Durabilidade de compósito biomassa vegetal-cimento modificado por polímero

The durability of the cellulose-cement composites is a decisive factor to introduce such material in the market. Polymers have been used in concrete and mortar production to increase its durability. The goal of this work was the physical and mechanical characterization of cellulose-cement composites modified by a polymer and the subsequent durability evaluation. The work also evaluated the dispersion of acrylic polymer in composites made of Pinus caribaea residues. The physical properties observed were water absorption by immersion and bulk density. Rupture modulus and toughness were determined by flexural test. The specimens were obtained from pads, produced by pressing and wet curing. Samples were subjected to accelerated aging tests by repeated wetting and drying cycles and hot-water bath and natural aging. The scanning electron microscopy (SEM) allowed verifying the fiber and composite characteristics along the time. For the composite range analyzed, it was observed the polymer improved the mechanical properties of composites besides a significant decreasing in water absorption. The use of polymer improved the performance of vegetable fiber-cement composites when compared to the conventional mortar, due to water absorption decreasing.

Durabilidade de compósito biomassa vegetal-cimento modificado por polímero

A durabilidade de compósito biomassa vegetal-cimento é um dos fatores mais importantes para a colocação desse material no mercado consumidor. A utilização de polímeros em concreto e argamassa, com o objetivo de melhorar sua durabilidade, é cada vez mais freqüente. Este estudo visou à caracterização de propriedades físicas e mecânicas de compósito biomassa vegetal-cimento modificado com polímeros e a análise da durabilidade desse compósito. Foi testado um polímero de base acrílica em compósitos produzidos com resíduo de Pinus caribaea. Foram realizados ensaios de envelhecimento acelerado, por meio de ciclos de molhamento e secagem, por imersão em água quente e ensaio de envelhecimento natural. As propriedades físicas do compósito avaliadas foram a massa específica aparente e a absorção total de água por imersão. As propriedades mecânicas foram determinadas por meio de ensaios de resistência à tração na flexão, analisando-se a tensão e a energia de ruptura. Os corpos-de-prova foram extraídos de placas executadas por simples prensagem. Ensaios de microscopia eletrônica de varredura foram utilizados para observar o estado da fibra e da matriz após os processos de envelhecimento. O uso de polímero melhorou o desempenho mecânico do compósito nas primeiras idades e também promoveu significativa redução da capacidade de absorção de água, demonstrando que o uso desse material pode vir a melhorar a durabilidade desses compósitos, uma vez que reduziu sensivelmente sua capacidade de absorção.

Fabricação e caracterização de material compósito de resina poliéster reforçada por tecido de fibra de tururi extraído da palmeira de ubuçu (Manicaria saccifera)

Neste trabalho é apresentada a fabricação e caracterização de um material compósito de matriz polimérica reforçada por fibras naturais. A matriz é um poliéster teraftélica insaturada préacelerada obtida comercialmente como Denverpoly 754 e o agente de cura utilizado foi o peróxido de Mek (Butanox M- 50), na proporção de 0,33 % , em volume. A fibra natural usada foi o tururi, obtida da região do Marajó, município de Muaná. O tecido de fibra de tururi foi submetido a dois tipos de abertura no sentido transversal, de [50 e 100]%, em relação a uma largura original. A fabricação do material compósito foi através do método da laminação manual (hand lay up), seguido de uma pressão controlada através de pesos previamente quantificados. Características físicas, mecânicas e microscópicas foram obtidas para a fibra e o material compósito, obtendo-se resistência a tração, massa específica, gramatura do tecido, fração mássica e imagens microscópicas antes e depois do ensaio de tração para o tecido da fibra e ensaio de tração depois do ensaio de tração para o material compósito. O tecido de tururi apresentou resistência a tração de 29,95 MPa (sem abertura), 12,27 MPa (abertura de 50 %) e 9,38 MPa (abertura de 100 %). A abertura provoca a diminuição da resistência à tração do tecido de tururi. A gramatura do tecido diminuiu com a abertura do tecido. A fração mássica do tecido do compósito foi de 14,39 % (sem abertura), 9,35 % (abertura de 50 %) e 7,19 % (abertura de 100 %). A resistência a tração do compósito foi de 35,76 MPa (sem abertura), 19,01 MPa (50 % de abertura) e 16,8 MPa (100 % de abertura). A resistência mecânica apresentou valores aproximados aos encontrados na literatura para materiais compósitos reforçados por fibras naturais. As imagens obtidas em microscopia eletrônica de varredura corroboraram com as propriedades mecânicas obtidas para cada situação do material e fibras.

Processamento e caracterização de compósito fibra de sisal/resina epóxi via RTM

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Compósito de argamassa de cimento reforçada por fibra de sisal com entalhe definidos: caracterização mecânica e mecanismo de falha

Neste trabalho, foi desenvolvido um novo material compósito utilizando-se como matriz a argamassa de cimento reforçado com fibra de sisal a 1% em peso, que foram cortadas manualmente nos comprimentos de 15 mm e 25 mm utilizadas sem tratamento superficial utilizando-se o menor nível possível de processamento tecnológico nas etapas de fabricação. A pesquisa foi direcionada para estudar os mecanismos de falha desse novo material. Os compósitos foram produzidos com moldagem manual utilizando-se vibrador de imersão para melhor adensamento. Foram confeccionados corpos de prova da matriz pura e do compósito com fibra de sisal, com entalhes pré definidos, de 1,7 mm, 3,0 mm e 5,0 mm. As propriedades mecânicas foram avaliadas por ensaio de flexão em três pontos e correlacionadas com o aspecto fractográfico realizados no Microscópio Eletrônico de Varredura. Os resultados mostraram que a presença das fibras de sisal, inseridas na pasta de cimento, provocou restrição à retração plástica da mistura fresca, possivelmente pela elevada capacidade de absorção de água do reforço fibroso, um incremento na resistência mecânica e aumento da tenacidade do compósito em relação a matriz entre as séries de entalhes, diminuindo a tendência de fratura brusca.

Análise de viabilidade técnica de utilização da Fibra de bananeira com resina sintética em Compósitos

This paper aims to present the feasibility of using a composite using discarded material from the cultivation of banana tree (pseudostem), which is fibrillated together with synthetic resin replacing glass fiber to be used in structural elements that do not demand large mechanical stress such as reservoirs, troughs, domes, sewage pipes etc.. For this, there were studies about the mechanical properties of a composite made with polyester resin and fiber of banana tree (Musa sp, musac), in which the splints were removed from the pseudostem, being made fibrillation by hand, with the aid of a brush steel, followed by natural drying. After treatment for cleaning and removal of wax, the fiber was cut into pieces of approximately 60 mm to 100 mm, for, together with synthetic resin, make cards of a features fiber composite with random orientation relative to the weight of the resin. We used three different percentages of fiber (3%, 6% and 9%), in order to make a comparative study between them and what would be the one with the best performance. Were manufactured specimens of each material and then subjected to uniaxial tensile tests, three point bending, moisture absorption and thermal characteristics. The results show that, in general, the use of banana tree fiber is feasible simply by an improvement in the production process (machining of the procedure) and greater care in the manufacture of parts

Material compósito de matriz frágil reforçado com fibras naturais de sisal e malva: caracterização e correlações das propriedades e mecânicas

Este estudo propõe avaliar o comportamento mecânico dos compósitos de matriz cimentícia reforçados com fibras de sisal e malva. Correlacionar o comportamento dos materiais com variação do tipo e do comprimento das fibras. O material base utilizado na fabricação do compósito foi cimento, areia, água e fibra de sisal e malva. Usou-se u traço 1 : 2 : 0,5 (cimento, areia e água), com adição de 1% de fibras em relação ao peso da mistura. As fibras foram previamente cortadas no comprimento de 15 mm e 25 mm e adicionadas manualmente à mistura. As correlações dos compósitos foram obtidos através do ensaio de flexão em três pontos, seguindo norma RILEM 49. As características micro-estruturais foram avaliadas através do uso do microscópio eletrônico de varredura.Os resultados obtidos indicam que a inserção de fibras na matriz cimentícia diminui a força máxima aplicada no corpo de prova, porém houve um ganho na tenacidade e na pseudo ductilidade do material após o aparecimento da 1ª trinca. As fibras mais longas mostraram melhor desempenho com um pequeno destaque às fibras de MALVA.

Argamassas de reboco com terra. Avaliação da suscetibilidade à contaminação biológica

Em tempos passados, em Portugal, as argamassas de cal aérea, de terra e mistas de cal e terra foram muito utilizadas na construção de edifícios. Foram aplicadas na realização de rebocos, exteriores e interiores, de betonilhas e no assentamento de alvenarias. Com o aparecimento de novos ligantes, como o cimento, a sua utilização reduziu-se drasticamente levando à perda de muitos conhecimentos sobre a sua correta formulação, produção, manuseamento e utilização. Com o aumento das preocupações ecológicas e com a necessidade de reabilitar edifícios antigos têm vindo a ser estudados diversas características destas argamassas de modo a tornar a sua utilização de novo corrente. A presente dissertação tem como objetivo estudar uma característica pouco analisada no que diz respeito a argamassas de cal e de terra: a suscetibilidade à contaminação biológica quando aplicadas em rebocos. Para tal, foram analisadas ainda outras propriedades das argamassas como o pH e a rugosidade. Realizou-se um estudo preliminar sobre argamassas de cal aérea, cal e terra e fibras vegetais. Posteriormente o estudo incidiu sobre uma argamassa pré-doseada de terra e diversas argamassas elaboradas em laboratório com diferentes areias e adições (fibras vegetais e material de mudança de fase), de modo a ser possível determinar a influência de cada constituinte no risco de contaminação por fungos. Os resultados dos ensaios revelam que as argamassas de terra são bastante suscetíveis à contaminação biológica, sendo que o risco é agravado com a introdução de fibras e materiais de mudança de fase. Foi também possível concluir que a presença de cal inibe o desenvolvimento de fungos, apesar da presença de fibras numa argamassa de cal também aumentar o risco de contaminação. Conclui-se que a rugosidade e o pH são fatores muito importantes para controlar o nível de colonização. Foi ainda possível observar que diferentes composições levam a diferentes resultados e que é necessário estudar as características que se pretendem para uma determinada argamassa de modo a otimizá-la.

La fibra en la alimentación.

Programa emitido el 14 de noviembre de 1994

Adsorção de cobre e cromo utilizando fibra de sisal visando o tratamento da água produzida pela indústria petrolífera

Currently, the oil industry is the biggest cause of environmental pollution. The objective was to reduce the concentration of copper and chromium in the water produced by the oil industry. It was used as adsorbent natural sisal fiber Agave sp treated with nitric acid and sodium hydroxide. All vegetable fibers have physical and morphological properties that enablies the adsorption of pollutants. The basic composition of sisal is cellulose, hemicellulose and lignin. The features are typically found in the characterization of vegetable fibers, except the surface area that was practically zero. In the first stage of adsorption, it was evaluated the effect of temperature and time skeeking to optimize the execution of the factorial design. The results showed that the most feasible fiber was the one treated with acid in five hours (30°C). The second phase was a factorial design, using acid and five hours, this time was it determined in the first phase. The tests were conducted following the experimental design and the results were analyzed by statistical methods in order to optimize the main parameters that influence the process: pH, concentration (mol / L) and fiber mass/ metal solution volume. The volume / mass ratio factor showed significant interference in the adsorption process of chromium and copper. The results obtained after optimization showed that the highest percentages of extraction (98%) were obtained on the following operating conditions: pH: 5-6, Concentration: 100 ppm and mass/ volume: 1 gram of fiber/50mL solution. The results showed that the adsorption process was efficient to remove chromium and copper using sisal fibers, however, requiring further studies to optimize the process.

Estudo térmico e de materiais na construção de casas populares com blocos confeccionados a partir de um composto a base de cimento, gesso, eps e raspa de pneu

We built an experimental house on an UFRN´s land using blocks made by a composite consisting of cement, plaster, EPS, crushed rubber and sand. Several blocks were made from various compositions and we made preliminary tests of mechanical and thermal resistance, choosing the most appropriate proportion. PET bottles were used inside the block to provide thermal resistance. In this work, a second function was given to the bottles: to serve as a docking between the blocks, because the ends of the cylinders came out of each block on top as well as at the bottom, with the bottom cut, allowing to fit of the extremities of the upper cylinder of a block in the lower holes of the other one, which were formed by the cutting already mentioned. Minimum compression tests were performed according to ABNT standards for walls closing blocks (fence). With that house built, we did studies of thermal performance in order to ascertain conditions of comfort, checking external and internal temperatures in the walls and in the ambient, among other variables, such as wind speed and relative humidity. The resulting blocks provided adequate thermal insulation to the environment, where the walls presented differences up to 11.7 ºC between the outer and inner faces, getting the maximum temperature inside the house around 31 °C, within the so-called thermal comfort zone for warm climates. At the end of the experiments it was evident the effectiveness of that construction in order to provide thermal comfort in the internal environment of the house, as well as we could confirm the viability of building houses from recyclable materials, reducing the constructive costs, becoming a suitable alternative for low- incoming families. Moreover, besides the low cost, the proposal represents an alternative use of various recyclable materials, therefore considered an ecological solution

Desempenho mecânico de compósitos híbridos de fibras naturais e poliéster não saturado

With the objective to promote sustainable development, the fibres found in nature in abundance, which are biodegradable, of low cost in comparison to synthetic fibres are being used in the manufacture of composites. The mechanical behavior of the curauá and pineapple leaf fibre (PALF) composites in different proportions, 25% x 75% (P1), 50% x 50% (P2) e 75% x 25% (P3) were respectively studied, being initially treated with a 2% aqueous solution of sodium hydroxide. Mechanical analyses indicated that with respect to studies of traction, for the combination of P1 and P3, better results of 22.17 MPa and 16.98 MPa, were obtained respectively, which are higher than that of the combination P2. The results of the same pattern were obtained for analysis of bending resistance where P1 is 1.21% and P3 represents 0.96%. In the case of resistance to bending, best results were obtained for the combination P1 at 49.07 MPa. However, when Young's modulus values were calculated, the values were different to the pattern of the results of other tests, where the combination P2 with the value of 4.06 GPa is greater than the other combinations. This shows that the PALF had a greater influence in relation to curauá fibre. The analysis of the results generally shows that in combinations of two vegetable fibers of cellulosic origin, the fiber which shows higher percentage (75%) is the best option than to the composition of 50%/50%. In the meantime, according to the results obtained in this study, in the case where the application should withstand bending loads, the better composition would be 50%/50%

Estudo de um compósito de matriz cerâmica com carga de recicláveis para o uso na construção civi

With a view to revitalizing public environments through criteria that include economy, tourism, aesthetics and respect for the environment, this paper proposes a model of kiosk manufactured with composite material blocks, to be employed as a public instrument. . The model consists of a structure composed of planned blocks and manufactured in cement-based composite, gypsum, ground and water, having the styrofoam inside filled with pet bottles of 500 ml dose. The social and environmental issue is the critical point of the work when it can, through the reuse of environmentally harmful materials such as polyethylene terephthalate PET, using such modules for the construction of various areas of Commerce, promoting the protection of the environment combined with the improvement of the quality of life of the population. The tourism factor, which is significant in the economy of the North, is also considered as the modulated kiosk has a visual aspect innovative and differentiated. The environmental issue is addressed by encouraging the reuse of PET material and EPS (polystyrene)

Compósito reforçado com sisal para aplicação na moda

The objective of this research is the fabrication of a composite reinforced with dyed sisal fiber and polyester matrix for application in the fields such as, fashion, clothing, interior textiles; fashion accessories are some of the examples. For the fabrication of the composite, the sisal fibers were subjected to processes such as: chemical treatment with sodium hydroxide (NaOH) in the removal of impurities; bleaching for removing the yellowish color of the natural fiber and dyeing with direct dyes to confer the colors blue, green and orange. The search for new technologies ecologically correct has become a major concern in recent decades. Studies show that composite polymer reinforced by natural fibers is suitable for a large number of applications, and its use is advantageous in terms of economic and ecological. The dyed fibers were cut to a length of 30 mm, is used in the confection of webs. For this purpose, a web preparer by immersion, developed in the Laboratory of Chemical Textile of UFRN. The composite sheets measuring 300 x 300 x3 mm were molded by compression, with unsaturated orthophthalic polyester as matrix, and the samples in sizes 150 x 25 x 3 mm were cut with the aid of a laser machine, to be subjected to traction and flexion. The mechanical properties of traction and flexion in three points were performed in the Laboratory of metal and mechanical tests of Materials Engineering of UFRN. The resulting samples from the tests were evaluated in scanning electron microscope (SEM) at CTGas RN. On the basis of the analysis of the results from the mechanical tests, it was observed that the composite had good mechanical behavior, both in traction as in flexion. Furthermore, it was observed that in the water absorption test, the samples had a different percentage among themselves, this occurred due to the variation of density found in the fibre webs. The images of the SEM showed the failures from the manufacturing process and the adhesion of fibre/matrix. When the samples were prepared with the dyed fibers to be applied in fashion, the results were positive, and it can be concluded that the main objective of this work was achieved

Caracterização e análise das propriedades da fibra de Macambira (Bromelia Laciniosa)

Concern for the environment and the exploitation of natural resources has motivated the development of research in lignocellulosic materials, mainly from plant fibers. The major attraction of these materials include the fact that the fibers are biodegradable, they are a renewable natural resource, low cost and they usually produce less wear on equipment manufacturing when compared with synthetic fibers. Its applications are focused on the areas of technology, including automotive, aerospace, marine, civil, among others, due to the advantageous use in economic and ecological terms. Therefore, this study aims to characterize and analyze the properties of plant fiber macambira (bromelia laciniosa), which were obtained in the municipality of Ielmo Marino, in the state of Rio Grande do Norte, located in the region of the Wasteland Potiguar. The characterization of the fiber is given by SEM analysis, tensile test, TG, FTIR, chemical analysis, in addition to obtaining his title and density. The results showed that the extraction of the fibers, only 0.5% of the material is converted into fibers. The results for title and density were satisfactory when compared with other fibers of the same nature. Its structure is composed of microfibrils and its surface is roughened. The cross section has a non-uniform geometry, therefore, it is understood that its diameter is variable along the entire fiber. Values for tensile strength were lower than those of sisal fibers and curauá. The degradation temperature remained equivalent to the degradation temperatures of other vegetable fibers. In FTIR analysis showed that the heat treatment may be an alternative to making the fiber hydrophobic, since, at high temperature can remove the hemicellulose layer, responsible for moisture absorption. Its chemical constitution is endowed with elements of polar nature, so their moisture is around 8.5% which is equivalent to the percentage of moisture content of hydrophilic fibers. It can be concluded that the fiber macambira stands as an alternative materials from renewable sources and depending on the actual application and purpose, it may achieve satisfactory results