution on heating without gel forming, such a phase transition behavior was studied in terms of DS value, length of oxyethylene and concentration. The precipitation temperature (T-p) of the amphiphilic derivatives is range from 54 degreesC to 96 degreesC. It decreases with increasing the total DS value, and increases with an increase in the length of oxyethylene chains. The T-p value of the derivatives was found to be almost independent in the concentration range of 1-15 wt %, however the T-p value increases sharply with decreasing polymer concentration when the concentration is lower than 1 wt%.

  • 2454.
    Zhou, Xiamo
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Sun, Yang
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymerteknologi.
    Finne Wistrand, Anna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymerteknologi.
    van der Wijngaart, Wouter
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Haraldsson, Tommy
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Core-Shell Microparticle Synthesis In Droplet Microfluidics Using A Single Step Polymerization2015Ingår i: Micro Electro Mechanical Systems (MEMS), 2015 28th IEEE International Conference on, IEEE conference proceedings, 2015, s. 472-475Konferensbidrag (Refereegranskat)
    Abstract [en]

    We present, for the first time, a method for the synthesis of core-shell microparticles in a single polymerization step using two-phase droplet microfluidics. We verify the successful generation of core-shell microparticles using the novel synthesis approach. 

  • 2455.
    Zhu, Baohua
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Simonsson, Daniel
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Comparison of electrochemical and surface characterisation methods for investigation of corrosion of bipolar plate materials in molten carbonate fuel cell Part I. Electrochemical study1999Ingår i: Corrosion Science, Vol. 41, nr 8, s. 1497-1513Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The corrosion of bipolar plate and current collector materials in molten carbonate fuel cells (MCFC) was investigated. Tafel extrapolation, linear polarisation resistance, chronopotentiometry and electrochemical impedance spectroscopy (EIS) were used to determine corrosion rates of iron and iron-based alloys in molten carbonate melts for both cathode and anode MCFC environments. During the initial stages, agreement among the methods was good but could have differed after a corrosion layer formed on the surface. The corrosion rate for a fully immersed sample at the open circuit potential seemed to be controlled by external mass transfer of water. Iron-chromium alloys exhibit reasonable corrosion resistance on the cathode side, provided that the chromium concentration exceeds 25%. The corrosion of bipolar plate and current collector materials in molten carbonate fuel cells (MCFC) was investigated. Tafel extrapolation, linear polarisation resistance, chronopotentiometry and electrochemical impedance spectroscopy (EIS) were used to determine corrosion rates of iron and iron-based alloys in molten carbonate melts for both cathode and anode MCFC environments. During the initial stages, agreement among the methods was good but could have differed after a corrosion layer formed on the surface. The corrosion rate for a fully immersed sample at the open circuit potential seemed to be controlled by external mass transfer of water. Iron-chromium alloys exhibit reasonable corrosion resistance on the cathode side, provided that the chromium concentration exceeds 25%.

  • 2456.
    Zhu, Baohua
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Simonsson, Daniel
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Comparison of electrochemical and surface characterisation methods for investigation of corrosion of bipolar plate materials in molten carbonate fuel cell Part II. Surface analysis1999Ingår i: Corrosion Science, Vol. 41, nr 8, s. 1515-1528Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The corrosion of bipolar plate materials in molten carbonate fuel cells (MCFC) was studied by electrochemical techniques. These methods were complemented by thermogravimetric analysis (TGA) and surface analyses, such as SEM, EDX and XRD. The concentration profiles of oxygen, lithium, iron, chromium and nickel in the oxide scales were determined by means of glow discharge optical emission spectroscopy (GDOES). It has been shown that corrosion layers, formed on the iron-chromium and stainless steels surfaces, consist of two layers. The outer layer is porous and has large pores; the inner layer is more compact and may contain small pores. The corrosion of bipolar plate materials in molten carbonate fuel cells (MCFC) was studied by electrochemical techniques. These methods were complemented by thermogravimetric analysis (TGA) and surface analyses, such as SEM, EDX and XRD. The concentration profiles of oxygen, lithium, iron, chromium and nickel in the oxide scales were determined by means of glow discharge optical emission spectroscopy (GDOES). It has been shown that corrosion layers, formed on the iron-chromium and stainless steels surfaces, consist of two layers. The outer layer is porous and has large pores; the inner layer is more compact and may contain small pores.

  • 2457.
    Zhu, Bin
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Advanced hybrid ion conducting ceramic composites and applications in new fuel cell generation2005Ingår i: HIGH-PERFORMANCE CERAMICS III, PTS 1 AND 2 / [ed] Pan, W; Gong, JH; Ge, CC; Li, JF, 2005, Vol. 280-283, s. 413-418Konferensbidrag (Refereegranskat)
    Abstract [en]

    Our developments on ceramic composite conductors have experienced about 15 years from the oxyacid-salts oxide proton-based conductors, non-oxide containment salts, the ceria-based composite electrolytes, hybrid proton and oxygen ion conductors and nano-composites. A special emphasis is paid to new functional nano-composites based on hybrid proton and oxygen ion conductors that have demonstrated advanced properties and fuel cell applications, e.g., excellent ionic conductivity of 0.01 to 1 Scm(-1) and performances of 200 - 1000 mWcm(-2) for temperatures achieved for fuel cells between 400 and 700degreesC. Some proton and oxygen ion conducting mechanisms in the materials are reviewed and discussed. The hybrid ion conduction and dual electrode reactions and processes create a new generation fuel cell system.

  • 2458.
    Zhu, Hongli
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Helander, Mikaela
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Moser, Carl
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Ståhlkranz, Adam
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Söderberg, Daniel
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Henriksson, Gunnar
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Lindström, Mikael
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    A novel nano cellulose preparation method and size fraction by cross flow ultra- filtration2012Ingår i: Current organic chemistry, ISSN 1385-2728, E-ISSN 1875-5348, Vol. 16, nr 16, s. 1871-1875Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A novel energy-efficient method called nanopulping (patent pending) to produce nanocellulose from chemical pulp, and a novel cross-flow ultra-filtration method to separate nanofibrils fractions of different size were applied in this study. Pretreatment with endoglucanase or 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) oxidation seems to enhance the nanopulping process. Results were evaluated with atomic force microscope and ultrafiltration. The nanopulping produced a relatively inhomogeneous material with larger particles/ fibers in addition to nanofibers. However, by ultrafiltration of the material it was possible to obtain more homogeneous material in different dimensions with methods industrially acceptable.

  • 2459.
    Zhu, Jiqing
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap, Väg- och banteknik.
    Birgisson, Björn
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap, Väg- och banteknik.
    Kringos, Niki
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap, Väg- och banteknik.
    Polymer modification of bitumen: Advances and challenges2014Ingår i: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 54, nr 1, s. 18-38Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Advances and challenges in the field of bitumen polymer modification for road construction during the last 40 years are reviewed in this paper. The history of bitumen polymer modification is described chronologically. Some popular plastomers and thermoplastic elastomers in bitumen modification are discussed regarding their advantages and disadvantages, including polyethylene (PE), polypropylene (PP), ethylene-vinyl acetate (EVA), ethylene-butyl acrylate (EBA), styrene-butadiene-styrene (SBS), styrene-isoprene-styrene (SIS) and styrene-ethylene/butylene-styrene (SEBS). Although these polymers all improve bitumen properties to some extent, there are still some drawbacks limiting the future development of bitumen polymer modification, such as high cost, low ageing resistance and poor storage stability of polymer modified bitumen (PMB). Researchers attempted various ways to remove these drawbacks. Some technical developments for removing drawbacks are reviewed in this paper, including saturation, sulfur vulcanization, adding antioxidants, using hydrophobic clay minerals, functionalization and application of reactive polymers. The future development of polymers for bitumen modification is analyzed as well. Since it is currently challenging to perfectly achieve all expected PMB properties at the same time, some compromised recommendations are given in this paper, among which greatly enhancing the properties with an acceptably high cost, significantly reducing the cost with relatively poor properties and their combinations. Functionalization is emphasized as a promising way to enhance the properties of currently used polymers and develop new-type polymer modifiers with much greater success in the future. It is also recommended that future research on bitumen polymer modification focuses more on function development towards enhancing: adhesion with aggregates, long-term performance and recyclability.

  • 2460. Zhu, Liangliang
    et al.
    Li, Xin
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Sanders, Samuel N.
    Ågren, Hans
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Unimolecular Photopolymerization of High-Emissive Materials on Cylindrical Self-Assemblies2015Ingår i: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 48, nr 15, s. 5099-5105Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We report a novel self-assembly pathway from a bis(imidazolyl) diphenyl-diacetylene (DPDA) compound as a realization of self-templated photopolymerization with high polymerization degrees. The work takes advantage of a cylindrical self-assembly that strengthens the preorganization of the diphenyl-diacetylene moiety at the single molecular level. On this basis, photopolymerization of DPDA can be conducted smoothly to form high-molecular-weight polydiphenyl diacetylene. Such a cylindrical self-assembly is highly dependent on molecular structure, and control studies show that only oligomers can be formed on random self-assemblies from a monoimidazolyl or nonimidazolyl diphenyl-diacetylene compound. Moreover, the cylindrical self-assembly based systems bear aggregation-induced emission enhancement characteristics and are solution processable. The leading thin-film could afford a selectively tunable function in luminescent micropatterns.

  • 2461.
    Zhu Ryberg, Yingzhi
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Wood hydrolysates- New concepts in renewable material design2013Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Hydrolysat är processvätskor från träindustrin. Istället för komplicerade utvinningsprocesser av ren hemicellulosa från processvätskor, används här det oförädlade hydrolysatet, som innehåller till största delen hemicellulosa och en del lignin. Den här avhandlingen beskriver hur vi framgångsrikt utvecklade detta hydrolysat till syrgasbarriärfilmer och bestrykningar som kan användas till matförpackningar samt hur modellering av strukturerna och interaktionerna mellan hydrolysatets komponenter kan förutsäga deras prestanda som barriärmaterial.

    Fristående filmer och bestrykningar skapades från blandningar av vedhydrolysat och en samkomponent: antingen kitosan eller karboximetylcellulosa (CMC). Filmerna hade utmärkta syrgasbarriäregenskaper som till och med var bättre än filmer beredda av motsvarande renade hemicellulosa. Hansens löslighetsparametersteori (HSP) påvisade och kvantifierade interaktioner mellan molekylerna i både hydrolysat och hydrolysat-baserade blandningar vilket ger en förståelse för de goda barriäregenskaperna. Vår hypotes var att dessa starka interaktioner ökade affiniteten i matrisen vilket leder till tät molekylär packning och därmed bra syrgasbarriäregenskaper. Med Positron annihiliation lifetime spectroscopy (PALS) uppmättes de fria volymerna i de hydrolysat-baserade matriserna. HSP resultaten, storlek och fördelning av fri volym, samt termisk analys, verifierade hypotesen väl.

    HSP-modellen användes sedan för att prediktera kompositionen hos syrgasbarriärbestrykningar från hydrolysat-baserade blandningar. Genom att använda HSP-modellen, kan interaktionerna mellan olika hydrolysat och CMC beräknas och interaktionerna i matrisen utvärderas. De fria volymerna uppmätta med PALS, syrepermeabilitet (OP)-resultaten var generellt överensstämmande med förutsägelserna från HSP-modellen, vilket visar potentialen för HSP- modellen som verktyg i formuleringen av barriärbestrykningarr för matförpackningar.

    För att utveckla en industriellt realistisk och effektiv process för produktion av hydrolysat-baserade bestrykningar provades flera angreppssätt. Först gjordes bestrykningar manuellt från hydrolysat-baserade blandningar och dessa hade utmärkta syrebarriäregenskaper. Sedan utvecklades en spraytorkningsbeläggningsteknik (SPD) som en reproducerbar, effektiv bestrykningsprocess för hydrolysat utan tillsatser eller andra samkomponenter. Dessutom förbättrade töjbarheten hos bestrykningarna genom tvärbindning med glyoxal vilket i sin tur förbättrade kvalitet och syrgasbariäregenskaperna för bestrykningen. SEM integrerat med en dragprovutrustning gjorde det möjligt att i realtid observeraytan av bestrykningen under deformationsprocessen. Detta gjorde det möjligt att studera de mekaniska egenskaperna för beläggningarna utan inverkan av substratet.

  • 2462.
    Zhu Ryberg, Yingzhi
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Edlund, Ulrica
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Albertsson, Ann-Christine
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Innovative Approaches for Converting a Wood Hydrolysate to High-Quality Barrier Coatings2013Ingår i: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 5, nr 16, s. 7748-7757Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An advanced approach for the efficient and controllable production of softwood hydrolysate-based coatings with excellent oxygen-barrier performance is presented. An innovative conversion of the spray-drying technique into a coating applicator process allowed for a fast and efficient coating process requiring solely aqueous solutions of softwood hydrolysate, even without additives. Compared to analogous coatings prepared by manual application, the spray-drying produced coatings were more homogeneous and smooth, and they adhered more strongly to the substrate. The addition of glyoxal to the aqueous softwood hydrolysate solutions prior to coating formation allowed for hemicellulose cross-linking, which improved both the mechanical integrity and the oxygen-barrier performance of the coatings. A real-time scanning electron microscopy imaging assessment of the tensile deformation of the coatings allowed for a deeper understanding of the ability of the coating layer itself to withstand stress as well as the coating-to-substrate adhesion.

  • 2463. Zikeli, Florian
    et al.
    Ters, Thomas
    Fackler, Karin
    Srebotnik, Ewald
    Li, Jiebing
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Fractionation of wheat straw Dioxane lignin reveals molar mass dependent structural differences2016Ingår i: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 91, s. 186-193Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Dioxane lignin was isolated from ball-milled wheat straw by neutral dioxane-water extraction and subsequently molar-mass-fractionated by flash chromatography in dimethylformamide. The eluted lignin containing material was pooled into six distinct molar mass fractions that were in turn structurally characterized in detail by wet chemistry and NMR spectroscopy methods. Fractions of higher molar mass were found to be enriched in p-hydroxyphenyl units and contained more p-hydroxycinnamic acid units. They were found mainly associated with linear arabinoxylan, while in low-molar-mass fractions additional glucan contributions were found. Fractions of lower molar mass consisted of relatively more guaiacyl units and showed exclusive association with tricin units. One distinct lignin fraction with lower lignin content supposedly contained high ratios of arabinoxylan chains esterified by ferulic acid and cross-linked via ferulic acid dimerization, structures which were considered to represent lignin nucleation sites. High abundance of dibenzodioxocin type structures in this fraction indicated that they could be involved in cross-linking hemicelluloses networks with lignin moieties.

  • 2464. Zou, Qi
    et al.
    Li, Xin
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Zhou, Ji
    Bai, Kangkang
    Ågren, Hans
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Synthesis and photochromism of a spirooxazine derivative featuring a carbazole moiety: Fast thermal bleaching and excellent fatigue resistance2014Ingår i: Dyes and pigments, ISSN 0143-7208, E-ISSN 1873-3743, Vol. 107, s. 174-181Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A novel photochromic spirooxazine derivative bearing a carbazole moiety (SOC) was synthesized and studied in solution under flash photolysis conditions. It is found to exhibit excellent characteristics like high photochromic response, large steady-state optical density, fast thermal bleaching rate and good fatigue-resistance. The effect of different solvents on the photochromic properties of the compound was evaluated, revealing that the photochromic properties can be modulated by different solvents based on the corresponding polarity. The mechanism and kinetics of the thermal fading process of compound SOC were additionally investigated by theoretical simulations, where the isomerization pathway from the trans-trans-cis conformation was found to be several times faster than that from the cis-trans-cis conformation. This type of fast-bleaching and fatigue-resistent photochromic compounds is expected to pave an exciting avenue in future development of high-performance photochromic materials.

  • 2465. Zou, Yidong
    et al.
    Liu, Yang
    Wang, Xiangxue
    Sheng, Guodong
    Wang, Suhua
    Ai, Yuejie
    Ji, Yongfei
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Liu, Yunhai
    Hayat, Tasawar
    Wang, Xiangke
    Glycerol-Modified Binary Layered Double Hydroxide Nanocomposites for Uranium Immobilization via Extended X-ray Absorption Fine Structure Technique and Density Functional Theory Calculation2017Ingår i: ACS SUSTAINABLE CHEMISTRY & ENGINEERING, ISSN 2168-0485, Vol. 5, nr 4, s. 3583-3595Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Novel, efficient, glycerol-modified nanoscale layered double hydroxides (rods Ca/Al LDH-Gl and flocculent Ni/Al LDH-Gl) were successfully synthesized by a simple one-step hydrothermal synthesis route and showed excellent adsorption capacities for U(VI) from aqueous solutions under various environmental conditions. The advanced spectroscopy analysis confirmed the existence of abundant oxygen-containing functional groups (e.g., C-O, O-C=O, and C=O) on the surfaces of Ca/AI LDH-Gl and Ni/Al LDH-Gl, which could provide enough free active sites for the binding of U(VI). The maximum adsorption capacities of Macro-application (Environment U(VI) calculated from the Sips model were 266.5 mg.g(-1) for Ca/Al LDH-Gl and 142.3 mg.g(-1) for Ni/Al LDH-Gl at 298.15 K, and the higher adsorption capacity of Ca/Al LDH-Gl might be due to more functional groups and abundant high-activity "Ca-O" groups. Macroscopic experiments proved that the interaction of U(VI) on Ca/Al LDH-Gl and Ni/Al LDH-Gl was due to surface complexation and electrostatic interactions. The extended Xray absorption fine structure analysis confirmed that U(IV) did not transformation to U(VI) on solid particles, and stable inner sphere complexes were not formed by reduction interaction but by chemical adsorption. The density functional theory (DFT) calculations further evidenced that the higher adsorption energies (i.e., E-ad = 4.00 eV for Ca/AI LDH-Gl-UO22+ and E-ad = 2.43 eV for Ca/Al LDH-Gl-UO2CO3) were mainly attributed to stronger hydrogen bonds and electrostatic interactions. The superior immobilization performance of Ca/AI LDH-Gl supports a potential strategy for decontamination of UO22+ from wastewater, and it may provide new insights for the efficient removal of radionuclides in environmental pollution cleanup.

  • 2466.
    Zuleta, Marcelo
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Electrochemical and ion transport characterisation of a nanoporous carbon derived from SiC2005Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    In this doctoral project, a relatively new form of carbon material, with unique narrow pore size distribution around 7 Å and with uniform structure, has been electrochemically characterised using the single particle microelectrode technique. The carbon has been used as electrode material for supercapacitors. This type of capacitors is used as high power energy buffers in hybrid vehicles and for stationary power backup. The principle for the microelectrode technique consists of connecting a carbon particle with a carbon fibre by means of a micromanipulator. The single particle and carbon fibre together form a microelectrode. Combination of this technique with electroanalytical methods such as cyclic voltammetry and potential step measurements allows for the survey of electrochemical phenomena and for the determination of ion transport parameters inside the nanopores.

    A mathematical model based on Fick’s second law, for diffusion of ions inside the nanopores at non steady state, was used for the determination of effective diffusion coefficients (Deff). The coefficients were calculated from an asymptotic solution of Fick’s equation, applied for a thin layer adjacent to the external surface of the carbon particles and valid for the current response in a short time region. Another asymptotic solution was obtained, using spherical geometry and valid for the current response in a long time region.

    In this doctoral work, the carbon particles have been exposed to potential cycling, which mimics that of large electrodes during operation of a double layer capacitor. The potential-current response, E-I, for the nanoporous carbon, shows a pure capacitive behaviour between –0.5 V and 0.1 V vs. the Hg|HgO reference electrode. The detection of the faradaic processes beyond these potentials was possible by lowering of the voltammometric sweep rate. The electrochemical processes occurring at positive and at negative potential were investigated separately.

    Cyclic voltammometric measurements showed that the chemisorption of hydroxyl groups, occurring between 0.1 and 0.3 V, leads to a mild oxidation of the carbon structure, resulting in surface groups containing an oxygen atom at a specific carbon site (e.g., phenolic or quinine type). These oxygen-containing surface groups caused an increase of the specific capacitance, which remained constant throughout a number of voltammometric cycles. The Deff decreased on the other hand with the number of cycles. The Deff decreases also with the positive potential. The evaluation of Deff indicates adsorption of hydroxyl groups and an increase of the effective tortuosity of the pore system.

    The oxidation of the carbon particles, between 0 and 0.5 V, leads to more extensive oxidation and to surface groups containing two oxygen atoms at a single carbon site, followed by formation of carbonate ions. The oxygen-containing surface groups and carbonate ions formed at these potentials do not contribute to the specific capacitance and drastically retard or obstruct the ion transport inside the nanopores.

    At negative potentials the carbon particles show a dominantly capacitive behaviour. The faradaic processes taking place below –0.5 V vs. Hg|HgO reference electrode are generation and adsorption of hydrogen. These processes do not perturb significantly the electrochemical and ion transport properties of the nanoporous carbon particles. It was found that hydrogen generation occurs at –0.5 V vs. Hg|HgO and that two hydrogen oxidation processes take place at positive potentials. The results indicate that the weakly adsorbed hydrogen undergoes oxidation between 0 and 0.1 V and that the strongly adsorbed hydrogen is oxidised at more positive potentials.

    The single particle technique was adapted for the determination of diffusion coefficients of an organic electrolyte. The different size of the anions and cations caused different transport characteristics at negative and positive potentials. Slow cycling was found important for ion penetration inside the nanopores and for the evaluation of the effective diffusion coefficients.

    The effective diffusion coefficients for the nanoporous carbon using aqueous 6M KOH and 0.1M TEABF4 in acetonitrile were estimated to 1.4 (±0.8).10-9 cm2 s-1 and 1.3 (±0.4) 10-8 cm2 s-1, respectively.

  • 2467.
    Zuleta, Marcelo
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Björnbom, Pehr
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Lundblad, Anders
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Characterization of the electrochemical and ion-transport properties of a nanoporous carbon at negative polarization by the single-particle method2006Ingår i: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 153, nr 1, s. A48-A57Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this work, the electrochemical processes occurring in a nanoporous carbon, obtained from silicon carbide and used as negative electrode material for supercapacitors, have been investigated by means of the single-particle microelectrode method. The processes studied deal with hydrogen adsorption, evolution, and oxidation using 6 M KOH as electrolyte. It was found that adsorption of hydrogen started at -0.5 V, hydrogen evolution at -1.4 V vs Hg vertical bar HgO, and that hydrogen oxidation occurs in two steps. The first oxidation process takes place between 0 and 0.1 V, shown by a well-defined current peak on the voltammograms. The second oxidation stage occurs between 0.1 and 0.5 V, indicated by a successive increase in current with the number of cycles. It was also found that after the first oxidation process, subsequent cycling between -0.5 and -1 V leads to a larger accumulation of hydrogen inside the nanopores and to a decrease of the effective diffusion coefficient (D-eff) of potassium ions. Subsequent oxidation, in a second process, leads to a total consumption of hydrogen and to an increase of D-eff.

  • 2468.
    Zuleta, Marcelo
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Björnbom, Pehr
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Lundblad, Anders
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Nurk, G.
    Kasuk, H.
    Lust, E.
    Determination of diffusion coefficients of BF4- inside carbon nanopores using the single particle microelectrode technique2006Ingår i: Journal of Electroanalytical Chemistry, ISSN 0022-0728, E-ISSN 1873-2569, Vol. 586, nr 2, s. 247-259Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The electrochemical and mass transport properties of TEABF(4) in a nanoporous (NP) carbon material, obtained from silicon carbide, was studied using single particles and a microelectrode technique. The carbon particles of size 100-200 mu m were studied by cyclic voltammetry and potential step measurements. The effective diffusion coefficients (D-eff) were calculated starting from the asymptotic solutions of Fick's second law for short and long time regions. The results show that cycling at low sweep rates was needed in order for the electrolyte to penetrate the inner porosity of the particles. The carbon material showed different electrochemical and mass transport properties depending on the applied potential. At negative polarisation, the results suggest that TEA(+) was adsorbed on the pore wall, however, being transported very slowly inside the pores. The average D-eff after cycling at both positive and negative potentials was 1.1(+/- 0.4) x 10(-8) cm(2) s(-1), using the Cottrell relation and 1.5(+/- 0.6) x 10(-8) cm(2) s(-1), using the radial diffusion solution. The average value of D-eff after cycling at negative potentials was 1.7(+/- 0.6) x 10(-8) cm(2) s(-1) using both mathematical solutions.

  • 2469.
    Zuleta, Marcelo
    et al.
    KTH, Tidigare Institutioner, Kemiteknik.
    Bursell, Martin
    KTH, Tidigare Institutioner, Kemiteknik.
    Lundblad, Anders
    KTH, Tidigare Institutioner, Kemiteknik.
    Characterization of ion transport in a nanoporous carbon for double layer capacitors2000Ingår i: Proceedings of Advances in Science and technology 29: (Mass and Charge Transport in Inorganic Materials: Fundamentals to devices, part A), 2000, s. 439-446Konferensbidrag (Refereegranskat)
  • 2470.
    Álvarez Asencio, Rubén
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Sababi, Majid
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Pan, Jinshan
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Ejnermark, Sebastian
    Ekman, Lars
    Rutland, Mark W.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap. SP Tech Res Inst Sweden, Sweden.
    Role of microstructure on corrosion initiation of an experimental tool alloy: A Quantitative Nanomechanical Property Mapping study2014Ingår i: Corrosion Science, ISSN 0010-938X, E-ISSN 1879-0496, Vol. 89, s. 236-241Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The adhesion properties of a FeCrVN experimental tool alloy immersed in pure water and sodium chloride solution have been studied by Quantitative Nanomechanical Property Mapping to understand the influence of microstructure on corrosion initiation of this alloy. The approach used here allows early observation and identification of pre-pitting events that may lead to passivity breakdown of the alloy. Adhesion provides a good distinction between the different regions and we ascribe this to their vanadium and nitrogen contents. Finally, the prepitting is characterized by generation of small particles in specific regions of the surface with low chromium content.

  • 2471.
    Ågren, Niklas
    KTH, Tidigare Institutioner, Kemiteknik.
    Advanced Gas Turbine Cycles with Water-Air Mixtures as Working Fluid2000Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Since the early 80's, the worldwide utilization of gas turbines for thermal power generation has increased rapidly. They have less pollution than any other major combustion energy converters. One important development trend in gas turbine technology is new processes for better flue gas heat recovery (gaining better efficiency, power density and environmental impact), so called advanced cycles. The purpose of this work has been to evaluate the performance and process system and subsystems of advanced gas turbine cycles with air/water mixture as working medium. The focus of the thesis is on the evaporative gas turbine cycle. This cycle has extraordinary heat recovery possibilities. An increased understanding of the interaction of the different process components is sought, with an emphasis on modeling the high pressure humidification column. Efforts have been made to synthesize innovative strategies for EvGT humidification. Theoretical and experimental work concerning the water recovery and purification issues are also presented.

    Some important results are that the flow of air through the humidifier should be optimized. For the different cases presented in this thesis, the optimal fraction (with regard to efficiency) varies from about 12% to 40% of the compressor inlet air. Savings in heat exchanger area and reduced pressure work for booster fan are advantages of using only a part of the compressor air in the humidifier. For obtaining best efficiency of the evaporative cycle, the heat flows above the boiling point should preferably be taken care of by conventional boilers for steam injection or by a separate humidifier section working only slightly below boiling temperature. This is particularly important in gas turbines without intercooling or without recuperation due to high temperatures in exit streams. The unique nature of the humidifier is its ability to evaporate water below the boiling point, by the use of air dilution. However, the best temperature performance (lowest temperature of outlet water from humidifier) is reached if the thermal loading on the humidifier is not excessive.

    The need for large quantities of demineralized water has previously been identified as a possible drawback for the EvGT cycle. In favor of the EvGT-technology, the first water testing experiments on a pilot EvGT-plant, presented in this work, contradict this notion. It is theoretically and experimentally shown that an EvGT-plant can be run with no external water feed at all, by means off lue gas condensation and condensate recovery. After internal condensate treatment, the recycled condensate was of equal quality or better than the deionized fresh feed used for initial system fill-up.

  • 2472.
    Åhlander, Åsa
    KTH, Skolan för kemivetenskap (CHE).
    Defense activation in strawberries: Terpenes and other volatile compounds2016Självständigt arbete på grundnivå (yrkesexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
  • 2473.
    Ålander, E.M.
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Uusi-Penttilä, M. S.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Rasmuson, Åke Christoffer
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Agglomeration of Paracetamol during Crystallization in Pure and Mixed Solvents2004Ingår i: Industrial & Engineering Chemistry Research, ISSN 0888-5885, E-ISSN 1520-5045, Vol. 43, nr 2, s. 629-637Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The agglomeration of paracetamol during crystallization has been investigated. It is shown that the agglomeration behavior depends on the solvent composition. The following solvent systems were used in isothermal desupersaturation experiments: five different acetone-toluene-water mixtures and the pure solvents acetone, 2-propanol, acetic acid, and ethylene glycol. Sieving, image analysis processed by principal component analysis, and agglomerate strength measurements were used to characterize the product particles. Mixtures with a high concentration of acetone were found to produce a highly agglomerated product with strong agglomerates. In contrast, products from crystallization in ethylene glycol, 2-propanol, acetic acid, and acetonetoluene-water mixtures having a high concentration of water contained not only agglomerates but also a significant fraction of single crystals. Furthermore, the agglomerates formed in these solvents were much weaker than those produced in mixtures with a high content of acetone. The results were correlated with the polarity and the viscosity of the solvents.

  • 2474. Ålander, E.M.
    et al.
    Uusi-Penttilä, M. S.
    Rasmuson, Åke Christoffer
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik.
    Characterization of paracetamol agglomerates by image analysis and strength measurement2003Ingår i: Powder Technology, Vol. 130, nr 1-3, s. 298-306Artikel i tidskrift (Refereegranskat)
  • 2475.
    Ålander, Eva
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Influence of Solvent Composition on Crystal Agglomeration of Paracetamol2005Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Agglomeration is an important phenomenon which often controls the particle size distribution and morphology in the crystallization of organic compounds. In this thesis the influence of solvent composition on crystal agglomeration of paracetamol is investigated.

    Particles from (i) isothermal desupersaturation experiments with initiated nucleation and (ii) fully seeded isothermal crystallization experiments operating at constant supersaturation have been characterized. The number of crystals in each particle has been determined by image analysis using multivariate data evaluation and a set of calibration particles. A parameter defining the degree of agglomeration is extracted from the number distribution of crystals per particle. In addition, the agglomerate strength determined by the crushing of single agglomerates has been measured.

    The results clearly show that the solvent composition has an influence on the crystal agglomeration. This observed influence cannot be explained by differences in the solution viscosity (fluid mechanics), or by differences in the overall crystal growth rate. The product is less agglomerated and the agglomerates are weaker when the crystallization is carried out in a more polar solvent, e.g. water. In the systems studied, a high solvent polarity coincides with hydrogen-bond-donating and hydrogen-bond-accepting capabilities. These solvents can interact strongly with paracetamol crystal surfaces which exhibit both donating and accepting sites. In less polar solvents like acetone, only donating sites on the surfaces can be occupied.

    Surfaces of large, well-grown paracetamol crystals have been characterized by contact angle measurements according to the Lifshitz-van der Waals acid-base theory. The surface free energy varies between 50-57 mJ/m2, and all faces indicate a strong hydrogen-bond acceptance.

    The free energy of adhesion between crystal faces in different solvents has been calculated from the surface free energy components. The findings in this thesis strongly support the hypothesis that the mechanism by which the solvent influences on the agglomeration relates to the molecular interaction at the crystal-solvent interface and the physico-chemical adhesion forces between crystal faces in the solution.

  • 2476.
    Ålander, Eva M.
    et al.
    KTH, Tidigare Institutioner, Kemiteknik.
    Uusi-Penttila, Marketta S.
    KTH, Tidigare Institutioner, Kemiteknik.
    Rasmuson, Åke C.
    KTH, Tidigare Institutioner, Kemiteknik.
    Agglomeration of paracetamol during crystallization in pure and mixed solvents2004Ingår i: Industrial & Engineering Chemistry Research, ISSN 0888-5885, E-ISSN 1520-5045, Vol. 43, nr 2, s. 629-637Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The agglomeration of paracetamol during crystallization has been investigated. It is shown that the agglomeration behavior depends on the solvent composition. The following solvent systems were used in isothermal desupersaturation experiments: five different acetone-toluene-water mixtures and the pure solvents acetone, 2-propanol, acetic acid, and ethylene glycol. Sieving, image analysis processed by principal component analysis, and agglomerate strength measurements were used to characterize the product particles. Mixtures with a high concentration of acetone were found to produce a highly agglomerated product with strong agglomerates. In contrast, products from crystallization in ethylene glycol, 2-propanol, acetic acid, and acetone-toluene-water mixtures having a high concentration of water contained not only agglomerates but also a significant fraction of single crystals. Furthermore, the agglomerates formed in these solvents were much weaker than those produced in mixtures with a high content of acetone. The results were correlated with the polarity and the viscosity of the solvents.

  • 2477.
    Ålander, Eva
    et al.
    KTH, Tidigare Institutioner, Kemiteknik.
    Rasmuson, Åke Christoffer
    KTH, Tidigare Institutioner, Kemiteknik.
    Agglomeration of paracetamol in the acetone-water system Int. Conf. on Particle Technology, paper 14.3 CD Proceedings of PARTEC 20042004Ingår i: / [ed] S.E. Pratsinis, H. Schulz and R. Strobel, 2004Konferensbidrag (Refereegranskat)
  • 2478.
    Ålander, Eva
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Teknisk strömningslära.
    Rasmuson, Åke Christoffer
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Teknisk strömningslära.
    Crystal-solvent interaction in agglomeration of paracetamol2005Ingår i: the 16’th International Symposium on Industrial Crystallization / [ed] J Ulrich, VDI verlag Dusselsdrorf , 2005, s. 511-516Konferensbidrag (Refereegranskat)
  • 2479. Åvitsland, Grete
    et al.
    Sterner, Mirjam
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Ödberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    AKD sizing of TCF and ECF bleached birch pulp characterized by peroxide edge wicking2006Ingår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 21, nr 2, s. 237-241Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    To study the impact of extractable materials and xylan on the sizing efficiency of totally chlorine-free (TCF) bleached birch pulp and elemental-chlorine-free (ECF) bleached birch pulp, several pulps with different amounts of extractable material were studied. The content of extractable material in the pulp was shown to be detrimental for sizing efficiency, measured both as Cobb. values and edge penetration in a model liquid packaging board, and a higher content of extractable material causes a reduced sizing efficiency for a given pulp. No significant difference was observed between extracted TCF and ECF bleached birch pulps, while unextracted pulps containing the same amount of extractable material yielded different sizing efficiencies. The TCF bleached birch pulp had a lower sizing efficiency than did the ECF bleached birch, probably because of differences in the fatty acid composition. A greater amount of extractable material also resulted in a smaller fraction of non-extractable alkyl ketene dimers (AKD) relative to the total amount of AKD in the sheet. Enzymatic removal of xylan and thus the reduction of the surface charge had no measurable effect on sizing efficiency. Extracted TCF and ECF bleached pulps only need a content of 0.05 kg/ton non-extractable AKD or 0.08 kg/ton total AKD in the sheets produced to achieve a good sizing effect.

  • 2480. Çakir, S.
    et al.
    Eriksson, Magnus
    KTH, Skolan för bioteknologi (BIO), Industriell bioteknologi.
    Martinelle, Mats
    KTH, Skolan för bioteknologi (BIO), Industriell bioteknologi.
    Koning, C. E.
    Multiblock copolymers of polyamide 6 and diepoxy propylene adipate obtained by solid state polymerization2016Ingår i: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 79, s. 13-22Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Polyesteramide multiblock copolymers based on polyamide 6 and diepoxy propylene adipate blocks were synthesized. For this purpose a carboxyl-terminated polyamide 6 (Mn = 2400 g/mol, Tm = 205.5 °C) and diepoxy propylene adipate (Mn = 450 g/mol) were separately synthesized and characterized. The incorporation of the oligoester into the polyamide 6 backbone was performed by solid state polymerization (SSP) well below the melting temperature of the polyamide (80-140 °C) so that the physical and thermal properties of the original polyamide 6 block were retained. Formation of the multiblock structure was confirmed by following the increase in molecular weight by SEC, reaction of the end groups by 1H NMR and by following the maintained melting temperature after the copolymerization. These segmented copolymers have molecular weights up to 10 kg/mol, thermal stability of 325 °C at 5% weight loss and a melting temperature of 205 °C.

  • 2481.
    Öberg, Emma
    KTH, Skolan för kemivetenskap (CHE).
    Investigation of mineral oils as a compatibilizer between metallocene polyolefins and rosin resins in hot melt adhesives2016Självständigt arbete på grundnivå (yrkesexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Limning är en gammal fogningsteknik som har många olika användningsområden. Marknaden för limmer växer, smältlim förväntas ha stor tillväxt även med hårdare miljölagstiftning då appliceringen av limmet sker utan lösningsmedel.

    För att ta fram och tillverka lim används idag polymerer i stor utsträckning. Metallocen polyolefin (mPO) är en typ av polymer som används i limmer på grund av dess utmärkta prestanda som uppnås genom en smal molekylviktsdistribution (MWD). Detta gör det lätt att tillverka limmer med önskade egenskaper. Den här typen av polymerer tenderar dock att vara opolära vilket gör att de är inkompatibla med tallhartser, som ger klibbighet till limmet, eftersom tallhartserna har en högre poläritet.

    Mineraloljor används i limmer som mjukgörare, men används också i vissa fall för att öka kompabiliteten i olika typer av limmer. Därför har det undersökts om de kan användas i limmer med mPO och tallharts för att öka kompabiliteten.

    ”Cloud point”-tester och reologistudier har utförts för att undersöka om kompabiliteten påverkades av tillsatt mineral olja. Peel tester har också utförts för att mäta limegenskaperna för formuleringarna av smältlim.

    Resultaten visar att även om formuleringarna av smältlim har relativt låg peel styrka, så ökade kompabiliteten signifikant mellan mPO och tallhartser vid användning av mineraloljor.

  • 2482.
    Öberg Hed, Kim
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Ytbehandlingsteknik.
    Advanced polymeric scaffolds for functional materials in biomedical applications2014Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Advancements in the biomedical field are driven by the design of novel materials with controlled physical and bio-interactive properties. To develop such materials, researchers rely on the use of highly efficient reactions for the assembly of advanced polymeric scaffolds that meet the demands of a functional biomaterial. In this thesis two main strategies for such materials have been explored; these include the use of off-stoichiometric thiol-ene networks and dendritic polymer scaffolds. In the first case, the highly efficient UV-induced thiol-ene coupling (TEC) reaction was used to create crosslinked polymeric networks with a predetermined and tunable excess of thiol or ene functionality. These materials rely on the use of readily available commercial monomers. By adopting standard molding techniques and simple TEC surface modifications, patterned surfaces with tunable hydrophobicity could be obtained. Moreover, these materials are shown to have great potential for rapid prototyping of microfluidic devices. In the second case, dendritic polymer scaffolds were evaluated for their ability to increase surface interactions and produce functional 3D networks. More specifically, a self-assembled dendritic monolayer approach was explored for producing highly functional dendronized surfaces with specific interactions towards pathogenic E. coli bacteria. Furthermore, a library of heterofunctional dendritic scaffolds, with a controllable and exact number of dual-purpose azide and ene functional groups, has been synthesized. These scaffolds were explored for the production of cell interactive hydrogels and primers for bone adhesive implants. Dendritic hydrogels decorated with a selection of bio-relevant moieties and with Young’s moduli in the same range as several body tissues could be produced by facile UV-induced TEC crosslinking. These gels showed low cytotoxic response and relatively rapid rates of degradation when cultured with normal human dermal fibroblast cells. When used as primers for bone adhesive patches, heterofunctional dendrimers with high azide-group content led to a significant increase in the adhesion between a UV-cured hydrophobic matrix and the wet bone surface (compared to patches without primers).

  • 2483.
    Öberg, Viktor
    KTH, Skolan för kemivetenskap (CHE).
    Macroalgae as a renewable resource: Extraction and Characterization of the Major Components in Saccharina Latissima2014Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    A fractionation strategy was developed that made it possible to extract alginate, mannitol, laminarin and cellulose under various conditions from the brown algae Saccharina Latissima (previously known as Laminara Saccharina). The algae were harvested on the west coast of Sweden in the late summer of 2013. After extraction, the alginate and mannitol samples were identified and characterized using 1H nuclear magnetic resonance (1H NMR), Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA). The yield of alginate (in its sodium salt form) was estimated to be around 18,5 %, and the yield of mannitol was around 9 %. Mild hydrolysis and 1H NMR was performed on the alginate to estimate the ratio of mannuronic and guluronic acids, i.e. the M/G-ratio. The M/G-ratio was calculated to be around 1 for neutral batches and around 1,1 for batches extracted at low or high pH. Laminarin was identified and characterized by 1H NMR, FT-IR, TGA, size exclusion chromatography (SEC) and ion chromatography (IC). Approximately 12 % laminarin was extracted. Cellulose was identified and characterized by FT-IR and IC, and the yield was approximately 2,5 to 3,5 %.

    A three-level statistical factorial screening of the parameters temperature and pH was also performed using multiple linear regression (MLR) from 6 responses: the alginate, laminarin, cellulose, mannitol and total yield as well as the M/G-ratio. However, the yields of alginate, cellulose and mannitol were not possible to assess due to divergent data points. High temperature (75 °C) and pH 2 or 12 degrades alginate, thus decreasing the yield. The screening of laminarin yield showed that a decrease in pH had a significant positive effect. The screening of total yield indicated a negative effect when temperature was increased from 40 °C to 75 °C. At 3 or 40 °C, the M/G-ratio was significantly lower at neutral pH compared to those at pH 2 or 12. At 75 °C and pH 12, a degradation decreased the M/G-ratio to 0,83.

  • 2484.
    Ödborn, Sofia
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH).
    The Science of Deodorants2019Självständigt arbete på grundnivå (yrkesexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Deodoranter är kosmetiska produkter som dagligen används av människor världen över. I denna rapport undersöks möjligheterna att implementera en deodorant i det svenska kosmetikföretaget IDUN Minerals AB:s produktsortiment. I rapporten kartläggs deodorantsortimentet på svenska apotek, samtidigt som deodoranters innehåll och paketering undersökts. Vidare granskas kontroversiella ingredienser, såsom syntetiska aluminiumföreningar.

    Syntetiska aluminiumföreningar, vilka används som antiperspiranter i deodoranter, misstänks öka risken för bröstcancer hos människor. Efter en fullständig genomgång av befintliga studier kan det dock fastställas att det inte finns någon studie som kan bevisa eller motbevisa misstankarna. Användningen av aluminiumbaserade antiperspiranter fortsätter därför att vara ett kontroversiellt ämne.

    Slutsatsen av denna rapport är att det finns en marknadsöppning för IDUN Minerals, särskilt eftersom företaget strävar mot en deodorant utan syntetiska aluminumsalter, parfym eller konserveringsmedel. Dessutom kan slutsatsen dras att en eventuell Svanen-märkning skulle göra deodoranten unik i sin produktkategori. Slutligen har det fastställts att traditionella plastförpackningar är mer tillgängliga och att de erbjuder fördelaktiga egenskaper, men att bioplaster fortfarande bör undersökas ytterligare.

  • 2485.
    Örnek, Cem
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Yt- och korrosionsvetenskap. KTH Royal Inst Technol, Sch Engn Sci Chem Biotechnol & Hlth, Div Surface & Corros Sci, Drottning Kristinas Vag 51, S-10044 Stockholm, Sweden..
    Stress Corrosion Cracking and Hydrogen Embrittlement of Type 316L Austenitic Stainless Steel Beneath MgCl2 and MgCl2: FeCl3 Droplets2019Ingår i: Corrosion, ISSN 0010-9312, E-ISSN 1938-159X, Vol. 75, nr 6, s. 657-667Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The atmospheric corrosion, as well as environmentally assisted cracking behavior of 316L austenitic stainless steel (UNS S31603) beneath MgCl2 and MgCl2: FeCl3 droplets under elastic and elastic-plastic strain exposed for 6 months at 50 degrees C and 30% relative humidity were investigated. Shallow and deep corrosion sites with filiform corrosion along with stress corrosion cracking (SCC) were formed beneath the salt-laden droplets, and the potential role of hydrogen embrittlement (HE) and crevice corrosion in damage evolution elucidated. Elastic strain (0.1%) was sufficient to cause SCC cracking as well as HE under droplets with 145 mu g/cmth> of chloride, with the severity of cracking increasing with increasing chloride deposition density (CDD). Elastic-plastic strain (0.2%) increased the propensity to both corrosion and SCC/HE, with cracks seen under droplets having CDD as low as 14.5 mu g/cm(2). Elastic-plastic strain was further seen to facilitate and accelerate pitting corrosion, leading to pits with more penetration depth. The extent of corrosion and cracking increases with increasing chloride deposition density, with ferric ions having more severe effect, in particular promoting localized corrosion with multiple nucleation sites. The work reported here was brought into a larger context of stainless steel corrosion and discussed in light of better understanding atmospheric corrosion of structural components such as nuclear waste storage containers.

  • 2486.
    Örnek, Cem
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Yt- och korrosionsvetenskap.
    Leygraf, Christopher
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Yt- och korrosionsvetenskap.
    Pan, Jinshan
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Yt- och korrosionsvetenskap.
    Passive film characterisation of duplex stainless steel using scanning Kelvin probe force microscopy in combination with electrochemical measurements2019Ingår i: npJ Materials Degradation, ISSN 2397-2106, Vol. 3, nr 1, s. 1-8Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The characterisation of passive oxide films on heterogeneous microstructures is needed to assess local degradation (corrosion, cracking) in aggressive environments. The Volta potential is a surface-sensitive parameter which can be used to assess the surface nobility and hence passive films. In this work, it is shown that the Volta potential, measured on super duplex stainless steel by scanning Kelvin probe force microscopy, correlates with the electrochemical properties of the passive film, measured by electrochemical impedance spectroscopy and potentiodynamic polarisation. Natural oxidation by ageing in ambient air as well as artificial oxidation by immersion in concentrated nitric acid improved the nobility, both reflected by increased Volta potentials and electrochemical parameters. Passivation was associated with vanishing of the inherent Volta potential difference between the ferrite and austenite, thereby reducing the galvanic coupling and hence improving the corrosion resistance of the material. Hydrogen-passive film interactions, triggered by cathodic polarisation, however, largely increased the Volta potential difference between the phases, resulting in loss of electrochemical nobility, with the ferrite being more affected than the austenite. A correlative approach of using the Volta potential in conjunction with electrochemical data has been introduced to characterise the nobility of passive films in global and local scale.

  • 2487.
    Örnek, Cem
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Yt- och korrosionsvetenskap.
    Långberg, Marie
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Yt- och korrosionsvetenskap.
    Evertsson, Jonas
    Lund Univ, Div Synchrotron Radiat Res, SE-22100 Lund, Sweden..
    Harlow, Gary
    Lund Univ, Div Synchrotron Radiat Res, SE-22100 Lund, Sweden..
    Linpe, Weronica
    Lund Univ, Div Synchrotron Radiat Res, SE-22100 Lund, Sweden..
    Rullik, Lisa
    Lund Univ, Div Synchrotron Radiat Res, SE-22100 Lund, Sweden..
    Carla, Francesco
    European Synchrotron Radiat Facil, F-38000 Grenoble, France..
    Felici, Roberto
    Area Ric Roma 2 Tor Vergata, SPINCNR, I-00133 Rome, Italy..
    Bettini, Eleonora
    Sandvik Mat Technol, SE-81181 Sandviken, Sweden..
    Kivisakk, Ulf
    Sandvik Mat Technol, SE-81181 Sandviken, Sweden..
    Lundgren, Edvin
    Lund Univ, Div Synchrotron Radiat Res, SE-22100 Lund, Sweden..
    Pan, Jinshan
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    In-situ synchrotron GIXRD study of passive film evolution on duplex stainless steel in corrosive environment2018Ingår i: Corrosion Science, ISSN 0010-938X, E-ISSN 1879-0496, Vol. 141, s. 18-21Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper presents new findings about the passive film formed on super duplex stainless steel in ambient air and corrosive environments, studied by synchrotron grazing-incidence X-ray diffraction (GIXRD). The passive film, formed in air, was seen to be a nano-crystalline mixed-oxide. Electrochemical polarisation to the passive region in aqueous 1 M NaCl at room temperature resulted in an increase of the passive film thickness, preferential dissolution of Fe, and partial loss of crystallinity. After termination of polarization to the transpassive regime, reformation of the mixed-oxides was observed, showing a thicker, semi-crystalline, and more defective nature (more vacancies) with further new oxides/hydroxides.

  • 2488.
    Örnek, Cem
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap. University of Manchester, UK.
    Walton, J.
    Hashimoto, T.
    Ladwein, T. L.
    Lyon, S. B.
    Engelberg, D. L.
    Characterization of 475 degrees C Embrittlement of Duplex Stainless Steel Microstructure via Scanning Kelvin Probe Force Microscopy and Magnetic Force Microscopy2017Ingår i: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 164, nr 6, s. C207-C217Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Scanning Kelvin probe force microscopy (SKPFM) measured local Volta potentials in microstructure of 22Cr-5Ni duplex stainless steel have been correlated to microstructure development with aging treatments at 475 degrees C. Magnetic force microscopy (MFM) was employed to differentiate crystallographic phases to provide complementary information. The absolute Volta potentials of both ferrite and austenite increased after 5 hours of aging, indicating electrochemical ennoblement of the entire microstructure. Longer aging resulted in a gradual decrease of measured Volta potentials in both phases. The microstructure showed after 255 hours aging up to 2.5-times larger potential differences than in the as-received condition, indicating impaired electrochemical nobility. In the as-received microstructure, the ferrite phase was less noble than the austenite, whereas after 5 hours aging both phases had similar, balanced Volta potentials which indicated a balanced nobility of ferrite and austenite. Longer aging treatment caused severe loss of nobility for the entiremicrostructure, with ferrite showing larger changes in Volta potential than the austenite. Spinodal microstructure decomposition and associated phase reactions of the ferrite, with elemental redistribution in the austenite, are the reason for the observed changes in microstructure nobility.

  • 2489.
    Österberg, Anna
    KTH, Skolan för kemivetenskap (CHE).
    Removal and Recycling of Phosphorus from Wastewater Using Reactive Filter Material Polonite®2012Självständigt arbete på grundnivå (yrkesexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Literature reviews and laboratory work were used to examine the phosphorus removal efficiency of the reactive filter material Polonite®. This material is produced from the calcium carbonate and silica based rock Opoka. The thesis mainly focuses on adsorption of phosphorus from wastewater with Polonite® but also discuss the possibilities of recycling the filter and the adsorbed phosphorus back into agriculture. This would be beneficial to the environment and a path to a sustainable use of phosphorus. It is important to reduce the employment of phosphorus because of the upcoming “Peak Phosphorus” and the negative impact that an excess of the nutrient has on water bodies. The two main objectives of this thesis were to evaluate and display the phosphorus sorption capacity of Polonite® in a breakthrough curve and to obtain adsorption isotherms of phosphorus on Polonite®.  To achieve these objectives experiments were performed in a pilot-plant and in a laboratory at Hammarby Sjöstadsverk. A 500 kg Polonite® filter was connected to flow of wastewater of 400 L/hr and samples were collected and analyzed regularly. The filter did not perform as well as expected, having already shown promising results in other experiments. This is most likely due to the high flow of wastewater and to a too short residence time. The phosphorus reduction was down to 60 % after approximately 30 days and a breakthrough was noticed after 53 days. When saturated, the filter contained 0.6 kg of phosphorus, the equivalent of a sorption capacity of 0.12 %. The pH in the effluent from the Polonite® filter was 10.2 at the first measurement but then dropped fast. When the filter was saturated the pH was down to 8.7. The breakthrough curve gave some indications of that the saturated Polonite® filter might be able to release adsorbed phosphorus. It was also concluded that the Polonite® filter was acting mainly by sorption and thus reduced the dissolved, but not much of the particular, phosphorus.Equilibrium experiments were conducted using solutions with different concentrations of phosphorus. 1 g of Polonite® was added to each solution which was then stirred. With the help of adsorption isotherms the maximum loading capacity was estimated at 330 mg of phosphorus per gram of Polonite®. This corresponds to a 33 % capacity and is a very high number.   

    Recommendations for future studies would be to further examine the wastewater residence time in the Polonite® filter to improve sorption capacity of phosphorus. It could also be interesting to redo the equilibrium experiments to obtain a more probable loading capacity. The possible presence of pharmaceuticals and/or heavy metals in the filter is also important to investigate, as is the economic aspect of the employment of Polonite® filters for removal of phosphorus from wastewater.

  • 2490.
    Österdahl, Kerstin
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Teknisk strömningslära.
    Rasmuson, Åke C.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Teknisk strömningslära.
    Crystallization of beta-FEF3.3H2O in mixtures of nitric and hydrofluoric acid2005Ingår i: VDI-Berichte 1901, V D I Verlag GmbH , 2005, s. 17-22Konferensbidrag (Refereegranskat)
    Abstract [en]

    The solubility of β-heh 3·3H 2U has been measured in solutions with a range of different hydrofluoric acid concentrations (2, 4 and 6 mol/kg) and constant nitric acid concentration (3 mol/kg) in order to calculate a solubility constant applicable at the present ionic strength and temperature. Crystal growth of β-FeF 3·3H 2O has been measured in 3molal hydrofluoric acid and 3molal nitric acid solutions at 50°C by performing seeded isothermal desupersaturation experiments (1 < S < 3). The supersaturation was recorded by taking out solution samples which were analysed for total iron concentration with inductively coupled plasma atomic emission spectrometry (ICP-AES). The true supersaturation driving force was estimated by a proper speciation to account for the complexation, using the software SSPEC and relevant stability constants. Parameters of a desired growth rate equation were estimated by fitting the supersaturation balance equation directly to the supersaturation measurements. The results show that growth of β-FeF 3·3H 2O follows a parabolic rate law (g= 2,0 ±0,2). The growth rate at S= 2 was found to be 4,6×10- 11 m/s (50°C). The growth order and the low value of the growth rate suggest that the rate is surface integration controlled.

  • 2491.
    Österdahl, Kerstin
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Teknisk strömningslära.
    Rasmuson, Åke C
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Teknisk strömningslära.
    Solubility of beta-FeF3 center dot 3H(2)O in mixtures of nitric and hydrofluoric acid2006Ingår i: Journal of Chemical and Engineering Data, ISSN 0021-9568, E-ISSN 1520-5134, Vol. 51, nr 1, s. 223-229Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The solubility of beta-FeF(3) center dot 3H(2)O has been measured in solutions with different concentrations of nitric acid (0 to 7 in) and hydrofluoric acid (1 to 6 m) at the temperatures of (30, 40, and 50) degrees C. The total iron concentration at equilibrium was measured with inductively coupled plasma (ICP) spectroscopy. The solubility was evaluated in terms of the stepwise complexation of iron by fluoride ions at different ionic strength and temperature. The solubility of beta-FeF3-3H(2)O increases with decreasing concentration of HF and HNO3 and increasing temperature.

  • 2492.
    Österdahl, Kerstin
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Teknisk strömningslära.
    Rasmuson, Åke Christoffer
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Teknisk strömningslära.
    Tjus, Kåre
    IVL.
    Fortkamp, Uwe
    IVL.
    Schneiker, Torsten
    Åkesson, S.
    Precipitation of Iron Fluoride Trihydrate from Mixed Acid Pickle Liquors2006Ingår i: Iron control Technologies, Proc. 3rd Intern. Symp. on Iron Control in Hydrometallurgy / [ed] Dutrizac, J.E. and Riveros, P.A, Can. Inst. Of Mining, Metallurgy and Petroleum , 2006, s. 845-861Konferensbidrag (Refereegranskat)
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