Made available in DSpace on 2014-10-09T12:53:10Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:58:37Z (GMT). No. of bitstreams: 0 / É cada vez maior a utilização de polímeros reforçados com fibra de vidro no mercado nacional. Entre eles utiliza-se a poliamida 6 que apresenta ótima resistência à tração, ao impacto e à absorção de umidade comparada à poliamida 6 sem reforço de fibra de vidro, sendo atualmente utilizada na indústria automobilística em peças sob o capô, em especial em carcaças de radiadores. Este trabalho foi realizado com o objetivo de estudar o efeito da radiação ionizante nas propriedades mecânicas (resistência à tração, à flexão e ao impacto Izod) e térmicas (resistência ao fio incandescente e temperatura de fusão) da poliamida 6 com reforço de fibra de vidro, submetida à diferentes doses de radiação (100 a 600 kGy). As amostras foram preparadas e irradiadas em um acelerador JOB 188 com feixe de elétrons de energia de 1,5 MeV em diferentes doses e uma taxa de dose de 22,61 kGy/h. Após a irradiação, as propriedades das amostras da poliamida 6 com reforço de fibra de vidro irradiada foram determinadas e comparadas com as amostras não irradiadas e constatou-se que as propriedades mecânicas de resistência à flexão e à tração aumentaram e a de resistência ao impacto diminuiu. Em relação à propriedade térmica de temperatura de fusão diminuiu de 224,4ºC para 212,5ºC mas a perda de massa diante do aumento constante da temperatura também diminuiu. Em relação à propriedade de resistência ao fio incandescente a poliamida 6 com reforço de fibra de vidro irradiada teve um bom desempenho. As imagens captadas por Microscopia Eletrônica de Varredura mostram que a irradiação provocou uma boa integração entre a fibra de vidro e o polímero o que foi responsável pelo bom desempenho na propriedade de resistência ao fio incandescente. / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Made available in DSpace on 2014-10-09T12:48:42Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:00:56Z (GMT). No. of bitstreams: 1 09150.pdf: 3154679 bytes, checksum: f1a5a4085f6acc6064953483dddb2281 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

This thesis presents an alternative approach for pre-concentrating heavy metals in aqueous environments using electro spun polymer nanofiber sorbents. The conditions for electrospinning polyethersulfone, polystyrene, polysulfone and polyamide-6 were optimized. The morphologies and porosities of the electrospun nanofibers were studied using SEM and BET nitrogen gas adsorptions. The nanofibers had mesoporous morphologies with specific surface areas up to 58 m2/g. The electro spun nanofiber sorbents were characterized in terms of their tunability for both uptake and release of heavy metals. The usability of the sorbent was also assessed. The sorbents showed fast adsorption kinetics for heavy metals « 20 min for As, Cu, Ni and Pb) in different aqueous environments. The adsorption characteristics of the sorbents best fitted the Freundlich isotherm and followed the first order kinetics. The efficiencies of adsorption and desorption of heavy metals on both imidazolyl-functionalized polystyrene and amino-functionalized polysulfone sorbents were more than 95% up to the fifth cycle of usage. Reusability improved dramatically (up to 10 runs of usage) when mechanically stable amino-functionalized nylon-6 electro spun nanofibers were used. The capacity of the amino-functionalized nylon-6 sorbent to pre-concentrate heavy metals compared very favourably with those of aqua regia and HN03+H202 digestions especially in less complex matrices. Due to their highly porous nature, the electro spun nanofibers exhibited high adsorption capacities (up to 50 mg/g) for heavy metal ions. The loading capacities achieved with the imidazolyl-functionalized sorbent were higher than those for amino-functionalized mesoporous silica and biomass-based sorbents. The electro spun nanofiber sorbents presents an efficient and cost effective alternative for preconcentrating heavy metals in aqueous environments.

Orientadores: Wander José da Silva, Altair Antoninha Del Bel Cury / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-27T04:08:04Z (GMT). No. of bitstreams: 1 Panza_LeonardoHenriqueVadenal_D.pdf: 39498694 bytes, checksum: bcb5576864f239980a74f85ecab13ee6 (MD5) Previous issue date: 2015 / Resumo: O uso de PPRs continua como uma alternativa viável e eficiente na prática da reabilitação oral, no entanto a necessidade do uso de uma estrutura metálica, pode muitas vezes causar um comprometimento estético. O uso de materiais alternativos flexíveis para a substituição destes grampos ou de outras partes da PPR tem sido bastante divulgado, porém ainda existem controvérsias sobre as propriedades físicas e mecânicas dos mesmos. O objetivo deste trabalho foi comparar 2 materiais utilizados na confecção de PPRs nos quesitos sorpção de água, solubilidade em água e transmissão de forças ao rebordo na extensão distal da peça. Para análise de sorpção e solubilidade foram confeccionados discos em polimetilmetacrilato (PMMA) e poliamida (POL), seguindo as especificações da ISO 1567. Para análise da transmissão de forças ao rebordo foram confeccionados modelos classe I de Kennedy em resina fotoelástica e 3 diferentes tipos de PPR: tradicional com estrutura metálica e base em PMMA (controle), PPR conjugada feita com estrutura metálica e poliamida e uma PPR confeccionada totalmente em poliamida. Os conjuntos modelo-PPR foram submetidos à cargas de 0,5 e 1,0 KgF na extensão distal e as imagens de franjas formadas nos modelos foram capturadas de forma padronizada. O teste de Kruskal-Wallis foi utiilizado para analisar os dados, que mostraram não haver diferenças significantes entre os materiais para sorpção de água (p=0.6682) e solubilidade (p=0.4095). A análise fotoelástica mostrou uma transmissão de forças mais intensa pela extensão distal da PPR nos grupos de PPRs feitas em poliamida, quando comparadas ao grupo controle, especialmente no grupo da PPR sem metal. Com as limitações deste estudo foi possível concluir que o comportamento do PMMA e da poliamida foi similar para sorpção e solubilidade em água e que a transmissão de forças ao rebordo em próteses confeccionadas em poliamida sem metal contraindicam o seu uso / Abstract: The use of removable partial denture (RPD) still remains as a viable alternative to an efficient oral rehabilitation. However, due the metal framework lack of esthetic, it has been suggested the use of flexible materials as substitutes to the metal clasps, even thought this material maintains controversial regarding its dimensional properties. In this manuscript, our group compared two materials used in the fabrication of RPD regarding its water sorption and solubility and load transmission by distal extension. For this, poly (methyl methacrylate) (PMMA) and polyamide (POL) discs (n=7) were used to manufacture specimens that were evaluated regarding its water sorption and solubility. For load transmission by distal extension, Kennedy Class I mandibular models were made with photo elastic resin and 3 different RPD were tested: traditional RPD with metal framework and PMMA flange (Control); RPD with metal framework and clasps and flange in POL (POL-Metal); and RPD totally manufactured in POL (TOT-POL). Load of 0.5 and 1.0 kgF were applied to distal extension and the image of the load transmission in the photo-elastic model was captured. Kruskal-Wallis test were used for data analysis. Results showed no statistical difference between both materials regarding water sorption (p=0.6682) and solubility (p=0.4095). Photo-elastic analyses showed higher load transmission by distal extension by both POL group when compared to control group. Within the limitations of this study, it can be concluded that although POL had similar behavior to PMMA regarding water sorption and solubility, the load transmission by distal extension in RPD manufactured with POL shows the worst results, but clinical studies should de done with this material to indicates its use / Doutorado / Protese Dental / Doutor em Clínica Odontológica

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第20940号 / 理博第4392号 / 新制||理||1631(附属図書館) / 京都大学大学院理学研究科化学専攻 / (主査)教授 杉山 弘, 教授 三木 邦夫, 教授 秋山 芳展 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

An experimental and analytical study of the tribological behavior of polymer composites is presented. Glass, aramid, and carbon fiber-filled polyamide (Nylon 6,6) composites serve as models for understanding friction and wear processes encountered when polymer composites are used in tribological applications. Experimental results not only include measurements of friction and wear, but surface temperatures produced by frictional processes during oscillating contact experiments. Since an optically flat, transparent sapphire disk is used as the oscillating countersurface, surface temperatures can be measured directly at the interface using an infrared microscope. Experimental results show that the presence of fibers in the polyamide matrix lowers wear, friction, and surface temperature when compared with the unfilled polymer. Rationale for this improved tribological behavior is presented and discussed. Fiber-type is shown to have a direct influence on the tribological behavior of the polymer composite, and the chemical behavior at and near the interface is shown to be significant by examining worn and transferred material through surface analytical techniques. In particular, evidence is presented for the tribochemical degradation of intramolecular bonds in the polyamide macromolecule. Measurements of surface temperatures are compared with theoretical predictions using models for the real area(s) of contact, and results from “scanning” experiments are also presented in which the infrared microscope is used to measure surface temperatures at possible real areas of contact within the apparent contact region. Instantaneous measurements of surface temperature and friction over a single cycle of motion are also presented which allows for the performance of a frequency domain analysis. This technique not only shows the frequency content of the friction and surface temperature signals, but it also shows correlations between these two parameters. The role of intermolecular attractions in frictional processes is addressed, and evidence for relatively strong intermolecular attractions between the polyamide surface and sapphire disk is discussed. / Ph. D.

La préparation de polymères à base d’acides biliaires, molécules biologiques, a attiré l'attention des chercheurs en raison des applications potentielles dans les domaines biomédicaux et pharmaceutiques. L’objectif de ce travail est de synthétiser de nouveaux biopolymères dont la chaîne principale est constituée d’unités d’acides biliaires. La polymérisation par étapes a été adoptée dans ce projet afin de préparer les deux principales classes de polymères utilisés en fibres textiles: les polyamides et les polyesters. Des monomères hétéro-fonctionnels à base d’acides biliaires ont été synthétisés et utilisés afin de surmonter le déséquilibre stoechiométrique lors de la polymérisation par étapes. Le dérivé de l’acide lithocholique modifié par une fonction amine et un groupement carboxylique protégé a été polymérisé en masse à températures élevées. Les polyamides obtenus sont très peu solubles dans les solvants organiques. Des polyamides et des polyesters solubles en milieu organique ont pu être obtenus dans des conditions modérées en utilisant l’acide cholique modifié par des groupements azide et alcyne. La polymérisation a été réalisée par cycloaddition azoture-alcyne catalysée par l'intermédiaire du cuivre(Ι) avec deux systèmes catalytiques différents, le bromure de cuivre(I) et le sulfate de cuivre(II). Seul le bromure de cuivre(Ι) s’est avéré être un catalyseur efficace pour le système, permettant la préparation des polymères avec un degré de polymérisation égale à 50 et une distribution monomodale de masse moléculaire (PDI ˂ 1.7). Les polymères synthétisés à base d'acide cholique sont thermiquement stables (307 °C ≤ Td ≤ 372 °C) avec des températures de transition vitreuse élevées (137 °C ≤ Tg ≤ 167 °C) et modules de Young au-dessus de 280 MPa, dépendamment de la nature chimique du lien. / Bile acids have drawn attention in the synthesis of polymers for biomedical and pharmaceutical applications due to their natural origin. The objective of this work is to synthesize main-chain bile acid-based polymers. The step-growth polymerization was used to prepare two important classes of polymers used in textile fibers, polyamides and polyesters. Heterofunctional bile acid-based monomers were synthesized and used in order to overcome stoichiometric imbalances during step-growth polymerization. The lithocholic acid derivative bearing amine and protected carboxylic functional groups was polymerized in bulk at high temperatures, yielding polyamides that were poorly soluble in common organic solvents. Soluble triazole-linked polyamides and polyesters were obtained when the cholic acid derivative bearing azide and alkyne functional groups was polymerized under mild conditions via copper(Ι)-catalyzed azide-alkyne cycloaddition. Two different catalytic systems, copper(Ι) bromide and copper(ΙΙ) sulfate, were tested. Only copper(Ι) bromide proved to be an effective catalyst for the system, allowing the synthesis of the polymers with a degree of polymerization of ca. 50 and an unimodal molecular weight distribution(PDI ˂ 1.7). The main-chain cholic acid-based polymers are thermally stable (307 °C ≤ Td ≤ 372 °C) with high glass transition temperatures (137 °C ≤ Tg ≤ 167 °C) and Young’s moduli in excess of 280 MPa, depending on the chemical structure of the linker.

The development of small-molecules which target nucleic acids, more specifically the minor groove of DNA, in a sequence specific manner and control gene expression are currently being investigated as potential therapeutic compounds for the treatment of various diseases, including cancer, as well as viral and bacterial infections. The naturally occurring compounds netropsin and distamycin have been shown to demonstrate antitumor and antibacterial properties. Currently, there are synthetic efforts to create pyrrole and imidazole-containing polyamide derivatives of netropsin and distamycin that show potential as medicinal agents. Synthetic pyrrole and imidazole-containing polyamides are potentially useful for targeting and modulating the expression of genes, including those associated with cancer cell growth. The key challenges that must be overcome to realize this goal of using synthetic polyamides in the treatment of disease are the development of polyamides with low molar mass so the molecules can readily diffuse into cells and concentrate in the nucleus. In addition, the molecules must have appreciable water solubility, bind DNA sequence specifically, and with high affinity. As part of a systematic study within the authors’ laboratory, our goal is to develop polyamides which can be synthesized readily yet possess excellent sequence specificity, stronger binding affinity, high solubility in biological media and enhanced cell penetration and nuclear localization properties. There is a need to develop a library of modified polyamides which target DNA and exhibit improved biological properties. The present study is a systematic examination of the binding properties of various modified synthetic polyamide compounds. The synthetic polyamide derivatives presented have more potential as therapeutic candidates over other synthetic polyamides because of their increased water solubility, smaller molecular weights, and molecular design, thus, allowing them to penetrate into cells and localize in the nucleus.

In the last two decades, hyperbranched (hb) polymers have drawn much attention and obtained intensive research activities both from industry and academia. They are known to have unique and interesting properties which derive from their three dimensional structure and the large number of functional groups. These structural characteristics provide high possibilities for controlling functional group interactions and modifications of other polymers in blends and therefore, they are expected to result in novel materials with desired properties. Furthermore, the easy synthetic accessibility of hb polymers by one-pot synthesis is advantageous as well and allows easy scale-up of laboratory reactions. Having the characteristics as mentioned above, hb polymers are considered good candidates for blend components or melt processing modifiers. In fact, hb polymers have already been used as blend components or additives aiming for different effects. In many cases, reduced viscosity and formation of miscible blends were observed by modification of a linear matrix polymer with hb polymers. More information will be introduced in the following theoretical section. In this work two hb polyester systems based on AB2 and A2+B3 approaches were synthesized and studied. Their possible applications as additives in the blends of linear polyamides were investigated.

La préparation de polymères à base d’acides biliaires, molécules biologiques, a attiré l'attention des chercheurs en raison des applications potentielles dans les domaines biomédicaux et pharmaceutiques. L’objectif de ce travail est de synthétiser de nouveaux biopolymères dont la chaîne principale est constituée d’unités d’acides biliaires. La polymérisation par étapes a été adoptée dans ce projet afin de préparer les deux principales classes de polymères utilisés en fibres textiles: les polyamides et les polyesters. Des monomères hétéro-fonctionnels à base d’acides biliaires ont été synthétisés et utilisés afin de surmonter le déséquilibre stoechiométrique lors de la polymérisation par étapes. Le dérivé de l’acide lithocholique modifié par une fonction amine et un groupement carboxylique protégé a été polymérisé en masse à températures élevées. Les polyamides obtenus sont très peu solubles dans les solvants organiques. Des polyamides et des polyesters solubles en milieu organique ont pu être obtenus dans des conditions modérées en utilisant l’acide cholique modifié par des groupements azide et alcyne. La polymérisation a été réalisée par cycloaddition azoture-alcyne catalysée par l'intermédiaire du cuivre(Ι) avec deux systèmes catalytiques différents, le bromure de cuivre(I) et le sulfate de cuivre(II). Seul le bromure de cuivre(Ι) s’est avéré être un catalyseur efficace pour le système, permettant la préparation des polymères avec un degré de polymérisation égale à 50 et une distribution monomodale de masse moléculaire (PDI ˂ 1.7). Les polymères synthétisés à base d'acide cholique sont thermiquement stables (307 °C ≤ Td ≤ 372 °C) avec des températures de transition vitreuse élevées (137 °C ≤ Tg ≤ 167 °C) et modules de Young au-dessus de 280 MPa, dépendamment de la nature chimique du lien. / Bile acids have drawn attention in the synthesis of polymers for biomedical and pharmaceutical applications due to their natural origin. The objective of this work is to synthesize main-chain bile acid-based polymers. The step-growth polymerization was used to prepare two important classes of polymers used in textile fibers, polyamides and polyesters. Heterofunctional bile acid-based monomers were synthesized and used in order to overcome stoichiometric imbalances during step-growth polymerization. The lithocholic acid derivative bearing amine and protected carboxylic functional groups was polymerized in bulk at high temperatures, yielding polyamides that were poorly soluble in common organic solvents. Soluble triazole-linked polyamides and polyesters were obtained when the cholic acid derivative bearing azide and alkyne functional groups was polymerized under mild conditions via copper(Ι)-catalyzed azide-alkyne cycloaddition. Two different catalytic systems, copper(Ι) bromide and copper(ΙΙ) sulfate, were tested. Only copper(Ι) bromide proved to be an effective catalyst for the system, allowing the synthesis of the polymers with a degree of polymerization of ca. 50 and an unimodal molecular weight distribution(PDI ˂ 1.7). The main-chain cholic acid-based polymers are thermally stable (307 °C ≤ Td ≤ 372 °C) with high glass transition temperatures (137 °C ≤ Tg ≤ 167 °C) and Young’s moduli in excess of 280 MPa, depending on the chemical structure of the linker.