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Dissertations / Theses on the topic 'Epoxid'

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Published: 4 June 2021
Last updated: 3 February 2022

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1

Weiss, Felix. "Lyotrop flüssigkristalline Epoxid-Amin-Additionspolymere und Elastomere." [S.l.] : [s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=970132581.

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2

Czogalla, Katrin [Verfasser]. "Funktionelle Untersuchung der Vitamin K 2,3-Epoxid-Reduktase / Katrin Czogalla." Bonn : Universitäts- und Landesbibliothek Bonn, 2014. http://d-nb.info/1047622742/34.

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3

Hünerberg, Mirja Maaret. "Erstcharakterisierung des Vitamin K-Epoxid-Reduktase Komplex 1-like 1 Proteins." kostenfrei, 2009. http://www.opus-bayern.de/uni-wuerzburg/volltexte/2009/3616/.

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4

Wehlack, Carsten. "Chemische Struktur und ihre Entstehung in dünnen Epoxid- und Polyurethanschichten auf Metallen." Aachen Shaker, 2008. http://d-nb.info/99247891X/04.

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5

Gaukler, Jan Christoph [Verfasser]. "Lagerungsstabilität, Vernetzung und Eigenschaften von Epoxid-Dicyandiamid-Systemen für Nanoverbundwerkstoffe / Jan Christoph Gaukler." Aachen : Shaker, 2013. http://d-nb.info/1051575400/34.

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6

Bockenheimer, Clemens [Verfasser]. "Epoxid und Aluminium im Klebverbund nach mechanischer Vorbehandlung und nach Alterung / Clemens Bockenheimer." Aachen : Shaker, 2006. http://d-nb.info/1186589027/34.

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7

Ritter, Andreas [Verfasser]. "In vitro Untersuchung eines experimentellen Amin-Epoxid-Sealers im Vergleich zu zwei Standardprodukten / Andreas Ritter." Düsseldorf : Universitäts- und Landesbibliothek der Heinrich-Heine-Universität Düsseldorf, 2014. http://d-nb.info/1051734584/34.

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8

Scheiba, Joana Melanie [Verfasser]. "Die Wirkung von Benzo[a]pyren-diol-epoxid auf Zellen des vaskulären Systems / Joana Melanie Scheiba." Mainz : Universitätsbibliothek Mainz, 2019. http://d-nb.info/1201298091/34.

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9

Gaukler, Jan Christoph [Verfasser], and Wulff [Akademischer Betreuer] Possart. "Lagerungsstabilität, Netzwerkbildung und Eigenschaften von Epoxid-Dicyandiamid-Systemen für Nanoverbundwerkstoffe / Jan Christoph Gaukler. Betreuer: Wulff Possart." Saarbrücken : Saarländische Universitäts- und Landesbibliothek, 2012. http://d-nb.info/1052293107/34.

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10

Huber, Michael Peter [Verfasser], and Rolf [Akademischer Betreuer] Mülhaupt. "Dispersion und Ausrichtung von Korund-Nanoplättchen in bioinspirierten Epoxid- und Vinylester-Harzsystemen und deren Anwendung als chemische Verbundanker." Freiburg : Universität, 2017. http://d-nb.info/1140735578/34.

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11

Zimmermann, Anna Sophie [Verfasser], and Christian B. W. [Akademischer Betreuer] Stark. "Epoxidase- und Epoxid-Hydrolase-Enzyme in der Biosynthese des Polyetherantibiotikums Monensin / Anna Sophie Zimmermann. Betreuer: Christian B. W. Stark." Hamburg : Staats- und Universitätsbibliothek Hamburg, 2015. http://d-nb.info/1065805381/34.

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12

Steiniger, Phillip [Verfasser], and Stephan [Akademischer Betreuer] Schulz. "Neue bimetallische Komplexe für die Ringöffnungspolymerisation (ROP) zyklischer Ester sowie der CO2/Epoxid-Copolymerisation / Phillip Steiniger ; Betreuer: Stephan Schulz." Duisburg, 2018. http://d-nb.info/1166559440/34.

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13

Adamow, Katharina [Verfasser], Andreas [Akademischer Betreuer] Hartwig, and Franz-Peter [Akademischer Betreuer] Montforts. "Einfluss von Wasser auf die Kohlenstofffaser/Epoxid-Polymermatrix Wechselwirkung / Katharina Adamow. Gutachter: Andreas Hartwig ; Franz-Peter Montforts. Betreuer: Andreas Hartwig." Bremen : Staats- und Universitätsbibliothek Bremen, 2014. http://d-nb.info/1072157187/34.

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14

Blum, Maximilian. "Analytik von CYP-Eicosanoiden und ihre Rolle bei ischämischem Organversagen." Doctoral thesis, Humboldt-Universität zu Berlin, 2020. http://dx.doi.org/10.18452/21298.

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Cytochrom P450 (CYP) Enzyme tragen zur Bioaktivierung von langkettigen mehrfach ungesättigten Fettsäuren bei. Die gebildeten Monoepoxy- und Monohydroxy-Metaboliten werden zusammenfassend als CYP-Eicosanoide bezeichnet und fungieren als Mediatoren bei der Regulation des Gefäßtonus, der Herz- und Nierenfunktion, sowie einer Vielzahl weiterer physiologischer Prozesse, wobei die biologische Aktivität oftmals abhängig von der Positions- und Stereoisomerie der Eicosanoide ist. Prominente Vertreter der CYP-Eicosanoid-Familie sind die aus der Arachidonsäure gebildeten Epoxyeicosatriensäuren (EETs) und 20-Hydroxyeicosatetraensäure (20-HETE). EETs und 20-HETE haben zum Teil gegensätzliche biologische Aktivitäten, die zur Aktivierung bzw. Inhibition antiinflammatorischer und weiterer Zell- und Organ-protektiver Signalwege beitragen. Ziel der vorliegenden Arbeit war es, durch Analyse endogener Metabolitenprofile zum besseren Verständnis der Rolle von CYP-Eicosanoiden bei der Entstehung von Ischämie/Reperfusions (I/R)-bedingten Organschäden beizutragen. Als Hauptergebnisse ergaben sich (i) die Entdeckung und Charakterisierung einer protektiven Rolle von EETs in Tiermodellen der Initiationsphase des akuten Nierenversagens, sowie des therapeutischen Potentials stabiler EET-Analoga; (ii) die Identifizierung von 8,9-EET und 20-HETE als mögliche prädiktive Biomarker für das post-operative Auftreten von akutem Nierenversagen nach offener Herzoperation; und (iii) die Entwicklung und Validierung eines analytischen Verfahrens der chiralen Lipidomik (chiral-LC-ESI-MS/MS), das eine Analyse endogener Enantiomere sowohl von Monoepoxy- als auch Monohydroxy-Eicosanoiden in komplexen biologischen Proben erstmalig ermöglichte und dafür genutzt werden konnte, die stereospezifische Regulation der EETs durch Epoxid-Hydrolasen in vitro wie auch in vivo zu beschreiben.
Cytochrome P450 (CYP) enzymes contribute to the bioactivation of long-chain polyunsaturated fatty acids. The monoepoxy- and monohydroxy-metabolites generated by CYP enzymes are collectively termed CYP-eicosanoids. CYP-eicosanoids act as mediators in the regulation of vascular tone, heart- and kidney function and several further physiological processes, mostly in a regio- and stereospecific manner. Arachidonic acid-derived epoxyeicosatrienoic acids (EETs) and 20-hydroxyeicosatetraenoic acid (20-HETE) are prominent members of the CYP-eicosanoid family. EETs and 20-HETE show partially opposing biological activities that contribute to the activation or inhibition of anti-inflammatory and other cell- and organ-protective mechanisms. The aim of the present work was to study the role of CYP-eicosanoids in ischemia/reperfusion (I/R) related organ damage by analyses of endogenous metabolite profiles. The main results were (i) discovery and characterization of the EETs protective role in animal models of the initiation phase of acute kidney injury (AKI) and the therapeutic potential of stable EET-analogs, (ii) identification of 8,9-EET and 20-HETE as potential predictive biomarkers for AKI in patients who underwent open heart surgery, (iii) the development and validation of a novel analytical method for chiral lipidomics (chiral LC-ESI-MS/MS) that allows to study endogenous enantiomers of monohydroxy- and monoepoxy-eicosanoids in complex matrices of biological and clinical samples. Furthermore, the approach was applied to describe the stereospecific regulation of EETs by epoxide hydrolases in vitro and in vivo.
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15

Jaenecke, Frank [Verfasser], Milton T. [Akademischer Betreuer] Stubbs, Klaus [Akademischer Betreuer] Gawrisch, and Ralf Bernd [Akademischer Betreuer] Klösgen. "Etablierung der in vitro Renaturierung von Vitamin K Epoxid Reduktase / Frank Jaenecke. Betreuer: Milton T. Stubbs ; Klaus Gawrisch ; Ralf Bernd Klösgen." Halle, Saale : Universitäts- und Landesbibliothek Sachsen-Anhalt, 2012. http://d-nb.info/1025352963/34.

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16

Heintz, Sonja Carolin [Verfasser], and Wolfgang [Akademischer Betreuer] Bauhofer. "Über die Auswirkung von Scherbelastung auf das rheologische und elektrische Verhalten von Kohlenstoffnanoröhrchen, Epoxid Suspensionen / Sonja Carolin Heintz. Betreuer: Wolfgang Bauhofer." Hamburg-Harburg : Universitätsbibliothek der Technischen Universität Hamburg-Harburg, 2012. http://d-nb.info/1048543056/34.

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17

Capar, Özgür [Verfasser], Laura [Gutachter] Hartmann, and Helmut [Gutachter] Ritter. "Von Epoxid-Bausteinen zu funktionalen Polymeren: Synthese von Cyclocarbonat-Monomeren und Polyhydroxyurethanen sowie Polymer-Proteinkonjugaten / Özgür Capar ; Gutachter: Laura Hartmann, Helmut Ritter." Düsseldorf : Universitäts- und Landesbibliothek der Heinrich-Heine-Universität Düsseldorf, 2021. http://d-nb.info/1239413599/34.

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18

Drobilič, Ivo. "Návrh efektivnější technologie výroby dveří pro rozváděč UniGear." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2018. http://www.nusl.cz/ntk/nusl-378853.

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The diploma thesis deals with the analysis of suitable technologies to produce the switchgear door of product UniGear with a design of more efficient production technology. Thesis is divided into four main chapters, in which the first part describes the doors of individual switchgear compartments, design of door materials, technology for achieving desired shape of a base plate, possibilities of sheet metal forming and other technologies not linked with sheet metal processing. The second part of the thesis deals with study of the whole current production process of doors in ABB s.r.o. from sheet metal processing till powder coating. The thesis also contains proposal of innovated production technologies with a selection and evaluation of the final variant with technical and economic evaluation of current and proposed solutions.
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19

Šácha, Dominik. "Ověřování možnosti využití recyklovaného autoskla jako náhrady křemičitého písku v polymerbetonových průmyslových podlahách." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2019. http://www.nusl.cz/ntk/nusl-392365.

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This diploma thesis has goal to find out possibility of substitution sand in polymer crete flooring system by recycling car glass. Polymer crete is made from sand and epoxy resin. Companies use it in industrial flooring system. Polymercrete industrial flooring systems are new types of floor surface. It aims to customers with high requirements to floor properties and short time of realisation. Polymercrete floors are 4-6 mm thin. They are waterproof, they has higher compressive strength then 60 MPa and tensile strength is more than 20 MPa. Polymercretes does not make dust. This study includes also suggestion of recycling process to make glass sand from car glass windows. The diploma thesis was prepared in cooperation with company Atemit, s.r.o.
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20

Pereira, Denise de Souza. "Propriedades de materiais nanoestruturados do sistema epoxídico DGEBA/TETA modificado com um éster de silsesquioxano /." Ilha Solteira : [s.n.], 2006. http://hdl.handle.net/11449/92011.

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Orientador: Newton Luiz Dias Filho
Banca: Devaney Ribeiro do Carmo
Banca: Adley Forti Rubira
Resumo: Resinas epoxídicas são uma das mais importantes classes de polímeros termorrígidos usados para aplicações estruturais e como adesivos. Entretanto, os problemas em aplicações de resinas epoxídicas na engenharia incluem a baixa resistência à propagação de trincas devido a sua fragilidade. Para superar esta fragilidade, muitas vezes, dentre os aditivos em formulações multicomponentes de resinas epoxídicas, é utilizado um componente para aumentar a resistência, tais como enchimentos, oligosilsesquioxanos poliédricos (POSS), dendrímeros, etc. POSS (RSiO1,5)n podem ser incorporados em polímeros termorrígidos para melhoramento de suas propriedades térmicas e mecânicas. O uso de POSS nanoestruturados na preparação de polímeros orgânicos pode levar a materiais nanocompósitos. Neste trabalho, um POSS contendo oito grupos ésteres por molécula (MDPS) foi incorporado a uma matriz de polímeros termorrígidos epoxídicos DGEBA/TETA para melhorar suas propriedades mecânicas. Através de ensaios mecânicos foi observado um aumento de aproximadamente 90% (formulação 0,67/5) na resistência a fratura (K1C) com um leve decréscimo no modulo de Young (E). Os valores de Tg, verificados por DMTA mostraram pequeno decréscimo nas composições modificadas. As análises termogravimétricas mostraram que a adição de silsesquioxano não influenciou na estabilidade térmica do material. A cinética de cura foi analisada pelo método de Ozawa. As possíveis e prováveis causas deste significante reforço podem ser atribuídas à formação de uma segunda fase, à miscibilidade residual dos grupos ésteres com a matriz epoxídicas e às interações interfaciais entre a matriz epoxídicas e os cubos de silsesquioxanos devido as suas dimensões nanométricas.
Abstract: Epoxy resins are one of the most important classes of thermosetting polymers used for structural and adhesive applications. However, the current problems in engineering applications of epoxy thermosets include the poor resistance to the crack propagation because they are brittle. To overcome brittleness, among other additives of the multicomponented formulation of the epoxy resin, a toughening agent is often used, such as fillers, polyhedral oligosilsesquioxanes (POSS), dendrimers, etc. POSS, (RSiO1.5)n, can be incorporated into thermosetting polymers to improve their thermal and mechanical properties. The use of such nanosized POSS in the preparation of an organic polymer can lead to a nanocomposite materials. In this work, a POSS containing eight ester groups per molecule (MDPS) was incorporated to an epoxy matrix of DGEBA/TETA thermosetting polymers to improve their mechanical properties. Through the mechanical tests an increase of about 90% (formulation 0,67/5) was observed in the fracture toughness (K1C) with a little decreasing in the module of Young (E). The Tg values verified by DMTA showed smaller values for the compositions with the modifier. The thermogravimetric analyses showed that the addition of the silsesquioxane ester did not influence on the thermal stability of the material. The cure kinetics was analyzed by Ozawa's method. The probable and possible causes of this significant reinforcement can be attributed to the formation of a second inorganic phase, residual miscibility of the ester groups with the epoxy matrix and to interfacial interactions between the epoxy matrix and silsesquioxanes cubes due their nanometric dimensions.
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21

Chen, Lu Shi. "Triagem de alto desempenho para detecção de atividade de epoxido-hidrolases e monooxigenases utilizando celulas integras." [s.n.], 2006. http://repositorio.unicamp.br/jspui/handle/REPOSIP/249351.

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Orientador: Anita Jocelyne Marsaioli
Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Quimica
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Doutorado
Quimica Organica
Doutor em Ciências
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22

Dinh, Nghia Trong, and Olfa Kanoun. "Temperature-Compensated Force/Pressure Sensor Based on Multi-Walled Carbon Nanotube Epoxy Composites." Universitätsbibliothek Chemnitz, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-175255.

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In this study, we propose a multi-walled carbon nanotube epoxy composite sensor for force and pressure sensing in the range of 50 N–2 kN. A manufacturing procedure, including material preparation and deposition techniques, is proposed. The electrode dimensions and the layer thickness were optimized by the finite element method. Temperature compensation is realized by four nanocomposites elements, where only two elements are exposed to the measurand. In order to investigate the influence of the filler contents, samples with different compositions were prepared and investigated. Additionally, the specimens are characterized by cyclical and stepped force/pressure loads or at defined temperatures. The results show that the choice of the filler content should meet a compromise between sensitivity, temperature influence and noise behavior. At constant temperature, a force of at least 50N can be resolved. The measurement error due to the temperature influence is 150N in a temperature range of –20°C–50°C.
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23

Lee, W. H. "Elastomer modified epoxies : Toughening of tetraglycidyl diamino diphenyl methane epoxy." Thesis, Brunel University, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234017.

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24

Pereira, Denise de Souza [UNESP]. "Propriedades de materiais nanoestruturados do sistema epoxídico DGEBA/TETA modificado com um éster de silsesquioxano." Universidade Estadual Paulista (UNESP), 2006. http://hdl.handle.net/11449/92011.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Resinas epoxídicas são uma das mais importantes classes de polímeros termorrígidos usados para aplicações estruturais e como adesivos. Entretanto, os problemas em aplicações de resinas epoxídicas na engenharia incluem a baixa resistência à propagação de trincas devido a sua fragilidade. Para superar esta fragilidade, muitas vezes, dentre os aditivos em formulações multicomponentes de resinas epoxídicas, é utilizado um componente para aumentar a resistência, tais como enchimentos, oligosilsesquioxanos poliédricos (POSS), dendrímeros, etc. POSS (RSiO1,5)n podem ser incorporados em polímeros termorrígidos para melhoramento de suas propriedades térmicas e mecânicas. O uso de POSS nanoestruturados na preparação de polímeros orgânicos pode levar a materiais nanocompósitos. Neste trabalho, um POSS contendo oito grupos ésteres por molécula (MDPS) foi incorporado a uma matriz de polímeros termorrígidos epoxídicos DGEBA/TETA para melhorar suas propriedades mecânicas. Através de ensaios mecânicos foi observado um aumento de aproximadamente 90% (formulação 0,67/5) na resistência a fratura (K1C) com um leve decréscimo no modulo de Young (E). Os valores de Tg, verificados por DMTA mostraram pequeno decréscimo nas composições modificadas. As análises termogravimétricas mostraram que a adição de silsesquioxano não influenciou na estabilidade térmica do material. A cinética de cura foi analisada pelo método de Ozawa. As possíveis e prováveis causas deste significante reforço podem ser atribuídas à formação de uma segunda fase, à miscibilidade residual dos grupos ésteres com a matriz epoxídicas e às interações interfaciais entre a matriz epoxídicas e os cubos de silsesquioxanos devido as suas dimensões nanométricas.
Epoxy resins are one of the most important classes of thermosetting polymers used for structural and adhesive applications. However, the current problems in engineering applications of epoxy thermosets include the poor resistance to the crack propagation because they are brittle. To overcome brittleness, among other additives of the multicomponented formulation of the epoxy resin, a toughening agent is often used, such as fillers, polyhedral oligosilsesquioxanes (POSS), dendrimers, etc. POSS, (RSiO1.5)n, can be incorporated into thermosetting polymers to improve their thermal and mechanical properties. The use of such nanosized POSS in the preparation of an organic polymer can lead to a nanocomposite materials. In this work, a POSS containing eight ester groups per molecule (MDPS) was incorporated to an epoxy matrix of DGEBA/TETA thermosetting polymers to improve their mechanical properties. Through the mechanical tests an increase of about 90% (formulation 0,67/5) was observed in the fracture toughness (K1C) with a little decreasing in the module of Young (E). The Tg values verified by DMTA showed smaller values for the compositions with the modifier. The thermogravimetric analyses showed that the addition of the silsesquioxane ester did not influence on the thermal stability of the material. The cure kinetics was analyzed by Ozawa's method. The probable and possible causes of this significant reinforcement can be attributed to the formation of a second inorganic phase, residual miscibility of the ester groups with the epoxy matrix and to interfacial interactions between the epoxy matrix and silsesquioxanes cubes due their nanometric dimensions.
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25

Polywka, R. "Epoxide chemistry." Thesis, University of Oxford, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.258024.

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26

Bláha, Tomáš. "Zesilování ocelových nosníků výztuží na bázi FRP." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2013. http://www.nusl.cz/ntk/nusl-226072.

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A study of an influence of strengthening steel beams using reinforcement based on FRP on a moment bearing resistance and bending stiffness. Evaluation of the theoretical calculation methods based on the performed experimental verification. Description of the production of carbon fibres and composite materials on the basis of carbon fibres.
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27

Dillman, Brian F. "The kinetics and physical properties of epoxides, acrylates, and hybrid epoxy-acrylate photopolymerization systems." Diss., University of Iowa, 2013. https://ir.uiowa.edu/etd/2476.

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Photopolymerization, which uses light rather than heat to initiate polymerization, is a facile technique used to fabricate adhesives, protective coatings, thin films, photo-resists, dental restoratives, and other materials. Epoxide monomers, which are polymerized via cationic photoinitiation, have received less attention in fundamental research in comparison to free radical polymerized acrylate monomers. The characterization of propagation mechanisms, network structures, and physical properties is yet lacking. This project focused on the reactivity and physical properties of 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate (EEC), and the kinetic and physical effects of chain transfer agents (CTAs) in EEC based formulations were characterized. This characterization was carried out using real-time Raman spectroscopy, real-time infrared spectroscopy, dynamic mechanical analysis, simple gel fraction measurements, and atomic force microscopy. The effects of water, organic alcohols, processing conditions (e.g., UV light intensity, humidity, post-illumination curing temperature), and photoinitiation systems were investigated. In general, increasing the concentration of CTAs in a crosslinking epoxide resin increases the rate of polymerization and the overall epoxide conversion level. High CTA levels also correspond to lower glass transition temperatures (Tg) and lower crosslink densities. A post-illumination annealing was critical in obtaining stable physical properties for high Tg epoxide materials. In addition, humidity (water being the most universal contaminant type of CTA) was found to impact the surface properties of an epoxide polymer negatively by reducing the surface hardness. Hybrid acrylate-epoxide systems are much more complex and unpredictable in curing behavior. The use of hydroxy acrylates in hybrid systems allows for grafting between the epoxide and the acrylate domains, via the AM mechanism. Another intricacy of hybrid systems is the initiation system. In order to maximize the conversion of both the epoxide and the acrylate moieties, the free-radical photoinitiator must not hinder the polymerization of the epoxide monomer. Some very efficient free-radical photoinitiators limit the epoxide polymerization by absorbing the majority of the deep-UV incident photons. Finally, a renewable acrylate oligomer was synthesized to provide a green alternative to petroleum-based oligomers currently used. The oligomer was freely miscible and readily photopolymerized with a wide range of commercial monomers. The Tg relationship between the commercial monomers and the parent resin followed the Fox equation. The results of this research provide strategies for controlling epoxide kinetics and physical properties in neat and hybrid systems. This information is useful for tailoring resin formulations to specific end-use applications, especially in films, coatings, and adhesives. Hybrid epoxide-acrylate photopolymerization affords the unique opportunity to structure polymer networks in time and to engineer advanced material properties. These hybrid systems are based on formulations that contain both an epoxide moiety, which undergoes cationic ring-opening photopolymerization, and an acrylate moiety, which undergoes free-radical photopolymerization. Through the combination of these two independent reactive systems, hybrid polymers exhibit lower sensitivity to oxygen and moisture and offer advantages such as increased cure speed and improved film-forming properties. The ability to design the polymer network architecture and to tune mechanical properties can be realized through control of the cationic active center propagation reaction relative to the cationic chain transfer reaction. Specifically, grafted polymer networks can be developed through the covalent bonding of the epoxide chains to the acrylate chains via hydroxyl substituents. This work demonstrates the formation of these grafted polymer networks and overviews the physical properties obtained through control of hydroxyl content and hybrid formulation composition.
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28

Coniku, Anisa. "Production Of Epoxide Functionalized Boehmite Nanoparticles And Their Use In Epoxide Nanocomposites." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12614037/index.pdf.

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In the present study the effects of addition of organically functionalized boehmite nano-particles on the mechanical properties of epoxy polymers were analyzed. Nanosize platelets of boehmite powders were produced via a hydrothermal process from the raw material aluminum trihydroxide Al(OH)3 provided by a a chemical supplier, but which in future studies can be replaced by local resources of aluminum trihydroxide available in Seydisehir, Turkey. The ground aluminum trihydroxide particles were submitted to a two-step preliminary ageing procedure in different pH media. Particles were then converted to boehmite nanoparticles via hydrothermal ageing at high pressure and temperature. The product&lsquo
s chemical identity, size, structure and morphology were characterized with XRD, FT-IR, SEM and PSA analyses. By controlling the pH and the ageing time as parameters, hexagonal shaped nanoplatelets were obtained with dimensions ranging from 100 to 500 nm. Aiming at using these nanoparticles into surface coating polymers, the most favorable shape is the plate-like morphology, leading to adopting the last hydrothermal condition in the rest of the study. v The boehmite crystal surfaces are furnished with hydroxyls which can potentially be reacted with epoxy monomers of bisphenol A diglycidyl ether with the help of tin (II) chloride as catalyst through ring-opening reactions. The FT-IR and quantitative analyses indicated that this surface functionalization is possible under a temperature 80 oC and a weight ratio of 5:1 epoxy monomer to boehmite powder These novel inorganic/organic hybrid materials were then mixed with epoxy/hardener resin mixture to obtain nanocomposites. The properties of the composites were characterized accordingly with tensile, impact, micro hardness, micro-scratch tests, DMA analysis and observed with SEM analysis. A deterioration of the tensile strength from the neat polymer was observed, with a distinct trend between the functionalized and non-functionalized boehmite-epoxy polymers. The functionalized polymers showed a less deteriorative character. The tensile modulus instead showed a little improvement of (4%) in 5wt% loaded polymers. DMA analysis results revealed an improved glass transition temperature in the nanocomposites as well as in storage and loss modulus. As aimed in this work, the functionalized boehmite-epoxy polymers displayed a clear improvement in comparison to both non-functionalized and neat polymers in surface coating properties in hardness and scratch resistance.
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29

Gurell, Ann. "Biochemical Studies on a Plant Epoxide Hydrolase : Discovery of a Proton Entry and Exit Pathway and the Use of In vitro Evolution to Shift Enantioselectivity." Doctoral thesis, Uppsala universitet, Institutionen för biokemi och organisk kemi, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-122424.

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The work leading to this thesis has provided additional information and novel knowledge concerning structure-function relationship in the potato epoxide hydrolase. Epoxide hydrolases are enzymes catalyzing the hydrolysis of epoxides to yield the corresponding vicinal diols. The reaction mechanism proceeds via a nucleophilic attack resulting in a covalent alkylenzyme intermediate, which in turn is attacked by a base-activated water molecule, followed by product release. Epoxides and diols are precursors in the production of chiral compounds and the use of epoxide hydrolases as biocatalysts is growing. The promising biocatalyst StEH1, a plant epoxide hydrolase from potato, has been investigated in this thesis. In paper I the active site residue Glu35, was established to be important for the formation of the alkylenzyme intermediate, activating the nucleophile for attack by facilitated proton release through a hydrogen bond network. Glu35 is also important during the hydrolytic half reaction by optimally orienting the hydrolytic water molecule, aiding in the important dual function of the histidine base. Glu35 makes it possible for the histidine to work as both an acid and a base. In paper II a putative proton wire composed of five water molecules lining a protein tunnel was proposed to facilitate effective proton transfer from the exterior to the active site, aiding in protonation of the alkylenzyme intermediate. The protein tunnel is also proposed to stabilize plant epoxide hydrolases via hydrogen bonds between water molecules and protein. Enzyme variants with modified enantiospecificity for the substrate (2,3-epoxypropyl)benzene have been constructed by in vitro evolution using the CASTing approach. Residues lining the active site pocket were targeted for mutagenesis. From the second generation libraries a quadruple enzyme variant, W106L/L109Y/V141K/I155V, displayed a radical shift in enantioselectivity. The wild-type enzyme favored the S-enantiomer with a ratio of 2:1, whereas the quadruple variant showed a 15:1 preference for the R-enantiomer.
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30

Relosi, Natanael. "Obtenção e caracterização de tintas em pó base epóxi/poliéster com incorporação de argilominerais : montmorilonita (MMT) e mica muscovita." reponame:Repositório Institucional da UCS, 2016. https://repositorio.ucs.br/handle/11338/1176.

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Um dos sistemas de proteção de substratos metálicos mais comumente empregado na indústria é o de tintas. Os fatores favoráveis à utilização das tintas em pó incluem a não utilização de solventes, facilidades de processamento/aplicação e possibilidade de reaproveitamento do material que não aderiu na superfície da peça. As características térmicas, mecânicas e químicas da tinta são influenciadas principalmente pelo tipo de resina utilizada. As tintas em pó híbridas (epóxi/poliéster) visam conciliar a característica de resistência ao intemperismo e ação dos raios UV com as características de resistência química e mecânica. Nas tintas em pó podem ser adicionados nanocargas que tem por finalidade melhorar as propriedades térmicas, mecânicas e químicas dos revestimentos. Outra característica das nanocargas é o baixo custo financeiro, decorrente da utilização de uma menor quantidade de carga, com elevado nível de desempenho. Dentre as nanocargas utilizadas, pode-se citar a mica muscovita e a montmorilonita 30B (MMT 30B) que, quando incorporadas às tintas, mesmo em baixas concentrações, apresentam propriedades de barreira superiores que às cargas convencionais. Este trabalho tem por objetivo desenvolver e caracterizar uma tinta em pó híbrida contendo diferentes teores de mica muscovita e MMT 30B. Os argilominerais foram incorporados numa formulação padrão de tinta em pó híbrida nas proporções de 2, 4 e 6% (m/m), separadamente. Antes da aplicação da tinta, os substratos metálicos foram submetidos a um pré-tratamento de fosfatização com fosfato de zinco. Após isso, a tinta em pó foi aplicada em painéis com dimensões de 70 x 120 x 0,65 mm de aço carbono AISI 1010 através de pulverização eletrostática. Os argilominerais, a tinta em pó e o revestimento foram analisados empregando diferentes técnicas de caracterização, tais como análise granulométrica, análise termogravimétrica (TGA), calorimetria exploratória diferencial (DSC), espectroscopia de infravermelho por transformada de Fourier (FTIR) e microscopia eletrônica de varredura por emissão de campo (MEVFEG). O efeito da incorporação dos argilominerais nas propriedades físicas e de proteção à corrosão das tintas foi avaliado com ensaios de medida de brilho, aderência, flexibilidade, resistência ao impacto, impedância eletroquímica (EIE), exposição à névoa salina (NS) e ensaio de chama. Para todas as tintas contendo argilominerais foi constatado o aumento da dureza superficial e a redução de brilho com o aumento do teor do argilomineral, sendo este efeito mais pronunciado com a adição de 6% (m/m) de MMT 30B. A aderência da tinta ao substrato não foi alterada pela presença dos argilominerais. As tintas contendo mica muscovita apresentaram melhores resultados nos ensaios de resistência ao impacto e de flexibilidade quando comparados as tintas contendo MMT 30B, nas concentrações testadas. A amostra TH/6/MICA apresentou melhor resultado no ensaio de impedância eletroquímica em relação aos outros sistemas estudados. No ensaio de névoa salina todas as amostras apresentaram elevada proteção à corrosão. Não foram observados bolhas ou pontos de corrosão na superfície de nenhuma das amostras. Porém, no ensaio subsequente de migração subcutânea, a amostra TH/2/MMT 30B foi a que apresentou maior desplacamento. No ensaio de chama, as tintas com incorporação de mica muscovita apresentaram melhores resultados que as tintas com MMT 30B. Após a análise de todos os ensaios, conclui-se que a adição de mica muscovita na proporção de 4% resultou em uma tinta com melhores propriedades térmicas, mecânicas e químicas.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior.
One of metallic substrates protection systems most commonly used in the industry is the paint. Factors favorable to the use of powder coatings include non-use of solvents, processing facilities/application and the possibility of reuse of material that did not adhere to the surface of the pieces. The thermal, mechanical and chemical characteristics of the obtained paint are influenced principally by the type of resin used. Hybrid (epoxy/polyester) powder coatings aimed at reconciling the weathering resistance characteristic and action of UV rays with the chemical resistance and mechanical characteristics. In the powder coatings can be added nanofillers which aims to improve the thermal, mechanical and chemical coatings. Another feature of nanofillers is the low financial cost resulting from the use of a lesser amount of filler, with a high level of performance. Among the nanofiller used, it can be cited muscovite mica and montmorillonite 30B (MMT 30B) that, when incorporated into the coatings, even at low concentrations, have higher barrier properties than conventional fillers. This work aims to develop and characterize a hybrid powder coating containing different amounts of muscovite mica and MMT 30B. Clayminerals have been incorporated in a standard formulation hybrid powder coatings in proportions of 2, 4 and 6% (w/w). Before applying the coating, the metal substrates were subjected to a pretreatment phosphating with zinc phosphate. After this, the powder paint was applied to panels with dimensions 70 x 120 x 0.65 mm carbon steel AISI 1010 through electrostatic spraying. The clayminerals, the powder paint and coating were analyzed using various characterization techniques, such as particle size analysis, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), infrared spectroscopy in Fourier transform (FTIR) and scanning electron microscopy for field emission (SEM-FEG). The effect of the incorporation of clayminerals in the physical properties and corrosion protection of coatings was evaluated with brightness measurement tests, adhesion, flexibility, impact resistance, electrochemical impedance spectroscopy (EIS), exposure to fog saline (NS) and flame test. For all coatings containing clayminerals was found to increase the surface hardness of the coating and reduced gloss with increasing clay content, this being more pronounced effect with the addition of 6% (w/w) of MMT 30B. The adhesion of the coating to the substrate was not altered by the presence of clayminerals. The coatings containing mica muscovite showed better results in impact resistance tests and flexibility when compared to coatings containing MMT 30B. The sample TH/6/MICA showed better results in the electrochemical impedance test in relation to other systems studied. In the salt spray test all samples showed high corrosion protection. There were no blistering or corrosion spots on the surface of any of the samples. However, in the subsequent test of subcutaneous migration, the sample TH/2/MMT 30B showed the greatest peeling. In the flame test, coatings with incorporation of muscovite mica showed better results than coatings with MMT 30B. After analyzing all the tests, it is concluded that the addition of muscovite mica in the proportion of 4% resulted in an paint with improved thermal, mechanical and chemical properties.
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31

Hetti, Mimi. "Synthesis and Characterization of Polymeric Magnetic Nanocomposites for Damage-Free Structural Health Monitoring of High Performance Composites." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-211082.

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The poly(glycidyl methacrylate)-modified magnetite nanoparticles, Fe3O4-PGMA NPs, were investigated and applied in nondestructive flaw detection of polymeric materials in this research. The Fe3O4 endowed magnetic property to the materials for flaw detection while the PGMA promoted colloidal stability and prevented particle aggregation. The magnetite nanoparticles (Fe3O4 NPs) were successfully synthesized by coprecipitation and then surface-modified with PGMA to form PGMA-modified Fe3O4 NPs by both grafting-from and grafting-to approaches. For the grafting-from approach, the Fe3O4 NPs were surface-functionalized with α-bromo isobutyryl bromide (BIBB) to form BIB-modified Fe3O4 NPs (Fe3O4-BIB NPs) with covalent linkage. The resultant Fe3O4-BIB NPs were used as surface-initiators to grow PGMA by surface-initiated atom transfer radical polymerization (SI-ATRP). For the grafting-to approach, the Fe3O4 NP were surface-functionalized with (3-mercaptopropyl)triethoxysilane (MCTES) to form MCTES-modified Fe3O4 NPs (Fe3O4-MCTES NPs). The PGMA with Br-end group was pre-synthesized by ATRP and then was grafted to the surface of the Fe3O4-MCTES NPs by coupling reaction. Both bare and modified Fe3O4 NPs exhibited superparamagnetism and the existence of iron oxide in the form of Fe3O4 was confirmed. The particle size of individual Fe3O4 NPs was about 8 – 24 nm but they aggregated to form clusters. The PGMA-modified NPs formed stable dispersion in chloroform and had larger cluster sizes than the unmodified ones because of the PGMA polymer layer. However, the uniformity of the NP clusters could be improved with PGMA surface grafting. The PGMA surface layer of the grafting-from (Fe3O4-gf-PGMA) NPs was thin and dense while that of the grafting-to (Fe3O4-gt-PGMA) NPs was thick and loose. The hydrodynamic diameters (Zave) of Fe3O4-gf-PGMA NP clusters could be controlled between 176 to 643 nm, dependent on the PGMA contents and reaction conditions. During SI-ATRP, side reactions happened and caused NP aggregation as well as increase of size of NP clusters. However, the aggregation has been minimized through optimization of reaction conditions. Oppositely, Zave values of Fe3O4-gt-PGMA NPs had little variation of about 120 – 190 nm. And the PGMA content of the Fe3O4-gt-PGMA NPs was limited to 12.5% because of the spatial hindrance during grafting process. The saturation magnetization (Ms) of the unmodified Fe3O4 NPs was about 77 emu/g, while those of the grafting-from and grafting-to Fe3O4-PGMA NPs were 50 – 66 emu/g and 63 – 70 emu/g, respectively. For Fe3O4-PGMA NPs with similar Fe3O4 contents, the grafting-to NPs had slightly higher Ms than the grafting-from counterparts. In addition, the Ms of both kinds of the Fe3O4-PGMA NPs with higher Fe3O4 content (> 87%) were also higher than that of the fluidMAG-Amine, the commercially available amine-modified MNPs. Besides, both kinds of Fe3O4-PGMA NPs also had much higher Fe3O4 contents and Ms values than most of the reported PGMA-modified MNPs. The magnetic epoxy nanocomposites (MENCs) were prepared by blending the modified Fe3O4 NPs into bisphenol A diglycidyl ether (BADGE)-based epoxy system and the distributions of both kinds of the PGMA-modified NPs were much better than that of the oleic acid-modified Fe3O4 NPs. Similar to the NPs, the MENCs also exhibited superparamagnetism. By cross-section TEM observation, the grafting-to Fe3O4-PGMA NPs formed more homogeneous distributions with smaller cluster size than the grafting-from counterparts and gave higher Ms of the MENCs. Nondestructive flaw detection of surface and sub-surface defects could be successfully achieved by brightness contrast of images given through eddy current testing (ET) method, which is firstly reported. The mechanical properties of the materials were influenced very slightly when 2.5% or lower Fe3O4-gt-PGMA NPs were present while the presence of the Fe3O4-gf-PGMA NPs (1 – 2.5 %) gave mild improvement of the storage modulus and increase of the glass-rubber transition temperature(Tg) of the MENCs. Furthermore, the Fe3O4-PGMA NPs could be evenly coated onto the functionalized ultra-high molecular weight poly(ethylene) (UHMWPE) textiles. The Fe3O4-gt-PGMA NPs were coated on the textile in order to prepare NP-coated textile-reinforced composite. Preliminary result of ET measurement showed that the Fe3O4-gt-PGMA NPs coated on the textiles could visualize the structure of the textile hidden inside and their relative depth. Accordingly, the incorporation of MNPs to polymers opens a new pathway of damage-free structural health monitoring of polymeric materials.
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32

Longhi, Marielen. "Influência da adição de diferentes oligômeros poliédricos de silsesquioxano (POSS) incorporados na resina epóxi no desempenho à corrosão em substrato de aço de baixa liga." reponame:Repositório Institucional da UCS, 2016. https://repositorio.ucs.br/handle/11338/1198.

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A resina epóxi é uma das matrizes mais empregadas na produção de compósitos e revestimentos. Destaca-se no grupo dos materiais termorrígidos devido à facilidade de processamento, suas propriedades mecânicas e à estabilidade térmica. Propriedades como resistência à temperatura e flexibilidade têm sido sistematicamente modificadas pelo uso de diferentes materiais, como argilominerais e, mais recentemente, oligômeros poliédricos de silsesquioxano – POSS, aplicados em matrizes epóxi. Os oligômeros poliédricos de silsesquioxano (POSS) usados na preparação de nanocompósitos termorrígidos têm sido estudados na obtenção de materiais híbridos capazes de suportar temperaturas mais elevadas, promover aumento de propriedades mecânicas e melhorar propriedades de superfície como, por exemplo, a hidrofobicidade do polímero. Os grupos funcionais mais comuns utilizados na preparação de nanocompósitos com resina epóxi são aminas, álcoois e grupos epóxi. A funcionalidade da nanogaiola é importante, uma vez que um termorrígido formado por uma microestrutura reticulada apresente uma microestrutura tridimensional que pode interagir em qualquer direção formando ligações ou interagindo na interface das gaiolas inseridas. Nesse contexto, foi avaliado a influência da adição de três diferentes oligômeros poliédricos de silsesquioxano – POSS (Glicidilisobutil-POSS, Triglicidilisobutil-POSS e Glicidil-POSS), em duas diferentes concentrações 2,5% e 5% (m/m), em resina epoxídica, no comportamento morfológico, mecânico e eletroquímico quando aplicados em aço de baixa liga. Com adição de POSS à resina epóxi, observou-se um aumento na rugosidade e hidrofobicidade do revestimento, além de se obter uma maior resistência à termoxidação e um aumento nos valores de temperatura de transição vítrea do material em comparação com a amostra de resina epóxi. Dentre os sistemas estudados, a amostra contendo Glicidilisobutil-POSS (POSSmono) apresentou os melhores resultados em relação à resistência à corrosão, promovendo um aumento nos valores de ângulo de contato e na impedância eletroquímica. No quesito dispersão na matriz polimérica, o Glicidil-POSS (POSSocta) apresentou uma dispersão ineficiente com a formação de aglomerados, o que hipoteticamente influenciou no seu baixo desempenho no comportamento eletroquímico em relação aos demais sistemas.
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The epoxy resin is one of the matrices most used in manufacturing composites and coatings. It is highlighted in the group of thermosetting materials due to good processability, mechanic behavior and thermal stability. Properties as thermal resistance and flexibility have been systematically modified by the use of different materials, as clays and, more recently, polyhedral oligomeric silsesquioxanes – POSS, applied in epoxy matrices. The polyhedral oligomeric silsesquioxanes (POSS) in thermosetting nanocomposites have been studied in hybrid materials able to support higher temperatures, promoting increase of mechanic properties and improving surface properties such as, for example, the hydrophobicity of the polymer. The most common functional groups used to preparing nanocomposites with epoxy resin are amines, alcohols and epoxy groups. The nanocage functionality is important, once a thermosetting formed by a reticulated microstructure presents a three-dimensional microstructure that can interact in any direction, making bonds or interacting on the interface of the inserted cages. In this context, it was evaluated the influence of three different polyhedral oligomeric silsesquioxanes – POSS (Glycidylisobutyl-POSS, Triglycidylisobutyl-POSS and Glycidyl-POSS), at two different contents 2.5% and 5% (w/w), in epoxy resin, in the morphological, mechanic and electrochemical behavior when applied on low alloy steel. Adding POSS in the epoxy resin, it was observed an increase in roughness and hydrophobicity of the coating. Moreover, it was reached a higher thermal oxidation resistance and an increase in the values of glass transition temperature of the material, regarding the epoxy resin sample. Among the studied systems, the sample containing Glycidylisobutyl-POSS (POSSmono) showed the best results, regarding the corrosion resistance. The addition of POSSmono in the epoxy resin promoted an increase of contact angle and electrochemical impedance values. Regarding the dispersion in the polymeric matrix, the Glycidyl-POSS (POSSocta) presented an inefficient dispersion, with formation of agglomerates, which hypothetically influenced in its low performance in the electrochemical behavior, regarding the other systems.
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33

Oblitas, Torrico Ruben Felipe Arturo. "Preparação e caracterização de híbridos orgânico-inorgânicos à base de epoxí-silica /." Araraquara, 2016. http://hdl.handle.net/11449/139461.

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Orientador: Peter Hammer
Banca: Cecilio Sadao Fugivara
Banca: Hudson Wallace Pereira de Carvalho
Resumo: Este projeto visa a investigar a relação entre a estrutura e as propriedades dos materiais epoxi-silica preparados pelo método sol-gel. Os híbridos foram preparados pela reação de cura entre o poly(Bisphenol A-co-epichlorohydrin) (DGBEA), e o dietil triamina (DETA) assim como pelo processo Sol-Gel de hidrolise e condensação entre GPTMS (3-Glycidoxypropyl)methyldiethoxysilane) e TEOS. Ressonância magnética nuclear (RMN), espectroscopia de fotoelétrons de raios X (XPS), espalhamento de raios X a baixo ângulo (SAXS), espectroscopia de Infravermelho e RAMAN, microscopia de força atômica (AFM) assim como termogravimétria foram utilizadas com o proposito de investigar a morfologia e as propriedades estruturais do material. Finalmente as propriedades anticorrosivas dos filmes foram testadas em uma solução salina por meio de espectroscopia de impedância eletroquímica (EIS). Durante a fase inicial do projeto diferentes amostras com diferentes concentrações de TEOS foram preparadas. A estabilidade térmica como as propriedades anticorrosivas foram testadas. Os resultados mostraram que para maiores concentrações de TEOS, as propriedades anticorrosivas e térmicas dos híbridos melhoram significativamente. Vários resultados interessantes foram obtidos, para híbridos com razoes molares de TEOS : GPTMS : DGBEA = 1 : 1: 1, tendo módulos de impedância de até 1010 Ω cm-2. Durante a segunda fase do projeto, duas series de amostras com concentrações diferentes de GPTMS a TEOS foram prepar... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: This work aims to investigate the relationship between the structure and the properties of the sol-gel prepared epoxy-silica materials. The organic-inorganic hybrids were prepared from the curing reaction of poly(Bisphenol A-co-epichlorohydrin) (DGBEA), with Diethyltriamine (DETA) and (3-Glycidoxypropyl)methyltriethoxysilane) (GPTMS) combined with the sol-gel hydrolysis and condensation reactions between Tetraethoxysilane (TEOS) and GPTMS. Nuclear magnetic resonance (NMR), X-ray photoelectron spectroscopy (XPS), Infrared and Raman spectroscopy (IR), Atomic force microscopy, as well as thermogravimetry (TG) have been used with the purpose to investigate the morphological and structural properties of the material. Finally the anticorrosive properties of the hybrid coated carbon steel were evaluated in saline solution using electrochemical impedance spectroscopy (EIS). During the initial phase of the project different samples with increasing concentrations of TEOS have been prepared and their thermal stability as well as their anticorrosive properties were tested. It was found, that for increasing TEOS concentration, the hybrid's anticorrosive and thermal properties can be improved. Several interesting results were obtained for hybrid coatings at a TEOS : GPTMS : DGBEA = 1 : 1 : 1 ratio, having an impedance modulus of up to 1010 Ω cm-2. During the second phase of the work, a series of epoxy-silica hybrids were synthetized varying the concentrations of GPTMS and TEOS. Their str... (Complete abstract click electronic access below)
Mestre
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34

Eom, Ho Seop. "Photopolymerizations of multicomponent epoxide and acrylate/epoxide hybrid systems for controlled kinetics and enhanced material properties." Diss., University of Iowa, 2011. https://ir.uiowa.edu/etd/2488.

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Cationic photopolymerization of multifunctional epoxides is very useful for efficient cure at room temperature and has been widely used in coatings and adhesives. Despite excellent properties of the final cured polymers, cationic photopolymerizations of epoxides have seen limited application due to slow reactions (relative to acrylates) and brittleness associated with a highly crosslinked, rigid network. To address these issues, two reaction systems were studied in this thesis: photoinitiated cationic copolymerizations of a cycloaliphatic diepoxide with epoxidized elastomers and acrylate/epoxide hybrid photopolymerizations. Oligomer/monomer structures, viscosity, compositions, and photoinitiator system were hypothesized to play important roles in controlling photopolymerizations of the epoxide-based mixtures. A fundamental understanding of the interplay between these variables for the chosen systems will provide comprehensive guidelines for the future development of photopolymerization systems comparable to the epoxide-based mixtures in this research. For diepoxide/oligomer mixtures, the observed overall enhancement in polymerization rate and ultimate conversion of the cycloaliphatic diepoxide was attributed to the activated monomer mechanism associated with hydroxyl terminal groups in the epoxidized oligomers. This enhancement increased with increasing oligomer content. The mixture viscosity influenced the initial reactivity of the diepoxide for oligomer content above 50 wt.%. Real-time consumption of internal epoxides in the oligomers was successfully determined using Raman spectroscopy. Initial reactivity and ultimate conversion of the internal epoxides decreased with increasing the diepoxide content. This trend was more pronounced for the oligomer containing low internal epoxide content. These results indicate that the reactivity of the hydroxyl groups is higher toward cationic active centers of the diepoxide than those of the internal epoxides in the oligomers. These conclusions are consistent with physical property results. The enhanced fracture toughness and impact resistance were attributed to multimodal network chain-length distribution of copolymers containing the oligomer content between 70% and 80%. For acrylate/epoxide hybrid mixtures, diacrylate oligomers significantly suppressed reactivities of cycloaliphatic mono/diepoxides, which was attributed to high mixture viscosity and highly crosslinked acrylate network. In this case, the dual photoinitiator system did not favor the epoxide reaction. Depending on the monovinyl acrylate secondary functionalities, enhanced reactivity and ultimate conversion of the diepoxide were attributed to a combined effect of a reduced viscosity and the radical-promoted cationic polymerization associated with the dual photoinitiator. The retarded and inhibited diepoxide reactivities with ether and urethane secondary groups were attributed to solvation and nucleophilicity/basicity effects, respectively. The influence of the diepoxide on the acrylate reactivity was attributed to dilution and polarity effects. In this case, high concentration of the free-radical photoinitiator is required for the dual photoinitiator system. Physical properties of hybrid polymers also varied with acrylate structures and monomer composition. Dynamic modulation methods were proposed to enhance the diepoxide reactivity and final properties in the presence of urethane acrylates.
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35

Naworyta, Agata. "Structure-function studies of epoxide hydrolases /." Uppsala : Department of Molecular Biology, Swedish University of Agricultural Sciences, 2010. http://epsilon.slu.se/201005.pdf.

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36

Prichanont, Seeroong. "Epoxide biotransformation in non-conventional media." Thesis, Imperial College London, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.307437.

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37

Strickland, Gary. "Epoxide polymerisations initiated by metaborate esters." Thesis, Bangor University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.263661.

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38

O'Connor, Norval. "Dianion-epoxide reactions : applications in synthesis." Thesis, University of Salford, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.327898.

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39

Nieh, Li-Shih World. "Synthesis and properties of lignin epoxide." Thesis, Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/101357.

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A lignin epoxide resin was synthesized and characterized. The epoxidation reaction was studied by reacting hydroxypropylated guaiacol (a lignin-like model compound) and epichlorohydrin using a catalyst system of potassium hydroxide and a phase transfer catalyst in toluene. The parameters studied were different epichlorohydrin level and temperature. The reaction was followed by HPLC and the structure of the product was identified with IR, ¹H and ¹³C NMR spectroscopy. The lignin epoxide was synthesized by reacting hydroxyalkylated (hydroxypropyl and hydroxybutyl) lignin with epichlorohydrin using the reaction conditions defined by the model compound studies. The reaction was studied at different epichlorohydrin level and at elevated and room temperature. The epoxy content of the lignin epoxide was determined by titration with HBr and its structure was identified with IR, ¹H and ¹³C NMR spectroscopy. Lignin epoxides were cured by crosslinking with a diamine and with phthalic anhydride. An amine-terminated rubber was added as toughening agent. Sol fraction and swelling behavior, stress-strain behavior and dynamic mechanical behavior of the cured lignin epoxides were studied in relation to cure conditions.
M.S.
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40

Trott, Gemma. "Heterodinuclear catalysts for CO2/epoxide copolymerisations." Thesis, University of Oxford, 2018. http://ora.ox.ac.uk/objects/uuid:4c4216cf-4e2e-4e3d-ac4b-c6ed9a312f5c.

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This thesis describes the preparation of new heterodinuclear catalysts for the selective copolymerisation of epoxides with CO2 or anhydrides. The catalysts are based on a symmetrical diphenol-tetraamine macrocycle to prepare heterocomplexes coordinated to zinc and magnesium. The coordination sphere is completed by co-ligands derived from carboxylates. Optimisation of the synthesis is carried out to enable a straightforward route to new catalysts through the metathesis of a dibromide complex using a range of potassium salts. The characterisation of these complexes is explored using multinuclear NMR spectroscopy, mass spectrometry, infrared spectroscopy and elemental analysis. The heterodinuclear complexes are highly active for the copolymerisation of cyclohexene oxide and CO2, under atmospheric pressures [TOF = 645 h-1, 120 °C, 0.1 mol%, 1 bar]. At higher temperatures (120 °C), excellent selectivity for poly(cyclohexene carbonate) formation (> 99 %) is maintained. The catalysts are highly active under low catalyst loadings, with excellent activities [TOF = 8830 h-1, 120 °C, 0.01 mol%, 20 bar]. Telechelic polymers are produced upon addition of chain transfer agents, and the system is stable under aerobic conditions. A linear increase in molar mass with conversion shows the polymerisation is controlled. The copolymerisation of CO2 with a range of epoxides is explored, allowing formation of poly(propylene carbonate), albeit with low selectivity [25 %, 60 °C, 0.01 mol%, 20 bar], and high molar mass poly(cyclopentene carbonate) in excellent (> 99 %) selectivity [TOF = 76 h-1, 80 °C, 0.01 mol%, 20 bar]. The catalysts are also tested in the copolymerisation of phthalic anhydride with cyclohexene oxide to yield polyesters in excellent (> 99 %) selectivity. These catalysts are also highly active and well controlled [TOF = 289 h-1, 100 °C, 0.13 mol%]. A range of anhydrides were tested, including succinic anhydride, glutaric anhydride and diphenic anhydride, which generally show high selectivity, although a variation in catalytic activity is observed. Kinetic studies are carried out to probe the rate equation for the copolymerisations of CO2 and phthalic anhydride, each with cyclohexene oxide. For the copolymerisation of phthalic anhydride and cyclohexene oxide, the data suggests a zero order dependence on anhydride and first order dependence on catalyst and epoxide. The rate equation determined for the copolymerisation of CO2 and cyclohexene oxide suggests a first order dependence on catalyst and epoxide, with a zero order dependence on CO2 pressure, and is in line with previous studies on similar systems. Computational analysis, applying density functional theory, shows that the previously hypothesised homodinuclear 'chain-shuttling' mechanism could be plausible for the analogous heterodinuclear systems.
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41

Strehmel, Veronika. "Bildung und Struktur vernetzter temperaturstabiler polymerer Materialien." [S.l. : s.n.], 2000. http://deposit.ddb.de/cgi-bin/dokserv?idn=961705426.

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42

Rangel, Sibeli Amália [UNESP]. "Nanocompósitos baseados no sistema epoxídico DEGBA/DETA modificado com uma resina epoxídica de silsesquioxano." Universidade Estadual Paulista (UNESP), 2006. http://hdl.handle.net/11449/92010.

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Made available in DSpace on 2014-06-11T19:25:33Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-08-30Bitstream added on 2014-06-13T18:29:01Z : No. of bitstreams: 1 rangel_sa_me_ilha.pdf: 1557624 bytes, checksum: 38398c09b8ff17af075a211027a27833 (MD5)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Polímeros epoxídicos são um dos mais importantes tipos de polímeros termorrígidos, extensivamente usados como adesivos e estruturas. Em reações epoxídicas são convertidos em um sistema termorrígido pela ação de agentes de cura. Tais reações químicas provocam uma mudança no estado físico do material, partindo de um líquido viscoso para um gel e se transformando em um material vitrificado. Os termorrígidos apresentam excelentes propriedades, tais como: alta tensão de ruptura e módulo de Young, fácil processamento, resistência térmica e química, e estabilidade dimensional. Entretanto, são quebradiços e possuem baixa resistência a propagação de trincas. Para superar estes inconvenientes, muitos tipos de compósitos de polímero com reforço foram desenvolvidos, em que as resinas epoxídicas são reforçadas com agentes modificadores, tais como enchimentos, oligômeros poliédricos de silsesquioxanos, dendrímeros, etc. Oligômeros poliédricos de silsesquioxanos (POSS), (RSiO1.5)n com n = 4, 6, 8, 10..., são nanoplataformas organo-funcionalizadas com 1 a 8 grupos reativos ou não reativos (R) ligados aos oito vértices possíveis do silsesquioxano cúbico. POSS octaédrico (n = 8) são os membros mais importantes desta família. No POSS, o núcleo cúbico de silicato é uma partícula rígida com 0,53 nm de diâmetro e um raio esférico de 1-3 nm, incluindo unidades orgânicas periféricas. Neste trabalho, um oligômero poliédrico de silsesquioxano contendo oito grupos epoxídicos por molécula (OG) foi incorporado ao sistema epoxídica DGEBA/DETA, como objetivo de avaliar a influência de um modificador reativo suas propriedades mecânicas e térmicas. Por meio de ensaios mecânicos foi observado um decréscimo de 30-50% na resistência à fratura (K1C)...
Epoxy resins are one of the most important kind of thermosetting polymers, extensively used for adhesives and structural applications. On cure, linear epoxy resins are undergoes in a thermoset system for the action of cure agents. Such chemical reactions cause a change into the physical state, from a viscous liquid to a gel and eventually to a vitrified material. They show various desirable properties such as high tensile strength and modulus, easy processing, good thermal and chemical resistance and dimensional stability, but they are brittle and have poor resistance to crack propagation. To overcome these drawbacks, many types of polymer-filler composites have been developed, in which the epoxy resins are reinforced with modifying agents, such as fillers, polyhedral oligosilsesquioxanes, dendrimers, etc. Polyhedral oligomeric silsesquioxanes (POSS), (RSiO1.5)n with n = 4, 6, 8, 10 ...., are organofunctional nanoplatforms with 1 to 8 reactive or nonreactive groups (R) connected to the eight possible vertexes of cubic silsesquioxanes. POSS Octahedral (n = 8) are the most important members of this family. In the POSS, the cubic core silica is a hard particle rigid with 0.53 nm diameter and a spherical radius of 1-3 nm including peripheral organic units. In this work, a polyhedral oligomeric silsesquioxanes containing eight epoxy groups per molecule (OG) was incorporated to an epoxy system of DGEBA/DETA thermosetting polymers in order to investigate the influence of a reactive modifier over the their mechanical and thermal properties. Through the mechanical tests an decrease of about 30-50% was observed in the fracture toughness (K1C) without or with a very soft decreasing in the module of Young (E)... (Complete abstract, click electronic address below)
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43

Simões, Tiago Henrique Nogueira. "Triagem de enzimas associadas à biotransformação de hidrocarbonetos a partir de metagenoma de sedimentos contaminados com petroléo e metais pesados." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/87/87131/tde-29042010-101614/.

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A metagenômica trouxe novas perspectivas ao estudo de comunidades microbianas no ambiente, permitindo explorar tanto a diversidade taxonômica de microrganismos ainda não-cultivados, como o acesso direto a genes e vias metabólicas. Neste trabalho, foram construídas bibliotecas metagenômicas a partir de amostras de sedimentos de mangue da Baía de Guanabara (RJ), impactadas com hidrocarbonetos de petróleo e metais pesados. Proteobacteria (33,3%), bactérias afiliadas a redutoras-de-sulfato (29,7%) e Firmicutes (20%) representaram os grupos principais nas amostras ambientais, baseado em análises filogenéticas de rDNA 16S, ao passo que isolamentos seletivos utilizando diesel e naftaleno permitiram a recuperação preferencial de delta-Proteobacteria e actinomicetos. Bibliotecas metagenômicas dos sedimentos enriquecidos com óleo diesel, com insertos entre 25 e 35 Kb clonados em fosmídeos, foram triadas para detecção de genes catabólicos de monoxigenases (alkB1) e expressão de epóxido-hidrolases, esterases, lipases e monoxigenases em ensaios de alto desempenho (HTS, high throughput screening). Clones reativos a alkB1 foram detectados, porém não foram funcionais nas condições de HTS testadas. Nas bibliotecas de fosmídeos triadas, vários clones apresentaram atividade enzimática, sendo que dois apresentaram atividade de lipase-esterase com alta seletividade, elevada taxa de conversão de substratos e excesso enantiomérico (ee >99%). Os resultados de HTS comprovaram a eficiência do uso da clonagem direta de DNA ambiental na expressão de vias metabólicas de interesse com potencial de aplicação biotecnológica.
Metagenomics brought a new perspective to the study of microbial communities in the environment, enabling access to the taxonomic diversity of uncultured microorganisms, as well as direct access to genes and metabolic pathways. In the current study, metagenomic libraries were constructed from mangrove sediment samples of the Guanabara Bay (RJ, Brazil), impacted with oil hydrocarbons and heavy metals. Proteobacteria (33.3%), sulfate-reducing affiliated bacteria (29.7%) and Firmicutes (20%) represented the main groups in the environmental samples based upon 16S rDNA phylogenetic analysis, whereas selective isolation using diesel and naphtalene yielded delta-Proteobacteria and actinomycetes. Metagenomic libraries of diesel-enriched sediment samples, with 25 to 35 Kb fosmid inserts, were screened for detecting monooxigenase genes (alkB1) and expression of epoxide hydrolases, esterases, lipases and monooxigenases in high throughput screening (HTS) assays. Clones reactive to the alkB1 probe were detected, but were not functional under the HTS conditions used. Several functional clones were detected in the clone library, and two showed lipase-esterase activity with high rates of substrate conversion and enantiomeric ratio (ee >99%). The results obtained on HTS showed the efficiency of the direct cloning of environmental DNA for the expression of metabolic pathways with potential biotechnological application.
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44

Duflot, Thomas. "Rôle de l'époxyde hydrolase soluble dans les maladies cardiovasculaires." Thesis, Normandie, 2018. http://www.theses.fr/2018NORMR037.

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L’époxyde hydrolase soluble (sEH) est une enzyme ubiquitaire, bifonctionnelle, codée par le gène EPHX2. La partie hydrolase (sEH-H) est responsable de la dégradation de facteurs endothéliaux vasodilatateurs, les acides époxyeicosatriénoïques (EETs), alors que la partie phosphatase (sEH-P) est impliquée dans le métabolisme des acides lysophosphatidiques (LPAs).L’objectif de ce travail a été de développer des outils méthodologiques permettant d'évaluer le rôle de la sEH dans la physiopathologie des maladies cardiovasculaires.Nous avons développé une méthode de quantification par CLHP-MS² des EETs et de leurs métabolites, les acides dihydroxyeicosatrienoic acids (DHETs). L'application de cette méthode montre que la dysfonction endothéliale des patients atteints d’hypertension artérielle et de diabète de type 2 est associée à une diminution de la libération locale des EETs lors de l'augmentation du débit sanguin, notamment liée à une augmentation d’activité de la sEH-H. L’inhibition pharmacologique de la sEH-H a permis de diminuer l’inflammation et l’atteinte glomérulaire dans un modèle murin d’insulino-résistance. De plus, l’étude des polymorphismes génétiques du gène EPHX2, codant la sEH, a permis de démontrer que la fonction sEH-H joue probablement un rôle important dans le contrôle de la fonction rénale et vasculaire des patients transplantés rénaux. Enfin, les résultats expérimentaux obtenus dans un modèle d’inactivation génétique de la sEH-P et l'étude des polymorphismes génétiques d'EPHX2 chez les patients insuffisants cardiaques suggèrent un rôle important de cette partie dans la régulation du métabolisme des lipides ainsi que dans le contrôle de l’homéostasie cardiovasculaire.Ainsi, les résultats obtenus au cours de ce travail soutiennent l’intérêt de développer des inhibiteurs pharmacologiques de la sEH-H pour traiter les maladies cardiovasculaires, rénales et métaboliques chez l’homme et suggèrent que la modulation de la sEH-P pourrait également constituer une nouvelle cible d'intérêt dans la prise en charge de ces pathologies
Soluble epoxide hydrolase (sEH) is an ubiquitous bifunctional enzyme that is encoded by the EPHX2 gene. The hydrolase activity (sEH-H) is responsible for the conversion of the endothelial vasodilator epoxyeicosatrienoic acids whereas the phosphatase activity (sEH-P) is involved in the metabolism of lysophosphatidic acids (LPAs).The aim of this work was to develop chromatographic methods and molecular biology techniques to evaluate sEH activities in cardiovascular diseases.We developed a LC-MS/MS method to quantify EETs and their metabolites, the dihydroxyeicosatrienoic acids (DHETs). Using this method, we showed that the endothelial dysfunction of hypertensive and type 2 diabetic patients is associated with a decrease in the local production of EETs during flow increase notably due to increased sEH-H activity. In a murine model of insulin resistance, pharmacological inhibition of sEH-H improved renal function by decreasing inflammation, oxidative stress and glomerular lesions. Moreover, genetic investigations of EPHX2 revealed that sEH-H may play a substantial role in the control of renal and vascular function in kidney recipients. Finally, experimental results obtained in knock-in sEH-P deficient rats and genetics findings in patients with heart failure strongly suggest that sEH-P is involved in lipid metabolism and cardiovascular homeostasis.Taken together, these results strengthen the interest of developing pharmacological inhibitors of sEH-H to be tested in patients with cardiovascular, renal or metabolic diseases and suggest that the modulation of sEH-P represents a new therapeutic target to treat these pathologies
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45

Kim, Young-Min MacGregor John Frederick. "Photopolymerization of cycloaliphatic epoxide and vinyl ether /." *McMaster only, 2005.

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46

Hopmann, Kathrin H. "Quantum chemical studies of epoxide-transforming enzymes." Licentiate thesis, Stockholm : Department of Theoretical Chemistry, Royal Institute of Technology, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4390.

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47

Kroetz, Deanna L. "Inhibition of human liver microsomal epoxide hydrolase /." Thesis, Connect to this title online; UW restricted, 1990. http://hdl.handle.net/1773/7958.

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48

Argiriadi, Maria Anastasia. "Characterization and Modeling of Amino Epoxide Resins." W&M ScholarWorks, 1994. https://scholarworks.wm.edu/etd/1539625882.

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49

Morten, Christopher J. (Christopher John). "Endo-selective epoxide-opening cascades in water." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/65271.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2011.
Vita. Cataloged from PDF version of thesis.
Includes bibliographical references.
Chapter I. Introduction to the Ladder Polyethers. We introduce the bioactivity of the ladder polyether natural products and provide an overview of the puzzle that is their biogenesis. Cascades of endo-selective epoxide opening inspired by the biosynthetic proposal and promoted by simple neutral water can provide efficient access to these compounds. Chapter II. Water-Promoted Epoxide Opening Accommodates Methyl Substitution. ... Methyl (Me) substitution poses a challenge to the achievement of endo-selective epoxide-opening cascades, as these groups can direct the regioselectivity of epoxide opening. Water as reaction solvent and promoter overcomes such directing effects and enables the incorporation of proximally Me-substituted epoxides into endo-selective cascades. However, Me-substituted epoxides do reduce the overall efficiency of cascades. Chapter III. Kinetics of an Epoxide-Opening Cascade Promoted by Neutral Water. Evidence for a Stepwise Mechanism. ... Detailed investigation of the kinetics of an endo-selective epoxide-opening cascade in water reveals a stepwise mechanism, not a concerted one. While the first step proceeds with poor rate and selectivity, the second cyclization, which is templated by a fused THP diad, proceeds with excellent endo selectivity. Chapter IV. Preliminary Investigation of a Dioxane Template for Endo-Selective Epoxide-Opening Cyclization. ... Use of a 1,3-dioxane as template ring, a methylene acetal engenders endoselective epoxide opening under both acidic and basic conditions. Cyclization in neutral water proceeds with superb endo selectivity. Chapter V. Progress Toward the Synthesis of Gambierol via Endo-Selective Epoxide-Opening Cascades Promoted by Water. ... We report progress toward the biomimetic total synthesis of the ladder polyether gambierol. The FGH ring system has been synthesized in a 20 step longest linear sequence, via an endo-selective epoxide-opening cascade promoted by water. Chapter VI. Conclusion: Potential Implications of the Foregoing Work on the Biosynthesis of the Ladder Polyethers. We summarize lessons learned from in vitro emulation of the hypothesized biosynthesis of the ladder polyethers and speculate on the possibility of ring junction methylation subsequent to the epoxide-opening cascade step.
by Christopher J. Morten.
Ph.D.
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50

Punchaipetch, Prakaipetch. "Epoxy + Liquid Crystalline Epoxy Coreacted Networks." Thesis, University of North Texas, 2000. https://digital.library.unt.edu/ark:/67531/metadc2705/.

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Molecular reinforcement through in-situ polymerization of liquid crystalline epoxies (LCEs) and a non-liquid crystalline epoxy has been investigated. Three LCEs: diglycidyl ether of 4,4'-dihydroxybiphenol (DGE-DHBP) and digylcidyl ether of 4-hydroxyphenyl-4"-hydroxybiphenyl-4'-carboxylate (DGE-HHC), were synthesized and blended with diglycidyl ether of bisphenol F (DGEBP-F) and subsequently cured with anhydride and amine curing agents. Curing kinetics were determined using differential scanning calorimetry (DSC). Parameters for autocatalytic curing kinetics of both pure monomers and blended systems were determined. The extent of cure for both monomers was monitored by using Fourier transform infrared spectroscopy (FT-IR). The glass transitions were evaluated as a function of composition using DSC and dynamic mechanical analysis (DMA). The results show that the LC constituent affects the curing kinetics of the epoxy resin and that the systems are highly miscible. The effects of molecular reinforcement of DGEBP-F by DGE-DHBP and DGE-HHC were investigated. The concentration of the liquid crystalline moiety affects mechanical properties. Tensile, impact and fracture toughness tests results are evaluated. Scanning electron microscopy of the fracture surfaces shows changes in failure mechanisms compared to the pure components. Results indicate that mechanical properties of the blended samples are improved already at low concentration by weight of the LCE added into epoxy resin. The improvement in mechanical properties was found to occur irrespective of the absence of liquid crystallinity in the blended networks. The mechanism of crack study indicates that crack deflection and crack bridging are the mechanisms in case of LC epoxy. In case of LC modified epoxy, the crack deflection is the main mechanism. Moreover, the effect of coreacting an epoxy with a reactive monomer liquid crystalline epoxy as a matrix for glass fiber composites was investigated. Mechanical properties of the modified matrix were determined by tensile, flexural and impact testing. The improvement in toughness of the bulk matrix by the addition of a LCEs is seen also in the composites. The improvement is related to the enhancement of adhesion between the glass fibers and the matrix.
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