• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 18
  • 18
  • 14
  • 5
  • 4
  • 1
  • 1
  • 1
  • Tagged with
  • 63
  • 13
  • 8
  • 7
  • 7
  • 7
  • 6
  • 6
  • 6
  • 5
  • 5
  • 5
  • 5
  • 5
  • 5
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Nanocompósitos de elastômero termoplástico à base de PP/EPDM/argila organofílica / Nanocomposites based in PP / EPDM thermoplastic elastomer and organoclay

Fernanda Cristina Fernandes Braga 14 June 2010 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Neste trabalho foram preparados nanocompósitos de elastômeros termoplásticos à base de PP/EPDM/argila organofílica. Foram utilizados como agentes interfaciais polipropileno e terpolímero de etileno-propileno-dieno ambos modificados com grupos anidrido maleico, PP-MA e EPDM-MA, respectivamente. Dois tipos de argila organofílica, que se diferenciam pela estrutura química do surfactante e conseqüentemente pela estabilidade térmica, foram empregados como carga inorgânica. Os nanocompósitos foram preparados pela técnica de intercalação por fusão em câmara interna de mistura e a incorporação da argila foi feita pela adição de masterbatches previamente preparados. Foram investigadas as propriedades de tração, reométricas e ainda a morfologia (cristalinidade e estrutura obtida) dos nanocompósitos a fim de estabelecer a influência do tipo e quantidade de argila organofílica e agente interfacial. Os resultados mostraram que a adição de agente interfacial melhorou a dispersão da argila organofílica na matriz de PP/EPDM, particularmente o PP-MA. Foram obtidos nanocompósitos com estruturas mistas intercaladas e esfoliadas, que resultaram em maiores valores de módulo de elasticidade e manutenção dos valores de deformação. As propriedades reométricas confirmaram o maior grau de dispersão da argila organofílica em nanocompósitos contendo PP-MA. Teores crescentes de argila reduziram a cristalinidade dos nanocompósitos, os quais quando reprocessados, mantiveram as características inerentes ao TPE de origem. Por fim, a estrutura do surfactante presente / In this work it was prepared nanocomposites based in PP/EPDM thermoplastic elastomer and organoclay. Maleinized polypropylene and ethylene-propylene-diene rubber, PP-MA and EPDM-MA, respectively, were employed as interfacial agents. Also two kinds of organoclays, differing about surfactant chemical structure and as consequence thermal stability, were investigated as inorganic filler. Nanocomposites were prepared by melt intercalation in an internal chamber mix and organoclay was incorporated by masterbatches addition, which ones were previously made. It was investigated the influence of amount and kind of organoclay and interfacial agent on tensile properties, rheology and morphology (crystallinity and structure type) of nanocomposites obtained. The results showed that interfacial agents addition promoted a better dispersion degree of organoclay platelets in PP/EPDM matrix, mainly PP-MA. Nanocomposites with both intercalated and exfoliated structures were obtained. These exhibited higher Young modulus and kept their elongation values. The better dispersion degree of clay platelets in nanocomposites containing PP-MA was confirmed by rheology measurements. Increasing amounts of organoclay lowered the crystallinity degree of nanocomposites but the reprocessability was maintained similar to that of pure TPE. Finally, the chemical structure of surfactants did not change the intercalation/exfoliation process due to the similarity of organoclay basal spacing and moderated TPE processing temperature.
32

Nanocompósitos de elastômero termoplástico à base de PP/EPDM/argila organofílica / Nanocomposites based in PP / EPDM thermoplastic elastomer and organoclay

Fernanda Cristina Fernandes Braga 14 June 2010 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Neste trabalho foram preparados nanocompósitos de elastômeros termoplásticos à base de PP/EPDM/argila organofílica. Foram utilizados como agentes interfaciais polipropileno e terpolímero de etileno-propileno-dieno ambos modificados com grupos anidrido maleico, PP-MA e EPDM-MA, respectivamente. Dois tipos de argila organofílica, que se diferenciam pela estrutura química do surfactante e conseqüentemente pela estabilidade térmica, foram empregados como carga inorgânica. Os nanocompósitos foram preparados pela técnica de intercalação por fusão em câmara interna de mistura e a incorporação da argila foi feita pela adição de masterbatches previamente preparados. Foram investigadas as propriedades de tração, reométricas e ainda a morfologia (cristalinidade e estrutura obtida) dos nanocompósitos a fim de estabelecer a influência do tipo e quantidade de argila organofílica e agente interfacial. Os resultados mostraram que a adição de agente interfacial melhorou a dispersão da argila organofílica na matriz de PP/EPDM, particularmente o PP-MA. Foram obtidos nanocompósitos com estruturas mistas intercaladas e esfoliadas, que resultaram em maiores valores de módulo de elasticidade e manutenção dos valores de deformação. As propriedades reométricas confirmaram o maior grau de dispersão da argila organofílica em nanocompósitos contendo PP-MA. Teores crescentes de argila reduziram a cristalinidade dos nanocompósitos, os quais quando reprocessados, mantiveram as características inerentes ao TPE de origem. Por fim, a estrutura do surfactante presente / In this work it was prepared nanocomposites based in PP/EPDM thermoplastic elastomer and organoclay. Maleinized polypropylene and ethylene-propylene-diene rubber, PP-MA and EPDM-MA, respectively, were employed as interfacial agents. Also two kinds of organoclays, differing about surfactant chemical structure and as consequence thermal stability, were investigated as inorganic filler. Nanocomposites were prepared by melt intercalation in an internal chamber mix and organoclay was incorporated by masterbatches addition, which ones were previously made. It was investigated the influence of amount and kind of organoclay and interfacial agent on tensile properties, rheology and morphology (crystallinity and structure type) of nanocomposites obtained. The results showed that interfacial agents addition promoted a better dispersion degree of organoclay platelets in PP/EPDM matrix, mainly PP-MA. Nanocomposites with both intercalated and exfoliated structures were obtained. These exhibited higher Young modulus and kept their elongation values. The better dispersion degree of clay platelets in nanocomposites containing PP-MA was confirmed by rheology measurements. Increasing amounts of organoclay lowered the crystallinity degree of nanocomposites but the reprocessability was maintained similar to that of pure TPE. Finally, the chemical structure of surfactants did not change the intercalation/exfoliation process due to the similarity of organoclay basal spacing and moderated TPE processing temperature.
33

Desenvolvimento de composto de borracha EPDM utilizando cargas alternativas obtidas da regeneração de borrachas vulcanizadas para fabricação de mangueiras de arrefecimento

Pereira, Cicera Soares 06 February 2015 (has links)
Made available in DSpace on 2016-03-15T19:36:48Z (GMT). No. of bitstreams: 1 Cicera Soares Pereira.pdf: 1880149 bytes, checksum: 567b7a93fb26b45ecd44831c5d71f2c0 (MD5) Previous issue date: 2015-02-06 / The automotive industry uses infinity of different products and articles based on vulcanized rubber and, during the manufacturing, part of them are discarded due to the processing failures, causing damage to the environment. If these failures occur after the vulcanization of the rubber, there is no possibility of reprocessing the material. Due to the high cost of the raw materials, reusing the material from vulcanized pieces discarded can generate a reduction in the raw materials, as well as in the final cost of the formulation. Among the rubbers used to obtain these devices, the ethylene-propylene- diene monomer (EPDM) and nitrile rubber containing poly (vinyl chloride) (NBR-PVC) are included. This study aims to obtain and characterize EPDM rubber compound, vulcanized with sulfur containing different concentrations of waste ground vulcanized rubber (EPDM or mixed EPDM/NBR-PVC), observing possible changes in mechanical properties and in relation to chemical compounds without the addition of waste. Compounds were obtained containing 0wt%, 5wt% and 10wt%of ground vulcanized rubber waste. By checking the results, it was verified that the compounds containing different types of waste (EPDM or mixed EPDM/NBR-PVC), at concentrations 5wt% to 10wt% of waste, are more resistant to heat, oil immersion and coolant liquid (ethylene glycol), compared to the compound obtained without addition of waste rubber. The compounds without residue showed better surface finish compared to compounds containing waste. Comparing the surface finish of compounds containing the residue, it was observed that the surface finish obtained from the pressed samples was better than the finish obtained for the extruded samples. / A indústria automobilística utiliza uma infinidade de diferentes produtos e artefatos à base de borracha vulcanizada. Durante a fabricação, partes destes produtos são descartados em razão das falhas de processamento, gerando prejuízo ao meio ambiente. Se estas falhas ocorrem após a vulcanização da borracha, não há possibilidade do reprocessamento do material. Em razão do preço alto das matérias primas, o reaproveitamento de material proveniente das peças vulcanizadas descartadas pode gerar uma redução nos materiais utilizados e no custo final da formulação. Entre as borrachas utilizadas para a obtenção destes artefatos, destacam-se o terpolímero etileno propileno dieno (EPDM). Este estudo teve como objetivo obter e caracterizar compostos de borracha EPDM, vulcanizados com enxofre, contendo diferentes concentrações de resíduos de borrachas vulcanizadas moídas (EPDM ou misto EPDM/NBR-PVC), observando possíveis alterações nas propriedades mecânicas e químicas em relação aos compostos sem adição de resíduos. Foram obtidos compostos contendo 5% e 10% de resíduos de borrachas vulcanizadas moídas. Por meio dos resultados foi possível verificar que os compostos contendo diferentes tipos de resíduos (EPDM ou misto EPDM/NBR-PVC), nas concentrações de 5 % e 10% em massa de resíduos, são mais resistentes ao calor, à imersão em óleo e líquido refrigerante (etileno glicol) quando comparados com o composto obtido sem adição de resíduos de borracha. Os compostos sem resíduo apresentaram melhor acabamento superficial quando comparados com os compostos contendo resíduo. Comparando o acabamento superficial dos compostos contendo resíduos, observou-se que o acabamento superficial obtido para as amostras prensadas foi melhor do que o acabamento obtido para as amostras extrudadas.
34

Entwicklung und Charakterisierung von Elastomerkompositen auf Basis neuerer mikro- und nanoskaliger Füllstoffe

Uhl, Claudia 28 November 2007 (has links) (PDF)
In der Dissertation wurden Nanokomposite mit unterschiedlichen Kautschuken (HNBR, EPDM, MAH-g-EPDM) als Basismaterial sowie diversen modifizierten Schichtsilikaten als Füllstoff hergestellt und charakterisiert. Untersucht wurden die sich ausbildenden Strukturen bzw. die Morphologie (Aggregation, mögliche Orientierungen), die mechanischen Eigenschafte (Verstärkungswirkung) sowie die Füllstoff-Füllstoff-Wechselwirkungen und die Polymer-Füllstoff-Wechselwirkungen.
35

Apport des écoulements élongationnels lors de la mise en oeuvre de mélanges PP/EPDM réticulés dynamiquement et chargés à base de graphène / Elongational flows contribution to the dispersive mechanisms in immiscible blends : application for conductive thermoplastic vulcanizates (TPV) based on polypropylene/EPDM blends

Rondin, Jérôme 19 December 2012 (has links)
Le travail de thèse présenté dans ce manuscrit a consisté à mettre en avant un nouveau procédé de mélange des polymères développé au LIPHT lors de la mise en oeuvre de mélanges PP/EPDM réticulés dynamiquement et chargés à base de graphène. Ce nouveau mélangeur, appelé RMX®, se distingue de la plupart des mélangeurs existants par la présence d’écoulements élongationnels forts, la possibilité de mouler directement des éprouvettes à l’issue de l’étape de mélange ainsi qu’une étanchéité aux gaz et aux liquides. Après une optimisation des conditions opératoires de ce mélangeur, nous avons pu évaluer quantitativement l’efficacité du mélange dispersif par analyse numérique de tailles de particules d’EPDM dispersées dans une matrice PP. Le RMX® permet d’obtenir une dispersion fine (~ 1 μm) pour des énergies spécifiques et des temps de mélange inférieurs aux procédés existants. Des tailles significativement réduites ont été obtenues pour des mélanges présentant un rapport de viscosité élevé (p > 1). Ces résultats ont été attribués à la combinaison de taux de déformation en cisaillement élevés dans le canal de l’élément de mélange avec des taux de déformation en élongation majoritaires en entrée/sortie de ce dernier. L’impact des écoulements élongationnels sur l’intervalle de (co)-continuité de mélanges PP/EPDM a ensuite été étudié. Un décalage de la percolation de la phase dispersée (EPDM) vers les hautes concentrations ainsi qu’une borne supérieure de cet intervalle plus élevée ont ainsi pu être mis en évidence à l’aide de techniques complémentaires (MEB, extraction sélective de la phase EPDM, analyse rhéologique). Une procédure originale d’élaboration de matériaux TPV dans le RMX® a également été réalisée. La réticulation dynamique au moyen d’une résine phénolique d’un mélange PP/EPDM présentant une morphologie co-continue a été effectuée. Des taux d’insoluble proche de 100% ainsi que les propriétés élastiques des TPV formés ont permis de confirmer l’efficacité de cette étape de réticulation dans le RMX®. Une dernière étude a consisté à disperser une nanocharge graphitique lamellaire et conductrice (xGNPTM) dans une matrice PP. L’analyse par diffraction des rayons X, les seuils de percolation rhéologique et électrique obtenus autour de 7 et 8 wt% respectivement ainsi qu’un facteur de forme Af ~ 15 suggèrent une absence d’exfoliation ainsi qu’une agrégation importante des particules de xGNP. / A new mixing device (RMX®) based on elongational flows has been developed during this work. This device has specific technical features comparing to conventional mixers such as: variable mixing volume, direct molding of samples, air and water tightness. After an optimization of processing conditions, dispersive mixing efficiency was assessed on PP/EPDM blends by numerical analysis. Very fine dispersed morphologies were obtained for lower specific mixing energy and mixing times comparing to internal mixer (Haake Rheomix 600). Significantly reduced droplet sizes have been obtained for high-viscosity ratio blends (p > 1). These results indicate an enhanced droplet break-up mechanism in the RMX® which was attributed to the combination of high shear rates inside the mixing element and important elongational flows in the convergent/divergent zones. Impact of elongational flow mixing on the (co)-continuity interval of PP/EPDM blends was investigated. An important shift (~ 10 wt%) of the EPDM percolation threshold as well as a higher phase inversion concentration was observed. A combination of complementary techniques (SEM, selective extraction and rheological analysis) was successfully carried on in order to assess this (co)-continuity interval. Then, PP/EPDM blends with a co-continuous morphology were dynamically crosslinked in the RMX® using resole as a crosslinking agent. An original and specific procedure was developed for this purpose. Gel fraction close to 1 and significantly enhanced elastic properties after crosslinking confirmed the efficiency of this procedure. Finally, the dispersion of lamellar and conductive nanofillers (xGNPTM) in a polypropylene matrix was studied. Microstructural characterization by XRD and optical microscopy, rheological and electrical percolation thresholds (7 and 8 wt% of xGNP respectively) and corresponding aspect ratios (Af ~ 15) have shown no evidence of exfoliation.
36

Desenvolvimento de requisitos de desempenho para elastomeros de isoladores da rede de energia eletrica / Development of performance requirements for elastomers insulators of electricity network

Noronha, Fabio 15 August 2018 (has links)
Orientadores: Lucia Helena Innocentini Mei, Joceli Maria Giacomini Angelini / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-15T13:39:32Z (GMT). No. of bitstreams: 1 Noronha_Fabio_M.pdf: 6615415 bytes, checksum: f72688fb0000126501c64a7267950cb0 (MD5) Previous issue date: 2010 / Resumo: Atualmente, os materiais utilizados como isoladores elétricos vêm sendo substituídos por materiais poliméricos por apresentarem vantagens em relação aos isoladores cerâmicos. Dentre estas vantagens, podem-se citar maior desempenho, melhor resistência ao vandalismo e menor peso. O objetivo desta dissertação foi o estabelecimento de desenvolver requisitos de desempenho para os Isoladores Poliméricos (EPDM- Monômero Dieno/Etileno/Propileno e Silicone) usados na rede elétrica, através de resultados obtidos em ensaios de envelhecimento natural e artificial, tendo como enfoque as linhas de transmissão de 69 kV e 138 kV. Foi realizado um estudo do estado da arte em Isoladores Poliméricos e do estado atual de aplicação e desempenho dos mesmos em campo. Estudos experimentais foram desenvolvidos em produtos retirados de campo e produtos novos, envelhecidos artificialmente em laboratório, segundo metodologias aplicáveis a polímeros. Em paralelo foram estudadas mantas elastoméricas de Silicone e EPDM para elaboração de critérios comparativos. Através dos resultados obtidos, foram sugeridos alguns requisitos de desempenho que poderão ser utilizados em especificações dos mesmos. Nesta dissertação, são apresentados, principalmente, estes resultados obtidos por meio das técnicas de ensaio de Tensões Elétricas, Rugosidade, Densidade, Dureza, FTIR-Infravermelho com Transformada de Fourier, DSC-Calorimetria Exploratória, DMTA-Análise Térmica Dinâmico Mecânica e Resistência à Tração. Os resultados obtidos mostraram a importância de controle da rugosidade bem como da necessidade de aditivação do polímero com sistema de termo e foto estabilização / Abstract: Currently, the materials used as electrical insulators are being replaced by polymeric materials have advantages as compared to ceramic insulators. Among these advantages, we can cite higher performance, better resistance to vandalism and lower weight. The objective of this thesis was the establishment of developing performance requirements for Polymeric Insulators (EPDM monomer diene / ethylene / propylene and Silicone) used in power systems, through results from trials of natural and artificial aging, focusing on the lines transmission of 69 kV and 138 kV. We conducted a study of the state of the art in Polymeric Insulators and current state of implementation and performance of the same field. Experimental studies have been developed into products removed from the field and new, artificially aged in the laboratory, according to the methods applied to polymers. Were studied in parallel webs of silicone elastomer and EPDM for developing benchmarks. Through the results, suggested some performance requirements that could be used in the same specifications. In this thesis, are presented, mainly, these results obtained by the techniques of test voltages, roughness, density, hardness, FTIR-Fourier Transform Infrared, Scanning Calorimetry-DSC, DMTA Dynamic-Mechanical Thermal Analysis and Tensile Strength . The results showed the importance of controlling the roughness and the need for additives with the polymer system and picture stabilization term / Mestrado / Ciencia e Tecnologia de Materiais / Mestre em Engenharia Química
37

Analyse et modélisation cinétique de la perte physique et de la consommation chimique d'un mélange phénol/HALS au cours du vieillissement radio-thermique d'une matrice EPDM / Kinetic analysis and modeling of physical loss and chemical consumption of a phenol/HALS blend durind the radio-thermal ageing of an EPDM matrix

Bannouf, Wissam 02 December 2014 (has links)
La durée de vie des isolants synthétiques de câbles électriques installés en centrale nucléaire est l'une des préoccupations majeurs d'EDF R&D. Pour répondre à cette question, un modèle cinétique de vieillissement radiothermique a été développé pour une matrice EPDM stabilisée par un mélange phénol/HALS dans cette thèse. Ce modèle est dérivé d'un schéma mécanistique d'oxydation, établi dans une étude précédente pour la matrice PE pure, mais complété par les principales réactions de stabilisation des deux types d'antioxydants. Sa validité a été vérifiée avec succès pour une matrice EPDM pure et stabilisée par 0,1, 0,3 et 0,5% w/w de chaque type d'antioxydants, mais aussi par (0-0,3), (0,1-0,2), (0,15-0,15), (0,2-0,1), (0,3-0)% w/w de mélange des deux antioxydants. Le modèle cinétique prédit de manière satisfaisante la grande majorité des courbes cinétiques de consommation chimique des fonctions phénoliques et des fonctions amines, mais aussi des courbes d'accumulation des produits carbonyles dans l'air entre 140 et 160°C en absence d'irradiation γ, mais aussi sous 0,1 kGy/h-45°C, 1 kGy/h-51,5 °C et 10 kGy/h-63,5 °C. Différentes voies possibles d'amélioration sont proposées. / The lifetime prediction of synthetic insulations of electrical cables installed in nuclear power plants is one of the main concerns of EDF R&D. To answer this question, a radiothermal ageing kinetic model has been developed for an EPDM matrix stabilized by a phenol/HALS blend in this study. This model is derived from an oxidation mechanistic scheme, established in a previous study for the neat PE matrix, but completed by the main stabilization reactions of both antioxidants. Its validity has been checked successfully for an EPDM matrix unstabilized and stabilized by 0.1, 0.3 and 0.5% w/w of each antioxidant, but also by (0-0.3), (0.1-0.2), (0.15-0.15), (0.2-0.1), (0.3-0)% w/w of both antioxidants. The kinetic model predicts satisfyingly the large majority of kinetic curves of chemical consumption of phenolic and amine functions, but also the kinetic curves of carbonyl group build-up in air between 140 and 160°C in the absence of γ irradiation, but also under 0.1 kGy/h-45°C, 1 kGy/h-51.5 °C et 10 kGy/h-63.5 °C. Various possible ways of improvement are proposed.
38

Analyse morphologique des champs de cavités dans un élastomère sous décompression d'hydrogène : Influence des conditions de décompression et effets d'interaction / Morphological analyses of cavity fields in an elastomer under hydrogen decompression : effects of decompression condition and interaction effects

Kane-Diallo, Ousseynou 30 November 2015 (has links)
La morphologie de l’endommagement par cavitation est analysée dans un EPDM non chargé sous différentes conditions de décompression d’hydrogène. Les expériences permettent devisualiser l’évolution de l’endommagement au cours du temps. Les images obtenues sont traitées pour obtenir l’instant d’apparition, le nombre et la distribution de taille des cavités au cours du temps. Elles permettent également de suivre les cinétiques de croissance / décroissance des plus grosses cavités. Le tracé de covariogrammes permet de quantifier la distribution spatiale de ces cavités. L’analyse de cet ensemble de données porte donc sur deux échelles :celle de cavités indépendantes et celle de champs de cavités. A l’échelle de la cavité, les cinétiques expérimentales sont corrélées à des calculs numériques par Eléments Finis en conditions diffuso-mécaniques couplées sur une cellule élémentaire contenant une ou deuxcavité(s). Ces calculs permettent par ailleurs d’éclairer les évolutions locales des champs mécaniques et de concentration de gaz, ainsi que les mécanismes d’interaction entre cavités voisines. Les covariogrammes fournissent des éléments pour estimer les caractéristiques d’un Volume Elémentaire Représentatif (VER) (taille, isotropie) et discuter la représentativité d’untel modèle numérique selon les conditions de décompression. A l’échelle des champs de cavités,les conditions de décompression influencent la répartition spatiale. Le nombre et la taille des cavités augmentent avec la pression de saturation et/ou la vitesse de décompression, et une seconde population de petites cavités apparaît autour des premières sous conditions sévères.L’homogénéité et l’isotropie de la distribution à l’échelle macroscopique sont étudiées. Il est finalement montré que la morphologie des champs de cavités évolue au cours de cycles successifs. Cette analyse fournit des informations pour discuter et renseigner le cadre et les ingrédients de modèles d’endommagement. / The morphology of cavitation is analyzed in an unfilled EPDM under different hydrogen decompression conditions. The experimental device allows a time-resolved tracking of the evolution of damage. Images are processed to obtain the onset time, the number and sizedistribution of cavities over time, and the inflation / deflation kinetics of the biggest cavities.Covariograms quantifies the spatial distribution of cavity fields. The analysis is thus led at two scales: that of independent cavities and that of the full cavity fields. At the cavity scale, kineticsis shown to be identical for independent cavities but different between inflation and deflation.Experimental kinetics is compared to that issued from Finite Element calculations in a cell containing one or two cavities, in coupled diffuso-mechanical conditions. Calculationshighlight the evolution of local mechanical and gas content fields, as well as interaction effects between close cavities. At the scale of cavity fields, the spatial distribution is influenced by the decompression conditions. The number and size of cavities increase with saturation pressure and/or decompression rate and a second population of small cavities is nucleated around the first one under severe decompression conditions. The homogeneity and isotropy of the distribution at macroscopic scale are studied. The influence of cycling on the evolution of cavitation morphology is addressed in the final part. It was finally found that the morphology of cavity fields evolves during successive cycles. The analysis provides information to discuss and to inquire the framework and ingredients of damage models.
39

Estudo da influência da morfologia sobre as propriedades elétricas da blenda de PAni com EPDM desvulcanizado por microondas, proveniente do descarte da indústria de autopeças. / Study of morphology influence on the electric properties of the pani and devulcanizated EDPM blend.

Daniela de Assis Alvares 30 July 2008 (has links)
Blendas poliméricas de PAni dopada com ácido dodecilbenzeno sulfônico (PANI-DBSA) e copolímero etileno-propileno-monômero dieno desvulcanizado por microondas (dEPDM) foram obtidas por processo mecânico em diferentes concentrações. Caracterizações físico-químicas, morfológicas e elétrica foram realizadas para analisar as blendas. Um estudo sobre a desvulcanização da borracha EPDM foi descrito. Os ensaios de DSC mostraram temperaturas de transição vítrea diferentes nas blendas indicando que os componentes poliméricos não são totalmente miscíveis, o que permite a formação de uma rede condutora (PANI-DBSA) na matriz isolante (dEPDM). As análises de FTIR indicaram uma interação basicamente física entre o polímero PANI-DBSA e o copolímero dEPDM. As análises de raios-X confirmaram a presença de uma fase cristalina no interior das blendas atribuída à PANI-DBSA. Os ensaios de TGA mostraram que a PAni-DBSA diminuiu, significativamente, a estabilidade térmica do dEPDM. As análises de DMTA apresentaram a diminuição do amortecimento do sistema ocasionado pela presença da PAni, que é mais rígida, no segmento flexível do EPDM; ou seja, a mobilidade da cadeia fica mais limitada. Finalmente, o estudo de condutividade elétrica das blendas foi realizado e como esperado, esta aumenta com a concentração de PANIDBSA nas blendas, e um baixo limite de percolação pode ser observado devido à condutividade ocorrer para baixas concentrações de material condutor (<20%). A condutividade máxima alcançada foi de, aproximadamente, 102 S/cm para a composição de 50% de PANI-DBSA em massa. / Polyaniline doped with dodecylbenzenesulfonic acid (PAni-DBSA) and ethylene-propylene-diene-monomer (EPDM) rubber devulcanizated by microwave (dEPDM) blends have been prepared by mechanical process. Flexible, free-standing and stretchable films have been obtained, which have been characterized by electrical conductivity measurements, FTIR, XRD, DSC, TGA, DMTA and SEM. Study about EPDM rubber devulcanization has been described. DSC analysis have showed different glass-transition temperatures in the blends and it has been observed that the compositions present enough compatibility to form a conductive network (PAni-DBSA) in the elastomeric matrix (dEPDM). By FTIR analysis, it has been noted that there was not modification about the spectrum of blends; therefore the interactions between the components were, basically, physics. X-ray analysis have confirmed the presence of a crystalline phase into the blends that is attributed by PAni-DBSA. TGA analysis have showed that the PAni-DBSA decreased significantly the rubber thermal stability. DMTA analysis have indicated that the system damping decreased according to the presence of PAni because of its stiffness. Finally, blends electric conductivity study has been carried out and as expected, the conductivity have increased with PAni-DBSA concentration in the blends and a low percolation threshold has been observed with the onset of conductivity occurring at lower concentrations of the conductive materials (<20%).
40

Estudo da influência da morfologia sobre as propriedades elétricas da blenda de PAni com EPDM desvulcanizado por microondas, proveniente do descarte da indústria de autopeças. / Study of morphology influence on the electric properties of the pani and devulcanizated EDPM blend.

Alvares, Daniela de Assis 30 July 2008 (has links)
Blendas poliméricas de PAni dopada com ácido dodecilbenzeno sulfônico (PANI-DBSA) e copolímero etileno-propileno-monômero dieno desvulcanizado por microondas (dEPDM) foram obtidas por processo mecânico em diferentes concentrações. Caracterizações físico-químicas, morfológicas e elétrica foram realizadas para analisar as blendas. Um estudo sobre a desvulcanização da borracha EPDM foi descrito. Os ensaios de DSC mostraram temperaturas de transição vítrea diferentes nas blendas indicando que os componentes poliméricos não são totalmente miscíveis, o que permite a formação de uma rede condutora (PANI-DBSA) na matriz isolante (dEPDM). As análises de FTIR indicaram uma interação basicamente física entre o polímero PANI-DBSA e o copolímero dEPDM. As análises de raios-X confirmaram a presença de uma fase cristalina no interior das blendas atribuída à PANI-DBSA. Os ensaios de TGA mostraram que a PAni-DBSA diminuiu, significativamente, a estabilidade térmica do dEPDM. As análises de DMTA apresentaram a diminuição do amortecimento do sistema ocasionado pela presença da PAni, que é mais rígida, no segmento flexível do EPDM; ou seja, a mobilidade da cadeia fica mais limitada. Finalmente, o estudo de condutividade elétrica das blendas foi realizado e como esperado, esta aumenta com a concentração de PANIDBSA nas blendas, e um baixo limite de percolação pode ser observado devido à condutividade ocorrer para baixas concentrações de material condutor (<20%). A condutividade máxima alcançada foi de, aproximadamente, 102 S/cm para a composição de 50% de PANI-DBSA em massa. / Polyaniline doped with dodecylbenzenesulfonic acid (PAni-DBSA) and ethylene-propylene-diene-monomer (EPDM) rubber devulcanizated by microwave (dEPDM) blends have been prepared by mechanical process. Flexible, free-standing and stretchable films have been obtained, which have been characterized by electrical conductivity measurements, FTIR, XRD, DSC, TGA, DMTA and SEM. Study about EPDM rubber devulcanization has been described. DSC analysis have showed different glass-transition temperatures in the blends and it has been observed that the compositions present enough compatibility to form a conductive network (PAni-DBSA) in the elastomeric matrix (dEPDM). By FTIR analysis, it has been noted that there was not modification about the spectrum of blends; therefore the interactions between the components were, basically, physics. X-ray analysis have confirmed the presence of a crystalline phase into the blends that is attributed by PAni-DBSA. TGA analysis have showed that the PAni-DBSA decreased significantly the rubber thermal stability. DMTA analysis have indicated that the system damping decreased according to the presence of PAni because of its stiffness. Finally, blends electric conductivity study has been carried out and as expected, the conductivity have increased with PAni-DBSA concentration in the blends and a low percolation threshold has been observed with the onset of conductivity occurring at lower concentrations of the conductive materials (<20%).

Page generated in 0.0482 seconds