Magister Scientiae - MSc (Physics) / Zinc oxide (ZnO) is a wide and direct semiconductor with a wurtzite crystal structure. Its multifunctionality as the ideal candidate in applications such as blue-UV light emitting diodes, transparent conducting oxide, selective gas sensor and efficient catalyst support among others, has attracted a significant interest worldwide. Nano-scaled ZnO has been synthesized in a plethora of shapes. A rich variety of physical and chemical methodologies have been used in the synthesis of undoped or doped ZnO. However, such methods either necessitate relatively high vacuum infrastructures, elevated temperatures, or the use of toxic reagents. The "green chemistry" synthesis of metal oxide nanoparticles which is based on using natural plant extract as an effective 'reducing agent' of metal precursor, has been reported to be a cleaner and environment-friendly alternative to the physical and chemical methods. The thesis is based on the synthesis and the main physical properties of pure ZnO nanoparticles synthesized by a completely green chemistry process using the natural extract of Aspalathus Linearis to bio-reduce the zinc acetate precursor. The obtained ZnO nanopowdered samples were annealed at different temperatures from 300 °C to 600 °C. The samples were characterized using Scanning Electron Microscopy, Energy Dispersive Spectroscopy, Transmission Electron Microscopy, X-ray Diffraction, Differential Scanning Calorimetry, Thermogravimetric Analysis and Fourier Transform Infrared. Highly pure quasi-spherical ZnO nanoparticles with an average crystallite size of 24.6 nm (at 300 °C), 27.2 nm (at 400 °C), 27.6 nm (at 500 °C), and 28.5 nm (at 600 °C) were found. The results also showed that the average crystallite size increased with an increase in annealing temperature. It was successfully demonstrated that the natural plant extract of Aspalathus Linearis can be used in the bio-reduction of zinc acetate dihydrate to prepare highly pure ZnO nanoparticles.

L'utilisation extensive des combustibles fossiles, l'émission de gaz à effet de serre dans l'atmosphère et les difficultés de recyclage des résidus de consommation incitent au recours accru aux polymères biodégradables. Dans le domaine du génie électrique, de nombreux polymères trouvent des applications dans les systèmes d'isolation des matériels électriques. Ces polymères sont issus du pétrole, peu respectueux de l'environnement et la plupart d'entre eux ne sont pas biodégradables. Dans le but de les remplacer, des polymères biodégradables ont été explorés.Une revue des travaux de recherche sur les polymères biodégradables dans le domaine du génie électrique a été réalisée. Les propriétés thermiques et électriques de polymères biodégradables et conventionnels sont rapportées et comparées.Les polymères biodégradables et / ou biosourcés sélectionnés et mis en œuvre sont le Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), le polycaprolactone (PCL) et l’acide polylactique PLA. Un matériau nanocomposite basé sur PLA a également été préparé. Les propriétés diélectriques pour une large gamme de température et de fréquence ont été mesurées par spectroscopie diélectrique et analysées en s’appuyant sur les propriétés thermiques obtenues par DSC et DMA. La résistivité volumique et la tenue diélectrique ont pu également être mesurées. Ces polyesters biodégradables sont comparés aux polymères conventionnels. / The declining resources of fossil fuels, increase in wide-spread pollution, emission of green-house gases and difficulties in recycling waste materials are pushing biodegradable polymers into prominence. In the domain of electrical engineering, many polymers find applications in various electrical insulation systems. These polymers are petro-based, not eco-friendly and most of them are not biodegradable. With an objective to replace conventional products, biodegradable polymers are explored for their dielectric properties.In this work, a detailed study on the present status in the research work on biodegradable polymers in the electrical engineering domain is presented. Thermal and electrical properties of both biodegradable and classical polymers are compiled and compared.The polymers processed and studied were Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), Polycaprolactone (PCL), Poly(lactic acid) (PLA) and PLA based nanocomposite. Dielectric properties for a wide range of temperature and frequency were measured by dielectric spectroscopy and analyzed with the help of DSC and DMA experiments. Volume resistivity and electrical breakdown were measured on few polymers. These biodegradable polyesters were compared with conventional polymers.

Le sujet de l'étude concerne la caractérisation des propriétés thermiques de liquides semi-transparents à haute température : les liquides silicatés. La caractérisation de ces matériaux est particulièrement délicate car il faut séparer les contributions des différents modes de transfert thermique (conduction, convection et rayonnement) si l'on veut mesurer des propriétés intrinsèques. Le dispositif expérimental est basé sur une méthode pulsée de type flash. La cellule de mesure, placée au centre d'un four tubulaire, est soumise à une excitation délivrée par un laser continu et l'élévation de température est mesurée à l'aide d'un détecteur infrarouge sur la face opposée à l'excitation. La modélisation du problème direct prend en compte le couplage conducto-radiatif en résolvant l'équation de la chaleur en régime transitoire et l'équation de transfert radiatif (ETR) pour un milieu gris émettant, absorbant et non diffusant à l'aide de la méthode des harmoniques sphériques (approximation P1). La méthode développée permet d'estimer simultanément la diffusivité thermique et un coefficient d'absorption moyen (gris) par méthode inverse. Les résultats expérimentaux obtenus sur des liquides silicatés présentant des propriétés radiatives différentes (i.e., des coefficients d'absorption différents) valident la méthode de caractérisation développée et mise en œuvre dans nos travaux / The study deals with the characterization of the thermal properties of semi-transparent liquids at high temperature: molten silicates. The characterization of such materials is particularly challenging because the contributions of the different heat transfer modes (conduction, convection and radiation) should be accounted for to allow the measurement of intrinsic properties. The experimental setup is based on a transient pulse method derived from the flash method. A heat flux stimulation is generated on the front face of an experimental cell, placed at the center of a tube furnace, with a continuous laser beam and the temperature rise is measured by an infrared detector on the opposite side. The modeling of the direct problem takes into account the conducto-radiative coupling by solving both the heat equation and the radiative transfer equation (RTE) for a gray emitting, absorbing but non-scattering medium with the spherical harmonics method (P1 approximation). The developed method allows to simultaneously estimate the thermal diffusivity and a mean (gray) absorption coefficient by an inverse method. The experimental results obtained on molten silicates with different radiative properties (i.e., different absorption coefficients) validate the characterization method developed and implemented in our work

Afin de comprendre les mécanismes de transport de la chaleur dans des films très minces des matériaux amorphes, nous avons proposé et démontré expérimentalement une nouvelle technique de mesure des propriétés thermiques de membranes très minces. Cette technique consiste à coupler la méthode 3 oméga avec la géométrie Völklein (membrane suspendue allongée). L'échantillon d'intérêt est alors monté dans un pont de Wheatstone spécifique afin d'éliminer le signal électrique 1 oméga. Cette technique permet de mesurer avec une très haute sensibilité le signal thermique 3 oméga et donc les propriétés thermiques des membranes. Le nitrure de silicium étudié dans ce travail constitue un matériau amorphe typique. Nous avons été intéressés par l'étude du transport thermique dans un tel système de dimensions réduites en fonction de la température et du stress intrinsèque qui présente dans les films. Afin d'atteindre cet objectif, les membranes de nitrure de silicium de stress élevé et de faible niveau de stress ont été mesurées respectivement pour une épaisseur de 50 nm et 100 nm. Le comportement global de la conductivité thermique mesurée est une croissance quand la température augmente, une tendance généralement constaté pour un matériau amorphe. Le data de membrane de 50 nm présente une conductivité thermique inférieure à celle du 100 nm, ce qui est en accord avec l'effet des dimensions réduites. La chaleur spécifique mesurée s'écarte sensiblement de la loi en T3 de Debye. Cela est particulièrement important en dessous de 100 K où la chaleur spécifique est plus élevé que celle prévue par la modèle Debye. Ces résultats expérimentaux sont en excellent accord avec les prévisions d'un model théorique qui tient en compte de l'effet TLS (Two Level System) qui présente dans le matériaux amorphe. Il a été montré expérimentalement que le stress n'a pas d'effet sur la chaleur spécifique de nitrure de silicium. De plus, nous avons démontré que le stress n'affecte pas la dissipation dans nitrure de silicium, et la dissipation par dilution semble être la cause de la réduction de la dissipation. Par conséquent, le stress ne devrait pas affecter la conductivité thermique du nitrure de silicium, ce qui est cohérent avec les résultats expérimentaux. En terme d'application de la méthode 3 oméga-Völklein, nous avons démontré que la membrane de SiN peut être utilisée comme capteur thermique spécifique pour caractériser un autre matériau déposée sur la face arrière de la membrane. Nous avons testé ce modèle pour mesurer les propriétés thermiques d'un film de 200 nm de Bi2Te3. Les résultats obtenus sont en excellent accord avec la littérature. Comme le SiN est un matériau isolant, ce modèle est capable de mesurer des films très minces quelle que soit sa nature, isolant, semi conducteur ou métallique. / In order to understand the mechanisms of the heat transport in very thin amorphous films, we have proposed and experimentally demonstrated a new technique to measure the thermal properties of very thin membranes. This technique consists in coupling the 3 omega method to the Völklein geometry (elongated suspended membrane). The sample of interest is then implemented into a specific Wheatstone bridge in order to eliminate the electrical 1 omega signal. This technique allows the measurement with very high sensitivity of the 3 omega thermal signal and therefore the thermal properties of the membranes. Silicon nitride membranes studied in this work constitutes a typical amorphous material. We have been interested in the study on the thermal transport in such system of reduced dimensions as function of temperature and intrinsic modified stress. In order to accomplish this goal, silicon nitride membranes of high stress and low stress have been measured respectively with the thickness 50 nm and 100 nm. The overall behaviour of the measured thermal conductivity is an increase as the temperature is increased, a trend commonly found for amorphous material. The 50 nm data show thermal conductivity less than that of the 100 nm, this is consistent of the effect of reduced dimensions. The measured heat capacity is apparently higher than what is expected from the Debye phonon heat capacity. This is especially significant below 100 K where the heat capacity deviates significantly from the T3 Debye law. A theoretical model taking into account the presence of TLS in amorphous materials is then used to fit the experimental data. The theoretical fits are in excellent agreement with the experimental results. It was seen experimentally that stress has no effect on the specific heat of silicon nitride. Moreover, we have demonstrated that stress does not affect the dissipation in silicon nitride, and the dissipation dilution seems to be the sole cause of the reduction of dissipation by an applied stress in high stress silicon nitride. Therefore, stress should not affect thermal conductivity of silicon nitride, and this is consistent with the experimental results. As application for the 3 omega-Völklein method, we have demonstrated that the SiN membrane can be used as specific thermal sensor to characterize another material deposited on the backside of the membrane. We have tested this model to measure thermal properties of Bi2Te3 film and the results are in excellent agreement with literature. As the SiN is an insulator, this model is able to measure very thin films whatever its nature, insulator, semi conductor or metallic.

Submitted by Claudinei Pracidelli (cpracide@ipen.br) on 2015-04-10T16:38:07Z No. of bitstreams: 0 / Made available in DSpace on 2015-04-10T16:38:07Z (GMT). No. of bitstreams: 0 / Tese (Doutorado em Tecnologia Nuclear) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Made available in DSpace on 2016-12-08T17:19:16Z (GMT). No. of bitstreams: 1 Capitulo - 1.pdf: 90391 bytes, checksum: 33e046a11ac6f08cddd52a66b5806583 (MD5) Previous issue date: 2012-02-17 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / In this study PLLA nanocomposites have been produced with 0.25 and 0.50 (wt%) multiwall carbon nanotubes (MWCNT). The MWCNT were dispersed in solution using two different ways: with and without high energy sonication. The mechanical results were evaluated by means of nanoindentation and microhardness, the thermal results by differential scanning calorimetric, thermogravimetric analysis and the tribological results by pin-on-disc tests with two different normal loads (5 and 10N). It was observed a reduction of 4.2% in elastic modulus of neat PLLA produced by sonication. The largest increases in the modulus were obtained with a concentration of 0.25% (6.7% and 5.4% for sonication and without it). The microhardness showed an increase of 18% for the sample with 0.50%, regardless of treatment. It is also presented the results obtained by nanohardness which differ from microhardness. The sample with 0.25% had the lowest volume loss in most conditions tested in the pin-ondisk. Most of the samples, with normal load of 10N, showed a lower wear rate than the same sample with a load of 5N. The friction coefficient showed a high dispersion of data allowing only analyzes the trends. The wear mechanisms observed adhesion and abrasion, vary in their intensity after the addition of MWCNT. There is evidence that sonication causes a portion of the material to be removed through tribochemical wear. The glass transition temperature did not show variations. It was observed a progressive reduction in the onset temperature of degradation by thermogravimetric analysis with the incorporation of MWCNT. It was not obtained an increase in crystallinity with incorporation of MWCNT. / Neste trabalho produziu-se nanocompósitos de PLLA com 0,25% e 0,50% (m/m) de nanotubos de carbono de paredes múltiplas (NCPM). A dispersão dos NCPM foi feita em solução de duas maneiras distintas, sendo uma utilizando sonificação de alta energia e outra sem. Avaliou-se o módulo de elasticidade por nanoindentação, o comportamento térmico por calorimetria exploratória e pela análise termogravimetria e as propriedades tribológicas dos nanocompósitos e do polímero puro através do ensaio de pino sobre disco com cargas de 5 e 10N. Pode-se observar uma queda de 4,2% no módulo de elasticidade no PLLA puro produzido com a sonificação. Os maiores aumentos no módulo foram obtidos com a concentração de 0,25% (5,4% e 6,7% para as sem sonificação e com sonificação). A microdureza apresenta um aumento até 18% para a amostra com 0,50%, independente do tratamento. Também se apresentam os resultados obtidos pela nanodureza que diferem dos obtidos da microdureza. A amostra com 0,25% obteve o menor volume removido na maioria das condições testadas no ensaio pino e disco. O coeficiente de atrito apresentou grande dispersão permitindo somente analisar as suas tendências. Os mecanismos de desgaste observados, adesão e abrasão, variam de intensidade com a incorporação de NCPM. Há indícios que a sonificação faz com que parte do material removido seja através do desgaste triboquímico. A temperatura de transição vítrea não apresentou variações. Foi verificada uma redução progressiva na temperatura de início de degradação por análise termogravimétrica com a adição dos NCPM. Não foi notada uma variação significativa na cristalinidade com incorporação de NCPM.

Made available in DSpace on 2016-12-08T17:19:19Z (GMT). No. of bitstreams: 1 Juliana Paz.pdf: 1684316 bytes, checksum: 5c2617141f2eaa7e6d38f5e9791c52b5 (MD5) Previous issue date: 2012-07-27 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Epoxy-clay nanocomposites has been widely studied with interests in their thermal, mechanical and structural. A major breakthrough in research can be no use of solvents when the clay dispersion in epoxy resin, which reduces the environmental impact, although epoxies can not be recycled. This paper presents a study of the thermal properties (by Thermogravimetry, Differential scanning calorimetry and Dilatometry), mechanical (for traction, flexion and K1c) and structural (by Fourier Transform Infrared Microscopy and scanning electron) of epoxy-clay nanocomposites and as a rheological analysis (for viscosity) of the solutions of pre-cured composite at the moment of the load as first dispersion parameter selection of samples for later analyzes mechanical, thermal and structural characteristics. In the analyzes were chosen viscosity samples that had higher values, wherein the cured samples were used in two dispersion conditions, with and without sonication, and variations in concentration of 2, 4, 6 and 8 wt% as a means of comparison to obtain clear results improvements or not the properties of these nanocomposites, which are related to the respective condition dispersion. It is understood that nanocomposites with good dispersion is intercalated / exfoliated since the clay used in this work is called montmorillonite and has lamellar structure with nanometer thickness and large surface area, which results in an interface adhesion between clay and epoxy resin. In this, it is also observed that the condition of non-sonicated dispersion nanocomposites showed improvements in their thermal properties, but structurally the dispersion appears to be more efficient in samples sonificadas. The analysis shows improvements in their mechanical properties in samples with intermediate concentration (mainly 4 wt% clay), depending on the destination of the nanocomposite can indicate these materials for various applications, such as coatings and objects that require low chemical reactivity. / Nanocompósitos epóxi-argila vem sendo largamente estudados com interesses em suas propriedades térmicas, mecânicas e estruturais. Um grande avanço nas pesquisas pode ser a não utilização de solventes no momento da dispersão da argila na resina epóxi, o que diminui o impacto ambiental, apesar de os compostos epoxídicos não poderem ser reciclados. Este trabalho apresenta um estudo das propriedades térmicas (por Termogravimetria, Dilatometria e Calorimetria diferencial exploratória), mecânicas (por Tração, Flexão e K1c) e estruturais (por Infravermelho por Transformada de Fourier e Microscopia eletrônica de varredura) de nanocompósitos epóxi-argila, bem como uma análise reológica (por viscosidade) das soluções pré-curadas dos compósitos no momento da dispersão da carga como primeiro parâmetro de seleção das amostras para posteriores análises mecânicas, térmicas e estruturais. Nas análises de viscosidade foram escolhidas amostras que apresentavam maiores valores, na qual foram utilizadas as amostras curadas em duas condições de dispersão, com e sem sonificação e, em variações de concentração de 2, 4, 6 e 8% em massa como via de comparação para obter-se resultados claros de melhorias ou não das propriedades desses nanocompósitos, sendo estes relacionados com a respectiva condição de dispersão. Entende-se que nanocompósitos com boa dispersão são intercalados/esfoliados, uma vez que a argila utilizada neste trabalho é chamada montmorillonita e apresenta estrutura lamelar com espessura nanométrica e grande área superficial, que resulta numa interface de adesão entre argila e resina epóxi. Neste, observa-se também que a condição de dispersão não-sonificada os nanocompósitos apresentavam melhorias em suas propriedades térmicas, porém, estruturalmente a dispersão parece ser mais eficiente em amostras sonificadas. As análises mecânicas mostras melhorias em suas propriedades em amostras com concentração intermediária (principalmente 4% em massa da argila); dependendo do destino do nanocompósito pode-se indicar esses materiais para diversas aplicações, tais como revestimentos e objetos que necessitem baixa reatividade química.

Made available in DSpace on 2016-12-08T17:19:34Z (GMT). No. of bitstreams: 1 RESUMO.pdf: 12083 bytes, checksum: a5f4ea45fd2de1b6b09e1ac6c1fa5377 (MD5) Previous issue date: 2010-02-26 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / In this study we used an epoxy-acrylate fotocurável reinforced with multi walls carbon nanotubes (MWCN) in proportions of 0.25% wt/wt and NCPM 0.75% wt/wt MWCN. For the cure of nanocomposites as thin films for periods of 12 and 24 hours, manufactured from a chamber of ultraviolet radiation (UV-A). Aiming to analyze aspects related to properties mechanical, thermal and tribological adding NCPM in an epoxy-acrylate fotocurável were evaluated: elastic modulus, hardness, storage modulus, loss modulus, damping, coefficient of friction, wear rate and temperature of transition glass. In addition to these properties described previously, there was also the behavior of these nanocomposites related to thermal aspects (cure degree and thermal stability) and morphology of regions of fracture and wear parts. Tests performed were: nanoindentation, microhardness, dynamicmechanical analysis (DMA), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), test pin-on-disk and profilometry. The present results have shown gains of 67% in modulus, hardness at 77%, 154% in the storage module, 38% of the loss modulus, 24% reduction in friction and 24% reduction in the rate of wear with the addition of NC's in the nanocomposite studied. / Neste trabalho foi utilizado uma resina epóxi-acrilato fotocurável reforçada com nanotubos de carbono de paredes múltiplas (NCPM), nas proporções de 0,25% m/m NCPM e 0,75% m/m NCPM. Para a cura dos nanocompósitos na forma de filmes finos , por períodos de 12 e 24 horas, fabricou-se uma câmara de radiação ultra-violeta (UV-A). Buscando-se analisar aspectos ligados a propriedades mecânicas, térmicas e tribológicas da adição de NCPM em uma resina epóxi-acrilato fotocurável foram avaliados: módulo de elasticidade, dureza, módulo de armazenamento, módulo de perda, amortecimento, coeficiente de atrito, taxa de desgaste e temperatura de transição vítrea. Além dessas propriedades descritas anteriormente, verificou-se também o comportamento desses nanocompósitos relacionados a aspectos térmicos (grau de cura e estabilidade térmica) e aspectos morfológicos de regiões de fratura e regiões de desgaste. Os ensaios realizados foram: nanoindentação, microdureza, análise dinâmico-mecânica (DMA), calorimetria exploratória diferencial (DSC), análise termogravimétrica (TGA), microscopia eletrônica de varredura (MEV), ensaio pino-disco e perfilometria. Os resultados obtidos nesse trabalho comprovaram ganhos de 67% no módulo de elasticidade, 77% na dureza, 154% no módulo de armazenamento, 38% no módulo de perda, 24% de redução do coeficiente de atrito e redução de 24% na taxa de desgaste com a adição de NC s no nanocompósito em estudo.

Made available in DSpace on 2014-12-17T14:57:50Z (GMT). No. of bitstreams: 1 RannierMM.pdf: 3580955 bytes, checksum: f892200d861ab62414259c44c459e1b9 (MD5) Previous issue date: 2009-03-30 / The use of polymer based coatings is a promising approach to reduce the corrosion problem in carbon steel pipes used for the transport of oil and gas in the oil industry. However, conventional polymer coatings offer limited properties, which often cannot meet design requirements for this type of application, particularly in regard to use temperature and wear resistance. Polymer nanocomposites are known to exhibit superior properties and, therefore, offer great potential for this type of application. Nevertheless, the degree of enhancement of a particular property is greatly dependent upon the matrix/nanoparticle material system used, the matrix/nanoparticle interfacial bonding and also the state of dispersion of the nanoparticle in the polymer matrix. The objective of the present research is to develop and characterize polymer based nanocomposites to be used as coatings in metallic pipelines for the transportation of oil and natural gas. Epoxy/SiO2 nanocomposites with nanoparticle contents of 2, 4, and 8 wt % were processed using a high-energy mill. Modifications of the SiO2 nanoparticles‟ surfaces with two different silane agents were carried out and their effect on the material properties were investigated. The state of dispersion of the materials processed was studied using Scanning and Transmission Electron Microscopy (SEM and TEM) micrographs. Thermogravimetric analysis (TG) were also conducted to determine the thermal stability of the nanocomposites. In addition, the processed nanocomposites were characterized by dynamic mechanical analysis (DMA) to investigate the effect of nanoparticles content and silane treatment on the viscoelastic properties and on the glass transition temperature. Finally, wear tests of the pin-on-disc type were carried out to determine the effects of the nanoparticles and the silane treatments studied. According to the results, the addition of SiO2 nanoparticles treated with silane increased the thermal stability, the storage modulus and Tg of the epoxy resin and decreased wear rate. This confirms that the interaction between the nanoparticles and the polymer chains plays a critical role on the properties of the nanocomposites / A utiliza??o de pol?mero como revestimento ? algo promissor para redu??o de corros?o interna de dutos de a?o carbono utilizados no transporte de petr?leo e g?s natural na ind?stria petrol?fera. No entanto, os revestimentos polim?ricos convencionais apresentam propriedades limitadas, que muitas vezes n?o podem satisfazer os requisitos necess?rios, particularmente em rela??o ? temperatura empregada e ao desgaste. Nanocomp?sitos polim?ricos s?o conhecidos por apresentarem propriedades superiores e, portanto, apresentam potencial para este tipo de aplica??o. Por?m, o grau de refor?o de uma propriedade particular ? fortemente dependente dos materiais utilizados no sistema matriz/nanopart?culas, da liga??o interfacial e, tamb?m, do estado de dispers?o das nanopart?culas na matriz polim?rica. O objetivo do presente trabalho ? desenvolver e caracterizar nanocomp?sitos polim?ricos para utiliza??o como revestimento de dutos met?licos da ind?stria do petr?leo. Nanocomp?sitos Ep?xi/SiO2 com 2, 4 e 8% em massa de nanopart?culas foram processados usando um moinho de alta energia. Modifica??es nas superf?cies das nanopart?culas de SiO2 foram realizadas com dois tipos diferentes de silano e seus efeitos sobre as propriedades dos materiais foram investigados. O estado de dispers?o do material processado foi estudado usando micrografias de Microscopia Eletr?nica de Varredura e de Transmiss?o (MEV e MET). Foram realizadas an?lises termogravim?tricas (TG) para verificar a estabilidade t?rmica dos nanocomp?sitos. Al?m disso, foram realizadas an?lises din?mico-mec?nicas (DMA) para estudar os efeitos das nanopart?culas e dos tratamentos com silano nas propriedades viscoel?sticas e na temperatura de transi??o v?trea (Tg). Por fim, testes de desgaste do tipo esfera-disco foram realizados para determinar os efeitos da adi??o de nanopart?culas e dos diferentes tipos de tratamento de silaniza??o estudados. De acordo com os resultados, a adi??o nanopart?culas de SiO2 tratadas com silano aumentou a temperatura de in?cio de degrada??o do pol?mero, o m?dulo de armazenamento e a Tg da resina ep?xi, al?m de ter proporcionado uma menor taxa de desgaste. Isto confirma que a intera??o entre as nanopart?culas e as cadeias polim?ricas desempenha um papel cr?tico sobre as propriedades dos nanocomp?sitos

Submitted by Franciele Moreira (francielemoreyra@gmail.com) on 2018-06-08T13:46:39Z No. of bitstreams: 2 Dissertação - Juliana Aparecida Correia Bento - 2018.pdf: 3915998 bytes, checksum: 02825a5c8f16825aad6955538d1369a8 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2018-06-08T15:06:59Z (GMT) No. of bitstreams: 2 Dissertação - Juliana Aparecida Correia Bento - 2018.pdf: 3915998 bytes, checksum: 02825a5c8f16825aad6955538d1369a8 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2018-06-08T15:06:59Z (GMT). No. of bitstreams: 2 Dissertação - Juliana Aparecida Correia Bento - 2018.pdf: 3915998 bytes, checksum: 02825a5c8f16825aad6955538d1369a8 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2018-02-28 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Cochlospermum regium, a native plant of the Brazilian Cerrado, known as “Algodãozinho-do- campo”, is used in folk medicine for the treatment of infections and inflammation. Jatropha elliptica (Pohl) Muell Arg is a plant belonging to the Euphorbiaceae family, native to the Brazilian Cerrado, and popularly known as "Batata-de-teiú". There is a lack of scientific knowledge about the physico-chemical and technological aspects of Jatropha elliptic and its possible applications, in foods and or medicines. Hedychium coronarium Koen, native to Nepal, is considered an invasive plant in Brazil, as it presents rapid and negative growth for plant biodiversity. Rhizomes are man-made due to their medicinal properties, such as the treatment of headache, cancer and inflammation, but it can also be a potential source for starch extraction. Algodãozinho-do-campo, Batata-de-teiú and lírio-do-brejo are rhizomatous plants with the potential to obtain starch and flour. The objective of this work was to contribute with unpublished data on the characterization of flour and starch with a probable functional value, extracted from Hedychium coronarium Koen, Cochlospermum regium and Jatropha elliptica (Pohl) Muell Arg, as well as the application of these products as substrate in the semi-solid fermentation, aiming the production of enzymatic extracts, and to evaluate the effect of the ultrasound on the lírio-do-brejo starch. The extracted starches present peculiar technological characteristics, being: the algodãozinho-do-campo starch under cooking temperature absorbs less water and solubilizes less than the corn starch, maintaining more the structure of the granules in the final product, being able to contribute to the improvement of final product texture; the batata-de-teiú starch had a low tendency to retrograde; the lírio- do-brejo starch presented high amylose content (about 59.16%), crystallinity of 19.30%, and when it was submitted to ultrasound for 15 min at 62% intensity and 12.5 g 100g-1 an increase in viscosity peak (from 1917 to 2257 cP) and reduction in tendency to retrograde (from 2079 to 1295 cP) was observed. The flours presented peculiar nutritional characteristics, antioxidant capacity, presence of phenolic compounds, low toxicity in Artêmia salina, presence of antinutritional factors, and were not efficient for the production of enzymatic extracts by semi-solid fermentation. It is concluded that they are plants with potential to obtain starch and flour. / Cochlospermum regium, planta nativa do cerrado brasileiro, conhecida como algodãozinho- do-campo, é utilizada na medicina popular para o tratamento de infecções e inflamações. Jatropha elliptica (Pohl) Muell Arg é uma planta pertencente à família das Euphorbiaceae, nativa do cerrado brasileiro, e conhecida popularmente como “batata-de-teiú”, sendo que existe carência de conhecimentos científicos sobre os aspectos fisíco-quimicos e tecnológicos da Jatropha elliptica e suas possíveis aplicações, em alimentos e ou medicamentos. O lírio-do- brejo (Hedychium coronarium Koen), natural do Nepal, é considerado planta invasora no Brasil, pois apresenta crescimento rápido e negativo para a biodiversidade vegetal. Os rizomas são aproveitados pelo homem, devido suas propriedades medicinais, como o tratamento da cefaleia, câncer e inflamações, mas também pode ser uma fonte potencial para a extração de amido. Algodãozinho-do-campo, batata-de-teiú e lírio-do-brejo são plantas rizomatosas com potencial para a obtenção de amido e farinha. Com isso, este trabalho tem por objetivo contribuir com dados inéditos sobre a caracterização das farinhas e féculas, com provável valor funcional, extraídas do Hedychium coronarium Koen, Cochlospermum regium e Jatropha elliptica (Pohl) Muell Arg, bem como a aplicação destes produtos como substrato na fermentação semissólida, visando a produção de extratos enzimáticos, e avaliar o efeito do ultrassom sobre o amido de lírio-do-brejo. Os amidos extraídos apresentam características tecnológicas peculiares, sendo que: o amido de algodãozinho-do-campo sob temperatura de cozimento absorve menos água e se solubiliza menos que o amido de milho, mantendo mais a estrutura dos gânulos no produto final, podendo contribuir para a melhoria da textura do produto final; o amido de batata-de-teiú apresentou baixa tendência à retrogradação; o amido de lírio-do-brejo apresentou alto teor de amilose (cerca de 59.16%), cristalinidade de 19.30%, sendo que quando este foi submetido ao ultrassom, por 15 min, a 62% de intensidade e 12.5 g 100g-1 de concentração, observou-se um aumento do pico de viscosidade (de 1917 para 2257 cP) e a redução da tendência à retrogradação (de 2079 para 1295 cP). As farinhas apresentaram caracteristicas nutricionais peculiares, capacidade antioxidante, presença de compostos fenólicos, baixa toxicidade em ensaio com Artêmia salina, presença de fatores antinutricionais, e não foram eficientes para a produção de extratos enzimáticos por fermentação semissólida. Conclui-se que são plantas com potencial para a obtenção de amido e farinhas.