Caracterização do compósito obtido a partir de borracha natural com negro e resíduos de couro aplicado como pisos e revestimentos

Pós-graduação em Ciência e Tecnologia de Materiais - FC

Produção de nanocompósito utilizando diferentes fontes de celulose como reforço

Pós-graduação em Agronomia (Energia na Agricultura) - FCA

Otimização dinâmica de rotores com eixos em compósito

Pós-graduação em Engenharia Mecânica - FEG

Anatomização de pinos de fibra de vidro: estudo de propriedades mecânicas na interface restauradora adesiva

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

Estudo das células primárias dentais, viabilidade celular e bioatividade de materiais á base de silicato de cálcio

Pós-graduação em Odontologia - FOAR

Estudo da dureza e da resistência à compressão de resinas compostas para dentes posteriores após a imersão em água destilada. Efeito da aplicação de selante superficial

Novos compósitos têm surgido no mercado especificamente destinados à confecção de restaurações estéticas posteriores. Entretanto, embora tais materiais apresentem resultados iniciais animadores, há a necessidade de comprovações adicionais para que possam ser utilizados com segurança. Resinas compostas posteriores são submetidas a estresses complexos de compressão e abrasão durante a mastigação e a aplicação de selantes superficiais tem sido relatada como forma de aumentar a resistência ao desgaste destes materiais. O presente trabalho teve como propósito avaliar a dureza e a resistência à compressão das resinas compostas Alert (Jeneric/Pentron), Ariston (Vivadent), Definite (Degussa), P60 (3M), Solitarie (Kulzer), Surefil (Dentsply) e Z100 (3M) após 90 dias de imersão em água destilada, recobertas com selante Protect It (Jeneric/Pentron) e submetidas à ciclagem mecânica (10.000 ciclos, 600N, 5Hz). Os ensaios de dureza (n=8) foram realizados em aparelho Wolpert, com diamante Vickers e peso de 50gf aplicado por 30 segundos, antes e após períodos de imersão de 30, 60 e 90 dias. Os ensaios de resistência à compressão (n=8) foram realizados somente após 90 dias, em corpos-de-prova cilíndricos medindo 8mm de altura por 4mm de diâmetro. Apenas os espécimes destinados à compressão foram ciclados mecanicamente. Os ensaios foram realizados em máquina MTS 810, equipada com célula de carga de 10kN (ciclagem) e 100kN (compressão) e velocidade de 0,5mm/min. Após análise de variância (p<0,05), os resultados mostraram, previamente à imersão, maiores valores de dureza para os materiais Z100 (74,253VHN) e Ariston (71,308VHN). A seguir, com valor semelhante à resina Ariston, mas inferior à resina Z100, apresentou-se o material Surefil (69,969VHN)...(Resumo completo, clicar acesso eletrônico abaixo)

Avaliação da citotoxicidade, genotoxicidade e mutagenicidade de lentes de contato à base de celulose bacteriana com adição de complexos fármacos-ciclodextrinas

Nos últimos anos, a biotecnologia tem proporcionado avanços no desenvolvimento de biomateriais a serem utilizados como dispositivos médicos. Dentre esses dispositivos, podemos destacar aqueles que promovem a reparação tecidual e, também, a liberação controlada de fármacos. Partindo deste propósito, lentes de contato à base de celulose bacteriana (CB) foram desenvolvidas, visando o efeito curativo e reparativo para doenças da superfície ocular. A adição de ciclodextrinas (CDs) e fármacos, como o ciprofloxacino (CP) e o diclofenaco de sódio (DS) á essas lentes proporcionando propriedades terapêuticas e de liberação controlada dos fármacos. No entanto, para certificar-se do uso seguro desses compósitos pela indústria de dispositivos médicos, é necessário verificar se não possuem atividade citotóxica, genotóxica e/ou mutagênica. Sendo assim, a proposta do presente trabalho foi o desenvolvimento de uma adição eficaz de fármacos às lentes de contato de CB, para que sejam liberados de maneira controlada e, também, a verificação de sua biossegurança. Para essa verificação foram realizados ensaios in vitro de citotoxicidade (ensaio com o kit XTT e Sobrevivência Clonogênica), genotoxicidade (ensaio Cometa) e mutagenicidade (teste do Micronúcleo) com os respectivos. Após a análise estatística dos resultados foi possível verificar que o material CB-CP apresentou efeito citotóxico e os materiais CB-DS e CB-CD-DS apresentaram efeito citotóxico, genotóxico e mutagênico. Essa informação é fundamental para uma futura utilização segura desse biomaterial pela indústria de dispositivos médicos ...

Influência do uso de hipoclorito de sódio 2,5% e extrato glicólico de sálvia 20% durante o preparo biomecânico sobre a resistência adesiva de retentores intra- radiculares: avaliação através do teste de push-out

The aim of this study it was to evaluate the use of irrigating solution used during root canal preparation on the adhesive cementation of prefabricated fiberglass pins. The bond strength between different regions of the root and the fiberglass pins cemented into the root canal were evaluated by push-out assay. For this study, 36 human teeth were used, all equally prepared. The irrigating solutions used for biomechanical preparation were: saline solution, sodium hypochlorite 2,5% and glycolic extract of salvia 20%. The dual cure resin cement was used for cementation of pins. After cementation, specimens were sectioned to give 3 slices of approximately 2 mm each (cervical, middle and apical), which were submitted to mechanical push-out test. Were performed ANOVA and Tukey's test with a significance level of 5%, for the analysis of mechanical test. Comparing the thirds we observed that the only solution that presented statistical difference in the bond strength was sodium hypochlorite, which showed higher values for the middle and apical third compared with the cervical third, but when compared without taking into consideration the dental thirds, solutions studied showed no differences in bond strength. Therefore, it was concluded that the solutions studied can be used during endodontic treatment without causing harmful effects on the final adhesive restoration

Uma revisão sobre a resina uréia-formadeído (RUF) empregada na produção de painéis de madeira reconstituída

According to ABIPA (2009), Brazil is currently among the major producers of reconstituted wood panels, with one of the main factors for this condition, its climate and its large land area, which allows the cultivation of forests, which provide raw materials for these industries. To establish that market as power, Brazil has invested about R$ 1.3 billion in the last 10 years, yet designed an investment of 0.8 billion dollars over the next three years (BNDES, 2008). With the new investments in this segment, we expect a growth of about 66% in the resin consumption of urea-formaldehyde (GPC, 2009) which should also result in major investments by the companies producing this polymer. Currently employees are mainly three types of resins in the production industry panels, as follows: Urea-Formaldehyde Resin (R-UF), melamine-formaldehyde resin (R-MF) and Phenol-Formaldehyde Resin (R-FF). Especially the cost factor, the urea-formaldehyde resin is the most used by companies producing reconstituted wood panels. The UF-R is a polymer obtained by condensation of urea and formaldehyde reactors (usually batch type), characterized by being a thermosetting polymer which makes it very efficient for bonding wood composites. The urea-formaldehyde polymer, to present a quite complex, it becomes very difficult to predict the exact chain resulting in the process of condensation of urea with formaldehyde, so that a greater knowledge of its characteristics and methods for their characterization can result in greater control in industrial processes and subsequent decrease cost and improve the quality of reconstituted wood panels produced in Brazil

Otimização do braço inferior da suspensão dianteira do veículo Baja utilizando o método dos elementos finitos

Mass reduction coupled with the mechanical performance in service has been the goal of many projects related to the transport area, considering the advantages that mass reduction can bring. However, make a simple material substitution without design a new geometry to corroborate for the best component performance, often makes the replacement unviable. In this study, it was investigated the advantages of replacing the prototype BAJA SAE front suspension lower arm of Equipe Piratas do Vale de BAJA SAE - Universidade Paulista, Campus Guaratinguetá, actually produced with steel, for a new component made of carbon fiber composite. The new geometry has been developed to provide the best possible performance for this component and your easy manufacturing. The study was done using the 3D modeling tools and computer simulations via finite element method. The first stage of this work consisted on calculation of the estimated maximum contact force tire / soil in a prototype landing after jump at one meter high, drop test in the laboratory with the current vehicle, current front suspension lower arm 3D modeling, finite element simulation and analysis of critical regions. After all current component analysis, a new geometry for the part in study was designed and simulated in order to reduce the component mass and provide a technological innovation using composite materials. With this work it was possible to obtain a theoretical component mass reduction of 25,15% maintaining the mechanical strength necessary for the appropriated component performance when incited

Desenvolvimento de um sistema para caracterização de dispositivos eletroluminescentes

The materials designed to be used in electroluminescent (EL) devices construction are studied and improved since 1936. Great interests in the development of this kind of devices are mainly due to its low power consumption, flexibility, low cost and easy processing. One class of ELs devices with these characteristics are produced by employing a organic-polymeric/inorganic composite from a conductive polymer blend and an inorganic electroluminescent material (Zn2SiO4:Mn) dispersed in the polymeric matrix. This kind of device operates in d.c. or a.c. potentials, with EL of hundreds candela in the green region of the visible spectrum. However, few studies on the light emission were performed for these devices. In order to characterize devices made from composites, in this work is proposed a method of characterizing the electroluminescence associated with the impedance spectroscopy technique. To implement the technique of impedance spectroscopy was employ an experimental setup consisting of a source of a.c. voltage, an oscilloscope, and a reference resistor. Associated with this system, was use a photo diode and an analog electrometer to characterize the emitted light signal from the sample. The system was implemented allows characterization by impedance spectroscopy in the frequency range from 0.2 Hz up to 2 MHz and voltage amplitudes of 5 mV up to 20 kV. This system permits, at the same time, measurement of the RMS value of the luminance for devices in frequency range from 20 Hz up to 2 MHz. To test the system efficiency, an EL device was characterized showing analogous results to those reported in literature. By doing this, was demonstrated the efficiency of the system for electroluminescence characterization associated with the electrical characterization by impedance spectroscopy, for devices

Fácies, diagênese e arquitetura estratigráfica de reservatórios deltaico-lacustres da fase rifte (formação pendência), campo Serraria da Bacia Potiguar

Of the four lacustrine deltaic models, which were found in the Pendência formation, two are represented in the Serraria field. Respectively the deltaic models 1 and 3 shows the reservoir zones A and B. The Zone A is divided into six sub-areas. Each is representing a smaller cycle of development of sigmoidal lobes of deltaic front. Zone B produces in reservoirs of Model 3, or so called Full delta. The Zone B is formed by overlapping the deltaic plain system over the deltaic/prodeltaic front (model 1). This work uses the method of zooming with the aim to contextualize the geometric aspects of the sand bodies, highlighting the analysis of facies and diagenesis with help of pictures and testimonies of thin sections. The sigmoidal lobes of Zone A are fine to very fine sandstones, well sorted, with a arcosian composition.;practically with a weak compaction and cementation of a kind of film of clay (if very fine) and overgrowth feldspar (fine texture). This silicate phases are succeeded by cementation of poiquilotópica calcite, and after this a stage of dissolution, containing only regular permoporosity for this reservoir. Zone B has a combination of two types of deltaic plain reservoir. One is the rarest of distributary channel and the other the most common of lobes of crevasse. In the channel coarse to medium-grained and poor to moderate sorted sandstones are formed (tuning up), and with a lytic arcosiana nature. Rarely there are cements, including growth of feldspar and rhombohedral dolomite, which prevent a high permoporosity of the reservoir. In the crevasse lobes, the sandstones are laminated, fine and well sorted, arkosic, rarely with overgrowth feldspar and calcite poiquilotópica, and with a good intergranular permoporosity

Processamento do compósito de fibra de capim-sapê / epóxi e avaliação da resistência à flexão “t” de Student

In recent years a great worldwide interest has arisen for the development of new technologies that enable the use of products with less environmental impact. The replacement of synthetic fiber plants is a possibility very important because this fiber is renewable, biodegradable and few cost and cause less environmental impact. Given the above, this work proposes to develop polymeric composites of epoxy resin and study the behavior of these materials. Both, the epoxy resin used as matrix in the manufacture of sapegrass fiber composite, as tree composites formed by: epoxy/unidirectional sapegrass long fiber, 75% epoxy/25% short fiber, by volume, and 80% epoxy/20% short fiber, by volume, were characterized by bending, and the composites produced with short fibers random were inspected by Optical Microscopy and Acoustics Inspection (C-Scan). For the analysis of the sapegrass fiber morphology, composites 75% epoxy/25% short fiber (sheet chopped) and 80% epoxy/20% short fiber images were obtained by optical microscope and the adhesion between polymer/fiber was visualized. As results, the flexural strength of composites epoxy/unidirectional long fibers, 75% epoxy/25% short fiber and 80% epoxy/20% short fiber were 70.36 MPa, 21.26 MPa, 25.07 MPa, respectively. Being that composite showed that the best results was made up of long fibers, because it had a value of higher flexural strength than other composites analyzed

Avaliação de sistemas de pultrudados com diferentes tipos de matrizes para aplicação em cabos condutores

In the last decades it has been observed a substantial developing of the electrical energy demand in the societies all over the World. In consequence the electrical energy distribution companies are increasing the quantity of electrical energy through the electrical energy conductor cables, which had grown the sag in the towers of energy transmission. Furthermore, the construction of more transmission towers brings a lot of troubles due environmental protection laws. In this way, looking forward to increase the quantity of electrical energy transmitted through electrical cables conductors, reduce the need of constructing new transmission towers and the sag in them, we suggest in this work the replace of the traditional core of the conductors cables commonly used, made of steel, by a core made by a composite material, which one is made by carbon fibers pultruded with polymeric resins as matrix. In a order to evaluate if the resins more commonly used in structural composites can be applied as matrix to make possible to use the composite material as a core, we made carbon fibers systems pultruded with epoxy, phenolic and polyester resins as matrix and a mechanic and physic-chemistry characterization was done on the systems by Tensile and Poisson tests, differential sprobe calorimetry (DSC), thermogravimetric analysis (TGA) and Fourier transformed infrared spectroscopy (FTIR), following their correspondents standards

Produção e caracterização físico-mecânica do compósito cimento-madeira com variação granulométrica dos resíduos lignocelulósicos

The need to reduce environmental damage and add value to waste causes more and more new alternatives appear to unite these two points. One of the main ways to achieve this in timber industries and the use of waste for making panels. This work was aimed at studying the influence of particle size and density in Eucalyptus mechanical compressive strength of cement composite wood. For this study was performed production and physico-mechanical characterization of specimens, using portland cement, water and waste eucalyptus. The methodology consists of a statistical study of the results obtained by calculating the density and axial compression tests and a subsequent comparison of these results with other studies. The results showed that there are significant differences in density and compressive strength when using different particle sizes the particles of eucalyptus. In general, the smaller the particle size, the lower the compression strength and the greater the density when the samples are produced with the same trait