341 resultados para THERMOGRAVIMETRY
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Bi3NbO7 thin films were prepared by the polymeric precursor method. The precursor solutions were prepared with excess of bismuth ranging from 0% to 10% and the pH was controlled to be maintained between 8 and 9. This control was done by adding to the solution niobium and ethylene glycol. The final solution was clear and free of precipitation. After obtaining the precursor solution, has begun the process of characterization of powders with thermogravimetry (TG), differential thermal analysis and X-ray analysis (XRD). The films were obtained by the polymeric precursors, the method is advantageous because it is simple, and low cost involves steps and controlled stoichiometry. The films were annealed and characterized by XRD and SEM and also characterized according to their dialectics properties. We observed that the best results were obtained when the film is thermally at 800 ° C for two hours and 860 ° C for two hour. Under these conditions we obtain Bi3NbO7 thin films with good homogeneity, uniform distribution of the grains, but with the formation of secondary phase, which does not occur in treatments with lower temperature. The dielectric characterization showed that the produced film showed good characteristics with high dielectric constant and low loss
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In this work polymeric composites reinforced with cotton fibers, from the textile industry, were developed in order to manufacture printed circuit boards. It was used expanded polystyrene (EPS) as a thermoplastic matrix by melting it. For the obtention of 10% and 15% of fiber volume fraction in cotton fibers composites, it was used wasted cotton fibers as an incentive of recycling and reusing of the domestic and industrial wastes as well as for Expanded Polystyrene(EPS). The mechanical properties of the composites were evaluated by tensile and flexural strength from standardized test methods. Composites were characterized by a Scanning Electron Microscopy (SEM), Thermogravimetry (TG/DTG), Differential Scanning Calorimetry (DSC) and dielectric analysis. The analysis of the results showed that fiber in the composite directly influenced in the thermal and mechanical properties
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The study of ceramic materials is constantly evolving, especially in research related to advanced ceramics. Once these have many applications, this paper relates to synthesis by solid state reaction of calcium copper titanate (CCTO) ceramic material means doping with strontium. The powders were characterized using thermal analysis techniques such as TG (thermogravimetry), DTA (differencial thermal analysis), dilatometry, X-ray diffraction (XRD) and scanning electron microscopy (SEM). The compositions have submitted weight loss at around 6% with respect to carbonates used, and was attributed a temperature of 950° C to perform the calcination according to thermogravimetric analysis. After the process of calcination and milling, the particles presented approximately spherical shapes and high percentages of substitution Ca2+ with Sr2+ was evident by the presence of necks between to particles due to the milling calcination. Analyses with Energy Dispersive Spectroscopy (EDS) showed stoichiometries in different samples very similar to the theoretical stoichiometry
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In this work polystyrene composites reinforced with recycled sisal fibers were processed, in order to apply in the manufacture of printed circuit boards. A thermoplastic matrix of recycled polystyrene was used, this material came from waste expanded polystyrene (EPS) used in appliance's packages. Composites were prepared with 15% and 25% of sisal fibers. To obtain the composites, wasted EPS and natural sisal fibers were chosen, to encourage recycling and reuse of household waste and also the use of renewable resources. The composites were analyzed by standard tensile and flexural test, in order to verify the mechanical properties of the material. The characterization of the composite was done by scanning electron microscopy (SEM) , thermogravimetry (TGA / DTG) , differential scanning calorimetry (DSC) and dielectric analysis . The analysis of the results showed that the percentage of fibers in the composite influences directly the thermal and mechanical properties. Plates with a lower percentage of fibers showed superior properties at a higher percentage. The composite material obtained is easy to process and it's use is feasible for the confection of printed circuit boards, considering it's mechanical, thermal and insulative properties
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Pós-graduação em Química - IQ
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Pós-graduação em Engenharia Mecânica - FEG
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Biofuels and their blends with fossil fuel are important energy resources, which production and application have been largely increased internationally. This study focus on the development of a correlation between apparent activation energy (Ea) and NOx emission of the thermal decomposition of three pure fuels: farnasane (renewable diesel from sugar cane), biodiesel and fossil diesel and their blends. Apparent Activation energy was determined by using thermogravimetry and Model-Free Kinetics. NOx emission was obtained from the European Stationary Cycle (ESC) with OM 926LA CONAMA P7/Euro 5 engine. Results showed that there is a linear correlation between apparent activation energy and NOx emission with R2 of 0,9667 considering pure fuels and their blends which is given as: NOx = 2,2514Ea - 96,309. The average absolute error of this correlation is 2.96% with respect to the measured NOx value. The main advantage of this correlation is its capability to predict NOx emission when either a new pure fuel or a blend of fuels is proposed to use in enginees.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Pós-graduação em Química - IQ
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Pós-graduação em Química - IQ
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Pós-graduação em Química - IQ
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)