Made available in DSpace on 2017-07-21T20:42:40Z (GMT). No. of bitstreams: 1 Luiza Kupchak.pdf: 1787533 bytes, checksum: ed9f8e72989aa4cdbca14d73ae5bce65 (MD5) Previous issue date: 2007-02-23 / The polycrystalline ceramics study the base of SnO2 presents great interest due to the inherent properties of emiconductor, which allows the application in some types of components, such as, protective gas sensors, varistors, protects films for different refractory uses and for glasses fusion of heavy metals. The addition of ZnO to the SnO2, makes with that these ceramics get high densification when added the low concentrations. In this work it of sintering in the initial period of training was studied kinetic, of the SnO2 with addition of 0,6% and 1,2% in mol of ZnO. The used methods of study had been the considered ones for Venkatu-Johnson, Woolfrey-Bannister, Wang-Raj and Young-Cutler. With the application of these models it was determined the energy of activation and the possible operating mechanisms in the system. The samples had been gotten by means of mixture of oxides, isostatic pressing and sintering in dilatometer, under taxes of constant heating of 2,5, 5 and 10 ºC.min- 1 until the temperature of 1350 ºC to air. The techniques used to carry through the characterization of the sintered samples had been to the ones of pycnometry of helium, diffraction of rays X and electronic microscopy of sweepings. It was verified that the addition of ZnO to the SnO2 made possible the ceramics attainment with superior relative densities 90%. The values of energy of activation gotten for the SnO2 with 0,6% in mol of ZnO, for the diverse studied models are of: 500 kJ.mol-1; 555 kJ.mol-1; 540 kJ.mol-1; 491 kJ.mol-1, respectively. For the SnO2 with 1,2% in mol of ZnO, the values of activation energy supplied by the models had been of: 444 kJ.mol-1; 555 kJ.mol-1; 424 kJ.mol-1; 491 kJ.mol-1, respectively. The results for the dominant mechanism of the sintering gotten from the used models did not allow to determine precisions from the operating diffusional mechanism in the studied compositions. / O estudo de cerâmicas policristalinas a base de SnO2 apresenta grande interesse devido às propriedades inerentes a este semicondutor, as quais permitem a aplicação em vários tipos de componentes, tais como, sensores de gás, aristores, filmes protetores para diferentes usos e refratários para fusão de vidros de metais pesados. A adição de ZnO ao SnO2, faz com que estas cerâmicas obtenham elevada densificação quando adicionadas a baixas concentrações. Neste trabalho estudou-se a cinética de sinterização no estágio inicial, do SnO2 com adição de 0,6% e 1,2% em mol de ZnO. Os étodos de estudo utilizados foram os propostos por Venkatu-Johnson, Woolfrey-Bannister, Wang-Raj e Young-Cutler. Com aplicação destes modelos foi determinada a energia de ativação e os possíveis mecanismos atuantes no sistema. As amostras foram obtidas por meio de mistura de óxidos, prensagem isostática e sinterização em dilatômetro, sob taxas de aquecimento constante de 2,5, 5 e 10 ºC.min-1 até a temperatura de 1350 oC ao ar. As técnicas utilizadas para realizar a caracterização das amostras sinterizadas foram às de picnometria de hélio, difração de raios X e microscopia eletrônica de varredura. Verificou-se que a adição de ZnO ao SnO2 possibilitou a obtenção de cerâmicas com densidades relativas superiores a 90%. Os valores de energia de ativação obtidos para o SnO2 com 0,6% em mol de ZnO, para os diversos modelos estudados são de: 500 kJ.mol-1; 555 kJ.mol-1; 540 kJ.mol-1; 491 kJ.mol-1,respectivamente. Para o SnO2 com 1,2% em mol de ZnO, os valores de energia de ativação fornecidos pelos modelos foram de: 444 kJ.mol-1; 555 kJ.mol-1; 424 kJ.mol-1; 491 kJ.mol-1, respectivamente. Os resultados para o mecanismo dominante da sinterização obtido a partir dos modelos utilizados não permitiu determinar de forma precisa o mecanismo difusional atuante nas composições estudadas.

Submitted by Setor de Tratamento da Informa??o - BC/PUCRS (tede2@pucrs.br) on 2015-04-17T13:52:43Z No. of bitstreams: 1 467312 - Texto Completo.pdf: 12104060 bytes, checksum: fab068a173a82aab41a55d8875dc36ae (MD5) / Made available in DSpace on 2015-04-17T13:52:43Z (GMT). No. of bitstreams: 1 467312 - Texto Completo.pdf: 12104060 bytes, checksum: fab068a173a82aab41a55d8875dc36ae (MD5) Previous issue date: 2015-03-30 / In this study the spatial confinement effects on the topological (mass transport and particle ejection) and chemical modifications of poly(methyl methacrylate) thin films (1<?<360 nm) irradiated by swift heavy ions were systematically investigate. The surface tracks dimensions were characterized by atomic force microscopy and the results show that the surface effects are weakened when the length of the ion track is spatially confined down to few nanometers. The deviation from bulk-like behavior starts at a critical thickness ?1 as large as ~40 nm to the ridge volume, due to effects associated to cooperative action of excited material along the track. However, ?1 is much smaller for effects related to events close to the surface, such as the crater size (?1~10 nm). Analytical calculations based on the pressure pulse model were carried out to investigate theoretical aspects of the ion-matter energy transfer in the transport and dissipation of the deposited energy. The results obtained from these calculations match the experimental observations. Chemical modifications were investigated by quantifying bond breaking rates, extracted by x-ray photoelectron spectroscopy. Cross sections for carbon-oxygen bonds for films under Bi irradiation are slightly smaller for thinner films, whilst for proton irradiation the values do not show substantial difference down to the smallest thickness viable for analysis (?~5 nm). From these set of data it is verified that the ionic irradiation effects on polymer thin films are weakened under spatial confinement into layers with ? below a certain critical value ?1, dependent on the probed effect. Substantial difference on the surface track dimensions were not observed between the distinct substrates investigated. / Neste trabalho foram investigados sistematicamente os efeitos de confinamento espacial nas modifica??es topol?gicas (transporte de massa e eje??o de part?culas) e qu?micas induzidas por ?ons pesados de alta energia (de dezenas a milhares de MeV) em filmes finos de poli(metacrilato de metila) (1< ? <360 nm). As dimens?es dos efeitos de superf?cie induzidos pela irradia??o foram caracterizadas por microscopia de for?a at?mica e os resultados mostram claramente o enfraquecimento dos efeitos induzidos pela irradia??o quando o comprimento da trilha ? reduzido a poucos nan?metros. Desvios do comportamento observado para filmes bulk come?am em uma espessura cr?tica ?1 t?o grande quanto ~40 nm para o volume da protuber?ncia, devido ? redu??o dos efeitos de a??o cooperativa de material excitado ao longo da trilha. Entretanto, ?1 ? bem menor para efeitos relacionados a eventos pr?ximos ? superf?cie, como o tamanho cratera (?1~10 nm). C?lculos anal?ticos pelo modelo do pulso de press?o foram utilizados para investigar aspectos te?ricos da transfer?ncia de energia ?on-material no transporte e dissipa??o da energia depositada. Os resultados obtidos a partir desses c?lculos corroboram com observa??es experimentais. As modifica??es qu?micas foram investigadas atrav?s das se??es de choque de quebra de liga??es, extra?das por espectroscopia de fotoel?trons por raios x. As se??es de choque de danos para as liga??es carbonooxig?nio, obtidas para irradia??es com ?ons de Bi de 2,2 GeV, s?o levemente reduzidas para filmes mais finos, enquanto as se??es de choque para filmes irradiados com pr?tons de 2 MeV n?o mostram diferen?as significativas at? a espessura mais fina acess?vel por an?lise de XPS (?~5 nm). A partir desse conjunto de dados verificou-se o enfraquecimento dos efeitos induzidos pela irradia??o em filmes polim?ricos sob confinamento espacial em camadas com ? abaixo de um valor cr?tico ?1, sendo ?1 dependente do efeito sondado. N?o foram observadas diferen?as significativas do efeito da espessura para diferentes substratos.

Submitted by Setor de Tratamento da Informa??o - BC/PUCRS (tede2@pucrs.br) on 2015-04-23T12:59:33Z No. of bitstreams: 1 467471 - Texto Parcial.pdf: 1098717 bytes, checksum: dc907ba7a9887333798678bb2fb41cf1 (MD5) / Made available in DSpace on 2015-04-23T12:59:33Z (GMT). No. of bitstreams: 1 467471 - Texto Parcial.pdf: 1098717 bytes, checksum: dc907ba7a9887333798678bb2fb41cf1 (MD5) Previous issue date: 2014-10-31 / The search for new exploratory frontiers has led to the development of a wide variety of geological sampling equipment, especially for marine environments with water depths greater than 300 meters. Maintaining the in situ conditions of these environments, particularly the pressure, provides quality to the sampling process as it prevents loss of sample elements, especially gases, during the retrieval process. In this context the device developed for this research aimed to collect fluids, particularly gases, in an automated manner from deep-water environments at depths up to 3000 meters and to maintain them under the same pressure conditions as when collected. The device is programmed at the surface and subsequently transported to the collection site, for example, with the aid of an underwater inspection remotely operated vehicle (ROV). In addition to laboratory validation, the proposed device was also tested under real sea conditions. No equivalent equipment to the device developed in this dissertation exists and it was therefore patented. / Devido ? procura por novas fronteiras explorat?rias, uma grande variedade de equipamentos para amostragem geol?gica vem sendo desenvolvidos, em especial para ambientes marinhos com profundidades superiores a 300 metros. A manuten??o das condi??es in situ destes ambientes, notadamente a press?o, conferem qualidade ao processo de amostragem uma vez que evita a perda de elementos da amostra durante a recupera??o, especialmente gases. Neste contexto o dispositivo desenvolvido nesta disserta??o tem o prop?sito de coletar fluidos, em especial gases, de forma automatizada em ambientes subaqu?ticos em profundidades de at? 3000 metros e mant?-los nas condi??es de press?o da coleta. O dispositivo ? programado na superf?cie, sendo necess?rio transport?-lo at? o local de trabalho, com aux?lio de um ve?culo submarino de opera??o remota (ROV) de inspe??o, por exemplo. Al?m da valida??o em laborat?rio, o dispositivo proposto foi tamb?m avaliado em condi??es reais de mar. Por n?o existir equipamento igual ao desenvolvido nesta disserta??o, o mesmo foi patenteado.

Submitted by Setor de Tratamento da Informa??o - BC/PUCRS (tede2@pucrs.br) on 2015-06-02T16:53:40Z No. of bitstreams: 1 469858 Texto Completo.pdf: 7135001 bytes, checksum: 232fdeb10ae43ec70dca9941fb5b3828 (MD5) / Made available in DSpace on 2015-06-02T16:53:41Z (GMT). No. of bitstreams: 1 469858 Texto Completo.pdf: 7135001 bytes, checksum: 232fdeb10ae43ec70dca9941fb5b3828 (MD5) Previous issue date: 2015-03-24 / Ternary alloys of III-V semiconductor materials, in particular Ga1-xInxSb, are ideal candidates for substrates because of the possibility to define the lattice constant as a function of concentration of the third element, indium, enabling the adjustment of the lattice parameter in accordance to the subsequent epitaxial layer. Therefore, the mono-crystallinity of the epitaxial layer is favored and the tensions at the interface layer/substrate are reduced, allowing to numerous possibilities and applications. Aluminum (Al) is considered an isoelectric dopant for Ga and In, meaning that it does not change the number of charge carriers, but increases the mobility in GaSb crystals. When Al is added to the Ga1-xInxSb ternary alloy, it can have influence over native defects passivating and/or compensating them. To understand the influence of Al on the distribution of indium (In) in ternary alloys of Ga1-xInxSb, pure and doped Ga0,8In0,2Sb crystals were obtained with approximately 1020 atoms/cm3 of Al using a vertical Bridgman system.Analysis by scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS), X-ray diffraction (XRD), particle induced X-ray emission (PIXE) and particle induced gamma ray emission (PIGE) were used for the structural and compositional characterization of the crystals. The obtained crystals of Ga0,8In0,2Sb, doped with aluminum or not, exhibited segregation of the third element, however, for Ga0,8In0,2Sb:Al crystals the segregation decreased. The crystals of Ga0,8In0,2Sb:Al presented a good structural homogeneity when compared to the undoped alloy, and they were free from cracks and micro cracks. All of the obtained crystals presented precipitates, twins and grains with different concentrations of In. In the crystals doped with aluminum, single regions were observed in the solidification direction, which can be associated to a more uniform distribution of indium.The small compositional variation observed in the crystals, in radial direction, and measured by PIXE, may be related to the solid-liquid interface?s quasi-equilibrium behavior. The results indicated that aluminum has influenced the indium distribution in the crystals, in the solidification direction, and the electrical properties imply that the aluminum may have contributed to the generation of accepter defects such as GaSb, InSb e AlSb, wherein the number of charge carriers increased in the doped crystals. The possibility of complex defects generation such as (VGaGaSb), (VGaInSb) e (VGaAlSb) cannot be excluded, since the charge mobility in the doped crystals decreased. / Ligas tern?rias de materiais semicondutores III-V, nomeadamente Ga1-xInxSb, s?o candidatas ideais para substratos, pois a possiblidade de se definir a constante de rede em fun??o da concentra??o do terceiro elemento, o ?ndio, possibilita o ajuste do par?metro de rede de acordo com a camada epitaxial subsequente. Desta forma, a monocristalinidade da camada epitaxial ? favorecida e as tens?es na interface camada/substrato s?o diminu?das, introduzindo in?meras possibilidades e aplica??es. O alum?nio (Al) ? considerado um dopante isoel?trico do Ga e do In, isto ?, n?o altera o n?mero de portadores de carga, mas aumenta a mobilidade em lingotes de GaSb. Ao ser adicionando na liga tern?ria Ga1-xInxSb, pode influenciar passivando e/ou compensando os defeitos nativos. Para compreender a influ?ncia do Al na distribui??o do ?ndio (In) em ligas tern?ria de Ga1-xInxSb, foram obtidos lingotes de Gao,8In0,2Sb puros e dopados com aproximadamente 1020 ?tomos/cm3 de Al em um sistema Bridgman vertical.An?lises por microscopia eletr?nica de varredura (MEV), espectroscopia por dispers?o de energia (EDS), difra??o de raios X (XRD), emiss?o de raios X induzida por part?culas (PIXE) e emiss?o de raios gama induzida por part?culas (PIGE) foram utilizadas para a caracteriza??o estrutural e composicional dos lingotes. Os lingotes de Ga0,8In0,2Sb obtidos, dopados ou n?o com alum?nio, apresentaram segrega??o do terceiro elemento, por?m, para os lingotes Ga0,8In0,2Sb:Al a segrega??o foi menor. Os lingotes de Ga0,8In0,2Sb:Al apresentaram uma boa homogeneidade estrutural, livres de fissuras e micro trincas, quando comparados ? liga n?o dopada. Todos os lingotes obtidos apresentam forma??o de precipitados, maclas e gr?os com diferentes concentra??es de In. Nos lingotes dopados com alum?nio foram observadas regi?es com pequena quantidade de gr?os na dire??o da solidifica??o, que podem ser atribu?das a uma distribui??o do ?ndio mais uniforme. A pequena varia??o composicional observada nos lingotes, no sentido radial, mensurada por PIXE, pode ser atribu?da ao comportamento pr?ximo ao equil?brio da interface s?lido-liquido.Os resultados obtidos sugerem a influ?ncia do alum?nio na distribui??o de ?ndio nos lingotes, na dire??o da solidifica??o, ao mesmo tempo que as propriedades el?tricas sugerem que o alum?nio possa ter contribu?do para a gera??o de defeitos aceitadores como GaSb, InSb e AlSb, sendo que o n?mero de portadores de carga aumentou nos lingotes dopados. N?o se exclui a possibilidade da gera??o de defeitos complexos como (VGaGaSb), (VGaInSb) e (VGaAlSb), uma vez que a mobilidade das cargas nos lingotes dopados diminuiu.

Submitted by Setor de Tratamento da Informa??o - BC/PUCRS (tede2@pucrs.br) on 2015-06-24T21:45:32Z No. of bitstreams: 1 471013 - Texto Completo.pdf: 1943495 bytes, checksum: 36e051cefa7a9d47d6a0d608dff24d67 (MD5) / Made available in DSpace on 2015-06-24T21:45:32Z (GMT). No. of bitstreams: 1 471013 - Texto Completo.pdf: 1943495 bytes, checksum: 36e051cefa7a9d47d6a0d608dff24d67 (MD5) Previous issue date: 2012-07-16 / The following paper reports the synthesis of polyaniline (PANI) nanofibers and the making of nanocomposites that have polypropylene as their polymer matrix. Polyaniline nanofibers have been synthesized by the quick-mix method. Hydrochloridric and sulfuric acids were evaluated as dopant agents in different reaction temperatures: 25, 60 and 100 ?C. Polypropylene (PP) nanocomposites were prepared by adding 1 and 3% (m/m) of PANI nanofibers through three different methods utilized for dispersing the nanocharge in the polymer matrix. This way parameters such as quick-mix in the fusion chamber, masterbach prepping and pre- dispersion of the charge in ethanol were appraised. The morphology and the electric, thermic and mechanic properties of the PANI nanofibers as well as the nanocomposites prepared were evaluated by means of Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC) and Electrical Impedance Spectroscopy (EIS). Nanofibers of the upmost definition were obtained with hydrochloridric acid as the dopant agent in a temperature of 60 ?C. The nanofibers prepped using this methodology presented electrical resistivity of 10? Wcm and a decomposition temperature near 300 ?C. AFM pictures indicate good charge distribution in the polymer matrix regardless of the chosen preparation method. It was verified that the nanocomposites? thermic properties were not negatively affected by the addition of PANI nanofibers and composites with similar traction properties to PP?s matrices were produced with a larger ultimate elongation and electrical conducting properties. / O presente trabalho relata a s?ntese de nanofibras de polianilina (PANI) e a prepara??o de nanocomp?sitos contendo polipropileno como matriz polim?rica. Nanofibras de polianilina foram sintetizadas pelo m?todo da mistura r?pida. ?cido clor?drico e ?cido sulf?rico foram avaliados como agentes dopantes em diferentes temperaturas de rea??o: 25, 60 e 100 ?C. Nanocomp?sitos de polipropileno (PP) foram preparados adicionando-se 1 e 3% (m/m) de nanofibras de PANI por tr?s diferentes m?todos utilizados para dispersar a nanocarga na matriz polim?rica. Assim foram avaliados par?metros como a mistura direta na c?mara de fus?o, prepara??o de masterbach e pr?-dispers?o da carga em etanol. A morfologia, as propriedades el?tricas, t?rmicas e mec?nicas das nanofibras de PANI e dos nanocop?sitos preparados foram avaliados por Microscopia Eletronica de Varredura (MEV), Microscopia de For?a At?mica (AFM), An?lise Termogravim?trica (TGA), Calorimetria Diferencial Explorat?ria (DSC) e Espectroscopia de Imped?ncia El?trica (EIE). Nanofibras com morfologia mais definida foram obtidas quando foi utilizado o ?cido clor?drico como agente dopante, na temperatura de 60?C. As nanofibras preparadas por essa metodologia apresentaram resistividade el?trica na ordem de 102 ?cm e temperatura de decomposi??o pr?xima a 300?C. Imagens de AFM indicam uma boa distribui??o da carga na matriz polim?rica, independentemente do m?todo de prepara??o utilizado. Foi verificado que as propriedades t?rmicas dos nanocomp?sitos n?o foram afetadas negativamente com a adi??o das nanofibras de PANI, e foram produzidos comp?sitos com propriedades de tra??o semelhantes ? matriz de PP, com maior alongamento na ruptura e propriedades el?tricas condutoras.

Submitted by Setor de Tratamento da Informa??o - BC/PUCRS (tede2@pucrs.br) on 2015-06-24T22:19:49Z No. of bitstreams: 1 471017 - Texto Completo.pdf: 5708318 bytes, checksum: 28730b4a87bc0d3ea819556c7b2b4dc6 (MD5) / Made available in DSpace on 2015-06-24T22:19:49Z (GMT). No. of bitstreams: 1 471017 - Texto Completo.pdf: 5708318 bytes, checksum: 28730b4a87bc0d3ea819556c7b2b4dc6 (MD5) Previous issue date: 2015-03-12 / Lesions in bone tissue reach 15 million cases per year worldwide. Thus, a significant amount of bone tissue transplants have been performed in recent years. A promising alternative to bone graft is in the field of tissue engineering, which is based on the use of polymeric structures acting as support for hard tissue regeneration. The objective of this project was look for the association of the PLGA copolymer, to the bioceramic hydroxyapatite, to form a polymeric bioactive macroporous structure. The preparation was made through the PLGA dissolution in chloroform, followed by addition of sodium chloride and hydroxyapatite (porogenic agent). Molding of the samples was performed by compression in hydraulic press. After, was performed the leaching of the scaffolds, followed by treatment with NaOH. Finally the composites obtained were characterized by FEG - SEM, in order to analyze qualitatively the morphology, porosity and interconnectivity of the pores; the hydrophilicity of the surface was evaluated by wettability tests it was proved chemical treatment efficiency; in vitro hydrolytic degradation assays performed as a function of time demonstrate that the percentage of degradation of various types of scaffolds did not showed significant changes between 14 and 42 days. Hydrolytic degradation assays found yet that the fluid retention was higher in scaffolds chemically treated; compression tests evaluated the mechanical behavior of different types of scaffolds made. It was concluded then that the methodology used originated macroporous composites that may be applied in bone tissue engineering. / Les?es em tecido ?sseo chegam a somar 15 milh?es de casos por ano mundialmente. Diante disso, uma quantidade significativa de transplantes de tecidos ?sseos tem sido realizada nos ?ltimos anos. Uma alternativa promissora para enxertos ?sseos est? na ?rea da engenharia de tecidos, que se baseia na utiliza??o de estruturas polim?ricas atuando como scaffolds para regenera??o do tecido duro. O objetivo deste trabalho foi buscar a associa??o entre o copol?mero PLGA e a biocer?mica hidroxiapatita com a finalidade de formar uma estrutura polim?rica bioativa macroporosa. A confec??o foi dada atrav?s da dissolu??o de PLGA em clorof?rmio, seguida da adi??o de hidroxiapatita e cloreto de s?dio (agente porog?nico). A moldagem das amostras foi realizada por compress?o em prensa hidr?ulica. Ap?s, foi feita a lixivia??o das amostras, seguida do tratamento com NaOH. Finalmente os comp?sitos obtidos foram caracterizados atrav?s de MEV-FEG, visando analisar qualitativamente a morfologia, a porosidade e a interconectividade dos poros; a hidrofilicidade das superf?cies foi analisada por testes de molhabilidade em que foi comprovada a efici?ncia do tratamento qu?mico; ensaios de degrada??o hidrol?tica realizados em fun??o do tempo revelaram que o percentual de degrada??o dos diferentes tipos de scaffolds n?o apresentou mudan?a significativa entre os tempos de 14 e 42 dias. O ensaio de degrada??o hidrol?tica constatou ainda que a reten??o de l?quido fora maior em scaffolds tratados quimicamente; os ensaios de compress?o avaliaram o comportamento mec?nico dos diferentes tipos de scaffolds confeccionados. Concluiu-se, ent?o, que a metodologia utilizada originou comp?sitos macroporosos que podem vir a ser aplicados na engenharia de tecido ?sseo.

Submitted by Setor de Tratamento da Informa??o - BC/PUCRS (tede2@pucrs.br) on 2015-06-29T11:27:22Z No. of bitstreams: 1 471334 - Texto Completo.pdf: 4524191 bytes, checksum: f5450152427bd38ead2e27ad8d28c46b (MD5) / Made available in DSpace on 2015-06-29T11:27:23Z (GMT). No. of bitstreams: 1 471334 - Texto Completo.pdf: 4524191 bytes, checksum: f5450152427bd38ead2e27ad8d28c46b (MD5) Previous issue date: 2012-07-12 / This work aims to obtain polymer blends containing polypropylene wtih conductive nanofibers formed by polyaniline and graphite nanosheets. Will study the effects of morphology and the electrical and mechanical properties of the resulting polymer. The polyaniline nanofibers are synthesized in the presence of graphite nanosheets using the methodology of rapid mixing. The preparation of blends of polypropylene is made by melting in the inner chamber. The morphology and structure of the nanofillers and blends will be evaluated by scanning electron microscopy (SEM), and Atomic Force Microscopy (AFM). The mechanical properties through tensile testing. The electrical properties by impedance spectroscopy. It was observed that a better dispersion of graphite with polyaniline nanofibers occurs when made in the aqueous solution containing the monomer, aniline in the presence of APS ultrasound for 1 hour. The electrical properties of the synthesized nanocomposite indicate characteristics of semiconductor. The mechanical and thermal properties of the blends did not change significantly with the addition of nanofillers, Higher conductivity values were obtained for high values of frequency, 106 Hz / Este trabalho busca a obten??o de blendas polim?ricas de polipropileno contendo nanocarga condutiva formada por nanofibras de polianilina (PANI) e nanol?minas de grafite (NLG). Foram estudados os efeitos da nanocarga na morfologia e nas propriedades el?tricas e mec?nicas do pol?mero resultante. As nanofibras de PANI foram sintetizadas na presen?a das nanol?minas de grafite por meio da metodologia da mistura r?pida. A prepara??o das blendas com polipropileno foi realizada por fus?o em c?mara interna. A morfologia e estrutura da carga nanom?trica e das blendas foram avaliadas por meio da Microscopia Eletr?nica de Varredura (MEV) e Microscopia ?tica, as propriedades mec?nicas por meio de ensaio de tra??o, as propriedades el?tricas por meio da Espectroscopia de Imped?ncia. Foi observado que a melhor dispers?o das nanol?minas de grafite junto ? polianilina ocorre quando feita na solu??o aquosa contendo o mon?mero, anilina, na presen?a do Persulfato de Am?nio (APS) durante 1h de ultrassom. As propriedades el?tricas dos nanocomp?sitos sintetizados indicam caracter?sticas de semicondutor. As propriedades mec?nicas e t?rmicas das blendas n?o sofreram altera??es significativas com a adi??o da nanocarga. Maiores valores de condutividade foram obtidos para elevados valores de frequ?ncia, 106 Hz.

Submitted by Setor de Tratamento da Informa??o - BC/PUCRS (tede2@pucrs.br) on 2015-07-10T11:39:38Z No. of bitstreams: 1 471999 - Texto Completo.pdf: 2373737 bytes, checksum: 065804161c759cccca6c7119ea152d3f (MD5) / Made available in DSpace on 2015-07-10T11:39:38Z (GMT). No. of bitstreams: 1 471999 - Texto Completo.pdf: 2373737 bytes, checksum: 065804161c759cccca6c7119ea152d3f (MD5) Previous issue date: 2015-03-27 / People have rampantly consumed batteries, thereby obtaining mobile, low cost and highly durable energy. However, many consumers do not recognize that these batteries may contain high level of heavy metals in their composition and so discard them inappropriately with their household trash daily. In order to minimize the problems caused by batteries to the environment, legislations have been created throughout the world. In Brazil, Resolution CONAMA 401 of 2008 established the maximum levels of toxic metals in batteries. This thesis was developed with the objective of verifying the levels of cadmium, lead and mercury in order to validate an analytical method for the determination of theses toxic metals in alkaline batteries. 193 samples of alkaline batteries collected from the Brazilian market between 2010 and 2011 were evaluated; none of the evaluated samples had cadmium levels above the allowed maximum (0.002%). However, 10 samples were found to have levels of mercury that exceeded the allowed maximum of 0.0005% and 8 of the analyzed batteries had levels of lead that were higher than the allowed (0.1%). The results obtained show a high percentage of failure (9.3%) of the samples analyzed, which indicates the necessity of controlling the use of toxic metals. / A popula??o tem consumido desenfreadamente pilhas e baterias, obtendo assim energia m?vel de baixo custo e alta durabilidade. Muitas vezes n?o tendo o conhecimento de que estas pilhas e baterias possuem metais t?xicos em sua constitui??o, o descarte ? feito de forma inadequada, milhares de pilhas sendo descartadas em lixo comum diariamente. Para minimizar os problemas causados pelas pilhas ao meio ambiente, legisla??es foram criadas em diversas partes do mundo. No Brasil a Resolu??o CONAMA 401 de 2008 estabelece os limites m?ximos de metais t?xicos em pilhas e baterias. Com o objetivo de verificar os n?veis de c?dmio, chumbo e merc?rio, o presente trabalho foi desenvolvido para validar um m?todo anal?tico para a determina??o destes elementos t?xicos presentes em pilhas alcalinas. Foram avaliadas 193 amostras coletadas no mercado brasileiro nos anos de 2010 e 2011. Nenhuma das amostras possu?a quantidade de c?dmio acima do estipulado (0,002%). Por?m dez e oito amostras apresentaram concentra??o de Hg (0,0005%) e Pb (0,1%) excedendo o limite ambiental, respectivamente. Os resultados obtidos indicaram percentual de reprova??o elevado (9,30%) para as pilhas alcalinas ensaiadas, indicando a necessidade do controle desses metais.

Submitted by Setor de Tratamento da Informa??o - BC/PUCRS (tede2@pucrs.br) on 2015-09-16T22:28:34Z No. of bitstreams: 1 474863 - Texto Completo.pdf: 113191714 bytes, checksum: 284055c8f9508bc0fbd7e2b9c7022e03 (MD5) / Made available in DSpace on 2015-09-16T22:28:34Z (GMT). No. of bitstreams: 1 474863 - Texto Completo.pdf: 113191714 bytes, checksum: 284055c8f9508bc0fbd7e2b9c7022e03 (MD5) Previous issue date: 2015-06-05 / The concrete, due to its high strength, low cost and moldability, is the most popular building material at the moment when compared with other materials used for the same purposes. In this context, with the continued growth of urban areas, the number of buildings and large roads structures has also increased. For this reason, many animal species have had to adapt themselves to these new environmental conditions and have started to use human buildings, which can often simulate nature conditions, as shelters. Thus, the metabolism waste resulting from these animals began to chemically interact with these building materials, causing substantially degradation. The main aim of this work is to show how the biological waste, in this case, bat guano, can promote chemical degradation of the cement paste. To that purpose, the chemical attack of cement hardened sampleswas realized in different exposition times in with aqueous solutions of nitric acid and sulfuric acid at pH 4.5, simulating the bat guano oxidation conditions, where these acids, among other substances, are formed. The results indicate that nitric acid is more aggressive to cement paste than the sulfuric acid as evidenced by electron microscopy images where there was a more intensive deterioration of the cement matrix on the surface of cement hardened samples. The images generated by the X-ray microtomographyshowed that there is a difference on density of the cement matrix in the region chemically attacked, in particular when the sulfuric acid was used, which can be associated with the corrosion product properties formed due the sulfuric acid reaction with the cementitious matrix. The hardened cement paste samples showed mass increase with exposition time, probably due to the respective calcium salts deposition on the surface formed as products of chemical attack. / O concreto ? o material mais usado na constru??o de edifica??es na atualidade, devido a sua grande resist?ncia, moldabilidade, durabilidade e baixo custo, entre outras caracter?sticas, quando comparado com outros materiais utilizados para os mesmos fins. Neste contexto, com o cont?nuo crescimento das ?reas urbanas, o n?mero de edifica??es e grandes obras de arte da malha vi?ria tamb?m cresceram. Desta forma, muitas esp?cies animais necessitaram se adaptar a essas novas condi??es, devido ? modifica??o de seu ambiente natural e passaram a utilizar as edifica??es humanas, que muitas vezes simulam condi??es encontradas na natureza, como abrigos. Assim, os res?duos resultantes do metabolismo desses animais, passaram a interagir com os materiais constituintes dessas edifica??es, agredindo substancialmente este material. Este trabalho tem como principal objetivo mostrar como os res?duos da atividade de agentes biol?gicos, neste caso o guano dos morcegos, podem promover a degrada??o qu?mica na pasta ciment?cia. Para tal, realizou-se o ataque qu?mico,em diferentes de exposi??o, em corpos de prova com dois tipos de solu??es aquosas de ?cido n?trico e ?cido sulf?rico com pH 4,5, simulando as condi??es da oxida??o do guano dos morcegos, onde estes ?cidos, entre outras subst?ncias, est?o presentes. O ?cido n?trico mostrou-se mais agressivo do que o sulf?rico, sendo isso evidenciado pelas imagens de microscopia eletr?nica onde se observou uma deteriora??o maior da matriz ciment?cia na superf?cie dos corpos de prova. Nas imagens geradas no microtom?grafo de raios X verificou-se diferen?a de densidade na matriz ciment?cia, especialmente com o ataque de ?cido sulf?rico, devido aos produtos da rea??o deste ?cido com a matriz ciment?cia. Os corpos de prova apresentaram aumento de massa em fun??o tempo provavelmente devido ? deposi??o dos respectivos sais de c?lcio formados pelo ataque ?cido.

Submitted by Setor de Tratamento da Informa??o - BC/PUCRS (tede2@pucrs.br) on 2015-11-26T11:39:49Z No. of bitstreams: 1 476451 - Texto Completo.pdf: 8210475 bytes, checksum: d312c576e78b0f9de246885a55a53e56 (MD5) / Made available in DSpace on 2015-11-26T11:39:49Z (GMT). No. of bitstreams: 1 476451 - Texto Completo.pdf: 8210475 bytes, checksum: d312c576e78b0f9de246885a55a53e56 (MD5) Previous issue date: 2015-03-03 / The search for improvements in the properties of polymer matrices has been the subject of several studies. Among these, the use of inorganic fillers has shown results that demonstrate improvements in many properties of the polymers. In this context, this study aimed to preparation of titanates nanotubes (TNT) and its application in polyurethane nanocomposites (PU). In order to the TNT were synthesized from commercial TiO2 in anatase phase by hydrothermal method. After, these TNT were functionalized (TNTF) with hexamethylene diisocianato (HDI) and silanes compounds: aminopropyl trimethoxysilane (APTMS) and tetraethyl orthosilicate (TEOS) in order to study the interaction of the functionalizated charge with the polymer matrix. The titanates nanotubes (TNT) and titanates nanotubes functionalized (TNTF) were characterized regarding their morphological and structural properties. Nanocomposites of PU with TiO2, TNT and TNTF were synthesized, via in situ polymerization and characterized by FTIR, GPC, SEM, TEM (just NTT), AFM, TGA, DSC and DRX techniques. The results showed that the TNT synthesis by hydrothermal method was effective and was obtained nanotubes formed with a minimum of 3 staked sheets. The TNTF functionalized with APTMS and TEOS showed clustered structures whereas with HDI has a separation of nanotubes. The addition of TNT-HDI provided an increase of polymer molar weight. All nanocomposites showed higher thermal stability (between 330-340oC) than the pure PU (325oC). Nanocomposites PU/TNTF presented the highest values for crystallization temperature (? 6-10oC) when compared to pure PU (5oC), besides of its enthalpies, indicating that TNTF promote the increase of the polyurethane crystallinity. / A busca por melhorias nas propriedades de matrizes polim?ricas tem sido motivo de muitos estudos. Entre estes, a aplica??o de cargas inorg?nicas tem apresentado resultados que evidenciam melhorias nas diversas propriedades dos pol?meros. Dentro deste contexto insere-se este trabalho, que teve como objetivo principal a prepara??o de nanotubos de titanatos (NTT) e sua aplica??o em nanocomp?sitos de poliuretano (PU). Para tanto, os NTT foram sintetizados partindo de TiO2 comercial na fase anat?sio por m?todo hidrot?rmico. Ap?s, estes NTT foram funcionalizados (NTTF) com hexametilenodiisocianato (HDI) e os compostos: aminopropil trimetoxisilano (APTMS) e tetraetil ortosilicato (TEOS) a fim de estudar a influ?ncia destas funcionaliza??es na intera??o da carga com a matriz polim?rica. Os nanotubo de titanatos (NTT) e os nanotubos de titanatos funcionalizados (NTTF) foram caracterizados em rela??o as suas propriedades morfol?gicas e estruturais. Nanocomp?sitos de PU com TiO2, NTT e NTTF foram sintetizados, via polimeriza??o in situ, e caracterizados por t?cnicas de FTIR, GPC, MEV, MET (somente os NTT), AFM, TGA, DSC e DRX. Os resultados mostraram que a s?ntese dos NTT pelo m?todo hidrot?rmico foi eficiente e obteve-se nanotubos formados por no m?nimo 3 folhas empilhadas. Os NTTF funcionalizados com APTMS e TEOS apresentaram estruturas aglomeradas enquanto que com HDI houve afastamento dos nanotubos. A adi??o de NTT-HDI proporcionou um aumento da massa molar do pol?mero e maior mobilidade para a cadeia. Todos os nanocomp?sitos apresentaram maior estabilidade t?rmica (entre 330-340oC) que o PU padr?o (325oC). Os nanocomp?sitos PU/NTTF apresentaram os maiores valores para as temperaturas de cristaliza??o (? 6-10oC) comparado ao PU padr?o (Tc=5oC), al?m das respectivas entalpias indicando que os NTTF aumentam a cristalinidade do poliuretano.