In this study, the High Density Polyethylene (HDPE) and Low Density Polyethylene (LDPE) blends prepared by Plasticorder Brabender were strengthened by adding Carbon Black (CB). Blends were prepared at 190 &deg / C. Amounts of LDPE were changed to 30, 40, 50 and 60 percent by the volume and the percent amounts of CB were changed to 5, 10,15, 20 and 30 according to the total volume. Thermal and morphological properties were investigated by using Differential Scanning Calorimeter (DSC), Scanning Electron Microscope (SEM). Mechanical properties were investigated by tensile test and hardness measurements. Melt flow properties were studied by Melt Flow Index (MFI) measurements. Electrical conductivities were measured by four probe and two probe techniques. Temperature dependence of electrical conductivity was also studied. In general, it is observed that stress at break and MFI values decrease by the addition of CB / however, modulus and hardness increase. DSC results indicated that the crystallization of the polymer blend was decreased by the addition of CB. SEM results showed that the components were mixed homogenously. Increasing CB content increased electrical conductivity. Furthermore, by increasing the temperature, positive temperature coefficient behavior was observed which increases when CB content decreased.

Resumo: Neste trabalho foram estudadas as propriedades elétricas e dielétricas de um compósito à base de poliuretano derivado de óleo de mamona (PU) e negro de fumo (NF). As amostras de PU/NF foram preparadas com quantidades fixas de prépolímero e poliol (seguindo uma fração 10/7 em massa) e com diferentes quantidades de NF. Medidas de espectroscopia de impedância permitiram analisar as propriedades elétricas do compósito em campo elétrico alternado em diferentes temperaturas, enquanto que, o método de quatro pontas foi utilizado para calcular a condutividade dc das diferentes amostras. Neste trabalho, também, foi desenvolvido um modelo estatístico bidimensional de redes de resistores e capacitores que gera a estrutura morfológica e calcula a condutividade alternada do compósito PU/NF a partir de uma técnica de matriz de transferência proposto por Derrida . As curvas da permissividade real e imaginária em função da frequência para amostras de PU/NF com diferentes proporções de NF demonstraram o mesmo comportamento qualitativo, ou seja, possuindo maiores valores para baixas frequências e altas temperaturas e decrescendo com aumento da frequência. As medidas de permissividade dielétrica imaginária apresentaram picos de relaxação devido ao processo de polarização interfacial entre o negro de fumo e a matriz polimérica. No entanto, esses picos são mais pronunciados quando se utiliza o módulo elétrico, que minimiza os efeitos de condução dc. O modelo estatístico reproduziu bem os dados experimentais obtidos das medidas de espectroscopia de impedância. A partir dos ajustes teórico-experimentais pode-se observar que a condutividade elétrica para a amostra 99/01 ocorre predominantemente por condução eletrônica nas regiões isolantes, obedecendo ao modelo modificado de Abrahams e Miller. Entretanto, para as amostras 95/05 e 90/10 o modelo de Abrahams e... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: In this work we investigated the electrical properties of the polyurethane derived from castor oil (PUR) and carbon black (CB) composite. Samples of PUR/CB were prepared by fixed quantities of the pre-polymer and polyol (following a ratio of 10/7 by weight) and mixing different amount of the CB. Measurement of impedance spectroscopy was used to analyze the transport properties of the composite as function of applied electric field at different temperatures. The method of four probes was used to measurement the dc conductivity of the PUR/CB composites. A statistical model two-dimensional was developed based on networks of resistors and capacitors that generates the morphological structure and calculates the alternating conductivity of the PUR/CB composite using a transfer matrix technique proposed by Derrida et al. The plots of real and imaginary permittivity as a function of frequency for the samples of PUR/CB with different amount CB showed the same qualitative behavior with higher values for low frequencies and high temperatures. Measurement of imaginary dielectric permittivity showed peaks due to the process of interfacial polarization relaxation between the carbon black and polymeric matrix. However, these peaks are more pronounced when using the electrical modulus, which minimizes the effects of dc conduction. The statistical model reproduced well the experimental data obtained from the measurement of impedance spectroscopy. From theoretical and experimental settings it can be observed that the electrical conductivity for the 99/01 sample is predominantly by electron conduction in the insulating regions, in according at modified model of Miller and Abrahams. However, for samples 95/05 and 90/10 model of Abrahams and Miller dominates at low frequencies (below 103 Hz) and the Drude model is predominant in the higher frequency (above 104 Hz). / Orientador: Darcy Hiroe Fujii Kanda / Coorientador: Haroldo Naoyuki Nagashima / Banca: José Antônio Malmonge / Banca: Rodrigo Fernando Bianchi

Pour la confection des matériaux polymères à base de caoutchouc, le noir de carbone (NC) reste la charge renforçante la plus utilisée. Sa caractérisation morphologique et nano structurale est essentielle dans la maitrise des propriétés physico-chimiques qu’il confère aux matériaux auxquels il est mélangé. Les analyses classiques ne permettent d’accéder que de façon indirecte et incomplète à ces propriétés. Cette thèse propose une méthode de caractérisation innovante par le couplage d’un détecteur STEM (Scanning Transmission Electron Microscopy) et d’une chaine d’analyse d’images complètement automatique pour identifier les types de NC. Une étude statistique approfondie d’une centaine de caractéristiques morphologiques et structurales des NC a été réalisée sur les 6000 images STEM acquises. Cette étude a permis d’introduire 7 nouveaux descripteurs et de sélectionner les 37 descripteurs les plus discriminants pour la création du modèle d’identification. Pour rendre le processus le plus automatique possible, un algorithme de segmentation non supervisé a été développé et évalué. Cinq classifieurs ont ensuite été entraînés et comparés sur une base de près de 65000 agrégats. Le modèle le plus adapté s’avère les réseaux de neurones avec une identification des NC avoisinant les 100%. L’identification étant réalisée à partir de projections 2D des agrégats via les images STEM, une confrontation statistique valide la capacité des descripteurs 2D à caractériser la structure tridimensionnelle des NC observée par tomographies électroniques. L'approche complète proposée, depuis le protocole de préparation des échantillons et l'acquisition d'images STEM jusqu'à leur classification en passant par les étapes d'analyse d'images, offre une nouvelle méthode de caractérisation fiable des NC (à l’état natif ou au sein de mélanges élastomères) exploitable en routine. / In the field of rubber material development, CB is the most commonly used reinforcing filler. The characterization of CB morphology and nanostructure is therefore crucial to understand the physicochemical properties induced by the introduction of CB in rubber materials. Classical analytical methods only allow indirect and incomplete access to these properties. This PhD offers an innovative method that allows the automatic identification of CB grades by coupling Scanning Transmission Electron Microscopy (STEM) detector and image processing chain. A thorough statistical investigation over a hundred of morphological and structural characteristics of CB was performed on a set of 6000 STEM images. This study has introduced 7 new features and selected the 37 most discriminating descriptors to create the final model. An unsupervised segmentation algorithm has been developed and evaluated in order to build an automatic process as efficient as possible. Then, five classifiers were trained and compared on a base of nearly 65,000 aggregates. It appears that the most suitable descriptor is the Neuron networks as it gives a perfect recognition. As the recognition model is based on 2D projections of CB aggregates, it is necessary to verify that the chosen descriptors are indeed able to correctly characterize the three dimensional structure of CB. The statistical comparison of the 2D descriptors with 3D descriptors extracted from electronic tomography images has been successful, and therefore demonstrates the relevance of the model. The proposed approach, starting from the sample preparation and STEM acquisitions to their classification and through the image analysis steps, offers a new and innovative method for the reliable characterization of CB. This method can be used routinely on raw CB or CB extracted from vulcanizes rubbers.

Orientador: Prof. Dr. Gerson Luiz Mantovani / Dissertação (mestrado) - Universidade Federal do ABC, Programa de Pós-Graduação em Nanociências e Materiais Avançados, 2016. / Neste trabalho foram estudados processos de funcionalização de resinas epoxídicas. O processo de funcionalização foi realizado por meio da incorporação controlada de compósitos de polianilina (PANI) reforçada com negro de fumo (PANI/NF) na matriz epoxídica. A produção dos compósitos de PANI/NF foi realizada por meio da polimerização da anilina na presença do negro de fumo resultando na polimerização preferencial da anilina na superfície do negro de fumo. A formação da estrutura do tipo caroço-casca (core-shell) foi evidenciada pelas diferenças observadas na morfologia do material resultante da polimerização da anilina na presença e na ausência do negro de fumo. Na ausência de negro de fumo foi observada uma estrutura constituída de fibras curtas com diâmetro da ordem de 100 nm e na presença de negro de fumo foi observada uma morfologia essencialmente granular. As caracterizações da PANI, do NF, do compósito PANI/NF e da resina epoxídica foram realizadas por meio de técnicas de espectroscopia de absorção na região do ultravioleta e visível (UV-VIS), espectroscopia de infra vermelho por transformada de Fourier (FTIR), espectroscopia Raman, calorimetria exploratória diferencial (DSC) e microscopia eletrônica de varredura (MEV). A incorporação do compósito de PANI/NF à resina epoxídica ocorreu por mistura mecânica. Os resultados de espectroscopia Raman que o NF apresentou uma razão entre a intensidade das bandas D e G (ID/IG) igual a 8,7, característico de um sistema com uma alta quantidade de defeitos e de baixa cristalinidade. Os resultados de DSC mostraram que após esta mistura da resina epoxídica com PANI/NF o processo de cura da resina epoxídica não foi afetado de forma significativa. A capacidade de proteção contra a corrosão do revestimento foi avaliada por meio de ensaios eletroquímicos de corrosão, sendo, monitoramento de potencial de corrosão em circuito aberto e espectroscopia de impedância eletroquímica. Os resultados dos ensaios eletroquímicos mostraram um aumento na proteção contra a corrosão do revestimento epoxídico devido às propriedades anticorrosivas do compósito PANI/NF. / In this work it was studied the functionalization of epoxy resin. The functionalization process will be carried out by the modification of the epoxy resin matrix by adding polyaniline / carbon black composites (PANI/NF). The production of composite PANI / NF was performed by polymerizing aniline in the presence of carbon black resulting in preferential polymerization of aniline on the carbon black surface. The formation of core-shell type structure (core-shell) was evidenced by the differences in the morphology of the material resulting from the polymerization of aniline in the presence and absence of carbon black. In the absence of black smoke was observed structure composed of short fibers having a diameter of approximately 100 nm in the presence of carbon black essentially a granular morphology was observed. The characterization of the PANI, NF, composite PANI / NF and epoxy resin were carried out using the absorption spectroscopy techniques in the ultraviolet and visible region (UV-VIS), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The incorporation of the composite PANI / NF to epoxy resin occurred by mechanical mixing. The results of differential scanning calorimetry (DSC) showed that after this mixture of epoxy resin with PANI / NF, the epoxy resin curing process was not affected significantly. The ability to protect against corrosion coating was evaluated by, electrochemical tests of potential corrosion monitoring in open circuit and electrochemical impedance spectroscopy. The results of the electrochemical tests showed an increase in protection against corrosion the epoxy coating due the anticorrosive properties of PANI / NF composite.

Made available in DSpace on 2014-10-09T12:53:44Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:58:46Z (GMT). No. of bitstreams: 0 / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP

Made available in DSpace on 2014-10-09T12:53:44Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:58:46Z (GMT). No. of bitstreams: 0 / A tecnologia de células a combustível associada à crescente exigência de baixo impacto ambiental tornou-se bastante promissora no cenário mundial de energia. As células a combustível são, em princípio, dispositivos que convertem energia química diretamente em energia elétrica e térmica, possuindo, entretanto, uma operação contínua, graças à alimentação constante de um combustível. Particularmente, o negro de fumo Vulcan XC72 é usualmente empregado como suporte dos eletrocatalisadores, e alguns fatores como uma superfície acessível e área superficial suficientemente grande para uma máxima dispersão dos cristalitos dos eletrocatalisadores, além de tamanho dos poros, distribuição dos poros adequada e a presença de grupos funcionais na superfície do negro de fumo são considerados fundamentais para o desenvolvimento de materiais inovadores. Entretanto, o material denominado Vulcan XC72 ainda revela condições insuficientes para este fim. Este estudo consiste na preparação e caracterização físico-química de carbono funcionalizado por peróxido de hidrogênio e com cadeias poliméricas do tipo poliestireno sulfonado condutoras de prótons, visando sua posterior utilização como suporte de eletrocatalisadores para células a combustível tipo PEMFC e DMFC. Após a funcionalização do carbono, obteve-se uma melhora da dispersibilidade do negro de fumo em solução aquosa, efeito este benéfico para a preparação dos eletrocatalisadores. Observou-se também que os grupos funcionais e as cadeias poliméricas funcionaram como estabilizadores do crescimento dos cristalitos produzindo catalisadores mais homogêneos e com menor diâmetro médio dos cristalitos; e especialmente, no caso da funcionalização com cadeias poliméricas, obteve-se uma diminuição da queda ôhmica do sistema, referente à melhoria da transferência protônica. / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP

It is a challenge to assess the toxicity of environmental air particulate matter (PM) because PM composition is complex and variable, due to source contribution and atmospheric transformation. The goal of this study is to establish an in vitro model that can fingerprint the cytotoxic effects of airborne PM and their associated toxicity mechanisms. For this purpose, the cytotoxic effects of different reference and environmental particles on A549 human lung epithelial cells were characterized using multiple endpoint assays (cytokine release, LDH release, BrdU incorporation, cellular ATP and resazurin reduction) and proteomic analyses (2D-GE and MALDI-TOF-TOF-MS/MS). The results of this study demonstrated that proteomic analyses can distinguish the influences of different (carbon black and titanium dioxide) and similar (cristobalite and α-quartz) particles on various pathways in A549 cells (e.g., cell death and cell proliferation); and the cytotoxicity assays were capable of differentiating the phenotypic outcomes of the particles, which were complementary and supportive to pathway analyses. The ability of in vitro toxicoproteomics to differentiate the toxicity of environmental particles was tested on Ottawa urban dust (EHC-93) and its water-insoluble and soluble fractions. Findings from both cytotoxicity assays and proteomic analyses consistently indicated that the insoluble materials explained most of the toxic effects of the total PM. Interestingly, the toxic potency of EHC-93 total was not equal to the sum of its insoluble and soluble fractions, implying inter-component interactions between insoluble and soluble materials that may be reflected through synergistic or antagonistic in vitro responses. The insoluble and soluble fractions uniquely altered the expression patterns of the proteins involved in pathways such as cell death, cell proliferation and inflammation. For example, the insoluble and soluble fractions oppositely altered the expression of the proteins (e.g., TREM1, PDIA3, PKM and ENO1) involved in an inflammatory response pathway in A549 cells, and the insoluble fraction was more potent than the soluble fraction in increasing secretion of pro-inflammatory cytokines MCP-1 and IL-8 from A549 cells. In essence, in vitro toxicoproteomics is a valuable tool in relating the physicochemical characteristics of ambient air particles to their biological reactivity through understanding their mechanisms of toxicity.

Cette thèse porte sur les batteries en flux, une thématique en plein essor pour le stockage massif des énergies intermittentes. Ce travail a pour but de réaliser de nouveaux types d'électrolytes liquides, avec des particules de carbone, afin d'améliorer la puissance. Ce concept est appelé "électrodes liquides" et a été mis en pratique dans une batterie en flux à base de particules d'intercalation du lithium en milieu aqueux. Tout d'abord, l'objectif est de formuler les électrolytes de carbone avec une bonne conductivité électrique (1-4 mS/cm) et une viscosité raisonnable. Ce compromis a été trouvé grâce à l'étude de la méthode de mélange et du type de carbone. La conductivité électrique a été étudiée par impédancemétrie et en flux afin de tester la solidité du réseau de carbone en écoulement. Ces électrolytes de carbone ont été testés en présence d'espèces solubles, sur une batterie millifluidique modèle ferrocyanure/iode. L'étude a été complétée par une modélisation de la diffusion des espèces. L'effet du flux sur l'intensité a été étudié ainsi que l'influence de la cinétique de l'espèce redox. Enfin, ces électrolytes de carbone ont été utilisés pour réaliser des batteries en flux entièrement à base de particules. En particulier, la décharge d'une batterie LiFePO4{MnO2 en flux continu, a présenté une densité de courant entre 5 et 30 mA{cm2, ce qui est entre 10 et 100 fois supérieur aux valeurs de la littérature. / This project deals with flow batteries, which are very promising technologies for large scale energy storage, especially for intermittent energies. This work aims at developing new types of electrolytes with carbon particles to enhance power of batteries. This concept is called "liquid electrode" and is implemented in flow batteries with redox lithium intercalation particles in aqueous media. The first objective is to formulate the carbon electrolyte, with a good electronic conductivity (1-4 mS/cm) and a reasonable viscosity. A compromise is reached thanks to the study of the mixing procedure and the carbon type. Conductivity is also studied by impedance spectroscopy and in flow to visualize the strength of the carbon network. The electrolytes are then, tested in a ferrocyanide/iodine millifluidic battery. The conversion of the soluble species is compared with a modelisation. A particular attention is paid to the effect of the flow and the kinetic on the battery intensity. Finally, these carbon electrolytes are used in a particles-based flow battery. For example, a battery LiFePO4{MnO2 demonstrates in flow, an intensity recovery between 5 et 30 mA{cm2 which is around 10 to 100 times higher than values reported in literature.

No description available.

The strain amplitude dependency , i.e. the Fletcher-Gent effect and Payne effect, and the strain rate dependency of rubber with reinforcing fillers is modelled using a modified boundary surface model and implemented uniaxially. In this thesis, a split of strain instead of stress is utilized, and the storage and loss modulus are captured over two decades of both strain amplitudes and frequencies. In addition, experimental results from bimodal excitation are replicated well, even though material parameters were obtained solely from harmonic excitation. These results are encouraging since the superposition principle is not valid for filled rubber, and real-life operational conditions in general contain several harmonics. This means that formulating constitutive equations in the frequency domain is a cumbersome task, and therefore the derived model is implemented in the time domain. Filled rubber is used irreplaceable in several engineering solutions, such as tires, bushings, vibrations isolators, seals and tread belts, to name just a few. In certain applications, it is sufficient to model the elastic properties of a component during finite strains. However, Hooke’s law is inadequate for this task. Instead, hyperelastic material models are used. Finally, the thesis presents a methodology for obtaining the required material parameters utilizing experiments in pure shear, uniaxial tension and the inflation of a rubber membrane. It is argued that the unloading curve rather than the loading curve is more suitable for obtaining these parameters, even at very low strain rates. / <p>QC 20140917</p>