SYMPOSIUM E - Sociedade Brasileira de Pesquisa em Materiais



|SBPMat |

|BRAZIL-MRS |

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|2nd Brazilian MRS Meeting |

|October 26-29, 2003 |

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|Symposium E: |

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|Processing/Properties Structural |

|Composite Materials |

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|Symposium Organizers:____________________________________________________ |

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|Mirabel Cerqueira Rezende (CTA, IAE-ITA) |

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|Fernando Luiz Bastian (UFRJ) |

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|Gerson Marinucci (IPEN) |

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|José Maria Fernandes Marlet (EMBRAER) |

|iNVITED PRESENTATIONS |

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|E-I1 |Some aspects of the determination of adhesion parameters in composites |

| |B. LAUKE - INSTITUT FÜR POLYMERFORSCHUNG DRESDEN E.V., HOHE STR. 6, 01069 DRESDEN, GERMANY |

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| |The quality of adhesion between reinforcing components and matrix in composites, bonding between a substrate and adherent |

| |or the strength of a welding line in two component injection moulding are important for the mechanical properties of these|

| |materials. The characterisation of adhesion between different materials generally follows two concepts: determination of |

| |adhesion strength or determination of fracture mechanics parameters. The application of the strength concept at the |

| |interface between two materials involves major principle problems. Because of the inhomogeneous stress distribution in |

| |most of the applied test methods the normalisation of the applied critical force with the cross section of the sample |

| |provides only a rough approximative measure of the composite quality but not a material property describing adhesion |

| |strength between the components. Another way to characterise adhesion is given by the consideration of a composite with a |

| |crack, that leads to the fracture mechanical approach of bimaterial composites. In the following presentation some aspects|

| |of these two approaches are discussed. On the basis of fracture mechanics the critical energy release rate for the Single |

| |fibre pull-out test is determined. The strength concept is applied in the Necked test in tension and the Curved interface |

| |test to evaluate the fibre/particle-matrix bonding and the polymer-polymer bonding quality, respectively. |

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|E-I2 |DEGRADATION PROCESSES IN POLYMERIC FILMS CONFINED AT NANOMETER SCALE |

| |D. Hui1, M. Chipara2 - University of New Orleans, Department on Mechanical Engineering, New Orleans, LA, USA.1; 2Indiana |

| |University Cyclotron Facility, Bloomington, IN, USA. |

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| |In polymeric films confined at nanometer scale, the glass and melting transition temperatures are affected by the |

| |confinement. The intimate relationship between the glass transition temperature, the radius of gyration of these polymers,|

| |and the film thicknesses triggers an anomalous degradation. A model for the degradation of such polymeric films is |

| |proposed. For simplifications, it is assumed that the initial polymer has a narrow distribution of molecular masses, the |

| |shape of the molecular mass distribution is not affected by degradation, that each chain consists of a very large |

| |(infinite) number of monomers. |

| |For simplification, the reactions are decomposed into two independent processes. The first one is represented by the |

| |diffusion of reactants towards a small volume, named reaction volume, where the second step is represented by the proper |

| |chemical reactions of the process. Within this approach, it is possible to assume the second step occurs as in the gas |

| |phase. The maximum value of the reaction volume is imposed by film thickness, which is in fact the blob's radius of |

| |gyration. Two competing degradation processes, represented by a first order (K1) and a second order recombination constant|

| |(K2), were assumed. The temperature dependence of K1 and K2 was assumed to obey an Arhenius-WLF like dependence. The |

| |effect of thickness on the degradation of polymers, at nanometer scale is analyzed in detail and modeled. It is observed |

| |that the degradation shows a discontinuity within the glass transition range. The deviations from a simple Arrhenius like |

| |dependence are discussed in detail. |

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|E-I3 |COMPOSITE MATERIALS FOR ARCHITECTURE AND BUILDING – A REVIEW |

| |Philippe Martineau - Consulado Geral da França em São Paulo, Av. Paulista, 1842 – 14º andar, São Paulo – SP, CEP |

| |01310-200; philippe.martineau1@libertysurf.fr |

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| |The introduction of composite materials – based on resins reinforced by high mechanical performances fibers – took place |

| |in building industry in the 1950th. At that time, a few architects considered these materials as a new form of expression.|

| |However it’s only for the last twenty years that they have been used in applications others than prototypes or extravagant|

| |objects. Compared with traditional material such as wood, stone or steel, composite materials are ‘young’ and listed ‘new |

| |materials’ and still insufficiently known by professionals. We have a long way to go before their applications are |

| |generalized but, as we will see in this presentation, their development seems inevitable. In this paper we shall describe |

| |the numerous advantages presented by those materials and the main impediments to their development. Possible solutions |

| |will be detailed. The main families of existing applications will be presented as well as the reasons for their choice. |

| |Finally we shall consider the future of their development and the means which will be needed to promote these materials. |

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|E-I4 |TAILORING THERMAL RESIDUAL STRESSES FOR THE DESIGN OF COMPOSITE STRUCTURES |

| |Sérgio Frascino Müller de Almeida - Instituto Tecnológico de Aeronáutica - Department of Mechanical Engineering - |

| |12.228-900 São José dos Campos – SP – Brazil. |

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| |Thermal residual stresses are usually present in composite structures and may strongly affect their strength and |

| |mechanical behavior. The purpose of this work is to discuss the design of composite plates with reinforcers taking the |

| |effect of thermal residual stresses into account. The idea is not only to avoid configurations where the effect of the |

| |thermal stresses are deleterious but also take advantage of possible beneficial effects of the thermal stresses to enhance|

| |the mechanical behavior of the plate. In most situations, the complexity of the problem precludes the use of engineering |

| |common sense alone to identify favorable configurations. |

| |The problem of determining the thermal residual stresses is also complex due to its non-linear nature as the material |

| |properties and mechanical behavior change as the material cools down from the cure temperature to the room temperature. |

| |Moreover, a design that is optimal for a certain temperature may perform poorly at another operating temperature. In |

| |practice, an aircraft part must perform satisfactorily in any temperature within a certain operation temperature range. As|

| |a consequence, the design must take into account the fact that the structure operates within a given temperature range |

| |rather than at a fixed temperature when taking into account the residual thermal stress effects. |

| |Therefore, the problem involves three basic elements: (a) a simple and reliable numerical procedure to compute the thermal|

| |residual stresses; (b) experimental procedures to characterize the model parameters and verify the numerical results; (c) |

| |a design tool based on optimization techniques to determine optimal designs that take full advantage of the presence of |

| |the thermal residual stresses for a structure that operates within a given temperature range. The work discusses recent |

| |developments on the topics above. |

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|E-I5 |COMPOSITE POSTS FOR ORAL REHABILITATION |

| |C. A. Cimini Jr.1, R. C. Albuquerque2, W. A. Vasconcellos2 - 1 Mechanical Engineering Department, Engineering School, |

| |Federal University of Minas Gerais Belo Horizonte, MG, Brazil; 2Department of Restorative Dentistry, School of Dentistry; |

| |Federal University of Minas Gerais, Belo Horizonte, MG, Brazil |

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| |This study evaluated the effect of geometry and material of posts on the stress distribution in maxillary central |

| |incisors, using the Finite Element Method. Four threedimensional models were obtained, one of a healthy tooth and the |

| |others of restored teeth using tapered, cylindrical and two-stage cylindrical posts. The materials used for the posts were|

| |stainless steel, titanium, zirconium dioxide, carbon fibers and glass fibers on Bis-GMA matrix. The restored teeth had |

| |composed resin composite core and porcelain crowns. All materials were assumed to be homogeneous, isotropic and linearly |

| |elastic, except for the posts made of composite materials, considered orthotropic. Tensile and compressive stresses were |

| |concentrated on the lingual and facial surface, respectively, for all the analyzed models. Two regions of tensile stress |

| |concentration were verified: region A - adjacent to the alveolar bone crest, and region B - dentin-post boundary. In the |

| |dentin portion close to the alveolar bone crest, different anatomical form and material posts presented similar patterns |

| |of stress distribution. However, in the dentin-post boundary, more favorable results were presented by glass fibers and |

| |carbon fibers posts, followed by titanium, being the worst results associated to the use of stainless-steel or zirconium |

| |dioxide posts. Still in the dentinpost boundary, tapered posts presented more favorable results than cylindrical posts, |

| |followed by two-stage cylindrical posts, which presented the highest levels of stress concentrations. It was concluded |

| |that the insertion of post alters the pattern of stress distribution when compared to the healthy tooth and that smaller |

| |stress concentrations are associated to the use of glass fiber or carbon fiber tapered posts. |

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|E-I6 |LIQUID CRYSTAL THERMOSETS: NEW GENERATION OF HIGH PERFORMANCE MATERIALS |

| |C. Carfagna, University of Naples “Federico II”- Department of Materials and Production Engineering, Piazzale Tecchio 80 |

| |80125 Napoli (Italy), e.mail: carfagna@unina.it – ICTP CNR via Campi Flegrei Pozzuoli Napoli (Italy), e.mail: |

| |director@irtemp.r.it |

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| |Liquid crystal polymers have been widely investigated in the last decades, with particular attention to mechanical |

| |properties. Great emphasis was dedicated by scientific community to liquid crystal thermosets, which represents a |

| |promising family of materials with outstanding potential in many applications. Among different thermosets, epoxy resins |

| |present higher performances, thanks to physical properties. Liquid crystal epoxy resins (LCER) can find different |

| |applicability depending on the nature of the monomers and of the curing process. In the case of resins having low density |

| |of crosslinking, novel elastomers with unique mechanical properties can be generated. When aromatic amines are used as |

| |curing agent, very though materials can be produced for application as matrices for composites. With proper tailoring of |

| |the chemical composition novel family of adhesives to be used in the automotive industry for polymer joints can be |

| |produced. In this lecture, a review of chemistry and physical characterization of liquid crystal epoxy resins is |

| |presented. |

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|E-I7 |Effective Use of Composite Structures: Building Better Design Methodologies |

| |Paul A. Lagace - Professor of Aeronautics & Astronautics and of Engineering Systems - Technology Laboratory for Advanced |

| |Composites, Massachusetts Institute of Technology, Cambridge, Massachusetts, U.S.A. |

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| |The early use of composite materials in structural applications was dominated by the aerospace industry. The techniques |

| |that evolved to design, certify, and assure structural integrity of composite structures have therefore been predominantly|

| |based on the methodologies of the aerospace world with some even finding their roots in methodologies used for metallic |

| |applications. However, the extension of the use of composite materials to a wide variety of applications, such as civil |

| |infrastructure, calls for adaptations and development of methodologies suitable for those particular applications. |

| |Irrespective of the specifics of a particular application, one issue runs throughout -- the evaluative assessment of the |

| |current structural integrity. A key concept in this is damage in the structure as it is the development, growth, and |

| |sensitivity of damage, the associated ability to assess the level of damage, and the effect of the damage on structural |

| |performance that shapes the overall design of a particular structure. The evolution of design methodologies for composite |

| |structures leading to today’s state of practice is reviewed in this context. In addressing the wide variety of |

| |applications, approaches run the gamut from the relatively simple-minded make-and-break philosophy often used in consumer |

| |goods to the sophisticated building block approach practiced for composite aircraft structures. These methodologies tend |

| |to be slow, excessively cumbersome, and often struggle to reach a satisfactory, let alone good, design. The underlying |

| |cause of these shortcomings is the empirical nature of the current design methodologies in dealing with the critical issue|

| |of damage, particularly in regard to assuring structural integrity. |

| |A vision is proposed to work towards realizing the full potential of composites. A key is in utilizing the ability to |

| |tailor composite performance by choice of fiber, matrix, architecture, and associated processing. This involves |

| |considering the separate items of the process in an integral fashion in the development of the structure through the issue|

| |of damage. An overall design framework is described based on linking the behavior of composite material systems at |

| |various levels and lengthscales from the fiber, matrix, and associated interface/interphase (micromechanics) to the |

| |full-scale structure (structural macromechanics). The development of the proposed design methodology framework must be |

| |evolutionary and will have short- and long- term benefits leading to more versatile, more cost-effective, and more |

| |efficient composite products. Thoughts are offered as to the roles of industry, government and academia in cooperating to|

| |make this happen. |

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|E-I8 |DISCONTINUOUS OR CONTINUOUS REINFORCEMENTS FOR TI BASED COMPOSITES: A REVIEW |

| |Frédéric Dartigues and Yann Le Petitcorps - ICMCB-CNRS-UPR 9048 |

| |87, Av. A Schweitzer33608 - Pessac France. E-mail: lepetit@icmcb.u-bordeaux .fr |

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| |During the last two decades, many studies were devoted to titanium matrix composites reinforced with continuous boron or |

| |silicon carbide filaments. 20 years after, the field of applications is very restrictive or negligible. Many reasons have |

| |explained it : (1) the constituents are very expensive (mainly the SiC CVD filaments), (2) the quality of fabrication is |

| |difficult to get, (3) the reinforcement and the matrix are never in a thermodynamic or thermomechanic equilibriums and the|

| |chemical reaction is always present during the fabrication of the composite or in service. Recently, particles (TiC, B4C, |

| |TiB2) or whiskers (TiBw) have been of interest for the reinforcement of titanium without bringing too much drawbacks. |

| |These materials are often prepared by the « in-situ » precipitation of the reinforcement at a very low cost of |

| |fabrication. The properties and microstructures of all these materials are compared and discussed. |

| |KEYWORDS :Titanium Matrix Composites, SiC CVD filaments, « in-situ » precipitation, Fiber/matrix reaction. |

|E-I9 |STRUCTURAL CERAMIC-MATRIX COMPOSITES - AN OVERVIEW |

| |Roberto Tomasi, Universidade Federal de São Carlos - Departamento de Engenharia de Materiais (DEMa) - São Carlos/SP, CEP: |

| |13565-905. E-mail addreess: tomasi@power.ufscar.br. |

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| |An overview on the processing and general characteristics of ceramic-matrix composites is presented. Ceramic-matrix |

| |composites (CMC) may refers to a very wide diversity of two or more ceramic phase materials, but the term is most |

| |frequently adopted for advanced or high-performance structural ceramic materials developed for applications were high |

| |strength and improved toughness are required to be combined with low density and/or high work temperature, high wear and |

| |oxidation resistance. The most important types of CMC are composed by continuous fibers reinforcements. These also |

| |presents the most troublesome and expensive manufacturing processes. Different others types of CMC are obtained with |

| |reinforcement of chopped fibers, whiskers, platelets or particles. The CMC with particles inclusions have shown important |

| |applications for wear resistant materials with improved strength and toughness. The structural ceramic nanocomposites, |

| |defined as composites were at least one of the phases shows dimensions in the nanometer range, are shown novel and even |

| |outstanding properties, particularly the wear resistance and creep and high temperature performance. Although the effect |

| |of the nanostructure is not well understood, the continued interest in these materials is not only due the good properties|

| |but also due the large number of manufacturing alternatives. Some developments on ceramic matrix nanocomposites processing|

| |is briefly presented. |

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|E-I10 |ECO-FRIENDLY POLYMER COMPOSITES BASED ON VEGETABLE FIBERS |

| |L.H.de Carvalho, DEMa/CCT/UFCG, Caixa Postal 10034, Campina Grande, PB, Brazil |

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| |The use of vegetable fibers as reinforcements in plastics is increasing enormously worldwide. Polymer composites have been|

| |prepared combining almost all vegetable fibers – jute, sisal, banana, coir, ramie, flax, kenaf, pinneaple etc… - and most|

| |polymer matrices available– thermosets, thermoplastics and elastomers. The effects of fiber surface treatments, |

| |hybridization, stacking sequences, among others have been studied in order to enhance the performance of these materials. |

| |The cost and weight reduction, the excellent acoustic absorption and good impact properties of these products, their |

| |relatively easy processing and the possibility of forming complex shaped parts in single molding processes are the reasons|

| |for such an intense research activity in this area. Ecological aspects are also of major importance. Vegetable fibers are |

| |excellent candidates for the partial replacement of high-cost glass fibers for low load bearing applications and their |

| |composites can also replace wood in many end-uses. Ecological concerns have prompted studies on recyclable and/or |

| |biodegradable products as well as on renewable resource based composite products. An overview of the most promising |

| |systems currently being investigated as well as those studied by the polymer group at the Federal University of Campina |

| |Grande, PB, Brazil, will be presented and discussed. |

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|E-I11 |Composite Materials for Biomedical Applications |

| |L. Ambrosio, P.A. Netti, L. Nicolais - Institute of Composite and Biomedical Materials, CNR and Interdisciplinary |

| |Research Centre on Biomaterials, University of Naples “Federico II”, Piazzale Tecchio 80, 80125 Naples, Italy. Tel. |

| |+39.081.7682513; Fax: +39.081.2425932; Email: Ambrosio@unina.it |

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| |The present research is aimed to study in a systematic and quantitative manner the effect of the 3-D scaffold structure |

| |and stiffness upon cellular growth and remodelling. Replication of the structure and the functions of the extracellular |

| |matrix in vitro is performed by forming a semi-Interpenetrated Polymer Network (s-IPN) between Collagen type I and |

| |Hyaluronic acid (HL). The s-IPN collagen-HA was obtained by inducing collagen fibrillogenesis in HL solutions. The |

| |rheological behaviour of the semi-IPN collagen/HL have been analysed to evaluate the effect of Hyaluronic Acid and |

| |collagen in the composite gel. The rheological behaviour of our collagen gels was similar to that reported in the |

| |literature on other kinds of collagen. The gels behaved as a weak-gel (G'>G'') and the elastic (G') and viscous (G'') |

| |moduli did not depend strongly on the frequency. On the other hand, low molecular weight HL solutions behaved as viscous |

| |liquid (G”>G’) in all frequency range analyzed. The rheological behaviour of the semi-IPN collagen/HA was qualitatively |

| |similar to that of collagen gels but the value of elastic modulus was significantly higher. Cell viability, growth and |

| |morphology of cells were assessed with different cell line embedded in 3D gels of collagen with variable physical |

| |properties while maintaining a constant chemical environment. From the earliest experiments it was clear that on all these|

| |substrata cells were observed to adhere, loco mote, and divide and that the rate of movement depends on the nature of the |

| |surrounding gel. Both structure and stiffness of the scaffold influence the cellular activity within the material. In |

| |particular we report that the stiffness of cell seeded constructs, not just the molecular composition of the adhesion |

| |substrate, can affect the cellular density and different morphology of the cells embedded in 3D gels. The cellular |

| |response to the physical state of the matrix influences output parameters such as cell viability, cellular activity and |

| |neo-tissue formation which ultimately determine the functionality and efficacy of the tissue engineered construct in terms|

| |of structural stiffness and permeability. |

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|E-I12 |Sustainable Structural Biocomposites: The material for the 21st Century |

| |Lawrence T. Drzal, University Distinguished Professor, A. K. Mohanty, Associate Professor, and M. Misra, Visiting |

| |Associate Professor, Department of Chemical Engineering and Materials Science, Composite Materials and Structures Center, |

| |Michigan State University, 2100 Engineering Building, East Lansing, MI 48824, USA, e-mail: drzal@egr.msu.edu |

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| |There is a growing need to develop and commercialize new bio-based ‘green’ structural materials that can be competitive |

| |with current synthetic products. A multidisciplinary approach has been developed to produce biocomposites with desirable |

| |mechanical properties which requires: (i) new and novel processing to combine biofibers with plastics; (ii) low cost but |

| |effective surface treatment of the bio-fibers; (iii) selection and design of a multicomponent blend of bast and leaf |

| |biofibers; (iv) and suitable matrix polymer modifications to optimize biocomposite strength and stiffness. Biofiber |

| |reinforced petroleum-based plastic biocomposites can at this time produce a structural material with a balance between |

| |ecology, economy and technology. Some examples that will be discussed include: ‘biocomposites’ made by embedding |

| |natural/bio-fibers like Kenaf, Hemp, Flax, Jute, Henequen, Pineapple Leaf Fiber, Corn Stalk fibers and Native grasses into|

| |renewable resource-based bio-plastics such as Polylactides (PLA), cellulosic plastics, soy-based plastics, bacterial |

| |polyesters and urethanes produced from vegetable oil based polyols. |

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|ORAL PRESENTATIONS |

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|E-O1 |Mechanical Behavior of Composite Materials Used in the Repair of Damage Steel Pipelines |

| |R. T. FUJIYAMA; A. N. SOUSA; F. L. BASTIAN - COMPOSITE MATERIALS LABORATORY, PROGRAM OF METALLURGICAL AND MATERIALS |

| |ENGINEER, COPPE/FEDERAL UNIVERSITY OF RIO DE JANEIRO, POBOX 68505 – ZIP CODE: 21941-972 – RIO DE JANEIRO /RJ, BRAZIL. |

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| |Repair of oil and gas pipelines presenting corrosion damage can be done following conventional routes as cutting and |

| |substitution of the damage parts, double filling sleeve method or double sleeve welded method. Recently, the use of |

| |composite materials for repair of damage pipelines is increasing due to the advantages presented by this process like the |

| |case application and the possibility of performing the repair without interrupting the use of the line. A requisite for |

| |the composite materials is that they have adequate mechanical properties to guaranty the integrity of the repaired pipe |

| |during its operation. In the present work, a microstructural and mechanical characterization of two composites materials |

| |used in pipe repair is made. One is the composite materials is made of continuous fiber glass and the other of a fiber |

| |glass fabric, both with polymeric matrix. The first was pulltruded and the second was processed by hand lay up. The |

| |microstructural characterization was done through optical microscopy and the mechanical properties were evaluated tensile |

| |tests. The repair composite materials are subjected to humidity and sometimes environments containing oil, in the |

| |petroleum industry. The composite materials were submitted to petroleum aging at 60o C and atmospheric pressure and, |

| |after, the same mechanical and microstructural characterization was made. As the repaired pipe is under hydrostatic |

| |pressure it is important to guaranty the stresses that will be transferred to the composite repair in order to evaluate |

| |the integrity of the repaired pipe. From the mechanical properties of the composite materials and models available in the |

| |literature the stresses acting in the composite repairs due to the hydrostatic pressure were evaluated before and after |

| |aging the repair material in petroleum. |

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|E-O2 |Preparation and mechanical properties of polypropylene – clay nanocomposites |

| |F.G.R. FILHO, T. J. A. DE MELO, L.H. DE CARVALHO, S.M.L. SILVA, DEMA/CCT/UFCG, CAIXA POSTAL 10034, CEP 58109-970, CAMPINA |

| |GRANDE, PB, BRAZIL |

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| |In this work, polypropylene-clay nanocomposites have been prepared by melt extrusion of a masterbatch in a |

| |counter-rotating twin-screw Haake extruder. The master batch consisted of a 1:1 clay dispersed in a PP matrix. This system|

| |was melt processed in the Rheomix 600, accessory to a Haake System 90 torque rheometer operating at 210ºC, 60rpm with |

| |roller rotors for 10 minutes. The clay employed was a commercial sodium bentonite (Brasgel). An organophilic derivative of|

| |this clay was obtained by chemical reaction with Cetyl trimethyl ammonium bromide (Cetremide). Modified and non-modified |

| |clay masterbatches were blended with PP in order to obtain PP-clay nanocomposites with 1 and 3% w/w clay contents. The |

| |influences of clay modification and content (0-3wt%), on the mechanical properties of the composites were investigated. |

| |X-ray analysis showed organophilization to be successful. Mechanical property analysis suggests that nanocomposites were |

| |indeed obtained. Best overall mechanical properties were obtained for the PP-untreated clay system employed at 3% w/w clay|

| |content. This behavior was unexpected and DSC analysis suggests that the organophilic clay promotes PP matrix degradation.|

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|E-O3 |MATHEMATICAL MODEL OF THE FUNCTION BETWEEN PARTICLES DISTRIBUTION OF SiC IN ALUMINUM MATRIX AND THE COMPOSITE MATERIAL |

| |RESISTANCE |

| |Z. M. Boari1; W. A. Monteiro1; C. A. J. Miranda1 - 1IPEN-CNEN, Material Science and Technology Center, São Paulo; |

| |2IPEN-CNEN, Nuclear Engineering - Structural Mechanics Department, São Paulo. |

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| |This work deals with a composite material with SiC particles mixed in an aluminum matrix. Qualitative analyses indicate |

| |that microstructural characteristics were very influenced by SiC particulate distribution. Several studies have recognized|

| |the deviations from the periodicity of reinforcement distribution can markedly influence the composite elastic and plastic|

| |deformation characteristics. The composite overall response is influenced by the physical and geometrical properties of |

| |the reinforcing phases. The finite element method, the Eshelby method and dislocation mechanisms are usually employed in |

| |the formulation of the composite constitutive response. The aim of this work is to study the relationship between the |

| |particle distribution and the metal matrix composite resistance and to propose a mathematical model for the composite |

| |elastic behavior. The proposed formulation was applied to establish the thermal stress field in an aluminum-SiC composite |

| |due to its fabrication process – the mixing is done at 600oC and the material is supposed to be used at room temperature. |

| |The analytical results, presented as stress probabilities, were compared with the numerical ones, presented as stress |

| |distributions from the numerical model, obtained with a commercial finite element code. Both results compare well with |

| |same trends and very close average values of the thermal stresses. It is also shown that, if the Maxwell-Boltzmann |

| |distribution law is used, it is possible to obtain the relationship between the distribution particles and the material |

| |resistance through the Eshelby's thermal stress. |

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|E-O4 |STEAM CURING AND DELAYED ETTRINGITE FORMATION IN BRAZILIAN CEMENTS |

| |G. Camarini, E L. F. Júnior - Departamento de Arquitetura e Construção Faculdade de Engenharia Civil - Universidade |

| |Estadual de Campinas - Caixa Postal 6021 – Distrito Barão Geraldo – Campinas – SP – CEP 13083-970. |

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| |Delayed ettringite formation may be defined as the formation of ettringite in a cementitious material by a process that |

| |begins after hardening has substantially complete. The reaction occurs between the anhydrous cement compound C3A and |

| |sulphates in the paste. In recent years delayed ettringite formation has become a topic of major significance to the |

| |international community. Early ettringite formation, which occurs immediately (within hours) in a plastic fresh mixture, |

| |does not produce any damaging expansion and is associated with the regulation of setting time of Portland cement paste. |

| |Delayed ettringite formation may be defined as the formation of ettringite in a cementicious material by a process that |

| |begins after hardening is substantially complete and in which none of the sulphate comes from outside the cement paste. |

| |Delayed ettringite formation (DEF) can damage concrete that has experienced a temperature above about 70ºC. This process |

| |is associated with expansion. Expansion results from formation of ettringite crystals of submicrometre size in the paste, |

| |the large crystals largely observed in cracks and voids being recrystallization products. The rate and ultimate extent of |

| |expansion are influenced by factors of three types: chemistry, which determines how much ettringite can be formed; paste |

| |microstructure, which determines the stress produced by its formation; and concrete and mortar microstructure, which |

| |determines the response of the material to those stresses. Image analysis by Scanning Electron Microscopy (SEM) promotes |

| |the observation of ettringite crystals in Portland cement pastes, mortars and concretes. The aim of this work was to |

| |observe the DEF in steam-cured concretes made with Brazilian Portland cements (Blastfurnace Slag Cement – CP III, and High|

| |Initial Compressive Strength Portland Cement – CPV-ARI). The steam temperature was 80ºC. The image analysis showed that |

| |DEF was observed in both cements. |

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|E-O5 |REACTION-INDUCED PHASE SEPARATION IN EPOXY/POLYSULFONE/POLY (ETHER IMIDE) SYSTEMS: 1. PHASE DIAGRAMS |

| |M.I. Giannotti1; M.L. Foresti1; M.J. Galante1; P.A. Oyanguren1; J. B. Justo2; I. Mondragon - 1Institute of Materials |

| |Science and Technology (INTEMA), University of Mar del Plata and National Research Council (CONICET); 4302, 7600 Mar del |

| |Plata, Argentina; 2Materials + Technologies Group, Escuela Ingeniería Técnica Industrial, Universidad País Vasco/Euskal |

| |Herriko Unibertsitatea, Avda. Felipe IV, 1 B. 20011 San Sebastián – Donostia, España. |

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| |Epoxy-aromatic diamine formulations were simultaneously modified with two immiscible thermoplastics (TP), poly(ether |

| |imide) (PEI) and polysulfone (PSF). The epoxy monomer was based on diglycidyl ether of bisphenol A and the aromatic |

| |diamines (AD) were either 4,4´-diaminodiphenylsulfone or 4,4´-methylenebis(3-chloro 2,6-diethylaniline). The influence of |

| |TP on the epoxy-amine kinetics was investigated. It was found that PSF can act as catalyst. The presence of the |

| |thermoplastic provoked an increase of the gel times. Cloud-point curves (temperature vs. composition) are shown for |

| |epoxy/PSF/PEI and epoxy/PSF/PEI/AD initial mixtures. Phase separation conversions are reported for the reactive mixtures, |

| |for various thermoplastic contents and PSF/PEI proportions. On the basis of phase separation and gelation curves, |

| |conversion-composition phase diagrams at constant temperature were generated for both systems. These diagrams can be used |

| |to design particular cure cycles to generate different morphologies during the phase separation process. This will be |

| |discussed in the second part of the series. |

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|E-O6 |A DIRECT SINTERING ROUTE FOR MAKING ALUMINUM METAL MATRIX COMPOSITES |

| |E.N.Gregolin;H.Goldenstein, Department of Metallurgical and Materials Engineering, Escola Politécnica da Universidade de |

| |São Paulo, São Paulo SP, Brasil. |

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| |This paper reports preliminary results on a new route for the production of Metal Matrix Composites by direct sintering of|

| |aluminum with reactive silica. Fine commercial aluminum powder was mixed with apropriated particle oxides and cold pressed|

| |to obtain bars or cylinders with 85-90% of theoretical green density. The samples were sintered between 600 and 640oC for |

| |a range of 15 min to 2 hours under industrial N2 atmosphere. During sintering, the silica oxide powder was chemically |

| |reduced by the aluminum, forming Al2O3 particles and liberating the metallic silicon constituent of the original oxide. |

| |The silicon liberated was sufficient to promote an efficient Super-Solid Sintering Process with an effective densification|

| |of the samples. The alumina particles were porous, remained with the same external morphology and distribution of the |

| |silica and fully filled with the liquid phase. Moreover, the porous alumina presented a co-continuous morphology that |

| |improved the mechanical properties of the sintered samples as the original discrete interface between matrix and the |

| |reinforcements were completely eliminated and replaced by a new mechanical and chemical stable interface. |

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|E-O7 |SILICON NITRIDE/SILICON CARBIDE PARTICULATE COMPOSITES: SINTERING BEHAVIOR |

| |Rumbao, A.C.S.C; J. C. Bressiani; A. H. A. Bressiani - IPEN - Instituto de Pesquisas Energéticas e Nucleares- Centro de |

| |Ciências e Tecnologia de Materiais. Av. Prof. Lineu Prestes, 2242 – Cidade Universitária. CEP: 05508-000 - São Paulo - SP |

| |– Brasil. |

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| |In the last 20 years has been given increasing importance to ceramics materials for engineering applications, despite |

| |their inherent brittleness. Due of their high strength, hardness and thermal stability, silicon nitride ceramics are among|

| |the most important materials for structural applications. The need for further improvement in the mechanical reability of |

| |silicon nitride has led to the development of high strength and high toughness ceramics, such as fiber-, whiskers-, or |

| |particulate-reinforced silicon nitride ceramics. Silicon carbide was used as an addition to silicon nitride more than 20 |

| |years ago. In this work, Si3N4-SiC particulate composites was investigated. For this study was prepared a basis |

| |composition (CB) with 90wt% of (-Si3N4, 6wt% of Y2O3 and 4wt% of Al2O3. ( and (-SiC were added into CB and after mixture, |

| |in high-energy milling, the powder was compacted into pellets. The kinetics of sintering was studied by means of |

| |dilatometry. The presence of a second phase has a pronounces effect on the sintering kinetics of silicon nitride. The |

| |(((-Si3N4 phase transformation was complete, after sintering on graphite resistance furnace. |

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|E-O8 |ADHESIVENESS STUDY OF POLIMERYC MATRIX COMPOSITE MATERIAL FOR PIPELINES REPAIR |

| |R.C.O.M. Afonso, F.L. Bastian, Laboratory of Composite Materials, COPPE/UFRJ, CP 68505, 21941-972, Rio de Janeiro, Brazil.|

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| |The rehabilitation of pipelines due to damage caused by environmental factors with fast and low cost methods has been a |

| |challenge, mainly because corrosion is a type of defect almost inevitable in pipes. As a consequence, knowing a technology|

| |of pipe repair is very important to reduce costs of hidrocarbonates transportation. Many techniques are being developed, |

| |amongst them, the repair with composite materials that consists in involving the damaged pipe with the composite material.|

| |The characterization of the adhesion and the study of techniques to maximize it are of great scientific and technologic |

| |interest, because the efficiency of the repair will depend on the good adhesion of the composite material of the repair on|

| |the steel. The aim of this work is to study the adhesiveness of a composite material used in pipeline repair on a steel |

| |substrate. Hence, metal-composite adhesive joints are being manufactured with different mechanical surface treatments with|

| |the dimensions recommended by the ASTM D 5868-01 standard, with different adhesive thickness. The fracture surfaces were |

| |analyzed by electron scanning microscopy and classified according to the ASTM D 5573-94 standard. Specimens with the best |

| |surface treatments were submitted to hygrothermal ageing to evaluate the influence of the water on the mechanical |

| |properties of the joints. The fracture failure modes of the adhesive system were associated with the mechanical properties|

| |obtained in the adhesion tests. |

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|E-O9 |Reactive microspheres as active fillers for epoxy resins |

| |C. Carfagna, V. Ambrogi, Department of Materials and Production Engineering, University of Naples “Federico II”, Piazzale |

| |Tecchio, 80, 80125 Naples, Italy; G. Cicala, A. Pollicino, A. Recca, Department of Physical and Chemical Methodologies for|

| |Engineering, University of Catania, Viale A. Doria 6, 95125 Catania, Italy; G. Costa, IMAG-CNR, Via De Marini, 6, 16149 |

| |Genova, Italy. |

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| |Physical properties of epoxy resins filled with epoxy-based microparticles previously prepared are presented and |

| |discussed. Microspheres were obtained in form of micron-sized, cross-linked spherical particles, with an excess of |

| |reactive amino groups on their surface. Blends were prepared using EPON828-3,3’DDS as matrix and in different weight |

| |percents (10% wt. and 20% wt.) of microparticles. Differential Scanning Calorimeter (DSC), and Scanning Electronic |

| |Microscopy (SEM) were used in order to evaluate the properties of microspheres, such as surface properties, shape, sizes, |

| |and size distribution. Electron Spectroscopy for Chemical Analysis (ESCA) study was applied on particles, with the aim to |

| |relate the surface composition the reactivity of microspheres. Rheological, dynamical-mechanical and mechanical properties|

| |of these systems were studied in comparison with the neat system and with EPON828/3,3’DDS/15%wt.PES180, where PES180 is a |

| |modifier. It was demonstrated that the influence of microspheres on the reactivity is very high and this makes |

| |microspheres useful modifiers for medium temperature cycles. Moreover, the addition of the microspheres was proved to be |

| |very effective in increasing the Tg of the blends without sacrifying the fracture resistance but slighting increasing the |

| |Gc and Kc values. Finally, due to the presence of reactive amino groups, the adhesion between microspheres and matrix is |

| |improved, as inferred from SEM analysis. |

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|E-O10 |INFLUENCE OF ORGANO-BENTONITE CLAY ON THE PROCESSING AND MECHANICAL PROPERTIES OF NYLON 6 AND POLYSTYRENE COMPOSITES |

| |E. M. Araújo1; T. J. A. Mélo1; L. N. L. Santana1; G. A. Neves1; H. C. Ferreira1; H. L. Lira1; L. H. Carvalho1; M. M. |

| |A`vila Jr2; M. K. G. Pontes2; I. S. Araújo2 – 1 DEMa/CCT/UFCG, C. Postal: 10034, CEP 58109-970, Campina Grande, Paraíba; 2|

| |Student of the Materials Engineering/UFCG. |

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| |The development and characterisation of nanostructured polymer-clay composites has received special attention in resent |

| |years. Organoclays consist of a clay that has been modified with quaternary amine cations. Influence of organoclay on the |

| |processing and mechanical properties of nylon 6 and polystyrene was investigated. A bentonite sample from Boa Vista/PB, |

| |Northeast of Brazil, was treated by ion exchanged with alkyldimethylbenzylammonium chlorite quaternary ammonium salt. |

| |After the modifying, the powder was characterised by infrared spectroscopy, analysis chemistry, thermal analysis and X-ray|

| |diffraction. Composites were prepared using Haake Blucher Torque Rheometer. There results evidence effective intercalation|

| |of quaternary ammonium salt. In the structure of bentonite and show that the organo-bentonite produced significant changes|

| |on the processing of nylon 6 with increase in the viscosity and rigidity. However, the mechanical properties of |

| |polystyrene/organoclay system no showed significantly changes. |

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|E-O11 |EVALUATION OF THE MECHANICAL PROPERTIES OF SISAL-POLYESTER COMPOSITES AS A FUNCTION OF THE POLYESTER MATRIX FORMULATION |

| |V. M. Fonseca1; V.J.Fernandes Jr.1; L.H. de Carvalho2; J.R.M.d’Almeida3 - 1DQ/UFRN, Caixa Postal 1662, CEP 59078-970, |

| |Natal, RN, Brazil; 2DEMa/CCT/UFCG, Caixa Postal 10034, CEP 58109-970, Campina Grande, PB, Brazil; 3DCMM/PUC-RJ, Caixa |

| |Postal 38008, CEP 22453-900, Rio de Janeiro, RJ, Brazil |

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| |In this work a comparative study was undertaken on the impact and tensile properties of polyester– sisal composites. The |

| |polyester matrix was blended with a silane coupling- agent and/or with a flame retardant compound. The mechanical |

| |properties of modified and unmodified matrices composites were determined. The experimental results show the flame |

| |retardant to act as a particulate reinforcement to the polyester matrix and the silane coupling-agent to act as a |

| |plasticizer. The simultaneous addition of these two compounds to the polyester resin decreases the composites performance.|

| |Although none of the composites manufactured with modified polyester matrices showed a significant improvement on the |

| |fiber-matrix interface strength, a better compromise between impact and tensile properties was obtained using the blended |

| |polyester – silane matrix. The critical volume fraction of fibers was also evaluated, and was shown to be less than 10%, |

| |for the composite investigated here. |

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|E-O12 |J-R CURVES EVALUATION OF ARALL 2 FIBER-METAL LAMINATES BY UNLOADING COMPLIANCE METHOD |

| |M.R.W.S. Abdala, E.M. Castrodeza, F.L. Bastian - Laboratory of Composite Materials, COPPE/Federal University of Rio de |

| |Janeiro, CP 68505, 21941-972, Rio de Janeiro, Brazil. |

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| |Fiber-metal laminates (FMLs) are structural composites designed aiming to produce a damage-tolerant and high strength |

| |material. Their application in aeronautical structures demand a deep knowledge of a wide set of mechanical properties and |

| |technological values, including both fracture toughness and residual strength. To evaluate the residual strength of wide |

| |panels of Arall containing cracks it is necessary to use crack resistance curves. Arall 2 is a FML made of sheets of |

| |2024-T3 alloy reinforced by aramid fibers. Although nowadays it is clear that they are not suitable for primary |

| |structures, this laminate is successfully being used in many secondary structures (flaps, doors, etc.). The objective of |

| |the present work was to evaluate the applicability of the unloading compliance technique in J-R curve determination of |

| |Arall 2 3/2 0.3. C(T) specimens, 50.0 mm wide, with notches parallel to the fibers direction were tested. The initial and |

| |final crack length predictions done by using standardized compliance equations (ASTM) were compared to the physical ones, |

| |showing good agreement. The compliance method seemed to be useful for crack length evaluation when the notch is parallel |

| |to the fibers. |

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|E-O13 |ENVIRONMENTAL EFFECTS ON THE INTERLAMINAR SHEAR STRENGTH OF POLYMERIC COMPOSITES |

| |J. A. P. Cunha1; M. L. Costa2, M. C. Rezende2, 1Departamento de Engenharia Mecânica, ITA/SENAI – 12228-904-S. J. |

| |Campos/SP, Brazil; |

| |2Divisão de Materiais, AMR/IAE/CTA, Praça Mal.do Ar Eduardo Gomes nº 50, Vila das Acácias, 12228-904, S.J. Campos/SP – |

| |Brazil. |

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| |Environmental effects can lead to general reduction of the mechanical properties of polymeric composites due to changing |

| |of their physical and chemical properties. The way in which the composite materials absorb water depends upon many |

| |factors, such as temperature, matrix, fiber volume fraction, reinforcement orientation, fiber nature, area of exposed |

| |surfaces, diffusivity and surface protection. Although the moisture absorption process in epoxy matrix is well known, few |

| |works have been performed to characterize environmental effects (salt spray) on the carbon/epoxy composites. Aircraft and |

| |naval composite parts are exposed to water, salt, fuel and mechanical stresses. These combined effects may cause severe |

| |damage to composite structures. In this work, the influence of environmental effects on the interlaminar shear properties |

| |(ILSS) of carbon tape/epoxy 8552 composites ([0/0]s) have been investigated. The moisture absorption was monitored placing|

| |the samples for a long specified time (until saturation) in a humidity-controlled chamber (80°C and 95% relative humidity |

| |(RH)) and other samples in a salt spray chamber (36°C). It was observed that the samples submitted to the |

| |humidity-controlled chamber (88.1(11.9 MPa) presented a decrease of 9% in the ILSS when compared with specimens |

| |non-conditioned (97.6(5.2MPa). But the specimens submitted to the salt spray chamber (102.4 ( 3.35MPa) presented a small |

| |increase of the ILSS. These results suggest that the temperature cause more damage than the moisture and the salt in the |

| |interlaminar shear properties. |

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|E-O14 |TEM STUDY OF HOT-PRESSED AL2O3-NBC COMPOSITE MATERIAL |

| |W.Acchar1, C.A.A.Cairo2 and A.M.Segadães3 - 1 Departament of Physics |

| |Federal University of Rio Grane do Norte, Natal-RN, Brazil, CEP:59072-970; 2 Divisão de Materiais, Centro Técnico |

| |Aeroespacial, Instituto de Aeronáutica e Espaço, Praça Marechal do Ar Eduardo Gomes 50, São José dos Campos –SP; 3 |

| |Departament of Galss and Ceramics, Univeristy of Aveiro, Portugal. |

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| |Recent studies have been focused on reinforcing alumina with carbides and nitrides in order to improve both room and high |

| |temperature mechanical properties and wear resistance. However, data about the potential use and microstructural aspects |

| |of alumina-NbC is still scarce. In the present work Al2O3-NbC composites were uniaxial hot-pressed and their mechanical |

| |properties and microstructures analyzed. The compositions used in this study were Alumina – x NbC (x = 0,10,20,and 30 |

| |wt.%) and the sintering was performed at 1650 (C/30 min. Hot-pressed resulted in denser specimens ( 99.7 – 99 %TD) with |

| |hardness and fracture toughness comparable to Al2O3-TiC. TEM micrographs have indicated that NbC grains are preferentially|

| |located at grain boundaries, which is an evidence of the “pinning effect” produced by NbC particles. |

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|E-O15 |COMPARATIVE EVALUATION OF PROCESS PARAMETERS ON CORE MOVEMENT ON HONEYCOMB SANDWICH PANELS CURED IN AUTOCLAVE |

| |P. E. Ferrari; L. Matsura – EMBRAER, Av Brigadeiro Faria Lima, 2170 São Paulo, Brazil |

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| |Honeycomb sandwich structures are very susceptible to core movement during autoclave curing. Pressure, temperature, |

| |chamfer angle, face materials and core type are some of the variables responsible to this phenomena. The present work |

| |intends to investigate the influence of the combination of autoclave and inside vacuum bag pressures on core movement. For|

| |so, four specimen were prepared with 30o chamfer angle honeycomb and two layers of fiberglass each face, and cured in |

| |autoclave at 121oC, under autoclave relative pressures of 2.04 atm and 3.06 atm combined with relative pressures in the |

| |vacuum bag of 0 and -0.77 atm. The 2.04 atm autoclave / 0 atm vacuum bag pressure presented a very small movement in the |

| |transversal direction. Both 2.04 atm autoclave / -0.77 atm vacuum bag pressure and 3.06 atm / 0 atm vacuum bag pressure |

| |presented more severe movement being the former in all sides and the latter in just one side, being slightly better than |

| |the former. The 3.06 atm autoclave / -0.77 atm vacuum bag had the worst result, presenting a catastrophic failure of all |

| |sides. |

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|E-O16 |AGING OF STARCH-CHITIN COMPOSITES |

| |C.T. Andrade, R.C.R.S. Rosa - Instituto de Macromoléculas Professora Eloisa Mano, Universidade Federal do Rio de Janeiro, |

| |P.O. Box 68525-970, Rio de Janeiro, Brazil. |

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| |Composite materials were prepared from corn starch (CS) as the matrix and chitin at compositions up to 30% (wt/wt). Chitin|

| |was isolated from shells of adult Penaeus schmitti, after demineralization and deproteinization. Chitin films were milled |

| |and the resulting flakes were in average 1 mm in size. Water and glycerol were used as plasticizers, both at 15% (wt/wt) |

| |concentration, based on starch dry weight. The plasticized CS and CS/CH mixtures were injection molded into ASTM D638-72 |

| |type I specimens approximately 2 mm thick using a BOY 15/42 Petersen Irmãos Machine, provided with three electrically |

| |heating zones, maintained at 130-145oC from feed zone to die end. The specimens were stored at 28oC and 80% relative |

| |humidity for 370 days. During aging, the composites have been submitted to tensile tests, contact angle measurements, and |

| |wide-angle X-ray diffraction analyses. After conditioning for 30 days, the composite samples showed higher values of |

| |Young’s modulus than the unfilled starch matrix. Due to the less hydrophilic character of chitin, the same behavior was |

| |observed for the contact angle values determined for the composites in which the chitin content were less than 30%. The |

| |relative B-type crystallinity was shown to decrease as the chitin content was increased. Conditioning for longer periods |

| |of time revealed that the relative crystallinity continues to increase up to 200 days, when plateau values were reached. |

| |Comparing the results obtained for tensile tests after conditioning for 110 and 370 days, a tenacifying effect was |

| |observed with time, attributed to the increasing interaction between the starch matrix and the reinforcing filler. |

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|E-O17 |A Numerical -experimental approach for Identifying Elastic Parameters in Composite |

| |F. FIGUEIREDO1; M. SILVA1; L. BORGES1; F. ROCHINHA1; S. F. BASTOS2 - 1LMS - SOLID MECHANICS LABORATORY - DEPARTMENT OF |

| |MECHANICAL ENGINEERING, EE/COPPE - FEDERAL UNIVERSITY OF RIO DE JANEIRO-UFRJ - BOX 68503 – 21945-970 - RIO DE JANEIRO, RJ,|

| |BRAZIL; 2 SENAI – CETIQT; DR. MANOEL COTRIM 195, RIACHUELO. RIO DE JANEIRO, RJ, BRAZIL. |

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| |The aim of this work is to present a technique to identify elastic parameters of composite materials. The most |

| |conventional techniques of identification rely on static tests that do not seem to be adequate for non-conventional |

| |materials or structures as, for instance, laminates or any general sort of composites. For those materials, more reliable |

| |and robust identification approaches are required. The herein proposed methodology combines experimental modal analysis |

| |with optimization formulations and shows to be an adequate identification procedure to overcome the aforementioned |

| |troublesome. The present identification approach fits in the so-called model up dating that seeks matching experimental |

| |results to analytical modeling. The first step of the proposed approach consists of submitting a plate to standard modal |

| |tests, from which natural frequencies are obtained. In the second step of the identification process, those experimental |

| |results are compared to their analytical counterparts obtained either from finite element models or by means of the |

| |Rayleigh-Ritz method. Hence an optimization algorithm is used to fit those analytical results in order to yield the |

| |elastic constants of the plate material. In the numerical solution of the optimization problem different techniques were |

| |adopted, including a classical gradient method and two other ones based on heuristic numerical approach: the Downhill |

| |Simplex Algorithm and Genetic Algorithm. The proposed technique is assessed by a number of tests, encompassing different |

| |composites structures. |

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|E-O18 |GROUND RUBBER TIRE AS FILLER FOR ELASTOMERIC COMPOSITIONS |

| |T. A. de O. Bouças1, C.R.G. Furtado1, L.L.Y. Visconte2, R.C.R Nunes2, E.B.A.V. Pacheco2 - 1Instituto de Química/UERJ, Rio |

| |de Janeiro, Brazil; 2 IMA/UFRJ, Rio de Janeiro, Brazil. |

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| |One of the major environmental problems faced nowadays is the disposal of non serviceable tires. The amount of waste |

| |tire, a non-degradable material, is rising continuously. Recycling is the best alternative, and it is already made by |

| |using non serviceable tires as filler for asphalt, fuel for thermoelectric plants, etc. In this work the potential of |

| |ground rubber tire as a filler for butadiene-styrene rubber (SBR) was evaluated. The compositions were prepared in a roll|

| |mill according to ASTM D3182 and then the rheometric properties (ASTM D2084) were determined. After the vulcanization, |

| |the compositions were submitted to mechanical tests, as tensile strength (ASTM D412), tear strength (ASTM D 624) and |

| |hardness (ASTM D2240). The results showed that the addition of ground rubber tire even in large proportions (120 phr), |

| |does not adversely affect the vulcanization characteristics and does not change significantly the mechanical properties |

| |of the compositions, mainly the tear strength. |

| |Acknowledgements : The authors thank CETREINA/SR-1/SR-2/UERJ for financial support and Pneuback for the ground rubber |

| |tire. |

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|E-O19 |CONTROLLED MICROSTRUCTURE MORTAR MATERIALS TO BENEFIT CREEP PROPERTY FOR CIVIL CONSTRUCTION |

| |M. A. Coimbra;M. R. Morelli, Department of Materials Engineering, Federal University of São Carlos, PO BOX 676, São Paulo,|

| |Brazil. |

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| |The purpose of this work was to obtain a controlled microstructure mortar material for use in civil construction by the |

| |addition of two chemical micropore formers (laboratory grade and commercial additives) and two waste inorganic calcined |

| |materials (from different processes) to benefit creep property. The control mortar technique has recently emerged as an |

| |alternative for the construction of good prediction of structure, with satisfactory mechanical strength and |

| |micropore-controlled structure. The evaluation is based on a method that correlates thermal conductivity, additives, |

| |microstructural development and properties, seeking to identify a composition suitable for use in civil construction and |

| |for specific purposes with creep deformation. |

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|E-O20 |Characterization of Different Species of Functionally Graded Bamboo Composite Structures |

| |GHAVAMI, K., PH.D., FASCE.- PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO - RUA MARQUES DE SÃO VICENTE, N° 225, 22453|

| |-900, RIO DE JANEIRO- BRAZIL |

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| |The understanding of the mechanical behaviour of bamboo at micro, meso and micro levels has caught the attention of |

| |engineers, architects and materials researchers due to the bamboo’s potential to be used as a durable construction |

| |material. Bamboo presents many advantages such as lightness, high resistance capacity and cost, besides the fact that it |

| |requires simple and very low cost processing techniques. It is a quick renewable hence ecological natural resource. The |

| |bamboo structure can be generally viewed as a composite material roughly constituted by long and aligned cellulose fibres |

| |embedded in a lignin matrix. Analysing the transversal section of a bamboo culm, one can observe that the fibre |

| |distribution is variable through its thickness. The non-uniform distribution of fibres avoids the direct application of |

| |equations used to model the behaviour of composite materials, as the rule of mix equations for strength and modulus of |

| |elasticity. These equations assume, beside the perfect bonding between fibre and matrix, the uniform distribution of the |

| |fibres in the matrix. In the bamboo, the fibre distribution follows an organized pattern with a higher concentration of |

| |fibres on the outer surface of the culm. Establishing how this variation occurs, the basic equations from the composite |

| |materials approach can be modify in order to model the mechanical behaviour of bamboo.This paper presents the summary of |

| |several research programs carried out on macro, meso, micro and nano analyses of bamboo culms established through |

| |different techniques. The variation of the volume fraction of the cellulose fibres along the transversal section of |

| |different bamboo species has been established and appropriate mathematical equations have been found. The developed |

| |methodology is applied in different samples where the determination of the volume fraction variation was required for |

| |different purposes of the durability analysis of bamboo. |

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|E-O21 |A QUANTITATIVE MODEL OF EGGSHELL GROWTH |

| |P. Jeraldo, J. L. Arias, F. Lund, S. Maeckelberghe and D. Walgraef, Centro para la Investigación Interdisciplinaria |

| |Avanzada en Ciencias de Materiales (CIMAT), Universidad de Chile, Santiago, Chile. |

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| |Eggshells present remarkable properties, either from mechanical and structural point of view. Although its small |

| |thickness, lengthwise compressed eggshell can withstand an extreme amount of force. Eggshells consist of 97% calcium |

| |carbonate and 3% organic matrix, structured as columns of crystalline calcite leaving eight thousand of microscopic pores |

| |among them. It may thus be of practical importance to understand and model eggshell formation. The basic model we |

| |consider has two stages. In the first stage, calcium and carbonate ions are deposited on each mammillae (the nucleation |

| |structures of the eggshell) in the form of columns expanding thickness which eventually meet, and the interaction among |

| |the different growth sites is neglected. This appears to be a good approximation in view of the typical intermammillary |

| |distance of 150 (m and typical mammilla diameter of 30 (m. The second stage is initiated as the columns meet, and the |

| |shell grows as a whole due to two effects: diffusion and surface curvature. These two effects are captured by a |

| |modification of the Kardar-Parisi-Zhang (KPZ) equation, which is a differential equation that gives a local description of|

| |growth. Since eggshell curvature is very small compared to overall size, we believe a local description is adequate. Good |

| |agreement is obtained with observed pore structure as well as with observed surface roughness. |

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|POSTER PRESENTATIONS |

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|E-P1 |MANUFACTURE OF THERMOPLASTIC / CARBON FIBER COMPOSITES BY AQUEOUS SUSPENSION PREPREGGING |

| |L. B. NOHARA1; A. M. KAWAMOTO2; M. WILLS3; M. C. REZENDE4 - 1DEPARTAMENTO DE ENGENHARIA AERONÁUTICA E MECÂNICA – ITA / |

| |CTA, PÇA. MAL.-DO-AR EDUARDO GOMES, 50, SÃO JOSÉ DOS CAMPOS, 12228-904, SÃO PAULO, BRAZIL; 2DIVISÃO DE QUÍMICA / INSTITUTO|

| |DE AERONÁUTICA E ESPAÇO / CTA; 3CHEMISTRY DEPARTMENT, WARWICK UNIVERSITY; 4DIVISÃO DE MATERIAIS / INSTITUTO DE AERONÁUTICA|

| |E ESPAÇO / CTA. |

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| |The manufacture of thermoplastic composites is difficult due to the high melt viscosity values of these matrices, such as |

| |poly (ether ether ketone) (PEEK) and poly (phenylene sulfide) (PPS). The high viscosity causes a poor wettability of the |

| |reinforcement, besides the thermoplastic matrices be soluble in only a few common solvents. Several techniques such as dry|

| |powder prepregging, melt impregnation, and others has been used and modified aiming to minimize these problems. The |

| |aqueous suspension prepregging has been used successfully by many researchers. Suspension prepregging technique involves |

| |the impregnation of reinforcement, i.e., carbon fibers, by contacting them with a suspension of polymer particles, |

| |typically in a drumwinding operation. The aqueous suspension prepregging technique combines the matrix polymer with the |

| |fiber at the same time that the interphase polymer is deposited on the fiber. This technique has been studied by using a |

| |polyimide (PI) precursor - a water soluble polyamic acid (PAA) neutralized with a base, forming the “polyamic acid salt”. |

| |The matrix powder is dispersed in the aqueous PAA salt solution. At this, the PAA salt behaves as a dispersant |

| |electrostatically stabilizing the suspension by interaction with the matrix powder particles. The fiber tow is then coated|

| |with the PAA and the matrix powder in a single prepregging step. After take off the water from the prepreg, a heating |

| |cycle is used to convert the PAA into PI, by reaction of imidization. The aim of the present work is to show this |

| |technique and the results obtained at Divisão de Materiais / IAE / CTA, in the manufacturing of carbon fiber composites by|

| |suspension prepregging with dispersions of PEEK and poly (ether imide) (PEI) particles, with a tailored polyimide |

| |interphase. |

| |Acknowledgements: The authors thank FAPESP |

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|E-P2 |SHEAR STRENGTH OF COMPOSITE/METAL JOINTS BONDED BY EPOXY ADHESIVES |

| |R.C.O.M. Afonso, F.L. Bastian, Laboratory of Composite Materials, COPPE/UFRJ, CP 68505, 21941-972, Rio de Janeiro, Brazil.|

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| |The rehabilitation of pipelines due to damage caused by environmental factors with fast and low cost methods has been a |

| |challenge, mainly because corrosion is a type of defect almost inevitable in pipes. As a consequence, knowing a technology|

| |of pipe repair is very important to reduce costs of hidrocarbon transportation. Many techniques are being developed, among|

| |them, the repair with composite materials that consists in involving the damaged pipe with the composite material. The |

| |characterization of the adhesion and the study of techniques to maximize it are of great scientific and technologic |

| |interest, because the efficiency of the repair will depend on the good adhesion of the composite material of the repair on|

| |the steel. The aim of this work is to study the adhesiveness of a composite material used in pipeline repair on a steel |

| |substrate. Hence, metal-composite adhesive joints are being manufactured with different mechanical surface treatments with|

| |the dimensions recommended by the ASTM D 5868-01 standard, having different adhesive thicknesses. The fracture surfaces |

| |were analyzed by electron scanning microscopy and classified according to the ASTM D 5573-94 standard. Specimens with the |

| |best surface treatments were submitted to hygrothermal ageing to evaluate the influence of the water on the mechanical |

| |properties of the joints. The fracture failure modes of the adhesive system were associated with the mechanical properties|

| |obtained in the adhesion tests. |

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|E-P3 |MECHANICAL PROPERTIES OF PU/HESSIAN CLOTH COMPOSITES AS A FUNCTION OF THERMAL AND HYGROTHERMAL AGEING |

| |M.C.B. Costa & L.H. de Carvalho, DEMa/CCT/UFCG, Caixa Postal 10034, CEP 59109-970, Campina Grande, PB, Brazil. |

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| |The industrial application of composite materials is growing steadily. The reasons for this growth include primarily cost,|

| |performance and weight considerations as well as the fact that their properties can be tailor-made to fulfill different |

| |operational requirements. Ecological concerns and the quest for the development of new materials and processes less |

| |harmful to the environment have prompted the development of vegetable fiber reinforced polymer composites. Thermoset, |

| |thermoplastic and elastomer have been used as polymeric matrices. The properties of these composites are deleteriously |

| |affected by the relatively low thermal stability and the hygroscopic nature of lignocellulosic fibers. Therefore, for |

| |practical applications, studies on the effects of ageing on the properties of these materials must be undertaken. In the |

| |present work the mechanical properties as well as weight and volume changes of polyurethane/hessian cloth composites were |

| |investigated as a function of fiber content and ageing (thermal and hygrothermal) conditions. The matrix employed was an |

| |elastomeric polyurethane derived from castor oil and provided by Proquinor S.A. The results indicate that modulus and |

| |tensile strength significantly increase with fiber content and decrease with hygrothermal exposure. The tensile strength |

| |of thermal aged samples decreased in the initial stages and leveled off at longer times while the modulus increased with |

| |fiber content and exposure time. Hygrothermal aged samples exhibited significant increases in both their weight and volume|

| |with exposure time and fiber content. The thermal aged samples presented a decrease in weight while the volume remained |

| |unchanged. The extension of weight decrease was dependent on the fiber content and exposure times. |

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|E-P4 |APPLICATION OF THE LUMINESCENCE SPECTROSCOPY TO STUDY OF CURE PROCESS OF DIGLYCIDYL-ETHER OF BISPHENOL-A (DGEBA) |

| |R. C. M. SALES, D. DIBBERN BRUNELLI; DEPARTAMENTO DE QUÍMICA, INSTITUTO TECNOLÓGICO DE AERONÁUTICA, PRAÇA MARECHAL |

| |EDUARDO GOMES, 50, VILA DAS ACÁCIAS, CEP 12228-900, SÃO JOSÉ DOS CAMPOS, SP, BRAZIL. |

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| |This paper investigates the curing degree of the epoxy resin DGEBA (diglycidyl-ether of bisphenol-A) using the curing |

| |agents DDM (4,4’-diaminodiphenylmethane) and DDS (4,4’-diaminodiphenylsulfone) through the spectroscopy of luminescence |

| |under steady-state conditions. They were used two fluorescence methods: (a) intrinsic of the DGEBA and (b) extrinsic of |

| |the luminescent probe 9-AA (9-anthroic acid). The stoichiometric mixtures of the resin and the curing agents before cure |

| |reaction did not emit. In order to observe the DGEBA emission before the cure process, it was prepared solutions of DGEBA|

| |in n-butanol. The DGEBA emission spectrum of showed the wavelenght of the fluorescence maximum at 313 nm. The |

| |polymerization thermal process used of epoxy resin, using DDM and DDS, containing or not the probe 9-AA, was made by 2h |

| |and 120°C (5°C/min). It was observed that wavelength of the fluorescence maximum of the epoxy resin presented a red shift,|

| |due to the reaction of curing agents with epoxy resins, which converts primary amine group to secondary or tertiary |

| |groups. However, the cure of the resin with DDS is more effective, in relation to the cure with DDM, since the emission |

| |maximum of DGEBA was shifted to 393nm and 356nm, respectively. In relation to the extrinsic fluorescence method, it was |

| |verified that the local concentration of 9-AA increases during the cure process of the epoxy resin, resulting in a red |

| |shift of the wavelength of the fluorescence maximum. This red shift indicates the formation of hydrogen-bonded dimers, |

| |which present a broad structureless band at 486 nm. Therefore, it can conclude that both methods of fluorescence are |

| |useful to study the cure reaction in epoxy resin. |

| |Acknowledgments: FAPESP (2000/03186-8) and CAPES. |

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|E-P5 |NATURAL RUBBER AND CARBON BLACK COMPOSITES CHARACTERIZED WITH PRESSURE SENSORS |

| |F.A. Oliveria; N. Alves; C.J.L.Constantino; J.A. Giacometti; A.E. Job - Depto. de Física, Química e Biologia, FCT-UNESP, |

| |CP. 467, 19060-900, Presidente Prudente, SP, Brazil. |

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| |Composites of natural rubber and carbon black have attracted great interest due to their technological applications. This |

| |work shows the method of preparation of the composites obtained by the mixture of natural rubber (NR) and carbon black |

| |(CB) in different %, aimed at the development of composites with suitable mechanical properties, processability and |

| |electrical conductivity for using in pressure sensor applications. It is also presented the characterization of the |

| |composites through optical microscopy (MO), stress-strain test and thermal behavior using differential scanning |

| |calorimetry (DSC), thermal dynamic mechanical analysis (DMTA) and analysis thermogravimetry (TGA). The electrical |

| |conductivity changed from 10-11 to 10-2 S.cm-1 depending on the percentage of carbon black in the composite. Besides, it |

| |was observed that the conductivity varies reversibly and linearly with the applied pressure between 0 to 1.6 MPa with the |

| |sample 80/20 (NR/CB wt%) presenting the most appropriated thermo-mechanical and electrical properties to be used as |

| |pressure sensor. |

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|E-P6 |DEGRADATION OF PP/BENTONITE NANOCOMPOSITES: THE INFLUENCE OF CLAY CONTENT AND CHEMICAL MODIFICATION |

| |J.B.A. DA SILVA, J.C. MACEDO, S.M.L. SILVA, L.H. DE CARVALHO, DEMA/CCT/UFCG, CAIXA POSTAL 10034, CEP 58109-970, CAMPINA |

| |GRANDE, PB, BRAZIL. |

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| |There is a growing interest in the study of polymer-clay nanocomposites as a new class of materials display improved |

| |properties at very low loading levels (1-5 wt%) if compared with conventional composites. The ions present in the outer |

| |layers of many clays and clay-minerals may be exchanged and these clays may be chemically modified with a variety of |

| |salts. These ions may also affect the stability of the polymer matrix in which the clays are incorporated. In the present|

| |work the properties of PP/bentonite clays are reported as a function of clay content and chemical modification. The clays |

| |were modified with a quaternary ammonium salt and composites with clay contents of 1 and 3% w/w were obtained by melt of |

| |materials. The results show the mechanical properties of every composite under investigation to increase with clay |

| |incorporation and, surprising, this increase was greater for the composites prepared with the untreated clay. Probably, |

| |the lower properties obtained for the organophilic clay reinforced composites may be associated with the degradation of |

| |the matrix or the organophilic clay. The results show the MFI values of the composites reinforced by the organophilic clay|

| |to be higher, and their decomposition temperature (DSC) to be lower than those obtained with the unmodified clay |

| |composites at every concentration analyzed. The degradation was more evident for the composites with higher filler content|

| |and with the chemically modified filler. |

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|E-P7 |Water sorption of jute and jute/glass fiber fabric unsaturated polyester composites |

| |W.S. CAVALCANTI, CDEP/CCT/UFCG; L.H. DE CARVALHO; DEMA/CCT/UFCG, CAIXA POSTAL 10034, CEP 58109-970, CAMPINA GRANDE, PB, |

| |BRAZIL. |

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| |Studies have shown that vegetable fibers can be used as reinforcement in polymer composites due to their lightweight and |

| |good set of mechanical properties. These fibers, however, are hygroscopic and have poor adhesion with most polymer |

| |matrices, which deleteriou7sly affects the composites´ short and long term properties. Fiber modification and |

| |hybridization are among the most popular strategies employed to improve the performance of vegetable fiber reinforced |

| |composites. The use of hybrid vegetable/synthetic fillers can be advantageous for the development of new composite |

| |materials with improved performance. In the present work the water sorption characteristics of compression molded |

| |unsaturated polyester composites was investigated as a function of fabric composition and jute fiber content. Composites |

| |with up to 58% w/w total fiber content were investigated. A jute cloth and a hybrid jute-glass plain hand-weaved cloth |

| |(44%jute/56% glass) were used as reinforcement. For the jute cloth reinforced composites, up to 15% water sorption was |

| |observed for the composite with 50% jute content. As expected, lower water sorption values were obtained for the hybrid |

| |cloth reinforced composites (9% water sorption for the composites with 58% total fiber content, i.e., 26% jute/32% glass) |

| |and this behavior was attributed to the hydrophobic nature of the glass fibers. The amount of water absorbed by composites|

| |with similar jute contents was nearly equivalent, which indicates, in every case under investigation, that the water |

| |sorption of the composites was dominated by and to increase with jute fiber content. |

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|E-P8 |BIOGENIC SILICA MICROFIBERS / SILICONE COMPOSITE |

| |V. P. e Silva; I. V. P. Yoshida; M. do C. Gonçalves; M. Rodrigues - Instituto de Química da UNICAMP, Caixa Postal 6154, |

| |13083-970, Campinas/SP, Brazil. |

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| |Silicone polymers, specially high molecular weight poly(dimethylsiloxane), PDMS, exhibit some properties that make them |

| |suitable for use in rubbers. However, unlike other rubber polymers, unfilled silicone gums achieve only low mechanical |

| |strengths when cured. Appropriated strengths are only obtained by incorporating suitable reinforcing fillers. This work |

| |focuses on the processing and characterization of PDMS gum (~106g/mol) reinforced with biogenic silica microfibers. |

| |These microfibers represent the inorganic constituent of the internal supporting structure of sponges. They are abundant |

| |in some regions in Brazil and they have potencial applications as reinforcement fillers in polymeric matrixes. The |

| |composite was prepared by using 20phr (parts per hundred parts of rubber) of microfibers and 0,65phr of peroxide. |

| |Compounding was carried out on a two-roll mill and the compounds were cured by compression molding, with post cure |

| |treatment. Characterization was performed by Thermogravimetric Analysis (TGA), Differencial Scanning Calorimetry (DSC), |

| |Dynamic Mechanical Analysis (DMA) and Field Emission Scanning Electron Microscopy (FESEM). |

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|E-P9 |FRACTURE TOUGHNESS EVALUATION OF COMPOSITE MATERIALS FOR PIPELINE REPAIR USING SCWHALBE’S CTOD ((5) |

| |J.M.R. Touça; E.M. Castrodeza; F.L. Bastian - Laboratory of Composite Materials, COPPE/UFRJ, CP 68505, 21941-972, Rio de |

| |Janeiro, Brazil. |

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| |Recently much work has been done on the development of glass fiber reinforced polymer matrix composites for repairing |

| |damaged pipelines. On the other hand, little has been done to characterize the fracture resistance of these materials. |

| |Information about their fracture toughness is of great interest for structural integrity evaluation at the project stage |

| |and/or for residual resistance analysis in service. The objective of this work was to study the applicability of a new |

| |methodology for CTOD evaluation (Schwalbe’s CTOD, named (5) on this type of composites. The preliminary results showed |

| |that the Schwalbe’s CTOD methodology was useful for fracture toughness evaluation, being very attractive because it does |

| |not depend on mathematical models and can be easily applied to different specimens geometries. |

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|E-P10 |PREPARATION OF THE POLYESTER NONWOVEN COMPOSITE IMPREGNATED WITH POLYANILINE TO BE USED AS RAM |

| |L.C.FOLGUERAS1, R. FAEZ2; M.C. REZENDE3 - 1INSTITUTO TECNOLÓGICO DE AERONÁUTICA / CTA, PÇA. MARECHAL-DO-AR EDUARDO GOMES, |

| |50 – CEP: 12228-904 - S.J. CAMPOS - SP, BRAZIL; 2IP&D / UNIVAP, S.J. CAMPOS – SP, BRAZIL; 3AMR/IAE/CTA, S.J. CAMPOS, |

| |BRAZIL. |

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| |Conducting polymers have been extensively studied and applied in the electromagnetic shielding and the electrostatic |

| |discharge protection areas. Considering these applications the Radar Absorbing Materials (RAM), based on conducting |

| |polymers, have shown good results due to its low cost process and also its low density. This characteristic makes easier |

| |the transportation and the application of RAM on complex artifacts. In this work it was investigated the RAM processing by|

| |using polyester nonwoven substrate to support the polyaniline (PAni) conducting polymer attending the microwave frequency |

| |range of 8-12 GHz. This study aims to combine the flexibility of the polymeric substrate with the electrical conductivity |

| |of the polyaniline as a microwave absorber composite. PAni impregnation into the polyester nonwoven support was carried |

| |out by polymerization “in situ”. Due to the low compatibility of the substrate fibers with the PAni, a previous |

| |superficial treatment of the polyester substrate was performed in an oxidant liquid phase (chloridric acid solution) at |

| |different period times aiming to increase the mechanical anchorage of the polyaniline on the substrate. Scanning electron |

| |microscopy analysis showed that the acid treatment increased the adhesion of the conducting polymer on the polyester |

| |substrate making easier its handle. Reflectivity measurements using waveguide method (8-12 GHz) showed that the processed |

| |RAM attenuated the incident electromagnetic wave in approximately 90%. |

| |Acknowledgements: The authors thank FAPESP |

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|E-P11 |CHEMISTRY COMPOSITION OF MICROSTRUCTURE OF SYSTEM SnO2-ZnO-WO3 |

| |U. Coleto Jr., J. A. Varela, Y. R. P. Maniette, L. Perazolli. Instituto de Química-UNESP, Lab. LIEC, PO Box 355, ZIP |

| |14801-060, Araraquara, Brazil. |

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| |Ceramics in tin oxide base doped zinc and tungsten oxides, with concentratin between 0,05 and 2 mole% have great |

| |application as devices of high chemistry resistence and behavior varistor. The powders were obtained by conventional |

| |method of oxides mixture in ball mill, conformed in cylindrical cast, isostatically pressed and sintered in tubular |

| |furnace. The ternary system show high densification ((>95%), average grain size 5(m, and high electrical resistence. The |

| |studied system have ohmic character, which may be changed by doping with a increasing conductivity agent. The samples |

| |were characterized by MET-EDS, and the chemistry composition of the microstructure was observed the in grains, grains |

| |boundaries, triple points and precipitates. The tungsten is seem in grain boundaries and precipitates increasing the |

| |resistivity. |

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|E-P12 |Alkali treatment Effect on the Mechanical Properties of Polyurethane/Sisal Composites. |

| |S. F. M. Silva, L. H. de Carvalho, DEMa/CCT/UFCG,Caixa Postal 10034, CEP 58109-970, Campina Grande, PB, Brazil. |

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| |In this work the tensile properties of polyurethane/sisal composites were investigated as a function of fiber content and |

| |chemical modification. A castor oil derived polyurethane was used as the matrix and long aligned sisal fibers were used as|

| |the reinforcement. The castor oil derived polyol and isocyanate prepolymers were both dried in a vacuum oven for one hour |

| |at 90ºC before molding. The sisal fibers, alkali modified or not, were washed with running water and dried in an air |

| |circulating oven at 80ºC before use. Compression molded plates (150 x 200 x 3mm) were obtained and tensile samples (110 x |

| |13 x 3mm) obtained from these plates and tested according to ASTM D3039 on a Lloyd LR-10KN universal testing apparatus |

| |operating at 5 mm/min with a 10KN load cell. The results show the composite properties to increase with fiber content up |

| |to 40% w/w. The alkaline treatment caused a reduction in fiber strength and an increase in adhesion. The properties of |

| |alkali treated composites were depended on both two conditions, but the fiber content is prevailed. Best overall results |

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|E-P13 |RADAR ABSORBING MATERIALS (8-12 GHz) BASED ON RUBBER SILICONE AND NiZn FERRITE COMPOSITES |

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| |J.M.R.P.,GONÇALVES1; J.C.N. DUTRA2; I. M., MARTIN3; E. L., NOHARA4; M. C. REZENDE1 - 1DIVISÃO DE MATERIAIS / INSTITUTO DE|

| |AERONÁUTICA E ESPAÇO / CTA, PÇA. MAL.-DO-AR EDUARDO GOMES, 50, SÃO JOSÉ DOS CAMPOS, 12228-904, SÃO PAULO, BRAZIL; 2DIVISÃO|

| |DE QUÍMICA / INSTITUTO DE AERONÁUTICA E ESPAÇO / CTA; 3DEPARTAMENTO DE MATEMÁTICA E FÍSICA – UNIVERSIDADE DE TAUBATÉ / |

| |UNITAU; 4DEPARTAMENTO DE ENGENHARIA MECÂNICA – UNIVERSIDADE DE TAUBATÉ / UNITAU. |

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| |Radar Absorbing Materials (RAM) present chemical and physical characteristics that favor the conversion of the incident |

| |electromagnetic wave energy in thermal energy. Nowadays these materials are been used in space, aeronautical, |

| |telecommunication and medical fields, in applications that require the electromagnetic radiation level control. This work |

| |shows the study of RAM processing parameters, obtained by the adequate combination of silicon rubber sheet crosslinked |

| |with peroxide, filled with NiZn ferrite, as absorption centers of the electromagnetic wave. The RAM sheets were obtained |

| |by mixing the silicon matrix and the ferrite between two rolls and cured at 175ºC. The matrix rheological behavior and the|

| |curing properties were evaluated by rheological analysis (Monsanto-100 S Rheometer). The RAM sheets were also |

| |characterized by tensile strength tests, thermal behavior (Differential Scanning Calorimetry and Thermogravimetric |

| |Analysis), morphological (Scanning Electron Microscopy) and microwave attenuation by using the waveguide method. The final|

| |properties of the obtained RAM show the excellent potential for application in different areas, emphasizing its microwave |

| |absorption equal to -22 dB (99,3%) at 10 GHz. |

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|E-P14 |FRACTOGRAPHIC ANALYSIS OF STRUCTURAL POLYMERIC COMPOSITES IN TENSILE TEST |

| |L. A. L. FRANCO1;G. M. CÂNDIDO2; M. C. REZENDE1 - 1CENTRO TÉCNICO AEROESPACIAL/INSTITUTO DE AERONÁUTICA E ESPAÇO/DIVISÃO |

| |DE MATERIAIS; 2CENTRO TÉCNICO AEROESPACIAL/INSTITUTO DE FOMENTO INDUSTRIAL. PRAÇA MARECHAL-DO-AR EDUARDO GOMES, 50,VILA |

| |DAS ACÁCIAS - CEP 12228-904 SÃO JOSÉ DOS CAMPOS - SP – BRASIL. |

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| |The use of polymeric composite materials in the aerospace area is growing. At the same time there is also an increase of |

| |the probability of failure occurrence in service of components manufactured in polymeric composites. The failure analysis |

| |of composite material is an important subject to support the prevention and investigation area of aeronautical accidents. |

| |This work aims to characterize fractures of carbon fabric laminates impregnated with F155 and F584 epoxy resin systems and|

| |aramid and glass fabric laminates impregnated with F155 and F161 epoxy systems obtained in tensile test conditions. |

| |Scanning electron microscopy, optical microscopy and stereoscopy are used to analyze the fractured specimens. Comparing |

| |the fracture surfaces of the specimens it is observed that the aramid laminates present more significant differences. The |

| |type and the arrangement of the reinforcements also affect the fracture behavior of the laminates mechanically tested. |

| |Concepts like DAFF and the analysis of resin features, like scarps and river marks, can be applied allowing determining |

| |the failure steps of the fracture. |

| |ACKNOWLEDGEMENTS: THE AUTHORS THANK FAPESP |

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|E-P15 |FRACTOGRAPHIC ANALYSIS OF STRUCTURAL POLYMERIC COMPOSITES IN COMPRESSION |

| |L. A. L. FRANCO1;G. M. CÂNDIDO2; M. C. REZENDE1 - 1CENTRO TÉCNICO AEROESPACIAL/INSTITUTO DE AERONÁUTICA E ESPAÇO/DIVISÃO |

| |DE MATERIAIS; 2CENTRO TÉCNICO AEROESPACIAL/INSTITUTO DE FOMENTO INDUSTRIAL. PRAÇA MARECHAL-DO-AR EDUARDO GOMES, 50,VILA |

| |DAS ACÁCIAS - CEP 12228-904 SÃO JOSÉ DOS CAMPOS - SP – BRASIL. |

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| |The use of polymeric composite materials in the manufacture of aircraft is growing. At the same time there is also an |

| |increase of the probability of occurrence of failure in service of components made with this kind material. The failure |

| |analysis of composite material is a subject little studied, mainly in Brazil, although it is important to support the |

| |prevention and investigation of aeronautical accidents. This work aims to characterize fractures of carbon fabric |

| |laminates impregnated with F155 and F584 epoxy resin systems in compression conditions. Aramid and glass fabric laminates |

| |impregnated with F155 and F161 epoxy systems, respectively, were also investigated, analyzing the fractures obtained under|

| |compression. Scanning electron microscopy, optical microscopy and stereoscopy are used to analyze the mechanically |

| |fractured specimens. Comparing the specimens fractured under the same mechanical test, it is observed that the fibers with|

| |lower modulus present more significant differences on the fracture surface. The type and the arrangement of the |

| |reinforcements also affect the fracture behavior of the laminates mechanically tested. The fracture mode changes from |

| |microbuckling for the lower modulus fiber laminate, to delamination for the carbon fiber laminates. Some interesting |

| |aspects like the quantities of resin that stay bonded to the fiber surface are also analyzed. |

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|E-P16 |HYGROTHERMAL EFFECTS ON THE TENSILE MODULUS OF CARBON FIBER/EPOXY COMPOSITES |

| |E. C. BOTELHO, M. L. COSTA, M.C. REZENDE, L. C. PARDINI - DIVISÃO DE MATERIAIS – INSTITUTO DE AERONÁUTICA E ESPAÇO – CTA;|

| |CEP: 12228-904 – SÃO JOSÉ DOS CAMPOS – SÃO PAULO – BRAZIL. |

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| |The environmental factors can limit the applications of composites by deteriorating the mechanical properties over a |

| |period of time. The degradation of composites due to the chemical and/or physical damages caused in the polymer matrix, |

| |loss of adhesion of fiber/resin interface, and/or reduction of fiber strength can be monitored by tensile and shear tests.|

| |In this work, the influence of moisture in tensile and shear properties of carbon tape/epoxy composites (laminates [0/0]s,|

| |[+45/-45]s and [0/90]s) have been investigated. The interlaminar shear strength (ILSS) has been determined using short |

| |beam shear test. The tensile modulus values found by the non-conditioned specimens in [0/0]s, [+45/-45]s and [0/90]s were:|

| |128.6; 67.4 and 11.6 GPa and by conditioned specimens were: 113.8; 64.1 and 10.2 GPa, respectively. It was observed that |

| |the samples submitted to the environmental conditions presented a decrease of 13%, 5% and 14% in the tensile modulus when |

| |compared with specimens non-conditioned in [0/0]s, [+45/-45]s and [0/90]s, respectively The same behavior has been found |

| |during the short beam shear test. According with the ILSS results, the interlaminar shear strength values for carbon/epoxy|

| |composites presented a decrease of 21%, 18% and 20% for [0/0]s, [0/90]s and [+45/-45]s, respectively, in relation to their|

| |non-conditioned counterparts. |

| |Acknowledgements: FAPESP and EMBRAER |

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|E-P17 |HYGROTHERMAL AGEING INFLUENCE ON FRACTURE TOUGHNESS OF ARALL 2 3/2 FIBER-METAL LAMINATE |

| |G.Q. CHAVES1, E.M. CASTRODEZA2, F.L. BASTIAN2 - 1MATERIALS GROUP, IPD, AV. DAS AMÉRICAS, CP 23020, 28705, RIO DE JANEIRO, |

| |BRAZIL; 2LABORATORY OF COMPOSITE MATERIALS, COPPE/UFRJ, CP 68505, 21941-972, RIO DE JANEIRO, BRAZIL. |

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| |Fiber-metal laminates (FMLs) are structural composites designed aiming to produce a damage-tolerant and high strength |

| |material. Their application in aeronautical structures demand a deep knowledge of a wide set of mechanical properties and |

| |technological values, including fracture toughness after environmental ageing. The objective of the present work was to |

| |evaluate the hygrothermal ageing influence on critical toughness values (JC and δ5C) of unidirectional Arall 2 3/2 |

| |laminate. The material was exposed to 70( C and 85% RH up to 2025 hours in an environmental chamber. The fracture |

| |toughness was evaluated using small C(T) specimens (W = 50,0 mm) having notches transversally oriented to the fibers |

| |direction, following a recently proposed experimental methodology developed for this kind of composites. The results were |

| |compared to the ones of specimens without environmental influence. For the ageing times studied the results showed that |

| |there were not statistical differences in overall fracture toughness, whereas for intermediary times the toughness |

| |decreased. |

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|E-P18 |CVD DIAMOND FILMS GROWTH ON SiC-SiC CONVERTED COMPOSITE |

| |C. A. A. Cairo; M. Florian, M. L. A. Graça, N. G. Ferreira, Divisão de Materiais – Instituto de Aeronáutica e Espaço – |

| |Centro Técnico Aeroespacial - CEP: 12228-904 – São José dos Campos – São Paulo – Brazil. |

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| |Diamond film coating SiC/SiC composites offer excellent potential for wastewater treatments electrode due to your |

| |properties like good chemical stability and high specific area. The composite was completely CVR-converted from |

| |carbon-carbon composite. CVD diamond films were grown by hot-filament-assisted CVD technique at 1100 K from a 0.5% H2/CH4 |

| |mixture at a total pressure of 6.5 x 103 Pa. The films were deposited during 6 hours on SiC-SiC composite substrate, |

| |obtained from carbon-carbon composite by conversion reactions with reactive gaseous at high temperature, after seeding |

| |pre-treatment using 0.25 (m diamond powder by ultrasound dispersion in hexane . Sample was kept in the vertical position |

| |inside the reactor between two pairs of parallel tungsten filaments, which permitted the film growth on both sides. Top |

| |view and cross section images of diamond films were obtained by scanning electron microscopy (SEM) by using Leo 435 vpi |

| |microscope. The nucleation and coalescence of the diamond film around the fibers was evident. The grains are faceted with |

| |symmetrical and smooth faces with uniform texture that show a surface morphology with (111) and (100) orientations. Using|

| |a Renishaw microscopic system 2000, micro-Raman spectra were recorded in backscattering configuration at room temperature |

| |employing the argon-ion laser excitation line (514.5 nm). |

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|E-P19 |ELECTROSTATIC DEPOSITION OF NANOFIBERS FOR SENSOR APPLICATION |

| |A. N. R. da Silva1,2,3, I. Ramos1, R. Furlan1, J. J. Santiago-Avilés1 – 1University of Puerto Rico at Humacao, Puerto Rico|

| |USA; 2 LSI – EPUSP, São Paulo, Brazil; 3 FATEC-SP, Brazil |

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| |This work presents the characterization of an electrospinning process in order to obtain fibers in the nanometric range. |

| |The objective is the incorporation of carbon particles into the fibers, in order to facilitate/improve the crystallization|

| |thermal process, performed after deposition. These nanofibers can be used, for example as chemical sensors and |

| |interconnection in electronic circuits. The electrospinning process was conducted in a homemade setup that contains a DC |

| |high voltage power supply, a 3 ml syringe, and a copper plate electrode. The polymer fibers was collected over a 1.0 cm x |

| |1.0 cm silicon sample placed over the copper plate which is placed 15 cm from the tip. The potential difference between |

| |the tip and the grounded screen was 15 KV. The precursor solutions consist of polyacrylonitrile (PAN) and a solvent, |

| |dimethylformamide (DMF), blended with an aqueous based colloidal dispersion of micro graphite particles. It was observed |

| |that the solution viscosity decreases as more carbon is added to the solution. Also the current during the electrospinning|

| |process increases with the carbon concentration. These results suggest that the carbon concentration modifies the solution|

| |behavior during the electrospinning. SEM analyses revealed that the carbon particles are incorporated into the fibers, but|

| |there is no correlation between the carbon concentration in the solution and the presence o carbon in the fibers. It is |

| |also observed by SEM that the fibers with carbon show an irregular shape. FTIRS and Raman analysis confirms the presence |

| |of carbon inside the fibers. This work was supported by NSF-DMR-9872689 and NSF-SBE-0123654. |

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|E-P20 |conductive blEnd based on Epichlomer-C Rubber and polyanyline: An ELECTRODE FOR CAPACITORS |

| |M. A. Soto-Oviedo; V. C. Nogueira; C. Longo; O. A. Araujo; M.-A. De Paoli - Laboratório de Polímeros Condutores e |

| |Reciclagem, Instituto de Química, Unicamp. C. Postal 6154, 13083-971. Campinas, SP, Brazil. |

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| |The conductivity and mechanical properties of electrically conductive binary polymer blends for application as electrodes |

| |in capacitors were investigated, searching for an optimal electronic-ionic conductivity balance. Blends were prepared in a|

| |Haake Rheocord 90 rheometer coupled with an internal mixer using different ratios of the elastomer poly |

| |(epichlorohydrin-co-ethylene oxide), Epichlomer-C, and polyaniline doped with dodecyl benzene sulfonic acid (PAni-DBSA), |

| |obtained by chemical oxidative polymerization of anilium-DBS complex in aqueous dispersion. The blends show mechanical |

| |properties different from Epichomer-C and electrical conductivity between 10-7 and 10-6 S cm-1 with percolation threshold |

| |at low PAni-DBSA concentration (below 10 wt. %). Cyclic voltammetry and chronopotentiometry studies were performed for a |

| |cell consisting of films of the blends of Epichlomer-C with 30, 40 and 50 % (w/w) of PAni-DBSA as electrodes and a polymer|

| |electrolyte. A good cycling stability was observed, indicating that the ion insertion and extraction processes were |

| |reversible. The results obtained show that these blends are suitable for use as an electrode in high cycle life |

| |electrochemical devices, specifically capacitors. Fapesp,Capes, UEG. |

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|E-P21 |NANOCOMPOSITES EVOLVING TRANSPARENT POROUS GLASS AND CADMIUM SULFIDE |

| |R. Romano; O.L. Alves - Laboratório de Química do Estado Sólido – LQES/IQ – UNICAMP, Campinas, SP, Brazil. |

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| |The objective of this work was the preparation of transparent glasses impregnated with nanosized cadmium sulfide. Porous |

| |Vycor Glass (PVG) cod. 7930 was used as a transparent vitreous matrix. This glass was obtained from Corning Glass (USA) |

| |and is characterized by an appreciable transparency to visible spectrum and an interconnected network of nanoporous |

| |showing diameters ranging from 4 to 20 nm. Used as a kind of nano-reactors, these pores constitute a suitable environment |

| |for the stabilization of semiconductor nanocrystals showing quantum confinement effects. The source of cadmium and sulfur |

| |was a single-source molecule, cadmium (II) diethyl-dithiocarbamate, whose thermal decomposition leads to the respective |

| |sulfide. Initially, an adsorption kinetics curve of impregnation of the precursor in PVG was taken. From this curve, |

| |several periods of impregnation were chosen in order to control the quantity of precursor inside the pores. After then, |

| |the glasses were submitted to thermal treatment at 250 oC. The resultant nanocomposites maintained good transparency to |

| |visible spectrum and showed absorption band gaps ranging from 2.7 to 2.4 eV. Techniques like XRD, UV-Vis and FTIR |

| |spectroscopies were used in the characterization of the nanocomposites. [This is a contribution of Millennium Institute of|

| |Complex Materials] |

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|E-P22 |CHANGES IN PLASTER MICROSTRUCTURE BY ADDING GYPSUM: MECHANICAL PROPERTIES STUDIES |

| |R.D. PINHO, J.P. SOARES, E.V.A. OLIVEIRA, A.H. SHINOHARA, LABORATÓRIO DE TECNOLOGIA DO GESSO, DEMEC-CTG-UFPE, AV. ACAD. |

| |HÉLIO RAMOS, S/N, CDU, RECIFE-PE, BRAZIL; M.O.E. SCHWARTZ, CA-DQF-CCEN-UFPE, RECIFE-PE, BRAZIL; A.C. INOJOSA, J. INOJOSA |

| |FILHO, SUPERGESSO S.A. IND. E COM., BR316, ARARIPINA-PE, BRAZIL. |

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| |Plaster is a brittle material, which possess a good compression strength but poor flexural strength and impact resistence.|

| |It is known that the mechanical characteristics of the set plaster strongly depend on several factors such as nature of |

| |initial materials ((- and (-hemihydrate) and the preparation process: consistency (water/dry material mass ratio), and |

| |the presence of additives. To improve the mechanical properties of the set plaster, particulates, fibers and additives are|

| |added. In this work, evaluations of the mechanical properties were conducted on set plaster prepared from (- and |

| |(-hemihydrates with the addition of different amount of gypsum powder. A total of 280 samples of set plaster blocks were|

| |prepared adding powdered gypsum up to 70% in mass. The consistency varied from 0.4 to 0.75. The compression and flexural |

| |tests were conducted and correlated with density measurements. As result, the compressive strength varied from 1 MPa to to|

| |9 MPa. The flexural strengh varied from 0.5 MPa to 5 MPa. The density values varied from 0.84 g/cm3 to 1.19 g/cm3. |

| |Microtructural investigations were also performed and will be discussed in detail. |

| |Acknowledgements: FVA/FINEP, FACEPE, CNPq. |

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|E-P23 |FATIGUE BEHAVIOR OF INDUSTRIALLY MANUFACTURED LAMINATE COMPOSITES |

| |R. C. S. FREIRE JR1; E. M. F. DE AQUINO2 - 1 UFRN – CCET – PDCEM, CAMPUS UNIVERSITÁRIO – LAGOA NOVA, NATAL, RN, BRASIL |

| |CEP: 59072-970; 2 UFRN-DEM/PPGEM - CENTRO DE TECNOLOGIA, CAMPUS UNIVERSITÁRIO - LAGOA NOVA, NATAL - RN - CEP: 59072 – 970.|

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| |The objective of the present work was to analyze the fatigue resistance and to propose actions to prevent fatigue failure |

| |of industrially manufactured composite laminates used in the production of coal reservoirs. These materials are made of |

| |polyester resin reinforced with E-glass fibers. Two stacking sequences consisted of mats and (bi-direction) woven fabric |

| |textile were studied. Preliminary tests were carried out to evaluate density and calcination. Tensile and compressive |

| |mechanical tests were also performed. Next, the fatigue behavior of the composites was investigated. Tensile (R=0.1), |

| |compressive (R=10), and alternate axial fatigue (R=–1) tests were carried out varying the maximum tensile stress. The |

| |results were used to plot S-N curves as well as to propose Modified Goodman Diagrams for failure prevention. The study |

| |revealed the effect of different processing parameters on the fatigue behavior of laminates. |

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|E-P24 |The influence of filler drying temperature on the mechanical properties of Polyurethane/clay nanocomposites |

| |M. R. O. PINTO1; S. M. L. SILVA2, A. C. F. M. COSTA2, L. H. DE CARVALHO2, 1DEQ/CCT/UEPB, CAMPINA GRANDE, PB, BRAZIL; |

| |2DEMA/CCT/UFPB – C. POSTAL 10034 CEP 58109-970, CAMPINA GRANDE,PB, BRAZIL. |

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| |Polymer nanocomposites are a new class of materials in which inorganic substances of nanometric dimensions such as clays |

| |and other minerals are finely dispersed in a polymer matrix. One of the most promising systems is a hybrid based on |

| |organic polymers and layered silicate clay minerals. There is a growing interest in studying philosilicate nanocomposites |

| |as these materials display enhanced properties and broaden the application scope of many traditional polymers. |

| |Philosilicates can be made hydrophobic and the distance between their layers may be increased by organophilization. In |

| |these reactions, the philosilicate is dispersed in water and their sodium ion is exchanged by organic cations such as by |

| |quaternary ammonium salts. The philosilicate thus obtained will be water insoluble and, if the proper organic ammonium |

| |salts are chosen, the resulting product will be compatible with plastics. These reactions are strongly dependent on the |

| |experimental conditions (time, temperature, stirring speed…) selected. In this work the influence of a nanoparticulate |

| |filler drying time and temperature on the mechanical properties of polyurethane/ bentonite was ascertained. The matrix |

| |employed was a polyurethane thermoset resin obtained from castor oil and the filler was a sodium modified bentonite. The |

| |results show the drying conditions affect the mechanical properties of the composites strongly. Best overall results were |

| |obtained for the clay dried at 200ºC for 1 hour. |

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|E-P25 |FRACTURE TOUGHNESS OF Si3N4 BASED CERAMICS USING THE IF, SEVNB AND CNB METHODS |

| |C. V. ROCHA1; C. A. COSTA2 – 1 LABORATÓRIO DE MATERIAIS POLIMÉRICOS, CENTRO DE TECNOLOGIA, BL. F/211, CIDADE |

| |UNIVERSITÁRIA, CEP 21945-970, RIO DE JANEIRO, BRAZIL; 2CENTRO DE TECNOLOGIA, BL. F/210, CIDADE UNIVERSITÁRIA, CEP |

| |21945-970, RIO DE JANEIRO, BRAZIL. |

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| |Silicon nitride fluxed with Y2O3 + Al2O3 were gas pressure sintered (GPS), while the Si3N4 processed by hot pressing (HP) |

| |was fluxed with MgO and reinforced with Si3N4-whiskers. The processing route focused in developing a duplex microstructure|

| |of a “in-situ” reinforced composite. The fracture toughness of the materials were measured by indentation fracture (IF), |

| |single edge V notched beam (SEVNB), chevron notched beam (CNB) and the microstructure characterized via scanning electron |

| |microscopy (SEM). The present study evaluated how the fabrication process influences the microstructure and the |

| |mechanical behavior of Si3N4. |

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|E-P26 |THERMOGRAVIMETRIC ANALYSIS OF PLASMA TREATED FIBRE/RESIN COMPOSITES |

| |M. O. H. CIOFF1,2; H. J. C. VOORWALD3; M. L. C. P. SILVA4; G. L. J. P. SILVA4 -1UNESP CAMPUS DE SOROCABA - AV. 3 DE MARÇO |

| |CEP 18013/280 SOROCABA/SP. 2 DIVISION OF MATERIALS-AMR / IAE / CTA SÃO JOSÉ DOS CAMPOS / SP / BR-CEP:1288-904. 3UNESP |

| |CAMPUS DE GUARATINGUETÁ - AV. ARIBERTO PEREIRA DA CUNHA, 333 CEP 12516-410, GUARATINGUETÁ/SP. 4DEQUI/FAENQUIL - RODOVIA |

| |ITAJUBÁ - LORENA, KM 74,5 CAMPINHO, CXP 116 LORENA. |

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| |With the aim to develop and characterise the composites as Poli(methyl methacrylate) reinforced by the Poli(etilene |

| |therephtalate) fibres, in this research a choice for cold plasma superficial treatment on the PET fibres was made, which |

| |produce an increase of the superficial energy, retain their bulk properties and improve a suitable fibre/matrix adhesion |

| |providing the material performance. PMMA matrix was proved in several component compositions until a transparent material |

| |with adequate deformation was obtained. This material was thermo and mechanically characterised. A series of experiments |

| |with polyethylene terepthalate (PET) treated in radio frequency plasma reactor using argon and oxygen as gases, for |

| |treatment times equal to 5s, 20s, 30s and 100s, was carried out. This article presents the discussion about the |

| |thermogravimetric analysis conducted in the composites in all treatments conditions and for that not treated. It was |

| |observed that the plasma provide a decrease in the thermal stability of material. However, the higher fibre/matrix |

| |adhesion that occurred due to the treatment can be observed by uniform behavior observed during the tests. |

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|E-P27 |SYNTHESIS OF SILICA-TUNGSTEN COMPOSITE FOR BRACHYTHERAPY PROCEDURE |

| |ANA MARIA M. SANTOS; ADELINA P. SANTOS, JAQUELINE M. PAULO, VANESSA A. REGIS - CENTER OF NUCLEAR TECHNOLOGY |

| |DEVELOPMENT/CNEN, BRAZIL, RUA MÁRIO WERNECK S/NO - PAMPULHA, BELO HORIZONTE, MG, CEP-31120-970 BRAZIL. |

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| |Interstitial brachytherapy is a procedure that involves the implantation of radioactive seeds directly into the tumor |

| |region, allowing patients to receive higher radioactive dose than is possible with external irradiation with less normal |

| |tissue damage. The location and orientation of the seeds in the tumor region are determined through opacity to x-ray by |

| |radiographic techniques. Matrices of silica-tungsten will be utilized as host to 125I source. These matrices were obtained|

| |by sol-gel process employing tetrametylorthosilicate as precursor and the tungsten as absorber of x-rays. Processing |

| |conditions to obtain monolithic glass with different pore fractions were achieved. Specific surface areas, pore size |

| |distributions, porosity and volumetric densities of the glasses were obtained by nitrogen sorption and helium pycnometry. |

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|E-P28 |MICROSTRUCTURAL STUDY OF POLYMERIC COMPOSITE CYLINDERS |

| |G. Marinucci; A H. P. de Andrade - Instituto de Pesquisas Energéticas e Nucleares, SP Brasil. |

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| |Due to the anisotropy and construction in layers, defects and flaws in the composites come in great diversity, which |

| |depend not only of the direction of the load and orientation of the fibers in the layers, but also due to the production |

| |process. For this study, polymeric composite cylinders were manufactured by the process of filament winding and were made|

| |analyses in the microstructure of the cylinders, being evaluated defects originated from the interweaving method. In this |

| |method, each complete covering of the mandrel represents in fact two layers, one at +( and another one at -(, because the |

| |helical layers are wound up in pairs. Carbon fiber T300 and an epoxy system were used, with a fiber content of |

| |approximately 65% by volume. The cylinders were built with nine layers and the stacking sequence was: |

| |[90/(25º/90/(25/902]T. Voids were detected with characteristic forms, as well as rich matrix regions in the area of |

| |crossing of rovings. Flaws in these area must be avoided and can result in the beginning of cracks and delamination, that |

| |depending on its extension can contribute to the failure of the cylindrical structure. |

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|E-P29 |OPTIMIZATION OF THE PROCESSING PARAMETERS OF CARBON FIBER FABRIC /POLYAMIDE 6/6 COMPOSITE MATERIALS OBTAINED BY HOT |

| |COMPRESSION MOLDING |

| |E. C. Botelho, M. C. Rezende - Divisão de Materiais – Instituto de Aeronáutica e Espaço – Centro Técnico Aeroespacial CEP:|

| |12228-901 – São José dos Campos – São Paulo – Brazil. |

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| |Thermoplastic composite materials have received much interest in structural applications over the last 40 years, |

| |particularly in aerospace field. Advanced Thermoplastic Composites (ATC) have been lately introduced as structural |

| |composite materials for high-performance aerospace applications such as in the prototype of vertical stabilizer skin of |

| |the F-16 fighter and in the belly fairing skin of the C-130 cargo plane. The goal of the current research in polymeric |

| |composites area has been to produce thermoplastic composite materials using continuous carbon fibers and polymeric matrix |

| |with high performance. This work shows a study involving the manufacture of carbon fabric/polyamide 6/6 by hot compression|

| |molding system and the optimization of the processing parameters was based on rheological and thermal analyses. Based on |

| |the scanning electron microscopy and C-Scan ultrasound analysis, it was observed that the most adequate processing |

| |temperatures to be used in the hot compression molding is 290ºC for polyamide 6/6 matrix. The use of the established |

| |parameters based on the DSC, DMA and rheological analyses favored the manufacture of composites with a homogeneous |

| |distribution of reinforcement and matrix as observed through optical microscopy analysis. |

| |ACKNOWLEDGEMENTS: THE AUTHORS THANK FAPESP AND INSTITUTE OF POLYMER RESEARCH DRESDEN (GERMANY). |

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|E-P30 |HYGROTHERMAL EFFECTS ON THE ELASTIC CONSTANTS OF CONTINUOUS GLASS FIBER/EPOXY/ALUMINUM HYBRIDS COMPOSITE MATERIALS |

| |OBTAINED BY FREE VIBRATION METHOD |

| |E. C. BOTELHO, L. C. PARDINI, M. C. REZENDE. - DIVISÃO DE MATERIAIS – INSTITUTO DE AERONÁUTICA E ESPAÇO – CTA; CEP: |

| |12228-901 – SÃO JOSÉ DOS CAMPOS – SÃO PAULO – BRAZIL. |

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| |Continuous fiber/metal laminates (FML) offers significant improvements over current available materials for aircraft |

| |structures due to their excellent fatigue endurance and low density. Glass fibers/epoxy laminae and aluminum foil (Glare) |

| |are commonly used to obtain these hybrid composites. The environmental factors can limit the applications of composites by|

| |deteriorating the mechanical properties over a period of time. Usually, epoxy resins absorb moisture when exposed to humid|

| |environments and the combination of moisture and metals is known to lead to corrosion. Therefore, the combination of the |

| |two materials in Glare (polymeric composite and metal), does lead to differences that often turn out to be beneficial to |

| |its resistance to environmental influences. In this work, the viscoelastic properties such as elastic (E’) and viscous |

| |(E”) moduli were obtained from the aluminum 2024 alloy; and aluminum 2024 alloy/glass fiber/epoxy composites. The elastic |

| |modulus values found by the conditioned fiber/metal laminates after to be submitted to 0, 15, 30, 45 and 60 days were: |

| |49.7; 47.7; 46.4; 45.8 and 45.8 GPa, respectively. Experimental results were compared with theoretical values calculated |

| |by micromechanic computer program. |

| |Acknowledgements: FAPESP |

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|E-P31 |ELECTRIC BEHAVIOR OF TIN OXIDE DOPED WITH ZnO AND Ta2O5. |

| |F. P. Almeida, M. A. L. Margionte, J. A. Varela, L. Perazolli. Instituto de Química-UNESP, Lab. LIEC, PO Box 355, ZIP |

| |14801-060, Araraquara, Brazil; E. Longo. UFSCar, Lab. LIEC, PO Box 676, Rod. Washington Luiz, Km. 235, ZIP 13565-905, |

| |Brazil. |

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| |The sintering of zinc and tantalum oxides doped tin oxide was studied, to aim to obtain dense compacts for utilization |

| |like ceramic varistors, through oxides mixture, conformed in a cylindrical cast, isostatically pressed at 210 MPa and |

| |sintered in tubular furnace with pure oxygen atmosphere for 4h at 1400oC. The physical-chemistry properties of the samples|

| |was obtained by Archimedes method, MEV-EDS, and electrically (IxV). Devices with high densification ((>95%), homogeneous |

| |distribution of grain size, and breakdown tension (Ebr=220V/cm) show the potential of ternary system like low voltage |

| |varistors. |

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|E-P32 |INFLUENCE OF MOISTURE AND TEMPERATURE ON COMPRESSIVE STRENGTH OF CARBON/EPOXY COMPOSITES |

| |J. M. F. de Paiva, Mirabel Cerqueira Rezende - 1,2 Divisão de Materiais – AMR - Instituto de Aeronáutica e Espaço – IAE - |

| |Centro Técnico Aeroespacial – CTA - Praça Marechal do Ar Eduardo Gomes, 50 – Vila das Acácias; 12228-904 – São José dos |

| |Campos/SP – Brasil |

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| |Carbon fiber reinforced composites (CFRC) are very used in aeronautical industry to manufacture several components as |

| |flaps, aileron, landing-gear doors and others. These components can suffer mechanical damages mainly after moisture |

| |exposure. As a consequence, it is important to evaluate the influence of this parameter on the mechanical behavior, for |

| |example, the compressive strength. In this work were studied three types of composites combining the F155 epoxy matrix |

| |with carbon fiber fabric styles Plain Weave (PW) and Eight Harness Satin (8HS) and F584 epoxy matrix with 8HS. These |

| |laminates were obtained by autoclave molding using prepregs and following an appropriate curing cycle, i.e., heating rate |

| |at 2.5 ( 2ºC/min until reaching isothermals at 116ºC (60min) for F155 matrix and 177ºC (120min) for F584 matrix. In |

| |agreement with the supplier of prepregs (Hexcel Composite) the F155 epoxy matrix was not modified and the F584 matrix was |

| |toughened with rubber. After molding the laminates they were cut in twenty specimens attending the ASTM D3410. These |

| |specimens were tested at room temperature and after hygrothermal conditioning at 80 ( 5(C and 90 ( 5% of humidity in |

| |accordance with ASTM D5229. The conditioned sample weight became constant in eight weeks. The results showed that the |

| |hygrothermal conditioning provoked the decrease of the compressive strength in, approximately, 8-20% depending of the |

| |laminate family. In sequence, the failure modes of the tested specimens were evaluated showing good agreement with the |

| |literature. |

| |Acknowledgements: FAPESP |

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|E-P33 |PREPARATION OF NYLON6/ORGANOCLAY COMPOSITES BY MELT INTERCALATION METHOD FROM Na+ BENTONITE |

| |E. M. ARAÚJO1; T. J. A. MÉLO1; L. N. L. SANTANA1; G. A. NEVES1; L. H. CARVALHO1; M. M. A`VILA JR.2; E. LEAL2; P. M. SILVA2|

| |– 1DEMA/CCT/UFCG – C. POSTAL 10034, CEP 58109-970, CAMPINA GRANDE, PB; 2 STUDENTS OF THE MATERIALS ENGINEERING – UFCG. |

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| |Nanocomposites have a number of advantages over traditional polymer composites. Conventional composites usually require a |

| |high content (>10 wt.%) of the inorganic filler to impart the desired mechanical properties. For this reason, they have |

| |high density and processability worse. In contrast, nanocomposites can present enhanced thermal and mechanical properties,|

| |chemical resistance and low gas permeability with even a small amount clay. Nylon6 (Ny6)/organoclay composites have been |

| |prepared by melt intercalation technique from Na+ bentonite that was treated with cethyl trimethyl ammonium bromide |

| |quaternary ammonium salt. Composites were prepared using a Haake Blucher counter-rotating twin screw extruder, with 3 and |

| |6 wt.% of clay. Before mixing in extruder, a “master” with 50/50 wt.% Ny6/clay was produced. The obtained product was |

| |incorporated in nylon6 during the extrusion to promote a better dispersion of the clay in Ny6 matrix. The results showed |

| |significant changes on the processing of the nylon6 and an increase in the viscosity as compared with unmodified clay and |

| |the neat nylon6. |

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|E-P34 |NANOCOMPOSITES OF AMORPHOUS HYDROGENATED CARBON AND SILOXANE NETWORKS PRODUCED BY PECVD |

| |B. C. TRASFERETTI1; R. V. GELAMO1; F. P. ROUXINOL1, M. A. BICA DE MORAES1, C. U. DAVANZO2, M. C. GONÇALVES2 - 1LABORATÓRIO|

| |DE PROCESSOS DE PLASMA – IFGW/UNICAMP, CP 6165, CEP – 13087-970, CAMPINAS–SP, BRAZIL; 2IQ/UNICAMP, CP 6154, CEP – |

| |13083-970, CAMPINAS–SP, BRAZIL  |

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| |Nanocomposite thin films were deposited by plasma enhanced chemical vapor deposition from acetylene |

| |(AC)-hexamethyldisiloxane (HMDSO)-argon (Ar) mixtures. The flow rates of AC, HMDSO and Ar were varied from one deposition |

| |to another, while the rf power used to generate the plasma was kept constant. Samples obtained at various combinations of |

| |flow rates were investigated using transmission electron microscopy (TEM), single wavelength ellipsometry (SWE) and |

| |infrared spectroscopy (IRS). A nanometer scale phase separation was revealed by TEM; the amorphous hydrogenated carbon |

| |(a-C:H) grains average size varied according to the deposition parameters. The refractive index of the films at ( = 632.8 |

| |nm varied from 1.48 to 2.12. Both the index of refraction and the a-C:H average grain size increased with increasing |

| |proportions of acetylene in the gas feed. IRS was used to infer about the chemical groups present in the samples; the |

| |molecular structure was also investigated from the standpoint of longitudinal and transverse optics dielectric functions |

| |(LO and TO, respectively) in the infrared. The Si-O-Si absorption band position was very steady for all films but the |

| |LO-TO splitting related to this mode decreased as the AC:HMDSO flow rate ratio increased. The IRS results indicate that |

| |the siloxane phase has similar structure in all films but the Si-O-Si backbone continuity is limited by the a-C:H phase. |

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|E-P35 |STUDY OF GFRP COMPOSITES CURED BY ELECTRON BEAM |

| |M. C. Évora1; G. Marinucci2; D. A. Sishitsuji3; L. G. Andrade e Silva4 - 1Instituto de Estudos Avançados/CTA, São José |

| |dos Campos – SP, Brasil; 2Instituto de Pesquisas Energéticas e Nucleares-IPEN São Paulo, Brasil;3Centro Tecnológico da |

| |Marinha em São Paulo-CTMSP/SP- São Paulo, Brasil, 4 Instituto de Pesquisas Energéticas e Nucleares-IPEN - São Paulo, |

| |Brasil. |

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| |Advanced composites materials are used in the aircraft, aerospace, sporting goods and transportation industries. The |

| |electron beam curing is a non- thermal, non autoclave curing process to produce composites with several advantages: |

| |significantly reduced curing times; reduced environmental and health concerns; improvements in material handling; and |

| |reduced overall manufacturing costs compared to thermal curing. The aim of this work is to study the better curing process|

| |to produce reinforced plastic (GFRP) composite, based on glass fiber and epoxy, and cured by electron beam. The epoxy |

| |resin SL 5510 samples have been irradiated in the Nuclear and Energy Research Institute (IPEN) radiation facility and |

| |early experiments have shown that the results range from 20 kGy to 100 kGy. The differential scanning calorimetry (DSC) |

| |and thermogravimetry (TG) has been used to test the physical-chemistry properties. In order to guarantee the success of |

| |the experiment, new data are being taken. |

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|E-P36 |COMPUTER MODELLING FOR OPTIMIZATION POLIMERIC BLENDS |

| |G. de Carvalho, Gil; M. P.R. da Silva; J. M. P. Machado - IPRJ –UERJ, Rua Alberto Rangel, sn 28614-970 Nova Frigurbo - RJ.|

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| |Science and Technology development has been emphasized in last past decade. Such progress caused two major consequences to|

| |the science of materials: enlarged availability of new materials, and by the other hand, stated strict requirements for |

| |their performance. In this sense, the contribution of composites and polymeric blends plays relevant role. Synergism of |

| |properties pretended for polymeric blends faces against the decisive factor of their immiscibility within engineering |

| |polymers, so it requires the use of compatibility agents. The challenge consists on the optimal evaluation of fractions |

| |for each polymer and agent and in some cases it requires more than one compatibility agent. The aim of this work is to |

| |study formulations by using computational modeling to find out the better compositions for polymeric blends. |

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|E-P37 |WATER SORPTION KINETICS AND EFFECTS ON THE MECHANICAL PROPERIES OF PU/HESSIAN CLOTHS |

| |L.H. CARVALHO, G.S. MORAIS, DEMA/CCT/UFCG, CAIXA POSTAL 10034, CEP 58109-970, CAMPINA GRANDE, PB, BRAZIL & O.L.S. ALSINA, |

| |DEQ/CCT/UFCG, CEP 58109-970, CAMPINA GRANDE, PB, BRAZIL. |

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| |Composites materials have a unique set of properties not achieved by conventional materials. With proper choice of |

| |materials, concentrations and processing conditions, their properties can be tailor-made to fulfill different application |

| |requirements. Generally, synthetic fibers are employed in high performance polymer composites. Vegetable fibers, however, |

| |can successful replace synthetic fibers in composites with a less demanding set of property requirements and their use is |

| |desirable due to cost, weight and ecological considerations. In the present work, a nearly “all vegetable” biodegradable |

| |ecological PU matrix, derived from castor oil, was used to make PU/jute composites. The water sorption kinetics of these |

| |composites, as function of fiber content, was determined at two different temperatures (30 and 70ºC). The effect of water |

| |sorption on the tensile properties of these composites was also determined. The results show the water kinetics as well as|

| |the water sorption at long exposure times to be dependent on the water temperature and fiber content. Water sorption |

| |caused a reduction on the tensile strength and modulus of the composites investigated and these reductions were more |

| |accentuated for those with higher fiber contents. The elongation at break of the composites was not sensitive to fiber |

| |content or water sorption. |

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|E-P38 |MICROSTRUCTURAL AND FRACTURE SURFACE ANALYSIS OF ALUMINA-ZIRCONIA COMPOSITES |

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| |M. C. C. S B. MORAES1; C. N. ELIAS1; L. G. OLIVEIRA2; C. BARBOSA2 - 1DEPARTAMENT OF MECANICAL AND METALLURGICAL |

| |ENGINEERING (DE-4), IME, PRAÇA GENERAL TIBÚRCIO 80, PRAIA VERMELHA, 22290-270, RIO DE JANEIRO, BRAZIL; 2 INT, AV. |

| |VENEZUELA 82, SALA 604, SAÚDE, 20081-310, RIO DE JANEIRO, BRAZIL. |

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| |Abnormal grain growth may be influenced by the initial grain size distribution. In general, non-homogeneous grain size |

| |distributions on the raw materials ease the onset of abnormal grain growth during sintering. For all tested materials, the|

| |average size of the alumina and zirconia grains was determinated from scanning electron microscopy (SEM) images of |

| |randomly selected areas of the polished and thermally etched surface of composites. Microstructural homogeneity, fracture |

| |surface after four point flexural test and crack path induced by Vickers indentation in alumina-zirconia composites were |

| |observed with SEM. Crystallographic aspects were observed with TEM. The results thus obtained, associated with crack path,|

| |can be used to understand the mechanisms involved in the fracture of the analyzed composites. |

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|E-P39 |APLICATION OF THE Fourier Transform Infrared Spectroscopy (FTIR) TO THE STUDY OF THE CURE PROCESS OF PREPREG OF |

| |GLASS-PHENOLIC |

| |R. S. Rosa1, M. L. Pontarolli1, D. Dibbern-Brunelli1, R. C. L. Dutra2 - 1Departamento de Química, Instituto Tecnológico de|

| |Aeronáutica, Praça Marechal Eduardo Gomes, 50, Vila das Acácias, CEP 12228-900, São José dos Campos, SP, Brazil; 2Divisão |

| |de Química, Instituto de Aeronáutica e Espaço, Praça Marechal Eduardo Gomes, 50, Vila das Acácias, CEP 12228-900, São José|

| |dos Campos, SP, Brazil. |

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| |The objective of this work is: (a) determine the type of phenolic resin of a glass-phenolic pre-impregnated (prepreg) and |

| |(b) study the cure process of the polymeric matrix, through the Fourier Transform Infrared Spectroscopy (FTIR). The FTIR |

| |spectra of prepreg in the B stage was very silmilar to the spectra of a resol type resin obtained through the reaction of |

| |phenol with formaldehyde catalyzed by ammonia in alkaline medium. During the cure process, the spectra showed significant |

| |modifications in the following regions: (a) intensity decreasing of the band at 3338 cm-1 (stretching of the OH group) in |

| |relation to the bands at 2919 and 2865 cm-1 (axial deformation or stretching of groups CH), attributed to the elimination |

| |of water during the crosslinking process, (b) increasing of the relative intensity of the bands at the range of 2000 to |

| |1650 cm-1, attributed to the stretching carbon-carbon of substituted aromatic rings, (c) substitution in the aromatical |

| |ring evidenced by the disappearance of the bands at 885, 822, 754 cm-1. |

| |Ackonowledgments: FAPESP (2000/03186-8). |

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|E-P40 |Mechanical and morphological behaviour of PC/PCL blends |

| |F. L. B. O. Oliveira1; M. C. A. M. Leite1; C. R. G. Furtado1; L. R. Bocayuva2, C. M. F. Oliveira2 - 1 Instituto de |

| |Química/UERJ, Rio de Janeiro, Brazil;2 IMA/ UFRJ, Rio de Janeiro, Brazil. |

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| |The possibility of different polymers properties combination is one of the reasons for the great importance of polymer |

| |blends. The final materials can have very good performance which is related to their morphology. The objective of this |

| |work is to evaluate the fracture surface morphology and the mechanical behaviour of polycarbonate (PC) and |

| |poly(caprolactone) (PCL) blends. The blends of various compositions were prepared on Haake rheocord system and |

| |compression molded. The mechanical behaviour has presented a decrease on tensile strength and an increase on elongation at|

| |break with the increase of PCL level. The morphological study of the samples surface by scanning electron microscopy has |

| |shown ductile fractures with some distinctions between them. |

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|E-P41 |FINITE ELEMENT ANALYSIS OF INDENTATION IN WC-Co CERMETS |

| |A. S. Dias1, G. C. Godoy2, P. R. Cetlin2 - 1 Mechanical Department, Federal University of São João del-Rei, São João |

| |del-Rei P. J. Modenesi; 2Department of Metallurgical Engineering, UFMG, Belo Horizonte, Minas Gerais, Brazil. |

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| |This work aims to analyze the Vickers indentation testing by numerically modeling it with the Finite Element Method (FEM) |

| |using three-dimensional elements. These indentation tests have been considered by the literature as a reliable tool for |

| |the determination of mechanical properties such as hardness, Young modulus, yield strength, and fracture toughness. A |

| |numerical model was developed using the commercial explicit finite element package MARC( to analyze the indentation |

| |loading of tungsten carbide with cobalt (WC-Co) cermets. These materials are commonly used in work conditions that demand |

| |a high hardness in association with a high wear and compression strength. The numerical analysis has indicated that the |

| |model can capture the strain and stress fields during the loading and unloading phases of the Vickers indentation cycle. |

| |The three-dimensional model can predict superficial hardness of WC-Co as well as the load-depth (P-h) relationship during |

| |the indentation cycle that were found to agree well with experimental results. It is expected that this simulation will |

| |perform well not only to identify the stress and strain fields around an indentation but also to evaluate crack |

| |propagation mechanisms associated to it because fracture mechanics analysis can be incorporated to model. |

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|E-P42 |ORNAMENTAL ROCK CUTTING RESIDUE AS MINERAL FILLER TO POLYMERIC MATRIX MATERIALS |

| |I. C. Bigno1; P. F. Castro2 - 1 Instituto Militar de Engenharia - IME, Praça General Tiburcio 80, Praia Vermelha, CEP |

| |22290–270, Rio de Janeiro, Brasil; 2 Universidade Federal Fluminense - UFF, Rua Passo da Pátria 156, Bloco. D, Sala 365, |

| |CEP 22240–240, Niterói, Rio de Janeiro, Brasil. email: icbigno@.br |

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| |The cutting process of ornamental rocks presently provides, on the world basis, an outstanding volume of residue. Brazil |

| |generates an approximate weight of 240.000 tons per year, yet without a proper destination. This produces environmental |

| |issues, mainly associated with transport, storage and disposal maintenance, and health problems to the population. This |

| |paper presents a study on Ornamental Rock Cutting Residue (ORCR) used as mineral filler to composite materials of |

| |polymeric matrix. Through pre-casting plates of 200x200x4mm, the influence on flexural strength, wearing and staining |

| |surface was analyzed. The experimental program points out a maximum ORCR content of 50%, in volume, so that a good |

| |workability is kept. Test results and analyses show ORCR technically feasible to be used as filler in polymeric matrix |

| |products. |

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|E-P43 |MECHANICAL BEHAVIOR OF HIGH IMPACT POLYSTYRENE REINFORCED WITH SHORT SISAL FIBERS |

| |P. Antich; A.Vázquez; C. Bernal - INTEMA, Juan B. Justo 4302, B7608FDQ Mar del Plata, Argentina |

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| |In this work the mechanical behavior of high impact polystyrene (HIPS) reinforced with short sisal fibers was studied. |

| |Composites with different fiber contents ranging from 5 to 25 weight % were prepared by mixing the polymer pellets with |

| |sisal fibers in an internal mixer. Then thick plaques were compression molded from which test samples were obtained. |

| |Tensile and fracture tests were performed under quasi-static loading conditions. An increasing trend of Young's modulus |

| |with fiber loading was found whereas tensile strength was observed to decrease. Under quasi-static loading, all materials |

| |exhibited non-linear fracture behavior with stress whitened fracture surfaces. Hence Non-Linear Fracture Mechanics was |

| |used in this case by means of the J-Integral concept. The Normalization method to obtain J-R curves from a single specimen|

| |record was successfully applied for all materials. A maximum of fracture toughness was observed for a fiber content of |

| |around of 5 % of sisal fibers. Furthermore, roughness measurements were carried out for the HIPS matrix and the |

| |composites. Although a slight increasing trend of surface roughness with fiber loading was observed as expected, |

| |acceptable surface finishing was obtained for all composites. Finally, impact fracture properties are also being studied |

| |for the matrix and the composites through the Essential Work of Fracture concept as all materials also displayed ductile |

| |fracture under these loading conditions. |

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|E-P44 |MONITORING OF CURE KINETIC OF PREPREG |

| |M. L. Costa; M. C. Rezende - Divisão de Materiais/ AMR; Instituto de Aeronáutica e Espaço/IAE; Centro Técnico |

| |Aeroespacial/CTA; Praça Mal. do Ar Eduardo Gomes, nº 50 – Vila das Acácias; 12228-904, São José dos Campos/SP – Brazil. |

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| |Curing of the resin matrix is a key step in the fabrication of fiber-reinforced thermoset composites. The polymeric |

| |composite product quality is controlled to a great extent by the curing cycle parameters such as time, temperature, |

| |pressure and their combinations. Traditionally a downstream composite manufacturer just follows the cure schedule |

| |suggested by the supplier. This schedule was usually determined in an ideal situation where the resin was still “fresh” |

| |and may not represent the actual cure state of the resin in a composite manufacturing facility. The composite manufacturer|

| |must study the cure behavior of the matrix resin just prior to autoclave or press curing. This is necessary for |

| |processability verification and cure cycles optimization especially if the resin has been shelved for some time. Cure |

| |kinetic model is an integral part of composite process simulation, which is used to predict degree of cure and amount of |

| |heat generation. The reaction order (nth order) and autocatalytic models are most frequently cited among the existing |

| |models. Accurate cure kinetic model is crucial to identify correctly the amount of heat generated in the composite process|

| |simulation. In this work, a cure kinetic model for the epoxy resin is presented. The cure kinetic is based on a nth order |

| |model for the proposed method, which uses dynamic DSC data to determine the parameters. Three different epoxy prepreg |

| |materials, glass fiber/F161; carbon fiber/584 and carbon fiber/8552, were characterized and compared using the same cure |

| |kinetic model. The results show that the three systems present a n reaction order. Although, their heats of reactions were|

| |found to be slightly different, the kinetics of these systems were very similar. |

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|E-P45 |MICROSTRUCTURAL CHARACTERIZATION OF Al2O3-ZrO2-SiC COMPOSITE AFTER OXIDATION IN AIR AT HIGH TEMPERATURE |

| |C. A. A. Cairo1, M. L. A.Graça1; W. Acchar2 - 1Divisão de Materiais – Instituto de Aeronáutica e Espaço – Centro Técnico |

| |Aeroespacial; CEP: 12228-904 – São José dos Campos – São Paulo – Brazil; 2 Universidade Federal do Rio Grande do Norte. |

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| |The increasing use of ceramic materials in wear and structural applications is due to your properties like mechanical, |

| |thermal and chemical stability and higher wear resistance than metallic materials. The Al2O3-ZrO2-SiCw composite, |

| |commercially available like a cutting tool, combines the high wear resistance of the aluminum oxide (Al2O3) with the |

| |benefits of the addition of zirconium oxide (ZrO2) and silicon carbide whiskers (SiCw) reinforcements, seeking an |

| |improvement of the fracture toughness.The high temperature applications of that composite can be limited by the silicon |

| |carbide oxidation with the following formation of SiO2 amorphous phase and further dissolution of the alumina matrix and |

| |precipitation of intergranular phases. The presence of the amorphous phase can allow a larger mechanical deformation of |

| |the composite harming your performance at working temperatures. In this work, a microstructural characterization was |

| |performed by using Transmission Electronic Microscopy with phase identification techniques by EDX and x-ray Diffraction, |

| |in order to identify the phases formed by the interactions of oxidation reaction products with the alumina matrix, after |

| |the composite oxidation in air at high temperatures. |

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|E-P46 |STUDY OF CARBON FIBER/POLYAMIDE LAMINATES COATED WITH POLYANILINE BLENDS AS RADAR ABSORBING MATERIAL |

| |R. S. Biscaro1, E. C. Botelho2, R. Faez3, M. C. Rezende2 - 1Depto de Engenharia Aeronáutica e Mecânica – ITA – CTA; |

| |2Divisão de Materiais – Instituto de Aeronáutica e Espaço – CTA, CEP: 12228-904 – São José dos Campos – São Paulo – |

| |Brazil; 3 Instituto de Pesquisa & Desenvolvimento - Universidade do Vale do Paraíba, São José dos Campos – São Paulo – |

| |Brazil |

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| |Radar Absorbing Materials (RAM) manufactured as paintings, rubber sheets, polymeric foams, composites, among others, have |

| |been successfully used in different areas, such as: aeronautical, telecommunications and medical. In this work, composites|

| |based on carbon fiber/polyamide laminates and polyurethane (PU)/polyaniline (PAni) blends have been studied in order to |

| |obtain an efficient RAM with low specific weight. The carbon fiber laminates were manufactured with polyamides 6 and 6/6 |

| |matrices. The paints were prepared with two kinds of blends: PU with PAni doped with dodecylbenzene sulfonic acid |

| |(PU/PAni-DBSA) and with PAni doped with d,l-camphor sulfonic acid (PU/PAni-CSA). The interfaces between thermoplastic |

| |laminates and polyaniline blends have been evaluated by scanning electron microscopy. The microwave absorption behavior of|

| |the processed composites has been characterized by reflectivity measurements using the waveguide method in the frequency |

| |range of 8-12 GHz. The best attenuation results (99.9%) were found for laminates coated with PU/PAni-CSA and the adequate |

| |thickness of the blend applied on the composite material was 2 mm. Both thermoplastic composites, with polyamide 6 and 6/6|

| |matrices, presented good interface with PAni’s blends. |

| |Acknowledgements: FAPESP |

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|E-P47 |INFLUENCE OF SYNTHESIS CONDITIONS ON THE STRUCTURAL FEATURES OF SILOXANE-PMMA SOL-GEL DERIVATIVE NANOCOMPOSITES |

| |V.H.V SARMENTO1, M.R. FRIGÉRIO1, K. DAHMOUCHE1 C.V SANTILLI1 S.H PULCINELLI1 A.F. CRAIEVICH2 - 1INSTITUTO DE QUÍMICA, |

| |UNESP, C.P 355, ARARAQUARA-SP, BRAZIL; 2INSTITUTO DE FÍSICA-USP, SÃO PAULO-SP, BRAZIL. |

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| |Transparent siloxane-polymethylmethacrylate (PMMA) hybrids were synthesized by the sol-gel process through hydrolysis of |

| |methacryloxyproyltrimethoxysilane (TMSM), tetramethoxysilane (TMOS) and polymerization of methylmethacrylate (MMA) using |

| |benzoyl peroxide (BPO) as catalyst. These composites have a good chemical stability due to the presence of covalent bonds |

| |between the inorganic (siloxane) and organic (PMMA) phases. The effects of siloxane content, pH of the initial sol, BPO |

| |content and curing temperature on both the polymerization degree of PMMA and the final structure of the dried gels |

| |(xerogels) were analyzed by Small-Angle X-Ray Scattering (SAXS), Differential Scanning Calorimetry (DSC), Infrared |

| |Spectroscopy and 13C and 29Si NMR. Results show that the polymerization degree increases by decreasing the BPO or TMSM |

| |content, or by curing the obtained xerogels above 160oC during 3h. SAXS results revealed the presence of an interference |

| |peak at medium q-range for all compositions, suggesting that siloxane groups located at the ends of PMMA chains form |

| |isolated clusters that are spatially correlated. The average intercluster distance, estimated from the q-value |

| |corresponding to the maximum in SAXS spectra, decreases for samples prepared with increasing amount of TMSM-TMOS. This |

| |effect was assigned to the expected increase in the number density of siloxane groups for progressively higher siloxane |

| |content. The increase of BPO content has no noticeable effect on the average intercluster distance. High pH favors |

| |polycondensation reactions between silicon species of both TMOS and TMSM silicon alcoxides, leading to a structure in |

| |which all siloxane clusters are bonded to PMMA chains. This effect was confirmed by 29Si NMR measurements. Porosity |

| |measurements revealed that the higher the siloxane content the larger the porous volume. |

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|E-P48 |EVALUATION OF THE FLEXURAL AND SHEAR STRENGTH OF CARBON/EPOXY COMPOSITES USED IN AERONAUTICAL FIELD |

| |J. M. F. de Paiva 1, S. Mayer 2 , M. C. Rezende 1 - 1 Divisão de Materiais – AMR - Instituto de Aeronáutica e Espaço – IAE|

| |- Centro Técnico Aeroespacial – CTA - Praça Marechal-do-Ar Eduardo Gomes, 50 – Vila das Acácias, 12228-904 – São José dos |

| |Campos/SP – Brasil, 2 Embraer – Empresa Brasileira de Aeronáutica. |

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| |This work compares four types of carbon fiber reinforced composites (CFRC) used in aeronautical industry by flexural and |

| |interlaminar shear tests. The composites were obtained in autoclave by using prepregs with orientation of 0,90(. The used |

| |prepregs were based on epoxy matrices (F155 and F584) and carbon fiber fabric reinforcements (PW -“Plain Weave” and 8HS - |

| |“Eight Harness Satin”). The F155 epoxy matrix was cured at 121ºC and the F584-epoxy at 177ºC due to differences in these |

| |formulations. After molding both laminates were cut in specimens (ten for each test), attending the ASTM D790 for the |

| |flexural test and ASTM D2344 for the interlaminar shear test (ILSS). The results showed that the F584-epoxy matrix |

| |laminates presented improvement in the mechanical properties in both tests when compared with the F155-epoxy ones. The |

| |flexural strength of F584-epoxy laminates was nearly 1120 MPa for 8HS fabric and approximately 1290 MPa for PW fabric. The|

| |interlaminar shear strength was about 72 MPa for F584/8HS and 85 MPa for F584/PW. Subsequently, the samples submitted to |

| |the shear test were observed by scanning electron microscopy (SEM) and that ones tested in flexural were analyzed by |

| |stereoscopy, revealing characteristic aspects on these fracture surfaces. |

| |Acknowledgements: FAPESP |

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|E-P49 |EFFECTS OF THERMAL HISTORY ON CRYSTALLIZATION OF POLY(ETHER ETHER KETONE) (PEEK) AND POLY(PHENYLENE SULFIDE) (PPS) |

| |A. MOURA1; L. B. NOHARA2; E. L. NOHARA3; M. C. REZENDE1 - 1DIVISÃO DE MATERIAIS / INSTITUTO DE AERONÁUTICA E ESPAÇO / CTA,|

| |PÇA. MAL.-DO-AR EDUARDO GOMES, 50, SÃO JOSÉ DOS CAMPOS, 12228-904, SÃO PAULO, BRAZIL; 2DEPARTAMENTO DE ENGENHARIA MECÂNICA|

| |E AERONÁUTICA – ITA / CTA; 3DEPARTAMENTO DE ENGENHARIA MECÂNICA – UNIVERSIDADE DE TAUBATÉ / UNITAU |

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| |Considerable attention has been given to both PEEK and PPS polymers as high performance thermoplastics, as well as |

| |matrices for advanced composite processing. The crystallinity of both polymers can vary depending on their thermal |

| |histories. Alterations in crystallization conditions are known to result in different crystal morphologies, which |

| |influence physical and chemical properties of the polymers. This work shows the study of crystallization of both PEEK and |

| |PPS as a function of their thermal histories. Isothermal and non-isothermal crystallizations of the polymers have been |

| |conducted by differential scanning calorimetry (DSC) and the morphology, under the same conditions, have been monitored by|

| |polarized light optical microscopy, assisted with a hot plate and an optical camera. When the samples of PEEK and PPS have|

| |been submitted at or above 390ºC and 320ºC, respectively, the subsequent crystallization behavior is nearly independent of|

| |the prior melt temperatures. It is thus proposed that the residual crystalline regions only persist up to the |

| |thermodynamic melting point. Samples cooled very slowly (~0,5ºC/min) showed tendency to crystallize at higher temperature,|

| |and with a cristallinity degree higher than the samples cooled faster (~100ºC/min), indicating that the polymer |

| |cristallinity is highly dependent on the cooling rates, as well their thermal history. |

| |Acknowledgements: The authors thank FAPESP |

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|E-P50 |DYNAMIC PROPERTIES OF PVC-GREEN COCONUT FIBER COMPOSITES |

| |R.L.Ferreira1; C.R.G. Furtado1; M.F. Rosa2; A.A.L. Furtado2; R.C.R Nunes3; L.L.Y. Visconte3; J.L.Leblanc4 - 1Instituto de|

| |Química/UERJ, Rio de Janeiro, Brazil; 2EMBRAPA, Brazil; 3IMA/UFRJ, Brazil; 4RMOP/Université Pierre et Marie Curie, France.|

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| |The interest in using natural fibers as reinforcement in plastics has increased dramatically during the last few years. |

| |Natural fibers have many advantages over their inorganic counterparts, as lower density, less abrasiveness to expensive |

| |moulds and mixing equipment, and of course low cost. Additionally they are renewable raw materials and have relatively |

| |high strength and stiffness. Polyethylene (PE), polypropylene (PP), polystyrene (PS) and polyvinyl chloride (PVC) are |

| |suitable polymers for the manufacture of natural fibers-plastics composites. In this work, coconut fibers, native to the |

| |Brazilian coast, were incorporated as filler in PVC. The compounding were carried out in a Haake Rheocord System |

| |consisting of a Single Screw Extruder. The extrusion was carried at a rotor speed of 100 rpm and a temperature range of |

| |140-170 (C. The compounds were pressed and the dynamic properties analyzed on a Rubber Process Analyser (RPA 2000). It |

| |was observed that the presence of the fiber increases the storage modulus at any deformation amplitude and that the loss |

| |factor tan ( is higher in fiber composites. |

| |Acknowledgements: The authors thank PIBIC/CNPq and CAPES/COFECUB for financial support |

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|E-P51 |MICROSTRUCTURAL ANALYSIS OF SIC-SIC COMPOSITE OBTAINED BY CONVERSION REACTIONS IN DIFFERENT TEMPERATURES |

| |M. Florian1; C.A.A. Cairo2 - 1-Depto de Engenharia Aeronáutica e Mecânica – ITA – CTA, Pça Mal. Eduardo Gomes, 50, |

| |12228-901 - São José dos Campos/SP, Brazil; 2-Divisão de Materiais – Instituto de Aeronáutica e Espaço – CTA, Pça Mal. |

| |Eduardo Gomes, 50, 12228-904 São José dos Campos/SP, Brazil. |

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| |Silicon carbide based ceramics are interesting materials for thermal protection of reusable space vehicles due to mainly |

| |its high strength and low oxidation rate in high temperature and good heat emissivity. SiC-SiC composite like a SiC matrix|

| |reinforced with SiC polycrystalline continuous fiber, in form of bi-directional weave were obtained by conversion |

| |reactions in high temperature and controlled atmosphere, from a porous carbon/carbon composite precursor. The |

| |carbon/carbon composite is converted in SiC/SiC by the reaction with a gas of SiO generated by the misture Si/SiC/Al2O3. |

| |In this work is observe the microstructure of SiC/SiC composite varying the temperature of transformation of carbon/carbon|

| |composite from 1400oC at 1800oC was observed. The analysis of microstructure was made by scanning electron microscopy in a|

| |Leo mod. 435 vpi. The results shown that at temperature of 1400oC the conversion occurs only in the surface of the fibers |

| |and the center of the fibre remains carbon/carbon. In temperature 1600oC, the conversion is totally complete with the |

| |formation of (-SiC with small grain size. At temperature above 1700oC, the conversion is complete, but grain size of (-SiC|

| |grows up too much so that the fibers brake, losing their efficiency. |

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|E-P52 |Luminescence of the composite ThermoSETTING-Eu2O3 |

| |E. R. Santos, M. A. C. dos Santos, M. A. Macêdo, LPCM/DFI/UFS, C.P. 353, 49100-000, São Cristóvão/SE/Brazil. |

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| |The composite Thermosetting-Eu3O2 was prepared by EuCl3.6H2O (europium(III) chloride hexahydrate) dissolved in filtered |

| |coconut water. A concentration of 0.5 mol/litre of the salt in the solution of coconut water was stirred with a magnetic |

| |bar for 15 min. A viscous and homogeneous sol was obtained. It was annealed at 100 °C for 24 h in order to get a xerogel |

| |that was heated at 800 °C for 10 min to obtain the Eu3O2 powder. The powder was then mixed to thermosetting based in epoxi|

| |and after successive thermal treatments at 100 ºC the composite Thermosetting-Eu3O2 was obtained. The choice of the Eu ion|

| |is due to the high well known red luminescence (5D0-7F2 transition, ~612nm), when excited in the 5L6 (~395nm) or 5D2 |

| |(~465nm) levels. We have dealt with concentrations varying from 1% to 10% of Eu2O3 in volume. Excitation and emission |

| |measurements were performed in order to analyze the spectroscopic behavior of this old material with a brand new |

| |application. Emission measurements have confirmed a very high luminescence and that the original oxide structure of the |

| |luminescent ions remains unaltered, because the emission pattern did not change, when compared to the pattern of the |

| |Eu2O3. Looking forward applications, this composite material can be used in optically monitored corrosion. |

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|E-P53 |EFFECT OF ADDITION OF FELDSPAR AND TALC ON THE MECHANICAL PROPERTIES OF EPOXY ADHESIVES |

| |A. N. Sousa; R. T. Fujiyama; J. R. Albuquerque; F. L. Bastian -Laboratório de Materiais Compósitos, PEMM/COPPE/UFRJ- Caixa|

| |Postal: 68505 Cep: 21941-942 - Rio de Janeiro- Brasil. |

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| |A comparative study of the influence of the addition of two filler types, feldspar and talc, on the tensile mechanical |

| |properties of an epoxy resin polymeric adhesive was made. A DGEBA epoxy resin was used as matrix and different volume |

| |fractions of feldspar or talc were added. The volume fractions of filler started at an initial value, corresponding to 5 |

| |weight percent, and was increased at increments of 10% till the maximum homogenization. The tensile properties of |

| |composite materials were obtained following the ASMT D638-93 standard. The Young’s modulus, fracture strength and |

| |toughness were obtained from those tests. The optimum volume fraction of filler was selected based on the maximum value of|

| |the product of the fracture strength and toughness. |

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|E-P54 |NYLON-6/CLAY (NANO) COMPOSITES PREPARED BY MELT INTERCALATION |

| |T. J. A. Mélo; E. M. Araújo; M. P. Baracuhy, L. H. Carvalho – Departamento de Engenharia de Materiais, Universidade |

| |Federal de Campina Grande, Av. Aprígio Veloso, 882, Bodocongó, Caixa Postal 10034, 58109-970, Campina Grande, Brazil. |

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| |Nanocomposies of nylon-6 were prepared by melt blending the polymer with imported Na+ montmorillonite and montmorillonite |

| |modified by quaternary ammonium salt. The nanocomposites were obtained bymixing in a Haake closed mixer at 240ºC and 60 |

| |rpm for 10 min, with 3 wt% of clay. The effects of the incorporation of clay were observed by X-ray diffraction, Fourier |

| |transform infrared (FTIR) analysis and mechanical properties. The results from X-ray and FTIR suggest that has occurred |

| |intercalation of the salt but the mechanical properties no showed significant changes. This might be due the processing |

| |conditions are not enough to provide na appropriate nanometric dispersion of clay layers and na homogeneous distribution |

| |of the clay in the samples. |

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|E-P55 |INFLUENCE OF THE INTERFACE ON THE TENSILE AND IMPACT PROPERTIES OF CARBON FIBER REINFORCED POLYPROPYLENE MATRICES |

| |C. L. Nogueira1,2, J. M. F. de Paiva2, M. C. Rezende2 - 1 Departamento de Engenharia Aeronáutica e Mecânica / ITA; 2 |

| |Divisão de Materiais/IAE/CTA – Centro Técnico Aeroespacial - Pça. Marechal do Ar Eduardo Gomes, 50, São José dos Campos – |

| |SP, CEP: 12228-904. |

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| |Thermoplastic composites have applications in a wide variety of industrial products. Their main advantages are easy |

| |processing techniques and higher composite structural performance. The objective of this work is to evaluate the role of |

| |the interface on the tensile and impact strengths of carbon fiber reinforced polypropylene based matrices. The laminates |

| |were prepared by using carbon fiber fabric style Plain Weave (CF) with films of four different polypropylene matrices, |

| |described as (1) polypropylene-PP, (2) polypropylene-polyethylene copolymer-PP-PE, (3) PP-PE containing an interfacial |

| |compatibilizer-AM1 and (4) PP-PE containing an impact improvement additive-AM2. The composites were processed using hot |

| |compression molding. The CF homogeneity distribution in the laminates was verified by microscopic analyses and by fiber |

| |content determination according to ASTM-D3171. The mechanical testing results show that the FC-AM1 laminate presents the |

| |lowest impact strength and the highest tensile strength values when compared to the other laminates. Optical analyses of |

| |the tensile fractured surface of the FC-AM1 specimens reveal a fragile aspect. Scanning electron microscopy analyses |

| |confirm this result, showing a very strong interface between fiber/matrix that leads to a fragile behavior under tensile |

| |load. The FC-AM2 laminate shows a slightly lower tensile strength and higher impact strength when compared to the FC-AM1. |

| |PP-PE and PP laminates present the lowest mechanical strength. |

| |Acknowledgments: FAPESP (02/02057-5); CNPq (300599/96) and Polibrasil. |

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|E-P56 |MECHANICAL BEHAVIOR OF (-SIC-BASED NANOCOMPOSITES |

| |E. S. Lima1; P. L. Brandão1; C. A. Costa2; L. H. L. Louro1 - 1IME, Programa de Ciência dos Materiais, Praça General |

| |Tibúrcio 80, Rio de Janeiro; M. A. P. Santos, IPqM, Grupo de Materiais, Rua Ipirú (sem numero), Ilha do Governador, Rio de|

| |Janeiro; 2 PEMM/COPPE/UFRJ, Centro de Tecnologia, Cidade Universitária, Rio de Janeiro. |

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| |Silicon Carbide possess excellent thermomechanical properties such as high hardness and stiffness, good corrosion and |

| |oxidation resistance, high thermal conductivity and high chemical and thermal stability. The major applications involve |

| |mechanical seal, heat exchanger, optical device and armor. In this research, a nanocomposite of SiC + ZrO2, plus alumina |

| |and yttria as sintering aids, were sintered at 1780 0C for 30 min in argon atmosphere. The obtained result had densities |

| |greater than 96%. These nanocomposites were evaluated by hardness and fracture toughness, using the indentation fracture |

| |(IF) methodology. |

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