Desenvolvimento de modelos simplificados para o estudo da extrusão de polímeros

Neste trabalho, desenvolveram-se modelos matemáticos simplificados para o cálculo de duas variáveis importantes no estudo da extrusão de polímeros: vazão mássica (M&) e pressão na saída da extrusora (Psaída), em função das propriedades dos materiais e das condições de operação do equipamento. Podem-se utilizar esses modelos como ferramentas simples para a definição de critérios de ajustes que se devem fazer em uma extrusora de parafuso único para obter-se o desempenho desejado quando se alimenta o equipamento com um novo material. Para desenvolverem-se os modelos simplificados, utilizaram-se dados experimentais da extrusão de poliestireno (PS) e de polipropileno (PP), bem como resultados preditos por um programa computacional de simulação de extrusão disponível comercialmente. Mediram-se os dados experimentais de vazão mássica e de pressão na saída da extrusora em um equipamento de parafuso único de 45 mm de diâmetro. Realizaram-se esses testes, variando-se a velocidade de rotação do parafuso de 70 a 100 rpm para ambos os polímeros. No primeiro conjunto de simulações, utilizou-se o simulador Flow 2000 (Compuplast Inc.) para ajustarem-se os valores preditos de M& e de Psaída aos dados obtidos experimentalmente através da estimação dos fatores de atrito barril-polímero tanto para o PP quanto para o PS. Posteriormente, realizou-se um planejamento de experimentos, do tipo fatorial fracionado , para obter-se um segundo conjunto de simulações, considerando-se as propriedades dos materiais (reológicas e térmicas) e as condições de operação da extrusora (velocidade de rotação do parafuso e perfil de temperatura nas zonas de aquecimento da extrusora) como fatores de investigação. Com as novas simulações no Flow 2000, ajustaram-se os parâmetros dos modelos simplificados aos valores de vazão mássica e de pressão na saída da extrusora preditos no simulador. Elaboraram-se os modelos simplificados levando-se em conta as interações entre os fatores cujos efeitos consideraram-se significativos nas análises de variância (ANOVA). Obteve-se um modelo linear com 37 termos para o cálculo da vazão mássica e um modelo linear com 41 termos para o cálculo da pressão na saída da extrusora. Posteriormente, aplicou-se uma técnica de regressão multivariável para selecionar apenas os termos importantes dessas 1402IV2− XVI equações, conduzindo a um modelo linear com 10 termos para o cálculo da vazão mássica e a um modelo com 6 termos para o cálculo da pressão na saída da extrusora. Conseguiu-se boa concordância entre os dados experimentais e os valores preditos quando se aplicaram os modelos simplificados.

Produção de implantes de titânio, via moldagem por injeção de pós de hidretos de titânio

O objetivo deste trabalho foi a produção e caracterização de componentes sinterizados de titânio para aplicação biomédica, obtidos através do processo de fabricação chamado de Moldagem de Pós por Injeção ( MPI ), ou “Metal Injection Molding” ( MIM ) na língua inglesa. Para a produção dos componentes de titânio, utilizou-se de pós de hidreto de titânio produzidos pelo processo de Hidretação-Dehidretação ( HDH ), no Laboratório de Transformação Mecânica - UFRGS. Foram realizados ensaios para a caracterização dos componentes sinterizados quanto às suas propriedades mecânicas, resistência à corrosão, características morfológicas e de biocompatibilidade. Este trabalho concentra-se no desenvolvimento e produção de componentes para área odontológica ( implantodontia ) e médica, visando a implementar a técnica de Moldagem de Pós por Injeção ( MPI ) de hidreto de titânio para aplicação na produção de implantes, tendo em vista que, atualmente, este processo não é utilizado para tal fim. Para as análises de biocompatibilidade foram produzidos parafusos corticais para utilização como implantes. Após a caracterização morfológica e química dos implantes produzidos foram realizados ensaios in vitro de corrosão e in vivo de biocompatibilidade onde foi possível observar algumas características da superfície do implante como, por exemplo, a susceptibilidade à corrosão por frestas e elevado recobrimento ósseo do implante.

Rearranjo estrutural de PET durante compressão plana

As características da tensão – deformação do Poli(tereftalato de etileno) (PET) durante o processo de deformação por compressão plana tem sido estudadas. Amostras de PET com e sem tratamento térmico obtidas por injeção foram deformadas a diferentes temperaturas de deformação, abaixo e acima da temperatura de transição vítrea (Tg) utilizando diferentes taxas de deformação e tensões finais aplicadas. O comportamento mecânico foi analisado através das curvas de tensão – deformação obtidas por deformação por compressão plana usando equipamento específico chamado “Ampliador de Forças” conectado a um equipamento INSTRON. A morfologia e a cristalinidade aparente foram investigadas usando as técnicas de Calorimetria Exploratória Diferencial (DSC), densidade, Difração de Raios-X em Alto Ângulo (WAXD), Espalhamento de Raios-X em Alto Ângulo (WAXS), Espalhamento de Raios-X em Baixo Ângulo (SAXS) e Microscopia Eletrônica de Varredura (MEV). Os resultados tem mostrado que as propriedades dos materiais após deformação são fortemente relacionadas a temperatura de deformação, taxa de deformação e tensão final aplicada em ambas as regiões, vítrea e elastomérica. As modificações morfológicas do material tem sido analisadas em micro e nano escalas incluindo mudanças de cristalinidade e orientação em nível esferulítico e lamelar.

Firmament : um módulo de injeção de falhas de comunicação para linux

A execução de testes é um passo essencial na adoção de novos protocolos de comunicação e sistemas distribuídos. A forma com que estes se comportam na presença de falhas, tão comuns em ambientes geograficamente distribuídos, deve ser conhecida e considerada. Testes sob condições de falha devem ser realizados e as implementações devem trabalhar dentro de sua especificação nestas condições, garantindo explicitamente o funcionamento dos seus mecanismos de detecção e recuperação de erros. Para a realização de tais testes, uma técnica poderosa é a injeção de falhas. Ferramentas de injeção de falhas permitem ao projetista ou engenheiro de testes medir a eficiência dos mecanismos de um sistema antes que o mesmo seja colocado em operação efetiva. Este trabalho apresenta o projeto, desenvolvimento e teste do injetor de falhas FIRMAMENT. Esta ferramenta executa, dentro do núcleo do sistema operacional, microprogramas, ou faultlets, sobre cada mensagem processada para a emulação de situações de falha de comunicação, utilizando uma abordagem de scripts. A ferramenta é implementada como um módulo de núcleo do sistema operacional Linux, tendo acesso total aos fluxos de entrada e saída de pacotes de forma limpa e não intrusiva, permitindo o teste de sistemas baseados nos protocolos IPv4 e IPv6. Seu desempenho é significativo, já que a ferramenta evita que os mecanismos de injeção de falhas sejam invocados nos fluxos que não sejam de interesse aos testes, bem como dispensa a cópia de dados dos pacotes de comunicação a serem inspecionados e manipulados. A aplicabilidade da ferramenta, dada pela sua facilidade de integração a um ambiente de produção, é conseqüência de sua disponibilidade como um módulo de núcleo, podendo ser carregada como um plugin em um núcleo não modificado. As instruções por FIRMAMENT suportadas lhe dão alto poder de expressão dos cenários de falhas. Estas instruções permitem a inspeção e seleção de mensagens de forma determinística ou estatística. Além disso, fornecem diversas ações a serem realizadas sobre os pacotes de comunicação e sobre as variáveis internas do injetor, fazendo-o imitar o comportamento de falhas reais, como descarte e duplicação de mensagens, atraso na sua entrega e modificação de seu conteúdo. Estas características tornam a ferramenta apropriada para a realização de experimentos sobre protocolos e sistemas distribuídos.

Contribuição ao estudo do envelhecimento de ligantes asfálticos : influência da adição de polímeros e comportamento frente a radiação uv

A malha rodoviária brasileira apresenta-se, em sua maior extensão, em má condições de serventia. Uma das alternativas para se evitar deformações permanentes e trincamentos no pavimento é a adição, a quente e em reatores especiais, de polímeros ao asfalto. Esta prática já é realizada no Brasil há alguns anos, porém ainda não se tem um domínio do assunto, principalmente no caso da modificação de ligantes asfálticos brasileiros. O objetivo deste trabalho é avaliar a influência de algumas propriedades do polímero modificador no envelhecimento do ligante asfáltico modificado. Para tanto se realizou inicialmente um estudo sobre o mecanismo de envelhecimento de ligantes puros, inclusive frente a radiação ultravioleta do sol, e em seguida utilizou-se a mesma metodologia para avaliar o papel do polímero neste processo. Além disso, relacionou-se através de um projeto de experimentos a massa molar e teor de estireno do polímero SBS linear com suas propriedades clássicas, estabilidade, temperatura de transição vítrea e morfologia. Observou-se que a simulação de envelhecimento UV em laboratório, desenvolvida neste estudo, foi extremamente satisfatória. Os processos de foto-oxidação e termooxidação resultam em mecanismos diferentes de envelhecimento. A origem e composição química dos ligantes é de suma importância no mecanismo de envelhecimento UV destes. A massa molar e o teor de estireno do polímero modificador representam propriedades importantes para a estabilidade e durabilidade do ligante asfáltico modificado.

Estudo comparativo de carragenanas comerciais Kappa, Iota e Lambda no processo inflamatório em ratos :edema intraplantar e pleurisia

The Iota, Kappa and Lambda commercial carrageenans are rarely pure and normally contain varying amounts of the other types of carrageenans. The exact amount of impurity depends on the seaweed source and extraction procedure. Then, different analysis methods have been applied for determination of the main constituents of carrageenans because these three carrageenans are extensively used in food, cosmetic and pharmaceutical industry. The electrophoresis of these compounds proved that the carrageenans are constituted by sulfated polysaccharides. These compounds were characterized by colorimetric methods and was observed that the Lambda carrageenan shown the greater value (33.38%) of sulfate. These polymers were examined by means of 13C NMR spectroscopy and infrared spectra. The polysaccharides consisted mainly of units alternating of sulfated galactoses and anhydrogalactoses. The aim of the study was also to test the inflammatory action of these different polysaccharides. A suitable model of inflammation is acute sterile inflammation of the rat hind limb induced by carrageenan. Paw edema was induced by injecting carrageenans (κ, ι and λ) in saline into the hind paw of a male Wistar rats (175–200 g). The pathway to acute inflammation by carrageenan (kappa, iota and lambda) were expressed as time-edema dependence and measured by paw edema volume. For this purpose, was used an apparatus (pakymeter), which makes it possible to measure the inflammation (swelling of the rat foot) with sufficient accuracy. The results showed that κ-carrageenan (1%) have an edema of 3.7 mm and the paw edema increase was time and dose dependent; the ι-carrageenan (0.2%) caused an edema of 4 mm and the λ-carrageenan (1%) caused an edema of 3.6 mm. Other model was used in this study based in the inflammation of pleura for comparatives studies. Injection of carrageenans into the pleural cavity of rat induced an acute inflammatory response characterized by fluid accumulation in the pleural cavity, a large number of neutrophils and raised NO production. The levels of NO were measured by Griess reactive. The ι-carrageenan caused the greater inflammation, because it has high concentration of nitrite/nitrate (63.478 nmoles/rat), exudato volume (1.52 ml) and PMNs (4902 x 103 cells). Quantitative evaluation of inflammations of rats is a useful and important parameter for the evaluation of the efficacy of anti-inflammatory drugs

Influência da vermiculita expandida na resistência à compressão e reologia de pastas cimentantes de poços de petróleo

Several problems related to the loss of hydraulic seal in oilwells, causing gas migration and/or contamination of the production zone by water, have been reported. The loss of the hydraulic seal is a consequence of cracks which can be occasioned either by the invasion of gas during the wait on cement or by the expansion of the casing causing the fracture of the cement sheath. In case of the pressure of the formation is higher than the pressure in the annulus, gas can migrate into the slurry and form microannulus, which are channels where gas migrates after the cement is set. Cracks can be also occasioned by the fracture of the cement sheath when it does not withstand the thermal and dynamic loads. In reservoirs where the oil is heavy, steam water injection operation is required in order to get the oil flowing. This operation increases the temperature of the casing, and then it expands and causes the fracture of the cement sheath in the annulus. When the failures on the cement are detected, remedial cementing is required, which raise costs caused by the interventions. Once the use of cement in the construction civil sector is older than its use in the petroleum sector, it is common to bring technologies and solutions from the civil construction and apply them on the petroleum area. In this context, vermiculite, a mineral-clay widely encountered in Brazil, has been used, on its exfoliated form, in the civil construction, especially on the manufacture of lights and fireproof concretes with excellent thermal and acoustical properties. It has already been reported in scientific journals, studies of the addition of exfoliated vermiculite in Portland cements revealing good properties related to oilwell cementing operations. Thus, this study aimed to study the rheological behavior, thickening time, stability and compressive strength of the slurries made of Portland cement and exfoliated vermiculite in 5 different compositions, at room temperature and heated. The results showed that the compressive strength decreased with the addition of exfoliated vermiculite, however the values are still allowed for oiwell cementing operations. The thickening time of the slurry with no exfoliated vermiculite was 120 min and the thickening time of the slurry with 12 % of exfoliated vermiculite was 98 min. The stability and the rheological behavior of the slurries revealed that the exfoliated vermiculite absorbed water and therefore increased the viscosity of the slurries, even though increasing the factor cement-water. The stability experiment carried out at 133 ºF showed that, there was neither sedimentation nor reduction of the volume of the cement for the slurry with 12 % of exfoliated vermiculite. Thus, the addition of exfoliated vermiculite accelerates the set time of the cement and gives it a small shrinkage during the wait on cement, which are important to prevent gas migration

Análise do comportamento reológico de pastas de cimento contendo resíduos de pneu para poços de petróleo

The low tenacity presented by the Portland cement pastes used in the oil wells cementation has been motivating several researches with attention focused on alternative materials. Additives have been developed to generate flexible pastes with mechanical resistance capable to support the expansions and retractions of the metallic covering of the wells that submit to the steam injection, technique very used to increase the recovery factor in oil reservoirs with high viscosity. A fresh paste with inadequate rheological behavior may commit the cementation process seriously, involving flaws that affect the performance of the paste substantially in the hardened state. This work proposes the elaboration and the rheological analysis of Portland cement pastes with addition of residues of rubber tire in several proportions, with the aim of minimizing the damages provoked in the hem cementing of these wells. By thermogravimetric analysis, the particles of eraser that go by the sieve of 0,5mm (35 mesh) opening and treated superficially with NaOH solution of 1 mol/L presented appropriate thermal resistance for wells that submit to thermal cyclic. The evaluation of the study based on the results of the rheological analysis of the pastes, complemented by the mechanical analysis, thickening, stability, tenor of free water and filtrate loss, being used as parameter a paste reference, without rubber addition. The results showed satisfactory rheology, passive of few corrections; considerable loss of mechanical resistance (traction and compression), compensated by earnings of tenacity, however with established limits for its application in oil wells; satisfactory stability, free water and thickening time

Adição de vermiculita expandida mícron em pastas de baixa densidade para cimentação de poços de petróleo

The northeastern region of Brazil has a large number of wells producing oil using a method of secondary recovery steam injection, since the oil produced in this region is essentially viscous. This recovery method puts the cement / coating on thermal cycling, due to the difference in coefficient of thermal expansion between cement and metal coating causes the appearance of cracks at this interface, allowing the passage of the annular fluid, which is associated with serious risk socioeconomic and environmental. In view of these cracks, a correction operation is required, resulting in more costs and temporary halt of production of the well. Alternatively, the oil industry has developed technology for adding new materials in cement pastes, oil well, providing high ductility and low density in order to withstand the thermo-mechanical loads generated by the injection of water vapor. In this context, vermiculite, a clay mineral found in abundance in Brazil has been applied in its expanded form in the construction industry for the manufacture of lightweight concrete with excellent insulation and noise due to its high melting point and the presence of air in their layers lamellar. Therefore, the vermiculite is used for the purpose of providing low-density cement paste and withstand high temperatures caused by steam injection. Thus, the present study compared the default folder containing cement and water with the folders with 6%, 8% and 10% vermiculite micron conducting tests of free water, rheology and compressive strength where it obtained the concentration of 8 % with the best results. Subsequently, the selected concentration, was compared with the results recommended by the API standard tests of filtered and stability. And finally, analyzed the results from tests of specific gravity and time of thickening. Before the study we were able to make a folder with a low density that can be used in cementing oil well in order to withstand the thermo-mechanical loads generated by steam injection

Estudos de Durabilidade Frente ao Ataque Ácido de Compósitos Portland-Polímero para Cimentação de Poços de Petróleo

Portland-polymers composites are promising candidates to be used as cementing material in Northeastern oil wells of Brazil containing heavy oils submitted to steam injection. In this way, it is necessary to evaluate its degradation in the commonly acidizind agents. In addition, to identify how aggressive are the different hostile environments it is an important contribution on the decision of the acidic systems to be used in. It was investigated the performance of the Portland-polymer composites using powdered polyurethane, aqueous polyurethane, rubber tire residues and a biopolymer, those were reinforced with polished carbon steel SAE 1045 to make the electrochemical measurements. HCl 15,0 %, HCl 6,0 % + HF 1,5 % (soft mud acid), HCl 12,0 % + HF 3,0 % (regular mud acid) and HAc 10 % + HF 1,5 % were used as degrading environment and electrolytes. The more aggressive acid solution to the plain Portland hardened cement paste was the regular mud acid, that showed loss of weight around 23.0 %, followed by the soft mud acid, the showed 11.0 %, 15.0 % HCl with 7,0 % and, at last the 10.0 % HAc plus HF 1.5 % with just 1.0 %. The powdered polyurethane-composite and the aqueous polyurethane one showed larger durability, with reduction around 87.0 % on the loss of weight in regular mud acid. The acid attack is superficial and it occurs as an action layer, where the degraded layer is responsible for the decrease on the kinetic of the degrading process. This behavior can be seen mainly on the Portland- aqueous polyurethane composite, because the degraded layer is impregnated with chemically modified polymer. The fact of the acid attack does not have influence on the compressive strength or fratography of the samples, in a general way, confirms that theory. The mechanism of the efficiency of the Portland-polymers composites subjected to acid attack is due to decreased porosity and permeability related with the plain Portland paste, minor quantity of Ca+2, element preferentially leached to the acidic solution, wave effect and to substitute part of the degrading bulk for the polymeric one. The electrolyte HAc 10 % + HF 1,5 % was the least aggressive one to the external corrosion of the casing, showing open circuit potentials around +250 mV compared to -130 mV to the simulated pore solution to the first 24 hours immersion. This behavior has been performed for two months at least. Similar corrosion rates were showed between both of the electrolytes, around 0.01 μA.cm-2. Total impedance values, insipient arcs and big polarization resistance capacitive arcs on the Nyquist plots, indicating passivity process, confirm its efficiency. In this way, Portlandpolymers composites are possible solutions to be succeed applied to oilwell cementing concomitant submitted to steam injection and acidizing operation and the HAc 10,0 % + HF 1,5 % is the less aggressive solution to the external corrosion of the casing

Desevolvimento de nanocompósitos de poli(metacrilato de metila)/argila processados por mistura no estado fundido

Poly(methyl methacrylate)/clay nanocomposites were prepared by melt mixing using a montmorillonite-rich clay (MMT). The clay in natura was treated with acrylic acid to facilitate the dispersion in the polymer matrix. A masterbatch of PMMA/clay was prepared and combined with the pure PMMA and then subjected to extrusion process using singlescrew and twin-screw extruders followed by injection. Nanocomposites were processed with clay contents of 1, 3, 5 and 8 wt.%. The effect of shear processing on the morphology of the nanocomposites was evaluated by XRD, SEM and TEM. Thermal and mechanical properties of the nanocomposites were investigated through TGA, DSC, HDT, VICAT, tensile and impact tests, to evaluate the effect of the addition of clay to the PMMA matrix. Flammability tests were also conducted to investigate the effect of the addition of clay on the flame retardation properties. SEM images of the nanocomposites indicated the presence of clay agglomerates, which resulted in the reduction of properties such as thermal stability, mechanical strength and impact resistance, and increased the rate of burning for materials processed by both extrusion routes

Estudo morfológico da blenda polimérica poli(metacrilato de metila)/poli(tereftalato de etileno) reciclado (PMMA/PET)

Among the options for plastics modification more convenient, both from a technical-scientific and economic, is the development of polymer blends by processing in the molten state. This work was divide into two stages, with the aim to study the phase morphology of binary blend PMMA / PET blend and this compatibilized by the addition of the poly(methyl methacrylate-co-glycidyl methacrylate-co-ethyl acrylate) copolymer (MMA-GMA-EA). In the first stage is analyzed the morphology of the blend at a preliminary stage where we used the bottle-grade PET in a Haake torque rheometer and the effect of compatibilizer in this blend was evaluated. In the second stage the blend was processed using the recycled PET in a single screw extruder and subsequently injection molding in the shape of specimens for mechanical tests. In both stages we used a transmission electron microscopy (TEM) to observe the morphologies of the samples and an image analyzer to characterize them. In the second stage, as well as analysis by TEM, tensile test, scanning electron microscopy (SEM) and atomic force microscopy (AFM) was performed to correlate the morphology with the mechanical properties. The samples used in morphological analyzes were sliced by cryo-ultramicrotomy technique for the analysis by TEM and the analysis by SEM and AFM, we used the flat face of the block after cut cryogenic. It was found that the size of the dispersed phase decreased with the addition of MMA-GMA-EA in blends prepared in a Haake. In the tensile test, the values of maximum tensile strength and modulus of elasticity is maintained in a range between the value of pure PMMA the pure PET, while the elongation at break was influenced by the composition by weight of the PMMA mixture. The coupling agent corroborated the results presented in the blend PMMA / PETrec / MMA-GMA-EA (80/15/5 %w/w), obtained by TEM, AFM and SEM. It was concluded that the techniques used had a good morphologic correlation, and can be confirmed for final analysis of the morphological characteristics of the blends PMMA / PET

Adição do resíduo de biomassa da cana-de-açúcar em pastas para cimentação de poços petrolíferos produtores de óleos pesados

The Potiguar basin has large fields of viscous oil where the used method for recovering is based on vapor injection; this operation is carried out by injecting vapor in the oilwell directly, without the protection of a revetment through thermal insulation, what causes its dilation and, consequently, cracks in the cement placed on the annular, and lost of hydraulic insulation; this crack is occasioned by the phenomenon of retrogression of the compressive resistance due to the conversion of the hydrated calcium silicate in phases calcium-rich, caused by the high temperatures in the wells, subjected to thermal recuperation. This work has evaluated the application of composite pastes with addition of residue of biomass of ground sugar-cane bagasse as anti-retrogression mineral admixture for cementation of oil-wells subjected to thermal recuperation. The addition of the mineral residue was carried out considering a relative amount of 10, 20, 30, 40 and 59% in relation to cement mass, trying to improve the microstructure of the paste, still being developed a reference paste only with cement and a paste with addition of 40% of silica flour - renowned material in the oil industry as anti-retrogression additive. Pozzolanic activity of the ash was evaluated through XRD, TG/DTG, as the resistance to compression, and it was also determined the physical and mechanical behavior of the pastes when submitted to cure at low temperatures (22 and 38º C); besides it was evaluated the behavior of the pastes when submitted to two cycles of cure at high temperature (280ºC) and pressure (7 MPa). It was verified that the ash of the sugar-cane biomass presents pozzolanic reaction and has great efficiency in decrease the permeability of the paste by filler effect, as well as that addition of ash in a relative amount of 10, 20 e 30% increases cured compressive resistance at low temperatures. It was also showed that the ash in a relative amount of 40% and 59% has very significant efficiency as anti-retrogression additive, since it prevents the decrease of compressive resistance and forms hydrated calcium silicate type xenotlita and tobermorita which have more resistance and stability in high temperatures

Obtenção de polímeros de LCC para aplicação como antioxidante de biodiesel de soja

Biodiesel is a fuel obtained from vegetable oils, such as soy, castorbean, among others. The monoester of fatty acid of these oils have chains with mono, di and tri double connections. The presence of these insaturations are susceptible to oxidization. Antioxidants are substances able to prevent oxidization from oils, fats, fat foods, as well as esters of Alquila( biodiesel). The objective of this work is to summarize a new antioxidant from the Cashew Nut Shell Liquid (CNSL) using the electrolysis technique. A current of 2 amperes was used in a single cell of only one group and two eletrodos of stainless steel 304 in a solution of methanol, together with the eletrolits: acetic acid, sodium chloride and sodium hydroxide, for two hours of agitation. The electrolysis products are characterized by the techniques of cromatography in a thin layer, spectroscopy of infrared and gravimetric analysis. The material was submitted to tests of oxidative stability made by the techniques of spectropy of impendancy and Rancimat (EN 14112). The analyses of characterization suggest that the polimerization of the electrolytic material ocurred. The application results of these materials as antioxidants of soy biodiesel showed that the order of the oxidative stability was obtained by both techniques used

Processamento e caracterização de compósitos Poli(METACRILATO DE METILA)/Sílica (PMMA/SiO2)

Currently the search for new materials with properties suitable for specific applications has increased the number of researches that aim to address market needs. The poly (methyl methacrylate) (PMMA) is one of the most important polymers of the family of polyacrylates and polymethacrylates, especially for its unique optical properties and weathering resistance, and exceptional hardness and gloss. The development of polymer composites by the addition of inorganic fillers to the PMMA matrix increases the potential use of this polymer in various fields of application. The most commonly used inorganic fillers are particles of silica (SiO2), modified clays, graphite and carbon nanotubes. The main objective of this work is the development of PMMA/SiO2 composites at different concentrations of SiO2, for new applications as engineering plastics. The composites were produced by extrusion of tubular film, and obtained via solution for application to commercial PMMA plates, and also by injection molding, for improved the abrasion and scratch resistance of PMMA without compromising transparency. The effects of the addition of silica particles in the polymer matrix properties were evaluated by the maximum tensile strength, hardness, abrasion and scratch resistance, in addition to preliminary characterization by torque rheometry and melt flow rate. The results indicated that it is possible to use silica particles in a PMMA matrix, and a higher silica concentration produced an increase of the abrasion and scratch resistance, hardness, and reduced tensile strength