Degradação de membrana impermeabilizante de polietileno de alta densidade usada em tanques de armazenamento de vinhaça

High-density polyethylene (HDPE) water-proof membranes are used as coatings in vinasse (leachate from sugar cane) storage tanks. The leachate is pumped into the tanks at temperatures of 80-90 °C. Due to these high temperatures and acidity of the waste, these membranes can be degraded, cracked and then loose the function for which they have been designed. This may cause contamination of the soil and groundwater. This study evaluated the effect of vinasse in HDPE membranes after 4 months of exposure in a controlled environment. An aggressive, alkaline pH liquid (sodium hydroxide) was also used. The objective was to evaluate the membrane resistance in contact with acidic and alkaline residues. Physical and mechanical tests, measurement of the carbon black content and thermo gravimetric analysis (TGA) were used to determine degradation of polymer membranes after chemical immersion. While sodium hydroxide resulted caused only minor changes in the physical properties, vinasse induced a thickness change of 7.8%. With immersion in vinasse, an average decrease in strength and deformability (yield) of 34% and 23.5% were measured, respectively. The stiffness increased by 7.8% (average) and the tear strength decreased by 2.7% (average).

Biodegradação de filmes de polietileno de baixa densidade (PEBD), polihidroxibutirato-co-hidroxivalerato (PHBV) e blenda de PEBD/PHBV (70/30), em coluna de solo

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Caracterização mecânica e térmica de compósitos naturais modificados com ciclodextrina e fibras vegetais utilizando como matriz uma resina termofixa DGEBA/TETA

Pós-graduação em Ciência dos Materiais - FEIS

Estudo experimental do polietileno poroso de alta densidade (MEDPOR) fixado ao leito cirúrgico corticalizado e decorticalizado: análise histológica em cães

The aim of this study was to evaluate the influence of the bed in High Density Porous Polyethylene (Medpor) implants integration. Two different kind of beds -- corticalized and decorticalized -- were made in six dogs. The animals were killed thirty, sixty and ninety days after implantation. Blocks including implant and adjacent bone were harvested, submitted to histological procedures, stained in hematoxiline-eosine and analyzed in optic microscope. The results demonstrated an absence of infection and foreign body reaction associated with High Density Porous Polyethylene (Medpor) implants. Furthermore, bony and fibrovascular ingrowth could be observed into its pores. The best integration was noted in decorticalized group, in which occurred a greater bony and fibrovascular ingrowth in comparison to the corticalized group

Estudo da aplicabilidade do sistema pultrudado de fenólica/fibras de carbono em cabos condutores

Pós-graduação em Engenharia Mecânica - FEG

Avaliação da integração de esferas de hidroxiapatita sintética e de polietileno poroso em cavidades evisceradas de coelhos

Para a recuperação da estética facial,há necessidade de reposição do volume orbitário perdido em decorrência de eviscerações ou enucleações. Este estudo foi realizado com os objetivos de avaliar comparativamente a biocompatibilidade e a manutenção do volume orbitário com o uso de esferas de hidroxiapatita sintética e de polietileno poroso, na reconstrução de cavidades evisceradas de coelhos. Métodos: Para isso foram utilizados 56 coelhos albinos, submetidos à evisceração do olho direito, com colocação de esferas de hidroxiapatita sintética (G1 – 28 animais) ou polietileno poroso (G2 – 28 animais).Quatro coelhos de cada grupo foram sacrificados em 7 momentos experimentais: 7, 15, 30, 60, 90, 120 e 180 dias após a evisceração. Após o sacrifício, o conteúdo da cavidade orbitária direita foi removido e seccionado na porção central em duas hemi-metades,uma das quais foi preparada para exame histopatológico; exame ultra-estrutural em microscópio eletrônico de varredura foi feito em dois animais de 7, 60 e 180 dias, de ambos os grupos experimentais. Resumo 118 Resultados: Observou-se aos 7 dias, tecido conjuntivo frouxo, constituído de células inflamatórias e hemáceas, em meio à rede de fibrina, principalmente na periferia da esfera de hidroxiapatita e chegando até ao centro da esfera de polietileno; a reação tecidual tornou-se mais densa com o passar do tempo. Decorridos 60 dias, observou-se em G1, início de metaplasia óssea que se acentuou ao longo do experimento. Em todos os momentos experimentais, a inflamação,predominantemente macrofágica, foi muito mais acentuada em G1.O volume da cavidade esclero-corneana foi melhor mantido em G2. Conclusão: a esfera de hidroxiapatita sintética provoca mais inflamação que a de polietileno poroso e é menos eficiente na manutenção do volume orbitário... (Resumo completo, clicar acesso eletrônico abaixo)

Desenvolvimento e caracterização de compósitos de fibras naturais modificadas e híbridos: fibras da coroa do abacaxi/polipropileno e fibras da coroa do abacaxi/fibras de vidro/polipropileno

The concern with the environment preservation has done with that researchers as well as industries invest in the search for materials that come from renewable sources. Natural fibers, because they are ecologically correct and have low cost, have been studied as a possible substitute, even if partial, of synthetic fibers in the development of polymeric composites. In this context, the hybrid composites (natural/synthetic) increase considerably the range of application of natural composites. The auto industry, in its constant quest for good mechanical properties materials which are developed with sustainability, has in composites with hybrid reinforcement a very viable alternative. In the present work, the nature Crown pineapple fibers and nature Crown pineapple fibers treated with alkaline solution were studied in order to evaluate the influence of chemical treatment in its properties. For this techniques were used x-ray diffractometry, Thermogravimetry and Infrared Spectroscopy (FTIR). Composites have been developed using polypropylene, reinforced with pineapple fibers and pineapple fibers hybrids/glass fibres, both with levels of 5 and 10%. These composites were analyzed by Thermogravimetry techniques and tested by traction. The realization of this work indicated that although the chemical treatment did not affect the thermal stability of the fibers, caused an increase in crystallinity index fibers and decreased its hydrophilic. The tests performed on composite indicated that the composites process was suitable because it provided good dispersion of the polymer matrix. The addition of natural fibers from the pineapple's Crown, in a proportion of 10%, provided the greatest increase in modulus of elasticity (27%) when compared to the pure polymer

Uso de próteses oculares de polietileno granulado como biomaterial em cavidades anoftálmicas

Não disponível

Obtenção e caracterização de compósitos via RTM com alta fração de fibras de carbono processados à temperatura ambiente

After confirming the high specific mechanical properties of composite materials by scientific studies conducted over the last decades, one of the challenges of this new class of materials is the ability to achieve mass production at a more affordable cost, which has become indispensable. The Resin Transfer Molding (RTM) is an excellent method for manufacturing composite materials. Despite being a process widely used by international companies in the production of high performance structural composites, only a short time the national aviation industry has shown interest in implementing this type of processing to more complex structures and greater structural responsibility. In aeronautical projects, the reproducibility and the relative low cost of this process, several studies have been performed in Brazil for learning and perfecting this technique. This process is suitable for producing polymer components both simple as complex geometry, and allows to achieve consistent thickness, with high quality finish and without limiting range. Polymeric composite components for the high mechanical stress applications such as aircraft structures, satellites, etc., require a strict control of volume fractions of the composite constituents, beyond the knowledge of their mechanical and thermal properties. Therefore, in this experimental work degree study on the mechanical, thermal and of porosity composites processed by RTM processed characterization was performed. This characterization was performed targeting a possible aerospace application of this composite material. For the production of composites, process equipment (RTM RTM injector Radius 2100cc) was used. The processed carbono/epoxy composites were characterized via flexure tests mechanically and thermally analysis via DMA, DSC and TGA. To determine the volume fraction of fibers, the composite samples were analyzed via matrix digestion (ASTM D3171) ... (Complete abstract click electronic access below)

Estudos de degradação de filmes de polietileno

A produção de lixo pela humanidade é inevitável, porém, o destino dos residuos sólidos e seu acondicionamento inadequado têm trazido graves problemas ambientais. Dentre os resíduos sólidos, os plásticos merecem destaque, pois cresceram significativamente em uso e descarte, totalizando 20% do volume mundial de lixo. Isto decorre de algumas das propriedades destes materiais, como durabilidade, resistência, leveza e baixo custo de produção. Nas grandes cidades brasileiras, 7% do lixo produzido correspondem a produtos de plástico em filme, geralmente usado em aplicações de curta duração, como o polietileno. Este material persiste no ambiente por décadas, sendo, portanto, resistente à degradação. Diversos destinos podem ser tomados pelo resíduo de polietileno descartado, como a deposição em lixões e aterros sanitários, incineração, reciclagem e biodegradação. A biodegradação pode ser definida como a degradação catalisada por atividade biológica, levando, no final do processo, à mineralização e/ou formação de biomassa. Na natureza, a destruição destes materiais se dá, na verdade, por meio da “degradação ambiental”, na qual atuam sinergeticamente a biodegradação, a fotooxidação, a termo-oxidação e a hidrólise. Neste sentido, desde os anos 1970, diferentes formulações foram propostas para otimizar a susceptibilidade do PE à degradação ambiental. Sabe-se que o PE está sujeito a sofrer mudanças quando exposto à luz ultravioleta e/ou ao calor, e que estas modificações podem alterar a resposta dos microrganismos no processo de biodegradação. Desta forma, este estudo analisou as modificações ocasionadas por tratamentos com luz ultravioleta, calor e exposição ao sol, bem como a resposta da microbiota natural do solo a estes tratamentos, através de análises de espectroscopia... (Resumo completo, clicar acesso eletrônico abaixo)

Proposta de conector para ensaios de ligações CDE submetidas à tração perpendicular as fibras em madeira de pinus

The growth of urban population associated with the shortage of supply of public infrastructure such as hospitals, kindergartens, schools, among others, has reinforced the need to develop alternative methods that simplify the construction processes and allows for a reduction in these costs works. The conventional processes have increasingly been shown ineffective to solve the problem of demand for different types of urban and rural buildings. Given this fact, industrial construction processes can gain space and have proven to be highly interesting to solve the above problems, in particular, considering the cost-effective and time. Therefore, this study aimed to determine the influence of moisture on the strength of metal plate connections connectors (printed plate with teeth). For the sizing of the links between structural lumber using metal connectors with teeth prints; controlled process variables (drying of the wood and the different moisture contents), and finally found results and compare them with different literatures order to obtain a qualitative efficiency of the process. Some specimens had very low expectations, can be explained by the presence of bone marrow, and pre-existing cracks. Thus, the results were discarded for further analysis and more accurate results

Fibras naturais: características químicas e potenciais aplicações

This study has as objective determining the chemical properties that serve as the basis for potential scientific and technological applications of seven species of fibrous plants cultivated in Brazil, which are: Banana” (Musa spp.), “Coco” (Cocos nucifera), Curauá (Ananas erectifolius), Fique (Furcraea andina), Piteira” (Furcraea gigantea), Sisal(Agave sisalana) and “Taboa” (Typha domingensis). The tests for determining the percent dry completely, extractives soluble in cold water, in hot water, in sodium hydroxide 1% and in ethanol-toluene, and the percentages of ash, hydrophobicity, lignin, holocellulose and cellulose were performed at the Department of Environmental Sciences, Agronomy College (FCA) of UNESP – Botucatu, São Paulo State. It also presents a literature review about these fibers and their potential applications. Differences between the results obtained and those found by other authors are possibly explained by variations on the origin of plant material, the harvest season, the climate and soil where they were grown. However, the results and the methodology used, serve as a basis for further studies with natural fibers

Reciclagem de poliestireno expandido: compósito com fibras de algodão para a confecção de placas de circuito impresso

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

Reciclagem de poliestireno expandido: compósito com fibras de sisal para confecção de placas de circuito impresso

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

Análise da influência da concentração de feixeis de fibras de bambu em ensaios de piso

Bamboo has one of the highest growth rates among plants, however, its lignifications (which confers resistance) takes around a few years and, therefore, certain physical characteristics and mechanical, that depend on this process will only be acquired between the three to six years old. In addition, bamboo also has significant density variations in different parts of the stem, both in the radial direction as the axial. In particular the radial direction, where the density found in the inner and outer (near the bark) of a single stem can range on average from 0.5 to 0.9 g/cm3. Thus, the application of bamboo as a floor, there to examine whether both sides of the bamboo (internal and external), provide resistance properties required for that purpose. In this study sought to characterize and quantify the influence of the concentration of fiber bundles in the inner and outer sides of rules or bamboo strips of bamboo flooring through testing service. Analyses performed were based on ASTM D 2394- 83 for wooden floors and derivatives. This was necessary because of the absence of a specific prohibition of the use and testing of floors made of bamboo and its products. The data were analyzed by ball indentation test shooting, test for resistance to abrasion, indentation test for stress / load treadmill test and by indentation loads applied to small areas - test the jump. The results of the tests were extremely friendly bamboo, even this presents considerable differences between the resistances obtained from assay of the cover of the inner and outer face, being comparable with those of many commonly used to manufacture wood flooring. This comparison was made possible by information from technical trials of several floors made with wood