A combinação de excelentes propriedades mecânicas aliadas à biocompatibilidade torna a borracha natural um material amplamente empregado na fabricação de artefatos voltados à saúde, tais como bicos de chupetas e de mamadeiras, e luvas cirúrgicas e de procedimentos não-cirúrgicos. Esses artefatos são processados a partir de látices de poli(cis-isopreno) extraído de seringueiras. Entretanto, o grande número de insaturações presentes na cadeia polimérica, mesmo após a vulcanização, resulta em uma baixa resistência desse material ao envelhecimento, causado principalmente pela associação de fatores como temperatura, oxigênio, ozônio e radiação. Outro inconveniente associado à aplicação da borracha natural é a presença de proteínas no látex, com potencial alergênico, podendo promover reações fisiológicas em alguns usuários. Por esse motivo artefatos comerciais à base de material sintético também são encontrados no mercado. Esses artefatos também não são isentos dos processos naturais de desgaste e decomposição. Esta Dissertação teve como objetivo realizar um estudo comparativo de propriedades dos produtos comerciais à base de borracha natural e à base de material sintético (bicos de chupeta e de mamadeiras e luvas) de diferentes fabricantes, como adquiridos e após sofrerem envelhecimento acelerado. O estudo foi feito empregando-se as técnicas de espectroscopia na região do infravermelho com transformada de Fourier (FTIR) e termogravimetria (TG). Uma avaliação mecânica com métodos padronizados foi também realizada / By combining the excellent mechanical properties as well as biocompatibility, natural rubber is a suitable material to be applied in the manufacture of commercial articles as pacifiers, nursing bottles and gloves. Those products are processed from lattices of poly(cis-isoprene) extracted from rubber-trees. Nevertheless, the expressive amount of insaturations present along the polymeric chains, even after the vulcanization process, leads to degradation mainly caused by an association of factors as heat, oxygen, ozone and radiation. Another inconvenience in the application of natural rubber is the presence of some proteins in the latex, which causes allergic problems in a few usuaries. Thus synthetic materials are also employed in the production of such articles that are not free from degradation problems as well. The objective of this Dissertation was to carry out a comparative study of some properties of commercial products (nipples, of pacifiers and nursing bottles, and gloves) from different manufacturers. The materials were characterized, as received and after being submitted to accelerated degradation, by infrared spectroscopy (FTIR) and thermogravimetry (TG). Some mechanical properties were also evaluated by employing standard methods

<p>In this thesis, regioregularpoly( 3-hexylthiophene) (rr-P3HT) polymer was used as a light absorption and electron donating material, while the C60 fullerene and its derivative [6,6]-phenyl C61-butyric acid methyl ester (PCBM) were used as electron acceptor materials. The effect of solvent to control the degree of mixing of the polymer and fullerene components, as well as the domain size and charge transport properties of the blends were investigated in detail using P3HT:C60 films. The photo-physical, structural and electrical transport properties of the polymer blends were carried out according to their ratios. A distinctive photoluminescence (PL) quenching effect was observed indicating a photo-induced electron transfer. In this thesis, the effect of solvents on the crystallization and interchain interaction of P3HT and C60 fullerene films were studied using XRD, UV-vis, PL, Raman and FTIR spectroscopy. The polymer blends formed with non-aromatic solvents exhibited an improved crystallinity and polymer morphology than that formed with aromatic solvents. An improved ordering was demonstrated in the polymer films spin coated from non-aromatic solvents. This indicates that the limited solubility of rr P3HT in a marginal solvent such as non-aromatic solvents can offer a strategy to obtain highly ordered crystal structures and lead directly to optimal morphologies on the films.</p>

In this study, polymerization mechanisms of aromatic (C6H5 or C6F5) and alkyl (CH3, C2H5, C3H7, C6H13, C12H25 or C18H37) amine based naphthoxazine monomers (15-Na, 15Na-C1, 15Na-C2, 15Na-C3, 15Na-C6, 15Na-C12 and 15Na-C18) and thermal degradation mechanisms of polynaphthoxazines synthesized by curing the naphthoxazine monomers (P-15-Na, P-15NaF, P-15Na-C1, P-15Na-C2, P-15Na-C3, P-15Na-C6, P-15Na-C12 and P-15Na-C18) were studied by direct pyrolysis mass spectrometry. During the curing process, the evolutions of monomer and low mass aromatic or alkyl amines were detected below the curing temperature. The mass spectrometry findings indicated that the monomers were subjected to evaporation and degradation to a certain extent but also to polymerization during the curing process. It has been determined that the polymerization of aromatic amine based naphthoxazine monomer proceeded through the aniline units, either by coupling of the radicals produced by the ring opening of the side chains or by substitution to the benzene ring of aniline. However, even if no direct evidence to confirm polymerization by attack of &ndash / NCH2 groups to naphthalene ring was detected, it is not possible totally eliminate its existence. The evolution of aniline, the main thermal degradation product for this polymer was observed at relatively low temperatures indicating that thermal decomposition started by elimination of aromatic amine involving linkages. Coupling of &ndash / CH2 groups generated by loss of aniline, yielded naphthoxazines with unsaturated linkages that can recombine and form a crosslinked structure with higher thermal stability. Similarly, the polymerization of naphthoxazines based on alkyl amines followed opposing paths. The mass spectral data indicated that the coupling of alkyl amine radicals was the main polymerization pathway. Again, thermal decomposition of alkyl amine based naphthoxazines was started by loss of alkyl amines and diamines. The crosslinked structures produced by coupling of the radicals generated by lose of alkyl amines decomposed at relatively high temperatures.

The total amount of plastic wastes produced by our society has been growing rapidly. The low biodegradability of these wastes creates a serious environmental problem that is directing the governments and environmental agencies to take serious measures to solve the problem of the plastic wastes. Landfilling or incineration of these wastes are not the right solutions, because the former has the danger of leaching and soil impregnation of its degradation products and the latter produce air pollution problems due to the possible emissions of toxic and acid gases. An alternative approach to the solution of problem caused by these wastes is the recycling of them by chemical recovery. In this method, the waste plastics are thermally non-catalytically or catalytically degraded into gases and oils. In this study, pure and aluminum containing ordered mesoporous materials MCM-type and SBA-type, were synthesized using different aluminum sources and aluminum loadings in order to be tested in catalytic degradation of polypropylene. These catalysts, except aluminum containing SBA-type catalysts, were synthesized by hydrothermal synthesis method. Aluminum containing SBA-type catalysts were synthesized by impregnation method. Tetraethyl orthosilicate was used as the Si source and aluminum nitrate, aluminum sulphate and aluminum isopropoxide were used as the Al source. It was observed that these materials had high surface areas and exhibited Type IV isotherms. In MCM-type materials, the aluminum incorporated more effectively into the structure at low concentrations but not effectively at high concentrations. On the other hand, in SBA-type catalysts, the aluminum incorporation into structure was very effective. 27Al MAS NMR spectra of the catalysts exhibited a mixture of tetrahedral and octahedral aluminum. TEM images showed well-ordered hexagonal arrays of mesopores. As an initial step, the activation energy value of polypropylene pyrolysis reaction in the presence of synthesized catalysts was determined by the help of a thermal analyzer and these TGA results showed a marked reduction in the degradation temperature. In the case of using aluminum containing MCM-type materials, the activation energy values decreased to about 68-126 kJ/mol. On the other hand, when aluminum containing SBA-type catalysts were used, the activation energy values decreased from 172 kJ/mol to a value in the range of 51 &ndash / 89 kJ/mol. Heavier molecules degraded into lighter hydrocarbons in the presence of catalysts and they gave high ethylene selectivity among the gaseous products. Additionally, butane selectivity increased with the use of catalysts. SBA-type catalysts showed higher selectivity to lighter hydrocarbons (&lt / C14). C7 selectivity among the liquid products was high when aluminum isopropoxide was used in the synthesis of catalysts and C18 selectivity increased significantly when aluminum nitrate was used in the synthesis of MCM-type catalysts.

<p>In this thesis, regioregularpoly( 3-hexylthiophene) (rr-P3HT) polymer was used as a light absorption and electron donating material, while the C60 fullerene and its derivative [6,6]-phenyl C61-butyric acid methyl ester (PCBM) were used as electron acceptor materials. The effect of solvent to control the degree of mixing of the polymer and fullerene components, as well as the domain size and charge transport properties of the blends were investigated in detail using P3HT:C60 films. The photo-physical, structural and electrical transport properties of the polymer blends were carried out according to their ratios. A distinctive photoluminescence (PL) quenching effect was observed indicating a photo-induced electron transfer. In this thesis, the effect of solvents on the crystallization and interchain interaction of P3HT and C60 fullerene films were studied using XRD, UV-vis, PL, Raman and FTIR spectroscopy. The polymer blends formed with non-aromatic solvents exhibited an improved crystallinity and polymer morphology than that formed with aromatic solvents. An improved ordering was demonstrated in the polymer films spin coated from non-aromatic solvents. This indicates that the limited solubility of rr P3HT in a marginal solvent such as non-aromatic solvents can offer a strategy to obtain highly ordered crystal structures and lead directly to optimal morphologies on the films.</p>

Since the achievement of the first results from the Cassini Huygens mission, Titan's aerosols present an astrobiological interest as their characterization enables to evaluate the prebiotic chemistry that occurred on the primitive Earth. To better understand the physical chemistry of the aerosols of Titan is important for scientists. The laboratory via analyzing the properties of tholins (analogues of Titan's aerosols) overcomes the difficulties for analyzing Titan's aerosols directly. In this thesis work, the research object is tholins produced by the PAMPRE experiment. Pyr-GC-MS analysis technique was used to characterize the composition and structure of tholins. The thermal stability and the properties change with the temperature have been realized by thermal degradation study. Finally, the evolution of organic aerosols after precipitation on the surface of Titan was also investigated through GC-MS analysis of tholins. The results obtained can be used to interpret data collected by observations of Titan from Earth or by the Cassini-Huygens probe, to better characterize the satellite and its evolution.

In unserem alltäglichen Leben nehmen Kunststoffe eine immer größere Rolle ein. Die organische Struktur dieser Materialien bedingt die Brennbarkeit derselbigen und birgt somit eine Gefahr, die allgegenwärtig ist. Flammschutz von Polymeren ist daher eine wichtige Eigenschaft. Der Markt an Flammschutzadditiven ist bereits sehr breit gefächert. Allerdings gibt es nur wenig Studien, die systematisch Struktur und Flammschutzwirkung betrachten. So war es das Ziel dieser Arbeit, durch die Untersuchung zweier systematisch variierter Polymergruppen Struktur-Eigenschafts-Beziehungen zu entwicklen, die das Verständnis von Flammschutzadditiven erweitern. Die erste Gruppe bestand aus Polyestern mit einem gleichbleibenden Polymerrückrat an dem phosphorhaltige Seitenketten systematisch variiert wurden. In der zweiten Gruppe wurde das Polymergrundgerüst bei gleichbleibendem Substituenten variiert. Die Strukturen wurden umfassend hinsichtlich ihres Abbaus untersucht, so das durch Korrelation von Abbauverhalten und erarbeiteten Abbaumechanismen Zusammenhänge zwischen der nativen Polymerstruktur und dem Flammschutzverhalten gefunden werden konnten. Es lässt sich nachweisen, dass das Hauptabbaumaximum fast vollständig durch die Polymergrundkette dirigiert wird. Der Substituent hat wenig Einflauss darauf, womit sich die Möglichkeit ergibt Flammschutzadditive gezielt and das Abbaumaximum des zu schützenden Matrixpolymers anzupassen. Die strukturelle Veränderung des phosphorhaltigen Substituenten hingegen ermöglich es das Flammschutzadditv in seiner Wirkungsweise, also Aktivität in der Gasphase oder kondensierten Phase, anzupassen. Sehr wesentlich, besonders mit Blick auf die Rückstandbildung, ist das Zusammenspiel zwischen Substituent und Polymerrückgrat. Bei geeigneter Wahl aliphatischer und aromatischer Anteile lassen sich so Flammschutzadditive herstellen, die einerseits gut zu verarbeiten sind, andererseits aber auch einen möglichst hohen Rückstand erzeugen. Mit Kenntnis dieser Struktur-Eigenschafts-Beziehungen ist es zukünftig möglich, polymere Flammschutzadditive zielgerichteter zu entwickeln. So lässt sich das Additiv in seiner Wirkung nicht nur an das Matrixpolymer anpassen, sondern auch an die primären Brandgefahren in dessen Endanwendung. Eine Under-the-hood-Anwendung im Automobilbau fordert andere Flammschutzeigenschaften als die Verwendung im häuslichen Küchenbedarf.

Ample research has been published regarding the effects of environmental decomposition on volatile organic profiles of tissue, however literature concerning the volatile organic profiles of thermally degraded tissue is limited in quantity and scope. The purpose of this study was to investigate the effects of temperature on the headspace volatile organic compounds produced by muscle, subcutaneous fat, skin, and punch biopsy samples. The majority of the compounds for each tissue type were alcohols and aldehydes. Compounds were extracted using solid phase microextraction and identified using gas chromatography/mass spectrometry. Compounds such as nonanal, 1-octen-3-ol, octanal, and hexanal were present in the volatile organic compound profile for many tissue types at a majority of the temperatures, particularly from 150°C to 300°C. 2-pentylfuran was the most abundant component in the profile of skin samples from 150°C to 300°C. The profile of fresh subcutaneous fat had numerous branched alkanes, while thermally degraded subcutaneous fat profiles were comprised mostly of aldehydes and alcohols. The profile of muscle was primarily composed of alcohols and aldehydes up to 300°C, whereas the most abundant compound at 350°C was trimethylpyrazine. There were consistent compounds identified among each tissue group. The abundance patterns of alcohols and aldehydes over increasing temperatures differed for each tissue type. Analysis of the data gathered in this study indicates that muscle, subcutaneous fat, and skin contribute characteristic compounds, such as alcohols and aldehydes, to the profile of the punch biopsy samples. The findings further suggest that temperature affects the volatile organic profile of tissue in terms of the compounds identified and the abundance trends of certain compounds.

Philosophiae Doctor - PhD / In this thesis, regioregularpoly( 3-hexylthiophene) (rr-P3HT) polymer was used as a light absorption and electron donating material, while the C60 fullerene and its derivative [6,6]-phenyl C61-butyric acid methyl ester (PCBM) were used as electron acceptor materials. The effect of solvent to control the degree of mixing of the polymer and fullerene components, as well as the domain size and charge transport properties of the blends were investigated in detail using P3HT:C60 films. The photo-physical, structural and electrical transport properties of the polymer blends were carried out according to their ratios. A distinctive photoluminescence (PL) quenching effect was observed indicating a photo-induced electron transfer. In this thesis, the effect of solvents on the crystallization and interchain interaction of P3HT and C60 fullerene films were studied using XRD, UV-vis, PL, Raman and FTIR spectroscopy. The polymer blends formed with non-aromatic solvents exhibited an improved crystallinity and polymer morphology than that formed with aromatic solvents. An improved ordering was demonstrated in the polymer films spin coated from non-aromatic solvents. This indicates that the limited solubility of rr P3HT in a marginal solvent such as non-aromatic solvents can offer a strategy to obtain highly ordered crystal structures and lead directly to optimal morphologies on the films. / South Africa

Submitted by Claudinei Pracidelli (cpracide@ipen.br) on 2014-11-10T11:49:28Z No. of bitstreams: 0 / Made available in DSpace on 2014-11-10T11:49:28Z (GMT). No. of bitstreams: 0 / Dissertação (Mestrado em Tecnologia Nuclear) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP