Thesis (Ph. D.)--University of Texas at Austin, 2004. / Supervisor: Kenneth M. Liechti. Vita. Includes bibliographical references. Also available from UMI.

Thesis (M.S.)--University of Michigan, 1986.

Thesis--Universidade federal de Santa Catarina, 1975.

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Agradecemos a compreensão. on 2016-06-09T16:17:55Z (GMT) / Submitted by RUBEN FELIPE ARTURO OBLITAS TORRICO null (ro1485@my.bristol.ac.uk) on 2016-06-09T16:57:07Z No. of bitstreams: 1 Dissertacao.pdf: 2188934 bytes, checksum: 633201227bb5f6a322e3d0dec8645d34 (MD5) / Approved for entry into archive by Ana Paula Grisoto (grisotoana@reitoria.unesp.br) on 2016-06-13T20:07:22Z (GMT) No. of bitstreams: 1 torrico_rfo_me_araiq_par.pdf: 757530 bytes, checksum: 9e239d69620a743d05fb3a39c914d9bc (MD5) / Made available in DSpace on 2016-06-13T20:07:22Z (GMT). No. of bitstreams: 1 torrico_rfo_me_araiq_par.pdf: 757530 bytes, checksum: 9e239d69620a743d05fb3a39c914d9bc (MD5) Previous issue date: 2016-04-15 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / 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 preparadas. As propriedades estruturais foram obtidas por meio de Espectroscopia Infravermelho, Raman, RMN e XPS e espalhamento de raios X a baixo ângulo. A hidrofobicidade assim como as propriedades térmicas foram avaliadas por meio de testes de molhabilidade e análise termogravimétrica. Finalmente as propriedades anticorrosivas dos filmes em contato com solução salina foram testadas por meio de espectroscopia de impedância electroquímica. / 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 structural properties were characterized by means of Infrared, Raman, solid NMR and XPS spectroscopy. Their hydrophobicity as well as their thermal resistance were evaluated using the drop shape analysis and thermogravimetry. Finally the anticorrosive properties of the coatings in saline solution were tested using electrochemical impedance spectroscopy.

Orientador: Lucia Helena Innocentinni Mei / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-20T09:55:20Z (GMT). No. of bitstreams: 1 Carvalho_IviMartinsde_M.pdf: 1540327 bytes, checksum: 645ccaa60b4cb1206d1e1a77feb19416 (MD5) Previous issue date: 2012 / Resumo: Plastissois de PVC reticulados na presença de resina epóxi polifuncional foram obtidos através de espalmagem. Foi possível inferir que a presença de um acelerador tipo amina, ao menos nas condições de processamento utilizadas neste estudo, mostrou-se imprescindível para a ocorrência do processo de reticulação. Resultados de grau de reticulação mostraram que só houve formação de gel nas amostras onde o acelerador foi utilizado concomitantemente com a resina epóxi. Apesar da comprovação da reação química ser dificultada pelo grande número de diferentes sinais de FTIR presentes na formulação, resultados de teor de gel e módulo de Young parecem confirmar a hipótese de formação de uma rede tridimensional entre as moléculas do PVC e a resina epóxi, porém serão necessários estudos mais aprofundados no futuro para identificação do polímero hiper-ramificado formado / Abstract: Crosslinked PVC plastisols in the presence of polyfunctional epoxy resin were obtained from spreadcoating. It was possible to infer that the presence of an amine type accelerator, at least in the conditions used in this study proved to be essential for the occurrence of the crosslinking process. The results of reticulation degree showed that gel formation only happened in samples where the amine has been used concomitantly with the epoxy resin. Despite the evidence of chemical reaction is complicated by the large number of molecules present in the formulation, Young's modulus results seem to confirm the hypothesis of the formation of a three-dimensional network between the molecules of PVC and epoxy resin, but further studies are needed in the future to identify the hyperbranched polymer formed / Mestrado / Ciencia e Tecnologia de Materiais / Mestre em Engenharia Química

Interest in using renewable raw materials to prepare biobased monomers, polymers, and materials is rapidly increasing. The goal of the research described is to develop branched polyesters of plant oil fatty acids, using different core pol yo ls (i.e. sucrose, dipentaerythritol, and tripentaerythritol) and plant oils (i.e. linseed, safflower, and soybean), into curing systems that have potential uses in applications such as coatings, composites, and adhesives. This study is mainly focused on the use of sucrose as the core polyol in the soyate resins. Sucrose esters and their derivatives have a compact structure, high density, and high functionality-double bonds, epoxides, or hydroxyls. When considering the use of sucrose ester compounds to form cross linked materials, the rigid core of sucrose can potentially impart hardness to the thermoset, and the high functionality can lead to rapid gelation and high cross link density. Thus, these novel biobased resins using sucrose esters of plant oils have the potential to be a significant advance in biobased resin technology, as well as to be competitive with the conventional petroleum-based resins.

No description available.

Epoxy resins are used throughout the commercial field as coatings and adhesives. Commercially, these polymers are generally synthesized via the "Taffy Process" which involves the reaction of 4,4′ isopropylidene diphenol (Bis-A) with epichlorohydrin under basic conditions. They may also synthesized from the base catalyzed reaction of diglycidylether of Bis-A and Bis-A, which is referred to as the "Advancement Process". Both processes are complicated by a branching side reaction which consumes epoxy groups and upsets the stiochiometric control and hence influences the materials final molecular weight. A possible method to eliminate the side reaction and obtain high molecular weight polymers was investigated which involved the use of sterically hindered basic catalysts in a non-polar solvent to promote the reaction between the diglycidylether of Bis-A and Bis-A. Reactions conducted using quaternary ammonium hydroxides in diglyme solutions produced high molecular weight polymers. In contrast, trialkylamine catalyzed systems run under similar conditions only produced polymers of moderate molecular weights at best. A quantitative ¹H-NMR analysis for measuring the degree of branching in polyhydroxyethers has been developed. The ¹H-NMR analysis involved the derivatization of the polymers using trichloroacetyl isocyanate. This was performed in order to separate the methine proton into a branched and non-branched signal. Analysis of both polymers and oligomers synthesized by this method indicate that the degree of branching is less than 10% for all materials. However the low precision of the technique limited the analysis and the conclusion as to the best reaction conditions required to obtain the lowest amount of branching. The kinetics of crosslinking oligomeric epoxy resins with multifunctional isocyanates was also studied using Fourier transform infrared spectroscopy (FT-IR). The reaction was modeled by using phenyl isocyanate and a low molecular weight epoxy resin synthesized from para t-butyl phenol and diglycidylether of Bis-A. Tin octoate proved to be the most effective catalyst for this reaction. / M.S.

The shear strength of unidirectional glass-epoxy composites was determined experimentally by three standard shear tests. The tests consisted of short beam interlaminar shear tests, saw-cut shear tests, and torsion tests on circumferentially wound cylinders. Test results show that the short beam interlaminar shear tests and the torsion tests of circumferentially wound cylinders give approximately the same maximum shear stress. Test results also showed that the saw-cut shear test is not a good interlaminar shear test because of stress concentrations at the base of the saw cuts and high tearing stresses normal to the plane of shear. The shear strength determined by the beam and torsion tests is approximately 10 ksi, whereas the average shear strength for the saw-cut specimens is approximately 2.5 ksi. / Master of Science

An epoxy resin (Epon 828) was chemically modified with two different elastomers, poly(dimethyl-co-diphenyl) siloxane (PSX) and carboxyl-terminated butadiene-acrylonitrile (CTBN), to enhance its fracture toughness. The friction and wear of specimens modified with different amounts of elastomer were investigated in a pin-on-disk wear machine. An attempt was made to correlate the fracture toughness of the epoxy material to its fatigue wear rate for experiments in which a steel ball was sliding on a modified epoxy disk. A different type of experiment, modified epoxy pin sliding on an abrasive disk, was performed to detect whether abrasive wear of modified epoxies responds differently than fatigue wear to the fracture toughness. Other experiments were performed in which the wear debris produced during sliding was blown out of the interface to study its influence on friction and wear behavior. The effect of surface morphology on friction and wear was also studied. The results indicated that a marked improvement in fracture toughness was achieved for samples with higher elastomer content. Regardless of the type of the experiment, epoxy pin-on-abrasive disk or steel ball-on-epoxy disk, wear rates correlated positively with inverse of fracture toughness. Both friction coefficient and wear rate were found to be influenced by the removal of the wear debris, especially for samples with higher elastomer content. The friction coefficient was reduced for samples with higher elastomer content and this was attributed to the low surface energy of the elastomer. CTBN-modified epoxies exhibited lower friction coefficients than epoxies modified with polysiloxane. It was found that sample morphology had a significant effect on both friction coefficient and wear rate; the sample with approximately the same domain size but the least number of elastomeric domains exhibited the highest friction coefficient and the highest wear rate. / Ph. D.