Made available in DSpace on 2014-06-11T19:30:20Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-08-02Bitstream added on 2014-06-13T21:00:54Z : No. of bitstreams: 1 leonello_ec_me_botfca.pdf: 1914995 bytes, checksum: 57b29ba4eed421b275526c5dee3e7bc3 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / O látex é o principal produto extraído da seringueira (Hevea brasiliensis). No Brasil, a madeira de seringueira, ao final do ciclo produtivo de látex, é utilizada tradicionalmente para fins energéticos, mas trabalhos internacionais relatam práticas consolidadas de agregação de valor a ela. Diversos pesquisadores têm observado crescimento e agravamento do problema da seca do painel de sangria nos plantios nacionais, doença que compromete a produção de látex. O objetivo principal deste trabalho foi avaliar a qualidade da madeira de árvores dos clones comerciais GT 1 e RRIM 600 em três condições distintas de sanidade: árvores com produção normal de látex (sadias); árvores com presença de seca do painel de sangria por origem abiótica/fisiológica e árvores com presença da seca do painel de sangria por origem biótica/patológica. Foram amostradas seis árvores de cada condição de sanidade dos dois clones de plantios na região de São José do Rio Preto-SP com idade igual ou superior a 20 anos. Os parâmetros anatômicos e físico-mecânicos avaliados foram o comprimento das fibras (presença e delimitação de madeira juvenil e adulta), densidade básica e aparente da madeira, retratibilidade e índice de anisotropia, resistência à compressão paralela às fibras, resistência e rigidez à flexão e dureza Janka. Os resultados mostraram que a madeira juvenil ocorre desde a medula até cerca de 40% e 32% do raio para os clones GT 1 e RRIM 600, respectivamente, podendo-se associar a idade do plantio de 6 a 8 anos como transição entre madeira juvenil e adulta. A densidade básica média da madeira de seringueira dos dois clones... / Latex is the main product extracted from rubber tree (Hevea brasiliensis). In Brazil, at the end of the production cycle of latex, rubber wood is traditionally used for energy purposes but international studies have reported consolidated practice that result in added-value products. Several researchers have observed raised and worsening of tapping panel dryness, a disease that impairs the production of latex. The main objective of this study was to evaluate the quality of rubber wood of commercial clones GT 1 and RRIM 600 in three distinct health conditions: trees producing latex (healthy), trees with tapping panel dryness of abiotic/physiological origin and trees with tapping panel dryness of biotic/pathological origin. Six trees of each health condition of the two clones from plantations in the São José do Rio Preto region – Sao Paulo State, Brazil - aged 20 years or more were sampled. Anatomical and physical-mechanical parameters evaluated were fibers length (occurrence and delimitation juvenile–mature wood), specific gravity and apparent density, shrinkage and anisotropy index, compression parallel to grain strength, bending strength and rigidity and Janka hardness. Results showed that juvenile wood occurs from pith up to 40% and 32% of ray for GT 1 and RRIM 600 clones respectively, allowing the association of the age of 6 to 8 years of plantation as transition between juvenile and mature wood. The mean specific gravity of rubber wood from both clones varied from 580 kg/m³ to 595 kg/m³ and there wasn’t statistical difference of this parameter among health conditions and between clones. Rubber wood... (Complete abstract click electronic access below)

Orientador: João Sinezio de Carvalho Campos / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-06T12:51:18Z (GMT). No. of bitstreams: 1 Quaiatti_MarceloAntonio_M.pdf: 4091133 bytes, checksum: 025e60cd474cfd2f1d279b3d35d38843 (MD5) Previous issue date: 2005 / Resumo: Os elastômeros termoplásticos do tipo SBC são copolímeros em bloco de estireno que possuem uma alta tecnologia e que possibilitam um vasto campo de aplicações. Trata-se na verdade da união das vantagens da borracha natural e do plástico, e justamente pelas inúmeras vantagens que ele apresenta, sua atuação no mercado tem se tornado crescente, justificando grandes investimentos realizados para desenvolvimentos de mercado, dentre os quais podemos destacar o mercado de adesivos que engloba aplicações bastante diversificadas, como por exemplo fitas adesivas, adesivos para industrias de móveis, adesivos para fraldas descartáveis e higiênicos, etiquetas, etc. Neste trabalho apresenta-se a utilização destes elastômeros em formulações adesivas destinadas à aplicações em adesivos sensíveis à pressão (PSA) e tem por objetivo auxiliar as pesquisas e desenvolvimentos voltados para este segmento, uma vez' que os resultados abordados neste trabalho podem auxiliar no direcionamento correto de formulações adesivas juntamente com os respectivos processos produtivos, bem como eleger o tipo correto de matéria prima ou componente a ser utilizado, dependendo do tipo de aplicação final / Abstract: The SBC thermoplastic elastomers are styrene block copolymers and combine the advantages of Natural Rubber and Plastics. Not only have a high technology, but also allow a large variety of applications and due to the mentioned advantages, its market share has been growing and justifying strong investment to be developed, and adhesives can be highlighted as it conglomerates diversified applications, as for instance adhesives tapes, adhesives to forniture ind,ustries diapers, labels, etc. This study shows the thermoplastic elastomers in adhesives formulations with the main focus on pressure sensitive adhesives (PSA), and can help future research and developments over this segment, as the results can help to achieve the right choice of the formulations and the respective malilufacturing process, and also elect the correct type of raw material to be considered, always based on the final application / Mestrado / Ciencia e Tecnologia de Materiais / Mestre em Engenharia Química

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M.Ing. (Mechanical Engineering) / This dissertation evaluates the suitability of the finite element method as a tool for the design and analysis of elastomeric materials in general and flexible shaft couplings in particular. The theoretical background covers numerous aspects that are essential to the comprehension of the functioning of elastomeric materials and the difficulties inherent to the numerical modelling of such materials. These aspects include the properties of rubber, the functioning and selection of flexible couplings and some details regarding linear -, non-linear - 'and dynamic finite element analysis. The problems investigated for the purposes of this study may be divided into three categories: • The capabilities of the finite element method to compare different variations of a flexible coupling design parametrically is investigated. • Uni-axial tensile - and compressive material tests are numerically simulated to assess the ability of the finite element method to predict the response of materials subjected to large-scale nonlinear deformation. The numerical results are also verified by means of physical material tests. • Based on the modelling methods that were optimized in the first two categories, a numerical model of a flexible coupling in start up mode is developed. The accuracy of predictions is evaluated by comparison with physically measured results.

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Polymer electrolyte membrane fuel cell (PEMFC) stacks require sealing around the perimeter of the cells to prevent the gases inside the cell from leaking. Elastomeric materials are commonly used for this purpose. The overall performance and durability of the fuel cell is heavily dependent on the long-term stability of the gasket. In this study, the degradation of three elastomeric gasket materials (silicone rubber, commercial EPDM and a developed EPDM 2 compound) in an accelerated ageing environment was investigated. The change in properties and structure of a silicone rubber gasket caused by use in a real fuel cell was studied and compared to the changes in the same silicone rubber gasket material brought about by accelerated aging. The accelerated aging conditions were chosen to relate to the PEM fuel cell environment, but with more extreme conditions of elevated temperature (140°C) and greater acidity. Three accelerated ageing media were used. The first one was dilute sulphuric acid solution with the pH values of 1, 2 and 4. Secondly, Nafion® membrane suspended in water was used for accelerated ageing at a pH 3 to 4. Finally, diluted trifluoroacetic acid (TFA) solution of pH 3.3 was chosen. Weight change and the tensile properties of the aged gasket samples were measured. In addition, compression set behaviour of the elastomeric seal materials was investigated in order to evaluate their potential sealing performance in PEM fuel cells. The results showed that acid hydrolysis was the most likely mechanism of silicone rubber degradation and that similar degradation occurred under both real fuel cell and accelerated aging conditions. The effect of TFA solution on silicone rubber was more aggressive than sulphuric acid and Nafion® solutions with the same acidity (pH value) suggesting that TFA accelerated the acid hydrolysis of silicone rubber. In addition, acid ageing in all three acidic solutions caused visible surface damage and a significant decrease in tensile strength of the silicone rubber material, but did not significantly affect the EPDM materials. EPDM 2 compound had a desirable (low) compression set value which was similar to silicone rubber and much better than the commercial EPDM. It also showed a very good performance in the fuel cell test rig conforming that it a potential replacement for silicone rubber in PEMFCs.

At present, worrying quantities of tires are discarded due to the growth in demand for vehicles in the world, which has a direct impact on the deterioration of the environment since they normally go to landfills. Based on the background found, the use of this material for geotechnical applications can help reduce the pollution they generate and improve the physical and mechanical properties of soils. Therefore, this research seeks to evaluate a greater shear strength and capacity of support to the penetration of the clayey soil by means of the addition of 1.5%, 2.5% and 3.5% of rubber powder recycled. For this, the Atterberg limits analysis, the modified proctor compaction test, shear box and CBR were performed. For the shear box test, the results reflect that the cohesion of the mixture increased and the angle of internal friction decreased with respect to the natural soil, resulting in the sum in an increase of shear strength. On the other hand, the percentage of CBR increased, this means that the rubber helped the soil to be more rigid and have a greater resistance to penetration. These mixtures could be used in different projects within geotechnical engineering, as it presents an improvement in shear strength and an acceptable support index value (CBR).

Concrete plants consume 10 billion tons of natural aggregates annually from quarries and gravel plants for produce concrete, this demand requires exploiting natural resources from mountains and rivers producing an ecological imbalance. One solution is to use Palm Oil Clinker (POC), which is eliminated in large quantities in the dumps and rivers without taking advantage of its puzolanic, binding and resistance properties as an aggregate in the concrete; another alternative is to apply rubber from abandoned and discarded tires as waste in landfills or burned, without taking advantage of its performance of improvement in concrete, increasing its resistance to impact and fatigue. Unable to find joint POC and rubber information, this research studies its influence replacing 2.5% rubber (grained and crushed) with 10%, 12.5% and 15% POC in the fine aggregate on traditional concrete; results indicate that with 12.5% of POC as the ideal percentage, the compressive strength, tensile strength and flexural strength rise between 2.16 - 9.54%, so the concrete obtained has a cost of less than 4.09% and has 3.65% less CO2 emission.

Orientador: Aldo Eloizo Job / Banca: Mariselma Ferreira / Banca: Ivan Helmuth Bechtold / Banca: José Antonio Malmonge / Banca: Eduardo René Perez / Resumo: Atualmente é comprovado o poder de indução de angiogênese e neoformação tecidual através de membranas de borracha natural de Hevea brasiliensis. Este trabalho apresenta um estudo sobre as propriedades e a caracterização das frações não isoprênicas, separadas por centrifugação do látex, utilizado como biomaterial na indução de angiogênese e de neoformação. As frações constituintes, F2 e F3 sem o tradicional agente estabilizante de hidroxido de amônio (NH4OH), foram liofilizadas para a redução da quantidade de água e estabilização, em seguida tratadas termicamente a temperatura de 40,60,80, 100, 120 e 140ºC e novamente liofilizadas, sendo caracterizada através das técnicas de Kjeldahl, Soxhlet, de espectroscopia de absorção no infravermelho (FT-IR), Ressonância Magnética Nuclear (RMn-13C). Difração de raios x (DRX), termogravimetria (TG) acoplado ao FT-IR (IG/FT-IR), calorimetria exploratória diferencial (DSC), eletroforese, dosagens de citocinas e síntese de óxido nítrico considerando o fator limitate do uso do látex como um material bioativo, que é a temperatura de tratamento térmico, realizado para a obtenção das membranas de borracha natural, em torno de 85ºC. Foi possível verificar que a fração F3 constituinte do látex, tem propriedades anti-inflamatórias e que a fração F2 possui propriedades pró-inflamatórias / Abstract: Currently it is proven the hability of inducing angiogenesis and tissue neoformating through membranes of natural rubber Hevea brasiliensis, so this work presents a study on the properties and characterization of non-isoprene fractions, separated by centrifugation, the latex used as biomaterial for induction and neoformation of angiongenesis and lyophilized without the traditional stabilizing agent, ammonium hydroxide (NH4OH). The fractions constituents, F2 and F3 fractions were lyophilized without the traditional stabilizing agent, ammonium hydroxide (NH4OH). The fractions constituents, F2 and F3 fractions were lyophilized to reduce the amount of water and stabilization, and then heat treated at temperature of 40, 60, 80, 100, 120 and 140ºC bieng characterized by the techniques of kjeldahl, Soxhlet, of absorption spectroscopy infrared (FT-IR), Nuclear Magnetic Resonance (NMR-13C), X-ray Diffraction (XRD), thermogravimetry (TG) coupled to FT-IR (TG-IR), differential scanning calorimetry (DSC), electrosphoresis, serum cytokines and oxide nitric (NO) considering the limiting factor in the use of latex as a bioactive material, which is the thermal treatment temperature, held for obtaining membranes of natural rubber, about 85ºC. It was possible to verify that the fraction F3 constituent latex has anti-inflammatory and the fraction F2 take inflammatory properties / Doutor