Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第14634号 / 工博第3102号 / 新制||工||1461(附属図書館) / 26986 / UT51-2009-D346 / 京都大学大学院工学研究科材料化学専攻 / (主査)教授 大塚 浩二, 教授 木村 俊作, 教授 松原 誠二郎 / 学位規則第4条第1項該当

Ein fundiertes Verständnis der Mechanismen der Gummi-Vulkanisation von Dien-Kautschuken ist noch immer eine der größten Herausforderungen in der Chemie und Technologie der Elastomere. Die Schwefelvulkanisation von Elastomerwerkstoffen ist ein seit langem verwendeter, aber dennoch sehr anspruchsvoller Prozess, mit dessen Hilfe moderne Reifen hergestellt werden. Bei dieser chemischen Reaktion spielt Zinkoxid, zusammen mit den anderen Hilfsstoffen der Schwefelvulkanisation eine entscheidende Rolle. Um die Produkteigenschaften von mit Schwefel vulkanisierten Elastomermaterialien zu verbessern, sollten die Mechanismen der chemischen Vernetzung - und insbesondere auch die Rolle von Zink enthaltenden Verbindungen bei der Vulkanisationsreaktion besser verstanden werden. Zum Beispiel könnte das Eigenschaftsprofil von Reifen durch die Ausbildung von geeigneten Netzwerken aus Schwefel oder anderen Netzknoten optimiert werden. Nitrilkautschke aus der Klasse der Spezialelastomere und die meisten nicht-Tire- Kautschuk in der ganzen Welt eingesetzt, wecken ein großes Interesse der Forschung wegen ihrer einzigartigen Vulkanisationschemie bei der Vernetzung mittels Zinkverbindungen und wegen der besonderen Eigenschaften der dadurch erzeugten Elastomerwerkstoffe. In dieser Arbeit wurde besonderes Augenmerk darauf gelegt, die Rolle von verschiedenen Zinkverbindungen in der Schwefelvulkanisation von carboxylierten Nitrilkautschuken zu verstehen. In der vorliegenden umfangreichen und eingehenden Untersuchung konnte die Ausbildung einer weiteren Polymerphase im Elastomer nachgewiesen werden. Durch dieses Ergebnis kann nun das dynamische mechanische Verhalten von solchen Polymerwerkstoffen besser verstanden werden. Teile dieser Arbeit beschäftigen sich mit der Erforschung der Rolle von Zinkchlorid bei der Vernetzung von Nitrilkautschuken. Hierzu wurde festgestellt, dass Zinkchlorid einen besonderen Einfluss auf die chemische Vernetzung des NBR aufweist, auch in Abwesenheit anderer Vernetzungs- oder Vulkanisationsadditive. Die so vernetzten Elastomere weisen ein stark hydrophiles Verhalten auf, im Gegensatz zu den allgemeinen Eigenschaften solcher Elastomerwerkstoffe. Eine detaillierte Analyse dieser neuartigen Netzwerkstruktur, gebildet durch eine Koordinationsbindung zwischen dem Zinkatom des Zinkchlorids und dem Nitrilkautschuk, wurde durchgeführt. Carboxylierter Nitrilkautschuk (XNBR) wurde ebenfalls eingesetzt, um funktionale Kautschukmischungen mit neuartigen flammhemmenden Eigenschaften zu entwickeln. Zu dieser Thematik wurden Zink enthaltende Doppelhydroxide (Layered Doube Hydroxides, LDH) als multifunktionale Füllstoffe in XNBR-Kautschuk eingesetzt. Neben dem Flammschutzverhalten zeigt LDH einzigartige Eigenschaften als verstärkenden Füllstoff und gleichzeitig als aktivierendes Additiv für die Schwefelvulkanisation. Eine weitere Zink enthaltenden Verbindung, Zinkstearat, wurde eingesetzt um mechanoadaptive elastomere Materialien durch gezieltes Einstellen des kristallinen bzw. amorphen Charakters dieser Verbindung zu entwickeln. Dies könnte einen wichtigen Beitrag zur Entwicklung zukünftiger Reifenmaterialien mit intrinsisch adaptiven Eigenschaften liefern.

L’étude cinétique a permis de déterminer le temps d’équilibre atteint lors de la fixation du benzopurpurine 4B sur chaque composé, ainsi que l’ordre de la réaction et la nature du mécanisme de diffusion. Cette adsorption est favorisée par un milieu légèrement basique, et l’augmentation de la température a un effet positif sur l’amélioration des performances maximales de la fixation. L’étude des isothermes d’adsorption de ce colorant, a été établie pour déterminer l’efficacité de cette nouvelle classe d’adsorbants. Ces dernières sont de type L, et les donnés de sorption ont été traitées selon plusieurs modèles, afin de mieux comprendre le mécanisme d'adsorption du colorant sur les différents matériaux. L’analyse des résultats de l’étude thermodynamiques a montré que l’adsorption du colorant sur les différents composés est un phénomène spontané, endothermique et favorable, régie par une adsorption physique pour les matériaux CoFe-CO3/Ec, CoFe-CO3/A et MgAl-CO32- et par une adsorption physico-chimique pour les matériaux CoFe-Ac/p, CoNiFe-Ac/p , et MgAl-500. Ces résultats ont été confirmés par les analyses DRX et IR des différents matériaux avant et après adsorption. En comparant les résultats obtenus pour l’adsorption du colorant sur les différents matériaux, le composé CoNiFe-Ac/p constitue le meilleur adsorbant avec une capacité d’adsorption d’environ 593mg/g. Par conséquent, et compte tenu de l’ensemble des résultats fournis par cette étude, l’hydrolyse forcée en milieu polyol, s’avère une méthode très efficace pour l’élaboration des hydroxydes doubles lamellaire à base de métaux de transition avec une morphologie contrôlée, de taille nanométrique présentant un faible taux d’agglomération, et par conséquent une bonne dispersion de particules et un meilleur pouvoir adsorbant. Ces caractéristiques peuvent être à l’origine de l’application de ces matériaux avec succès dans l’élimination des colorants contenant dans les effluents industriels. / New layered double hydroxides (LDHs) CoFe-Ac, CoNiFe-Ac, ZnNiFe-Ac and ZnCoFe-Acwith MII/MIII molar ratio of 3, and acetate ions in the interlayer region have been preparedusing forced hydrolysis of acetate metallic salts in a polyol medium. The structure,morphology and properties of as-prepared product were investigated by X-ray Diffraction(XRD), FT-IR Spectroscopy, elemental analysis, transmission Electron Microscopy (TEM),Scanning Electron Microscopy (SEM), thermal analysis (DTA, TGA) and V-visibleSpectroscopy: showed that these nanocomposites present the typical features of hydrotalcitelikestructure, exhibit a turbostratic character and the intercalation of acetate anions into theinterlayer domain has been successfully done, giving an interlayer spacing value of 12.70,12.47, 13.64 and 14.69 Å for CoFe-Ac, CoNiFe-Ac, ZnNiFe-Ac and ZnCoFe-Acrespectively.We can note that there is some difference between the interlayer spacing for all synthesizedphases. That can be explained by the arrangement of inserted species (anions + water) indifferent orientation in the interlayer domain.57Fe Mössbauer spectrometry allows concluding the presence of Fe3+ cations which occupyoctahedral sites and confirming the absence of Fe2+ in the as-prepared compounds.In order to check the capacity of our materials synthesized in polyol medium to exchange theacetate anions inserted in their interlamellar space, anionic exchange in aqueous medium waseffected for CoFe-Ac compound as à model of synthesized LDH. All the physicochemicalmethods of analysis (DRX, IR, ATD/ATG and elemental analysis) carried out on the materialCoFe- Ac /EC (exchanged). The comparison with a lamellar phase containing oFeCO3/Asynthesized in aqueous medium, show a layered double hydroxide compound with aturbostratic disorder, and a new interlamellar distance d003 = 7.67Å which correspondsperfectly with the presence of the carbonate anions and the water molecules in the interfeuilletfield.In the second part of this study, we are interested to examine the capacities of these kinds ofmaterials for the adsorption of an anion dye benzopurpurine-4B-. The adsorption of direct red2 by CoFe-Ac, CoNiFe-Ac LDHs has been examined in order to measure the capability ofthis new organic/inorganic nanomaterial to eliminate this highly toxic azoic class of anionicdyes from wastewater. The sorption capacities of LDHs for Benzopurpurine4B are also compared with those of other adsorbents : CoFe- Ac /Ec, CoFeCO3/A (synthesized in aqueous medium), Mg-Al-CO3/A and its calcined product at 500°C “Mg-Al-500”. The quantity of dye eliminated was found to depend on contact time, pH, initial concentration of dye and heating temperature. The thermodynamic parameters ΔG°, ΔH° and ΔS° werecalculated to predict the nature of adsorption. Results suggested that the Benzopurpurine 4B adsorption on different compounds was a spontaneous and endothermic process. Adsorption kinetic data were tested using pseudo-first order, pseudo-second order, Elovitch’sequation and intra-particle diffusion models. Kinetic studies for all cases showed that the adsorption followed a pseudo-second order reaction. Studies revealed that intra-particle diffusion played an important role in the mechanism of dye adsorption by MgAl-500. Theequilibrium data were analyzed using Langmuir, Freundlich, Tempkin, Elovitch, Dubinin-Radushkevich, Redlich-Peterson and Toth isotherm models. [...] Taking these results into account, we can conclude that prepared LDHs by forced hydrolysis in a polyol medium can be used successfully in the removal of anionic dyes from aqueous solutions.

Cryptic trends in the trace element chemistry of Fe-Ti oxide minerals have been used to elucidate the magmatic processes responsible for the formation of Fe-Ti-V deposits in the Rivière Bell Complex layered mafic-ultramafic intrusion near Matagami, Quebec, Canada. Although metamorphism at greenschist-amphibolite facies conditions has modified the primary igneous compositions of magnetite and ilmenite, their Cr and V contents appear to have been unaffected. Chemostratigraphic variations of these elements in Fe-Ti oxides therefore remain valid tracers of magmatic differentiation, even in metamorphosed settings. Injections of compositionally evolved, Fe-Ti oxide-laden magma into a more primitive ferrogabbroic host are presumably responsible for sharp decreases in the Cr and V concentrations of Fe-Ti oxides that coincide with lithostratigraphic changes from predominantly disseminated gabbros to ultramafic sequences closely interlayered with massive oxides. These injections highlight the multistage magmatic history of the layered series of the Rivière Bell Complex and its vanadium ore horizons.

Orientador: Liliane Maria Ferrareso Lona / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-24T08:44:00Z (GMT). No. of bitstreams: 1 Botan_Rodrigo_D.pdf: 8541673 bytes, checksum: fc88cab0852acd3cb9bf0b6052e4458d (MD5) Previous issue date: 2014 / Resumo: Ao longo da última década, nanocompósitos poliméricos vêm atraindo grande atenção da comunidade científica e industrial. Este fato se deve à notável melhora em inúmeras propriedades destes novos materiais, proporcionado pelo uso de uma pequena quantidade de nanoreforços. Entre as propriedades melhoradas é possível citar com maior destaque as propriedades mecânicas e térmicas. Buscando alcançar melhores propriedades para o poli(estireno) (PS), o objetivo deste trabalho foi o de sintetizar nanocompósitos in situ de PS com hidróxidos duplos lamelares (HDLs) e hidroxissal lamelar (HSL). Para isto, foram sintetizados dois tipos de HDLs e um tipo de HSL, os HDLs foram modificados com ácido láurico, ácido palmítico e uma mistura destes dois ácidos e o HSL foi modificado com ácido palmítico. Os HDLs e HSL sintetizados foram caracterizados por difração de raios x (DRX), microscopia eletrônica de varredura (MEV), espectroscopia no infravermelho por transformada de Fourier (FTIR) e análise termogravimétrica (TGA). Os nanocompósitos foram sintetizados in situ por polimerização em massa e foram caracterizados por DRX, FTIR, TGA, calorimetria exploratória diferencial (DSC), microscopia eletrônica de transmissão (MET), ensaio de flexão, análise da fratura e teste de flamabilidade. Os resultados obtidos demostram que estes novos nanocompósitos foram sintetizados, apresentando, de uma forma geral, uma boa interação polímero ¿ reforço com morfologia variando da intercalada/esfoliada a esfoliada. A estabilidade térmica e, principalmente, a propriedade mecânica apresentaram ganhos significativos em todos os materiais estudados quando comparadas com o polímero puro, fato que possibilita uma vasta gama de aplicação destes novos materiais em diversos campos da pesquisa e engenharia / Abstract: Over the past decade, polymer nanocomposites have attracted interest, both in the industry and in the academia. They often exhibit remarkable improvement in their properties when compared with neat polymer or conventional micro and macrocomposites using low levels of reinforcements, usually maximum 5% by weight. The improvements mainly include mechanical, thermal, and physical properties. Seeking to achieve better properties for poly(styrene) (PS), the purpose of this work was to in situ synthesize PS with layered double hydroxides (LDHs) and layered hydroxide salt (LHS) nanocomposites. Thus, two types of LDH and a type of LHS was synthesized, the LDHs were modified with lauric acid, palmitic acid and a mixture of both, and LHS was modified with palmitic acid. The LDHs and LHS synthesized were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). The nanocomposites were synthesized by in situ bulk polymerization and were characterized by XRD, FTIR, TGA, differential scanning calorimetry (DSC), transmission electron microscopy (TEM), bend test, fracture analysis and flammability test. The obtained results show that indeed these new nanocomposites were synthesized. These nanocomposites have in general good interaction polymer ¿ reinforcement with morphology varying from intercalated/exfoliated to exfoliated. The thermal stability and mechanical property mainly, showed significant improvement in all materials studied, when compared with the neat polymer, a fact that enables a wide range of application of these new materials in various fields of research and engineering / Doutorado / Engenharia Química / Doutor em Engenharia Química

In this work we study vertical, acoustic propagation in a non-homogeneous media for a spatially-compact, time-harmonic source. An analytical, 2-layer model is developed representing the acoustic pressure disturbance propagating in the atmosphere. The validity of the model spans the distance from the Earth's surface to 30,000 meters. This includes the troposphere (adiabatic), ozone layer (isothermal), and part of the stratosphere (isothermal). The results of the model derivation in the adiabatic region yield pressure solutions as Bessel functions of the First (J) and Second (Y) Kind of order $-\frac{7}{2}$ with an argument of $2 \Omega \tau$ (where $\Omega$ represents a dimensionless frequency and $\tau$ is a dimensionless vertical height in z (vertical coordinate)). For an added second layer (isothermal region), the pressure solution is a decaying sinusoidal, exponential function above the first layer. In particular, the vertical, acoustic propagation is examined for various configurations. These are divided into 2 basic classes. The first class consists of examining the pressure response function when the source is located on boundary interfaces, while the second class consists of situations where the source is arbitrarily located within a finite layer. In all instances, a time-harmonic, compact source is implicitly understood. However, each class requires a different method of solution. The first class conforms to a general boundary value problem, while the second requires the use of Green's functions method. In investigating problems of the first class, 3 different scenarios are examined. In the first case, we apply our model to a semi-infinite medium with a time-harmonic source ($e^{-i \omega t}$) located on the ground. In the next 2 cases, a semi-infinite medium is overlain on the previous medium at a height of z=13,000 meters. Thus, there exist two boundaries: the ground and the layer interface between the 2 media. Sources placed at these interfaces represent the 2nd and 3rd scenarios, respectively. The solutions to all 3 cases are of the form $A \frac{J_{-\frac{7}{2}}(2 \Omega \tau)}{{\tau}^{-\frac{7}{2}}} + B \frac{Y_{-\frac{7}{2}}(2 \Omega \tau)}{{\tau}^{-\frac{7}{2}}}$, where \textit{A} and \textit{B} are constants determined by the boundary conditions. For the 2nd class, we examine the application to a time-harmonic, compact source placed arbitrarily within the 1st layer. The method of Green's functions is used to obtain a particular solution for the model equations. This result is compared with a Fast Field Program (FFP) which was developed to test these solutions. The results show that the response given by the Green's function compares favorably with that of the FFP. Keywords: Linear Acoustics, Inhomogeneous Medium, Layered Atmosphere, Boundary Value Problem, Green's Function Method

The effect of incorporation two clays; layered double hydroxides (LDH) and montmorillonite layered silicates (MLS) in linear low density polyethylene (PE) matrix was investigated. MLS and LDH were added of 5, 15, 30 and 60 weight percent in the PE and compounded using a Brabender. Ground pellets were subsequently compression molded. Dispersion of the clays was analyzed using optical microscopy, SEM and XRD. Both the layered clays were immiscible with the PE matrix and agglomerates formed with increased clay concentration. The thermal properties were studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Both clays served as nucleation enhancers increasing recrystallization temperatures in the composites. Flame retarding properties were determined by using the flammability HVUL-94 system. LDH indicated better flame retarding properties than MLS for PE. The char structure was analyzed by environmental scanning electron microscopy. Mechanical properties were studied by tensile testing and Vickers microhardness testing apparatus.

No description available.

Content: The wastewater of leather industry contains pollution loads which includes anionic contaminants such as chloride, sulfate and phosphate. Different treatment technologies for tannery wastewater have been investigated. Adsorption is a promising technique due to its greater selectivity, simple operation, faster regeneration kinetics and high uptake capacity even at trace levels. In the present study, Mg-Al and Zn-Al Layered Double Hydroxides were synthesized by the co-precipitation method at variable pH through a semi-batch system. The prepared material was characterized by XRD, BET surface area determination, TGDTA and FTIR. The chloride, sulfate and phosphate adsorption properties onto Mg-Al and Zn-Al Layered Double Hydroxides from aqueous solutions were evaluated. The adsorption experiments of chloride, sulfate and phosphate were investigated through batch studies at initial concentrations of 100 mg/L of these anions as NaCl, K2SO4 and KH2PO4, respectively. The experiments were carried out separately for each anionic specie by mixing 10 ml of solution with 1 g/L of adsorbent for 5 h. Mixing was performed on a thermostatic shaker at 200 rpm and at room temperature (25 °C). The effect of co-existing anions on the adsorption capacity were also analyzed. After ion adsorption, chloride, sulfate and phosphate concentrations were measured by ion chromatography. The results showed a removal ratio for Mg-Al Layered Double Hydroxide of 24% and 51% for sulfate and phosphate, respectively, while chloride was not removed from the solution. For the adsorbent Zn-Al Layered Double Hydroxide, the removal ratio of sulfate, phosphate and chloride reached 12.76 %, 69.07 % and 6.34%, respectively. Take-Away: Both adsorbents exhibited a satisfactory removal ratio of phosphate. Therefore, Mg–Al and Zn–Al LDHs can be used as effective adsorbents for phosphate removal from industrial wastewaters.

No description available.