Envelhecimento ambiental em compósitos poliméricos à base de tecidos de reforços híbridos

The utilization of synthetic fibers for plastic reinforcement is more and more frequent and this growing interest requires that their mechanic behavior under the most variable conditions of structural applications be known. The use of such materials in the open and exposed to the elements is one of them. In this case, it becomes extremely necessary to study their mechanical properties (strength, stiffness) and the mechanism of fracture by which the environment aging them out. In order to do that, the material must be submitted to hot steam and ultraviolet radiation exposure cycles, according to periods of time determined by the norms. This study proposal deals with the investigation of accelerated environmental aging in two laminated polymeric composites reinforced by hybrid woven made up of synthetic fibers. The configurations of the laminated composites are defined as: one laminate reinforced with hybrid woven of glass fibers/E and Kevlar fibers/49 (LHVK) and the other laminate is reinforced with hybrid tissue of glass fibers/E and of carbon fibers AS4 (LHVC). The woven are plane and bidirectional. Both laminates are impregnated with a thermofix resin called Derakane 470-300 Epoxy Vinyl-Ester and they form a total of four layers. The laminates were industrially manufactured and were made through the process of hand-lay-up. Comparative analyses were carried out between their mechanical properties by submitting specimen to uniaxial loading tractions and three-point flexion. The specimen were tested both from their original state, that is, without being environmentally aging out, and after environmental aging. This last state was reached by using the environmental aging chamber

Avaliação da estrutura de tecidos técnicos como elemento reforçante em compósitos poliméricos sistema poliéster isoftálico

Materials known as technical textiles can be defined as structures designed and developed to meet specific functional requirements of various industry sectors, which is the case in automotive and aerospace industries, and other specific applications. Therefore, the purpose of this work presents the development and manufacture of polymer composite with isophthalic polyester resin. The reinforcement of the composite structure is a technical textile fabric made from high performance fibers, aramid (Kevlar 49) and glass fiber E. The fabrics are manufactured by the same method, with the aim of improving the tensile strength of the resulting polymer composite material. The fabrics, we developed some low grammage technical textile structures in laboratory scale and differentiated-composition type aramid (100%), hybrid 1 aramid fiber / glass (65/35%) and hybrid 2 aramid fiber / glass (85/15% ) for use as a reinforcing element in composite materials with unsaturated isophthalic polyester matrix. The polymer composites produced were tested in uniaxial tensile fracture surface and it´s evaluated by SEM. The purpose of this work characterize the performance of polymer composites prepared, identifying changes and based on resistance to strain corresponding to the mechanical behavior. The objectives are to verify the capability of using this reinforcement structure, along with the use of high performance fibers and resin in terms of workability and mechanical strength; verify the adherence of the fiber to the matrix and the fracture surface by electron microscopy scanning and determination of tensile strength by tensile test. The results indicate that, in a comparative study to the response of uniaxial tensile test for tensile strength of the composites and the efficiency of the low percentage of reinforcement element, being a technical textile fabric structure that features characteristic of lightness and low weight added in polymer composites

Morfologia e propriedades mecânicas da fibra de sisal unidirecional e em sobreposição de compósito com resina epóxi

The composites manufactured with long fibres aligned in a single direction, and overlay has been shown to have better performance than the short fibers randomly distributed. In particular, the lignocellulosic fibers extracted from the sisal leaves, used in conjunction with the epoxy resin has attracted the attention of many researchers because the final properties of the system formed. In this work composites based on epoxy resin reinforced with sisal fibers were manufactured. The sisal fibres were treated with an alkaline solution of 0.06 mol/l NaOH. The treated, and untreated fibres were subjected to tension x extension tests. The composites were manufactured in the "Lossy" mold with the specifications of the samples to be produced (300x20x4 mm). The tension tests were carried out in accordance with the ASTM standards 3039 (for the composite aligned in a single direction) and ASTM D5573 (for composites in overlay), three point bending tests were performed according to ASTM D790. Analyzing the results of the tests of tension and three point bending tests, it was observed that the composites with the configuration of overlapping had the better elastic module in both tests. As to the maximum resistance to tension, the best result was the composites aligned in a single direction. Tests of absorption of water and micrographs are in progress

Tubulações de PRFV com adição de areia quartzosa visando sua aplicação na indústria do petróleo

Fillers are often added in composites to enhance performance and/or to reduce cost. Fiberglass pipes must meet performance requirements and industrial sand is frequently added for the pipe to be cost competitive. The sand is added to increase pipe wall thickness, thus increase pipe stiffness. The main goal of the present work is to conduct an experimental investigation between pipes fabricated with and without de addition of sand, to be used in the petroleum industry. Pipes were built using E-glass fibers, polyester resin and siliceous sand. The fabrication process used hand lay up and filament winding and was divided in two different parts: the liner and the structural wall. All tested pipes had the same liner, but different structural wall composition, which is the layer where siliceous sand may be added or not. The comparative investigation was developed considering the results of longitudinal tensile tests, hoop tensile tests, hydrostatic pressure leak tests and parallel-plate loading stiffness tests. SEM was used to analyze if the sand caused any damage to the glass fibers, during the fabrication process, because of the fiber-sand contact. The procedure was also used to verify the composite conditions after the hydrostatic pressure leak test. The results proved that the addition of siliceous sand reduced the leak pressure in about 17 %. In the other hand, this loss in pressure was compensated by a stiffness increment of more than 380 %. MEV analyses show that it is possible to find damage on the fiber-sand contact, but on a very small amount. On most cases, the contact occurs without damage evidences. In summary, the addition of sand filler represented a 27.8 % of cost reduction, when compared to a pipe designed with glass fiber and resin only. This cost reduction combined to the good mechanical tests results make siliceous sand filler suitable for fiberglass pressure pipes

Sentido de pulverização em culturas de soja e feijão com pulverizador de barras

O objetivo do experimento foi avaliar o melhor sentido de caminhamento de um pulverizador de barras, montado em três pontos no trator, nas culturas de soja e de feijão. As pulverizações foram orientadas no sentido longitudinal às linhas de semeadura, transversal às linhas de semeadura e no mesmo sentido das linhas de semeadura com os pneus percorrendo locais pré-definidos onde não houve a distribuição de sementes (tramlines). Foram avaliados os componentes de produtividade. Pelos resultados, pode-se observar que não houve diferença significativa quanto aos componentes de produtividade avaliados na cultura da soja quando se variou o sentido da pulverização. Na cultura do feijoeiro, a pulverização no sentido longitudinal apresentou maior produtividade.

Incorporação do resíduo oriundo do beneficiamento de caulim em concreto asfáltico

The municipal district of Equador-RN is located in an area of great amounts of ores, being your main economical activity the extraction and the kaolin improvement. The main originating from environmental problem that activity is the amount of generated residue, about 70% of the extracted kaolin. The residues are simply piled up in lands of the improvement companies, occupying like this a large area and causing impact in the existent flora. When dry, the residues transform powdered and for the action of the wind, they disperse, polluting the air. Being like this, the present work has as objective evaluates the incorporation of the great residue, originating from of the kaolin improvement, in partial substitution of all the employed aggregates in a conventional mixture of asphalt concrete, which was used in the paving of BR101/RN061 - passage between Ponta Negra and Ares. That evaluation was accomplished in three stages. The first refers to the evaluation of the physical, thermal and mineralogical characteristics of the residue with the intention of to classify it and to define your application as aggregate (small and great). The second refers to the physical characterization of the aggregates and of the asphalt material used in the conventional mixture. And the third, to the evaluation of the mixtures containing residue, which were elaborated starting from the conventional mixture with the gradual incorporation of the residue, from 5 to 40%, in substitution to the part of the conventional aggregates, in way to obtain similar particle size curves the one of the conventional mixture. That evaluation was accomplished through the comparison between the volumetric composition, the mechanical behavior and the susceptibility to the humidity of the mixtures containing residue with the one of the conventional mixture, and with the one of the DNIT specifications. The results show that the great residue originating from of the kaolin improvement has grains of the most varied size, being like this, it can substitute part of all the conventional aggregates and of the filler in an asphalt mixture. Besides, your mineralogical composition presented the same present minerals in the composition of conventional aggregates used in paving. The results evaluation of the volumetric composition of the mixtures containing residue indicates that it can use up to 30% of residue in substitution to the conventional aggregates. The evaluation of the mechanical behavior of those mixtures indicates that the residue increment in the studied mixtures caused an increase of the stability and a reduction of the resistance to the traction. The values obtained in the resistance to the traction meet below the minimum value specified by DNIT, but close to the value obtained in the conventional mixture. When taking in consideration the susceptibility of the same ones to the humidity, the results indicate that she can use up to 25% of residue

Incorporação do lodo de tanque séptico como matéria-prima de uma mistura asfáltica

In Natal/RN, 68% of the population uses some kind of individual system for their domestic sewers treatment, being that the most used it is septic tank, followed by sumidouro. Every treatment system of sewers, usually used, generates a by-product denominated sludge. That residue presents some components, in its constitution, undesirable under the environmental and sanitary point of view. In such case, to assure that the system treatment has satisfactory results, it is necessary to do the adjusted disposition of the sludge sewage. Several countries are looking for technical alternatives for the use and disposition of residues. Under technical and environmental conditions appropriate, these materials can be used, decreasing the consumption of the natural resources and the treatment need, storage or elimination of the wastes, what decrease the risks created. Some of the alternatives of recycling of the sludge sewage are: the application in the agriculture, in the production of energy and as raw material in the civil construction. This study evaluated asphalt mixtures behavior that partially substituted conventional aggregates by septic tank sludge. The septic tank sludge gave origin to two raw materials called raw sludge and sludge ash. The raw sludge was put as a small aggregate and the sludge ash as filler. In the first experiment it was made a comparison between the mixture with conventional aggregates and the mixtures that replaced sand by raw sludge in the proportions from 5% to 40%. In the second experiment, it was made comparison between mixtures with 1%, 2% and 3% of sludge ash and cement. The stages developed along the study were: physical characterization of the conventional materials; physical, chemistry, thermal, mineralogical characterizations and analysis of environmental risk of the raw sludge; physical characterization and analysis of environmental risk of the sludge ash; analysis of the mixtures performance through its volumetric and mechanical characteristics; forecast of the mixtures susceptibility in the moisture presence. For the grain size composition used and with the percentage asphalt adopted, the mixtures with up to 7,5% of raw sludge in his composition attend to the National Department of Transports Infrastructure (DNIT) specifications. However, in agreement with the mixtures susceptibility in the moisture presence, the mixtures with addition of raw sludge don't present satisfactory acting. In such case, they could be used in arid and semi-arid areas. The raw sludge application in mixtures increased their voids volume and their stability. However, it damaged mixtures adhesiveness. Mixtures with sludge ash and with cement presented similar behavior. However, mixtures with sludge ash presented a better performance than mixtures with cement as for their stability and their tensile strength ratio. The mixture with 1% of sludge ash is better. The wastes studied don't represent environmental risk

Estudo da influência de tratamentos químicos da fibra de sisal nas propriedades de compósitos com borracha nitrílica

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

Caracterização mecânica e térmica da borracha natural formulada e vulcanizada dos clones: GT 1, IAN 873, PB 235 e RRIM 600

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

O ensaio jornalístico na revista Veja: uma análise multidimensional

This work has as objective generality to make a multidimensional analysis in the genre journalistic assay, communicative genre that, beyond complex and multimodal, presents hybrid characteristics. Specifically, with the intention to propose defining criteria of the cited genre, this research looks for to establish differences and similarities between the assay and other genres of the same sphere, from the description and interpretation of used multimodal resources. The analysis of the formal, schematical and rhetorical resources identified in the formatting of the journalistic assay sample that the analyses are supported in the socio-semiotic and socio-rhetorical approaches. In the formal dimension, we contemplate elements that constitute design of the text, including the forms of representation from the typography, the colors, images, as well as the aspects communicative-linguistics: the modalization indices, the communicative operators and the category time; in the schematical dimension, we present the organizational structure, considering the rhetorical movements postulates for Swales (1990) and in the rhetorical dimension we observe the categories: who writes, for who it writes, on what it writes and where writes. The adopted methodologicals postulates are of qualitative nature and the procedure is documentary, data that in we are valid them written texts of this genre as analysis object. Corpus it is constituted by a composed sample for 14 extracted texts of a set of 173 propagated journalistic assays weekly for the magazine Veja, in the period between August of 2004 and January of 2008. The analysis of the data showed that the journalistic assay, object of this study, materializes through multiple symbolic representations and multiple subjects that turn since a small episode of the daily facts of great social relevance in the present time, of historical and cultural nature, nationwide or international. Used for the first time by Montaigne in 1580, to assign, in saying of the proper author, written fast on its life and historical events, which could nor be remembered later , the term `assay' was enriched with other specifications, of form to enclose the one that if they call scientific assay today, academic assay, journalistic assay and other types of specific assays. These denominations have to see with the enrollment of the members of diverse of practices communities, in virtue of the multiplicity of activities carried through in these spheres. The conclusions the one that we arrive had been the following ones: 1. the discursive genre is not a pure entity, in virtue of the multiplicity of situations where the sorts if insert in the social actions; 2. the institutions define the configuration of one definitive genre, also its proper assignment, since for backwards of all discursive genre a voice exists to discipline - institutional voice, and in the case of the assays for analyzed us, the institutional voice if it presents, really, as a defining trace; 3. the journalistic assay, for its multiple symbolic representations, multiple subjects and for passing explicit or implicit opinions of its author, resembles it other genres, being able, therefore, to be inserted in a colony of opinionatives genres

O impacto das tarefas de aprendizagem mediadas pela lousa digital interativa na motivação situacional de aprendizes de inglês

Some authors have suggested that learning tasks conducted in L2 classes can motivate learners in different ways. Similarly, Interactive Whiteboards (IWB) have already been linked as drivers to engagement and enthusiasm in L2 classes, which may cause some impact on affective variables that influence learning (e.g. motivation). This crosssectional mixed-methods study aims to understand how situational motivation caused by learning tasks mediated by the IWB impact participants. We seek to answer the following research questions: (1) How does motivation as a personality trait of the learner relate to his/her additional language learning performance?, (2) How does the type of learning task mediated by the IWB impact the learner s motivation?, (3) How does motivation vary along the learning task mediated by the IWB? and (4) What is the relation between the learning task motivation and the learners perception about the task mediated by the IWB? Data collection lasted four months with 29 learners from a private language school. The instruments used were the following: (a) an initial questionnaire (adapted from the Attitudes/Motivation Test Battery by GARDNER, 2004), (b) situation-specific on-line scales to assess learners motivation in three moments: before, during and after the task, and analyze how motivation varies along the task; (c) class observations and field notes resulting from these observations, (d) participants end-of-course grades to understand the connection between academic success and their motivational profiles and (e) a final questionnaire with the qualitative purpose to know learners perceptions about the tasks mediated by the IWB. Our theoretical framework is based on Task-Based Learning and cognitive aspects present in tasks (WILLIS, 1996; SKEHAN, 1996), theories on motivation and second language learning (GARDNER, 2001; DÖRNYEI e OTTÓ, 1998; DÖRNYEI, 2000; 2002) and conceptions about L2 learning mediated by technology (GIBSON, 2001; OLIVEIRA, 2001; MILLER et al, 2005). Our results do not point out to a significative correlation between learners end-of-course grades and their motivational profiles. However, they indicate that there is some variability in situational motivation along the tasks, even among learning tasks from the same type. Furthermore, they show that learners report different perceptions for each learning task and that the impact of the IWB on participants did not have a large proportion

Pelo escuro: a poesia afro-brasileira de Oliveira Silveira

O presente estudo traz uma reflexão sobre os discursos culturais afro-brasileiros e o lugar ocupado pela poesia em meio a uma sociedade racista. A pesquisa tem como propósito fazer um estudo da poesia de Oliveira Silveira (1968, 1970, 1977, 1981, 1987). Leva-se em consideração a relação da produção poética de Oliveira com as propostas do movimento da Negritude e o diálogo lúcido que o mesmo estabelece com poetas vinculados ao referido movimento e como Silveira sugere dentro da literatura a negritude como uma forma de intersecção na poesia brasileira. A proposta aqui apresentada observa também o hibridismo na poética de Oliveira Silveira ao se enfatizar um olhar sobre uma escrita comovida pelo traço do entre-lugar do discurso. Analisa-se a caracterização de uma literatura gerada pelo tom de denúncia ao desconstruir historicamente o que há muito tempo se estabelece como democracia racial . Em cumplicidade com a poesia regional do Rio Grande do Sul, a poesia de Oliveira vem permeada pela diversidade de ritmos que traduzem o legado da cultura negra mundo afora. Essa pesquisa sustenta-se nos estudos de Eduardo de Assis Duarte (2005, 2011) e Kabengelê Munanga (2008, 2009) sobre Negritude e Identidade na literatura afro-brasileira, que se caracteriza como um movimento de consciência pela reconstrução ou mesmo revisão histórica do que foi apagado no calabouço dos navios negreiros. As leituras de Eduardo de Assis Duarte fomentam novos questionamentos, põem em dúvida a existência de uma identidade essencialista. Aponta-se nessa travessia para uma pluralidade de identidades, construídas por inúmeros grupos culturais na encruzilhada dos diversos momentos históricos. Analisam-se, portanto, a partir da crítica que Stuart Hall (2011) faz ao considerar as ideias de diásporas, as fronteiras das margens no universo da pós-colonização. Por fim, há uma encruzilhada ao se pensar a partir de Kabengelê Munanga, o discurso da negritude e da identidade negra nas relações sociais e culturais afrodescendentes

Propriedades mecânicas do músculo de ratos adultos e idosos, exercitado pós-imobilização

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

O Uso de operações linguístico-discursivas da crítica genética na reescritura de textos

As a professor in Curso de Licenciatura em Letras, from Campus Avançado Profa Maria Eliza Albuquerque Maia (CAMEAM),do Estado do Estado do Rio Grande do Norte (UERN), in the town of Pau do Ferros, in the state of Rio Grande do Norte, we had the chance to carry out several writing activities , as well as guiding re-writing activities for the texts produced. From this experience, we started looking at the need of reflecting upon the writing process in higher education. Thus, we aim at analyzing, in this research, the methodology used in the moment of carrying out the writing practices activities in higher education, investigating, in particular, the rewriting practices, concerning the operations used for carrying out such activities, as well as the sense effects produced from the alterations which were made in the texts. Our theoretical foundation is grounded on a conception of text as a verbal action , what reveals a socio-interactional view of the language (MARCUSCHI, 2008; SAUTCHUK, 2003). As the production of written texts, our research focus, we assume that, for this activity, we deal with distinct figures (active writer and internal reader), so that we can, apart from writing, reflecting upon our writing and, this way, deciding about operations which are carried out to make the alterations which are necessary to the rewriting of our texts (SAUTCHUK, 2003). Still about the theoretical foundations used in this research, we made use of the theories from the Textual Analysis of Discourse (TAD) which discusses the belief on the evidence on the existence of the texts, which is opposite to the fixist view of textuality which believes that the texts exist by themselves. (ADAM, 2008; [2005]2010). Under this perspective, we have also adopted, the concepts which come from genetics criticism which is concerned about the relation between text and genesis, using as objects documents which bring traits of the text in progress, on the ground that the text is the result of work in progress, and the writing practice, on the other hand, as an activity in a continuous movement (HAY, [1975]2002; DE BIASI, [2000]2010; GRÉSILLON, 1989; [1990]2008; [1992]2002; SALLES, 2008a). The methodology in this research is an ethnography-based one, an approach which focuses on the process, as well as is meaning-based. To understand the objectives proposed in our research, we made use of different procedures of collecting data which include an ethnographic study, such as: observation, note-taking, document analysis. The data which were analyzed were collected during the semester of 2008.2, in a first term classroom of Curso de Letras from CAMEAM, when we were able to collect twenty-one written texts and all of them were rewritten based on rewriting activities, what provides a corpus of forty-two texts which will be analyzed based on the linguistics operations identified by Generative Grammar and adopted by Lebrave and Grésillon (2009). From these analyses, we were able to confirm that writing is a process, and rewriting has become an extremely important activity for this process. Still due to these data, we observed that substitution was the most used operation by text authors. We believe that this result is justified by the fact that the substitution, according to what proposes the Genetic Criticism, constitutes the source of all erasure, from which one can easily make a change in writing. Regarding the operations of addition and deletion, we found that they were used in quantitative terms, almost equivalently, which can be explained when we see that the two operations require, by the author of the text, different strategies from those used for the replacement, what includes , respectively, adding or removing a segment. Finally, we found out that the shift operation was the least used, since it works with a segment that will not be replaced, added or deleted, but transferred to another place of text, which requires a greater ability of the author to perform this operation and not compromising the meaning of his/her writing. As a result, we hope to contribute to the reflection on the teaching of writing, considering, in a particular way, those with a Bachelor in Arts. Our analysis will contribute to the teaching of Portuguese language, specifically for activities that guide the production of texts in order to explore with students the ability to rewrite their own text

Qualidade de Vida, Saúde Geral e Ansiedade em pacientes com diferentes tipos e níveis de disfunção temporomandibular

Some studies reported in the literature that emotional factors and quality of life may be involved both in aetiology, as in the progression of Temporomandibular disorders (TMD). Proposition: The purpose of this study is to observe a possible association between different forms of anxiety, quality of life and general health of patients diagnosed as carriers of various types and levels of Temporomandibular Dysfunction. Methodology: The sample consisted of 60 patients diagnosed as carriers of TMJD origin of muscle, joint, or both, with different levels of severity (mild TMD, moderate and severe). The patients were diagnosed with TMD-RDC (Research Diagnostic Criteria) to assess the type of dysfunction (muscle or joint) and by the Protocol of Fonseca to verify the degree of dysfunction (mild, moderate or severe). To evaluate the psychosocial aspects were used three self-applied, with the purpose of obtaining information about the general health (General Health Questionnaire - GHQ), the type of anxiety (Trait Anxiety Inventory-State - STAI) and quality of life (World Health Organization Quality Of Life Short WHOQOL-brief). Results: There was a correlation between all indicators studied in several forms of TMD with varying degrees of commitment. Quality of life appeared linked to the type and the level of TMD: Muscular and Articular TMD (p = 0,037), Disk Displacement With Reduction (p = 0.01) and Mild TMD (p = 0.042). The General Health showed association with the level of TMD, with the exception of the stress factor (p = 0.78). For the analysis of the types and levels to Severe Muscular TMD had a statistically significant indicator of the quality of life (p = 0049). The anxiety only showed association with the level of TMD (p = 0,047 for anxiety-trait). Conclusion: Besides the limitations of the study, it was concluded that anxiety, quality of life and general health are important psychosocial indicators, which are linked to several forms of TMD in different levels of severity