SBPMat BRAZIL-MRS

2nd Brazilian MRS MeetingOctober 26-29, 2003

Symposium E:

Processing/Properties Structural Composite Materials

Symposium Organizers:____________________________________________________

Mirabel Cerqueira Rezende (CTA, IAE-ITA)

Fernando Luiz Bastian (UFRJ)

Gerson Marinucci (IPEN)

José Maria Fernandes Marlet (EMBRAER)

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INVITED PRESENTATIONS

E-I1 SOME ASPECTS OF THE DETERMINATION OF ADHESION PARAMETERS IN COMPOSITESB. Lauke - Institut für Polymerforschung Dresden e.V., Hohe Str. 6, 01069 Dresden, Germany

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.

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.

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 REVIEWPhilippe Martineau - Consulado Geral da França em São Paulo, Av. Paulista, 1842 – 14º andar, São Paulo – SP, CEP 01310-200; philippe.martineau1@libertysurf.fr

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.

E-I4 TAILORING THERMAL RESIDUAL STRESSES FOR THE DESIGN OF COMPOSITE STRUCTURESSérgio Frascino Müller de Almeida - Instituto Tecnológico de Aeronáutica - Department of Mechanical Engineering - 12.228-900 São José dos Campos – SP – Brazil.

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 REHABILITATIONC. 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

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.

E-I6 LIQUID CRYSTAL THERMOSETS: NEW GENERATION OF HIGH PERFORMANCE MATERIALSC. 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.na.cnr.it

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 METHODOLOGIESPaul A. Lagace - Professor of Aeronautics & Astronautics and of Engineering Systems - Technology Laboratory for Advanced Composites, Massachusetts Institute of Technology, Cambridge, Massachusetts, U.S.A.

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.

E-I8 DISCONTINUOUS OR CONTINUOUS REINFORCEMENTS FOR TI BASED COMPOSITES: A REVIEWFrédéric Dartigues and Yann Le Petitcorps - ICMCB-CNRS-UPR 904887, Av. A Schweitzer33608 - Pessac France. E-mail: lepetit@icmcb.u-bordeaux .fr

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.

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E-I9 STRUCTURAL CERAMIC-MATRIX COMPOSITES - AN OVERVIEWRoberto 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.

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.

E-I10 ECO-FRIENDLY POLYMER COMPOSITES BASED ON VEGETABLE FIBERSL.H.de Carvalho, DEMa/CCT/UFCG, Caixa Postal 10034, Campina Grande, PB, Brazil

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 APPLICATIONSL. 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

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.

E-I12 SUSTAINABLE STRUCTURAL BIOCOMPOSITES: THE MATERIAL FOR THE 21ST

CENTURYLawrence 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

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

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.

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.

E-O2 PREPARATION AND MECHANICAL PROPERTIES OF POLYPROPYLENE – CLAY NANOCOMPOSITESF.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

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 RESISTANCEZ. M. Boari 1 ; 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.

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 600 oC 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.

E-O4 STEAM CURING AND DELAYED ETTRINGITE FORMATION IN BRAZILIAN CEMENTSG. 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.

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 DIAGRAMSM.I. Giannotti1; M.L. Foresti1; M.J. Galante1; P.A. Oyanguren 1 ; 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.

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.

E-O6 A DIRECT SINTERING ROUTE FOR MAKING ALUMINUM METAL MATRIX COMPOSITESE.N.Gregolin;H.Goldenstein, Department of Metallurgical and Materials Engineering, Escola Politécnica da Universidade de São Paulo, São Paulo SP, Brasil.

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 BEHAVIORRumbao, 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.

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.

E-O8 ADHESIVENESS STUDY OF POLIMERYC MATRIX COMPOSITE MATERIAL FOR PIPELINES REPAIRR.C.O.M. Afonso, F.L. Bastian, Laboratory of Composite Materials, COPPE/UFRJ, CP 68505, 21941-972, Rio de Janeiro, Brazil.

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 RESINSC. 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.

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.

E-O10 INFLUENCE OF ORGANO-BENTONITE CLAY ON THE PROCESSING AND MECHANICAL PROPERTIES OF NYLON 6 AND POLYSTYRENE COMPOSITESE. M. Araújo1; T. J. A. Mélo1; L. N. L. Santana 1 ; 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.

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 FORMULATIONV. 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

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.

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

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 COMPOSITESJ. A. P. Cunha 1 ; 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.

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 (88.111.9 MPa) presented a decrease of 9% in the ILSS when compared with specimens non-conditioned (97.65.2MPa). 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.

E-O14 TEM STUDY OF HOT-PRESSED AL2O3-NBC COMPOSITE MATERIALW.Acchar 1 , C.A.A.Cairo2 and A.M.Segadães3 - 1 Departament of PhysicsFederal 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.

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

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.

E-O16 AGING OF STARCH-CHITIN COMPOSITESC.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.

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 COMPOSITEF. Figueiredo1; M. Silva1; L. Borges 1 ; 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.

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.

E-O18 GROUND RUBBER TIRE AS FILLER FOR ELASTOMERIC COMPOSITIONST. A. de O. Bouças 1 , 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.

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

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.

E-O20 CHARACTERIZATION OF DIFFERENT SPECIES OF FUNCTIONALLY GRADED BAMBOO COMPOSITE STRUCTURESGhavami, K., Ph.D., FASCE.- Pontifícia Universidade Católica do Rio de Janeiro - Rua Marques de São Vicente, n° 225, 22453 -900, Rio de Janeiro- Brazil

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 GROWTHP. 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.

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

E-P1 MANUFACTURE OF THERMOPLASTIC / CARBON FIBER COMPOSITES BY AQUEOUS SUSPENSION PREPREGGINGL. 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.

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

E-P2 SHEAR STRENGTH OF COMPOSITE/METAL JOINTS BONDED BY EPOXY ADHESIVESR.C.O.M. Afonso, F.L. Bastian, Laboratory of Composite Materials, COPPE/UFRJ, CP 68505, 21941-972, Rio de Janeiro, Brazil.

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

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.

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.

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 SENSORSF.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.

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.

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

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 COMPOSITESW.S. Cavalcanti, CDEP/CCT/UFCG; L.H. de Carvalho; DEMa/CCT/UFCG, Caixa Postal 10034, CEP 58109-970, Campina Grande, PB, Brazil.

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.

E-P8 BIOGENIC SILICA MICROFIBERS / SILICONE COMPOSITEV. 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.

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.

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.

E-P10 PREPARATION OF THE POLYESTER NONWOVEN COMPOSITE IMPREGNATED WITH POLYANILINE TO BE USED AS RAML.C.Folgueras 1 , 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.

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.

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 5m, 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.

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.

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

J.M.R.P.,Gonçalves 1 ; 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.

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.

E-P14 FRACTOGRAPHIC ANALYSIS OF STRUCTURAL POLYMERIC COMPOSITES IN TENSILE TESTL. A. L. Franco 1 ; 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.

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 COMPRESSIONL. A. L. Franco 1 ; 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.

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.

E-P16 HYGROTHERMAL EFFECTS ON THE TENSILE MODULUS OF CARBON FIBER/EPOXY COMPOSITESE. 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.

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 LAMINATEG.Q. Chaves 1 , 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.

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.

E-P18 CVD DIAMOND FILMS GROWTH ON SiC-SiC CONVERTED COMPOSITEC. 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.

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 APPLICATIONA. 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

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.

E-P20 CONDUCTIVE BLEND BASED ON EPICHLOMER-C RUBBER AND POLYANYLINE: AN ELECTRODE FOR CAPACITORSM. 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.

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

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]

E-P22 CHANGES IN PLASTER MICROSTRUCTURE BY ADDING GYPSUM: MECHANICAL PROPERTIES STUDIESR.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.

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 COMPOSITESR. C. S. Freire Jr1; E. M. F. de Aquino 2 - 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.

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.

E-P24 THE INFLUENCE OF FILLER DRYING TEMPERATURE ON THE MECHANICAL PROPERTIES OF POLYURETHANE/CLAY NANOCOMPOSITESM. R. O. Pinto1; S. M. L. Silva2, A. C. F. M. Costa2, L. H. de Carvalho 2 , 1DEQ/CCT/UEPB, Campina Grande, PB, Brazil; 2DEMa/CCT/UFPB – C. Postal 10034 Cep 58109-970, Campina Grande,PB, Brazil.

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 METHODSC. V. Rocha 1 ; 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.

Silicon nitride fluxed with Y2O3 + Al2O3 were gas pressure sintered (GPS), while the Si 3N4

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.

E-P26 THERMOGRAVIMETRIC ANALYSIS OF PLASMA TREATED FIBRE/RESIN COMPOSITESM. O. H. Cioff 1,2 ; 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.

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 PROCEDUREAna 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.

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.

E-P28 MICROSTRUCTURAL STUDY OF POLYMERIC COMPOSITE CYLINDERSG. Marinucci; A H. P. de Andrade - Instituto de Pesquisas Energéticas e Nucleares, SP Brasil.

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 MOLDINGE. 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.

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).

E-P30 HYGROTHERMAL EFFECTS ON THE ELASTIC CONSTANTS OF CONTINUOUS GLASS FIBER/EPOXY/ALUMINUM HYBRIDS COMPOSITE MATERIALS OBTAINED BY FREE VIBRATION METHODE. 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.

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.

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.

E-P32 INFLUENCE OF MOISTURE AND TEMPERATURE ON COMPRESSIVE STRENGTH OF CARBON/EPOXY COMPOSITESJ. 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

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 5C 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+ BENTONITEE. M. Araújo 1 ; 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.

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.

E-P34 NANOCOMPOSITES OF AMORPHOUS HYDROGENATED CARBON AND SILOXANE NETWORKS PRODUCED BY PECVDB. C. Trasferetti1; R. V. Gelamo 1 ; 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 

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 BEAMM. C. Évora 1 ; 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.

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.

E-P36 COMPUTER MODELLING FOR OPTIMIZATION POLIMERIC BLENDSG. de Carvalho, Gil; M. P.R. da Silva; J. M. P. Machado - IPRJ –UERJ, Rua Alberto Rangel, sn 28614-970 Nova Frigurbo - RJ.

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 CLOTHSL.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.

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.

E-P38 MICROSTRUCTURAL AND FRACTURE SURFACE ANALYSIS OF ALUMINA-ZIRCONIA COMPOSITES

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.

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-PHENOLICR. S. Rosa1, M. L. Pontarolli1, D. Dibbern-Brunelli 1 , 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.

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).

E-P40 MECHANICAL AND MORPHOLOGICAL BEHAVIOUR OF PC/PCL BLENDSF. L. B. O. Oliveira1; M. C. A. M. Leite 1 ; 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.

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 CERMETSA. S. Dias 1 , 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.

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.

E-P42 ORNAMENTAL ROCK CUTTING RESIDUE AS MINERAL FILLER TO POLYMERIC MATRIX MATERIALSI. 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@bol.com.br

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 FIBERSP. Antich; A.Vázquez; C. Bernal - INTEMA, Juan B. Justo 4302, B7608FDQ Mar del Plata, Argentina

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.

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.

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 TEMPERATUREC. A. A. Cairo 1 , 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.

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.

E-P46 STUDY OF CARBON FIBER/POLYAMIDE LAMINATES COATED WITH POLYANILINE BLENDS AS RADAR ABSORBING MATERIALR. S. Biscaro 1 , 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

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 NANOCOMPOSITESV.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.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.

E-P48 EVALUATION OF THE FLEXURAL AND SHEAR STRENGTH OF CARBON/EPOXY COMPOSITES USED IN AERONAUTICAL FIELDJ. 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.

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. Nohara 2 ; 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

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

E-P50 DYNAMIC PROPERTIES OF PVC-GREEN COCONUT FIBER COMPOSITESR.L.Ferreira 1 ; 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.

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 TEMPERATURESM. Florian 1 ; 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.

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.

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.

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 ADHESIVESA. 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.

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.

E-P54 NYLON-6/CLAY (NANO) COMPOSITES PREPARED BY MELT INTERCALATIONT. 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.

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 MATRICESC. L. Nogueira 1,2 , 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.

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.

E-P56 MECHANICAL BEHAVIOR OF -SIC-BASED NANOCOMPOSITESE. S. Lima 1 ; 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.

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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