993 resultados para Borracha natural crua


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Pós-graduação em Ciência e Tecnologia de Materiais - FC

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Pós-graduação em Ciência e Tecnologia de Materiais - FC

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Pós-graduação em Ciência dos Materiais - FEIS

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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The development of composite materials encompasses many different application areas. Among the composites, it is had, especially, the materials of organic origin, which have the greatest potential for biodegradability and so, have been bringing relevance and prominence in the contemporary setting of environmental preservation and sustainable development. Following this perspective of ecological appeal, it was developed a biocomposite material with natural inputs typically brazilian. This composite was made from latex (natural rubber) and carnauba fiber in different mass proportions. Formulations had varied by 5%, 10%, 15% and 20% of fiber in relation the matrix. This material has been designed aiming at application in thermal insulation systems, which requirethermal protection surfaces and/or reduction of thermal energy loss. Therefore, the composite was characterized by thermal conductivity testing, specific heat, thermal diffusivity and thermogravimetry. As has also been characterized for their physical-mechanical, by testing density, moisture content, tensile strength, hardness and scanning electron microscopy (SEM). The characterization of the material revealed that the composite presents a potential of thermal insulation higher than the natural rubber, that was used as reference. And the formulation at 15% fiber in relation the matrix showed the best performance. Thus, the composite material in question presents itself as a viable and effective alternative for new thermal insulation material design.

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The development of composite materials encompasses many different application areas. Among the composites, it is had, especially, the materials of organic origin, which have the greatest potential for biodegradability and so, have been bringing relevance and prominence in the contemporary setting of environmental preservation and sustainable development. Following this perspective of ecological appeal, it was developed a biocomposite material with natural inputs typically brazilian. This composite was made from latex (natural rubber) and carnauba fiber in different mass proportions. Formulations had varied by 5%, 10%, 15% and 20% of fiber in relation the matrix. This material has been designed aiming at application in thermal insulation systems, which requirethermal protection surfaces and/or reduction of thermal energy loss. Therefore, the composite was characterized by thermal conductivity testing, specific heat, thermal diffusivity and thermogravimetry. As has also been characterized for their physical-mechanical, by testing density, moisture content, tensile strength, hardness and scanning electron microscopy (SEM). The characterization of the material revealed that the composite presents a potential of thermal insulation higher than the natural rubber, that was used as reference. And the formulation at 15% fiber in relation the matrix showed the best performance. Thus, the composite material in question presents itself as a viable and effective alternative for new thermal insulation material design.

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A borracha natural (BN) de três clones de seringueira [Hevea brasiliensis (Willd. exAdr. de Juss. Muell.-Arg.)] de um período de sete meses foi obtida por coagulação do látex com solução de ácido acético a 10% e seca a 65°C. As curvas TG-DTG foram utilizadas para monitorar as propriedades térmicas da BN. Os resultados indicaram pequenas variações entre clones e coletas, exceto no valor de Tf-T0, indicando que o clone IAC 301 sofre degradação mais rápida durante o processo termo degradação da BN seca. Não houve diferenças significativas nos valores de Tg entre clones e coletas.

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Pós-graduação em Ciência dos Materiais - FEIS

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All medicine, whether allopathic or homeopathic, must go through strict quality control, which must ratify their characteristics throughout the period of validity. During the time of preparation and storage, solutions of the drugs are in permanent contact with packaging materials that can release undesirable substances to the solution. Several factors may influence the release of packing materials, and factorial design (FD) is a useful tool for analyzing the phenomenon. The aim of this study was the determination of quality parameters for Homeopathic solid (globules) and liquid (drops) dosage forms. It was carried out analysis in homeopathic globules for weight variation, mechanical strength, and moisture content uniformity. For liquid preparations, standard solutions were prepared from natural rubber bulbs, which were subjected to exhaustive extraction with two ethanol solutions (30 and 70%) in the ultrasonic bath for 20 minutes at 25°C and 50°C in three successive cycles. Studies of transfer have been made within five days, by spectrophotometric analysis in the UV region at 312 nm with λmáx and 323 nm for samples in 70% ethanol and 30% respectively. PH values were analyzed. We also conducted two FD studies, where the first, the three-level variables were solvent (chloroform, ethanol and nhexane), sample mass (30, 60 and 90mg), particle size (large disk, small disk and powder sample). In the second study, the solvent level variables were different ethanolic degrees (EtOH 30%, 70% and pure). The percentage of lending in the solutions was 5.5%, 12.4%, 24.2% and 41% of the total estimated in the reference solution. The values of rate constants of transfer were determined in the order of 0.0134 days-1 and 0.0232 days-1 in absorbance values, the solutions in ethanol at 30% and 70% respectively. These results suggest that the speed of transfer of materials from rubber is affected both by the nature of the vehicle as by the temperature