SBPMat
BRAZIL-MRS
2nd Brazilian MRS Meeting
October 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)
1
INVITED PRESENTATIONS
E-I1
SOME ASPECTS OF THE DETERMINATION OF ADHESION PARAMETERS IN
COMPOSITES
B. Lauke - Institut für Polymerforschung Dresden e.V., Hohe Str. 6, 01069 Dresden, Germany
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 (K 1) 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.
E-I3
COMPOSITE MATERIALS FOR ARCHITECTURE AND BUILDING – A REVIEW
2
Philippe 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
STRUCTURES
Sérgio 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.
E-I5
COMPOSITE POSTS FOR ORAL REHABILITATION
3
C. A. Cimini Jr.1, R. C. Albuquerque2, W. A. Vasconcellos2 - 1 Mechanical Engineering
Department, Engineering School, Federal University of Minas Gerais Belo Horizonte, MG, Brazil;
2
Department 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 twostage 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
MATERIALS
C. Carfagna, University of Naples “Federico II”- Department of Materials and Production
Engineering, Piazzale Tecchio 80 80125 Napoli (Italy), e.mail: carfagna@unina.it – ICTP CNR via
Campi Flegrei Pozzuoli Napoli (Italy), e.mail: director@irtemp.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.
E-I7
EFFECTIVE
USE
OF COMPOSITE
4
STRUCTURES: BUILDING
BETTER DESIGN
METHODOLOGIES
Paul A. Lagace - Professor of Aeronautics & Astronautics and of Engineering Systems Technology Laboratory for Advanced Composites, Massachusetts Institute of Technology,
Cambridge, Massachusetts, U.S.A.
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 REVIEW
Frédéric Dartigues and Yann Le Petitcorps - ICMCB-CNRS-UPR 9048
87, 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 « insitu » precipitation of the reinforcement at a very low cost of fabrication. The properties and
microstructures of all these materials are compared and discussed.
KEYWORDS :Titanium Matrix Composites, SiC CVD filaments, « in-situ » precipitation,
Fiber/matrix reaction.
E-I9
STRUCTURAL CERAMIC-MATRIX COMPOSITES - AN OVERVIEW
5
Roberto Tomasi, Universidade Federal de São Carlos - Departamento de Engenharia de Materiais
(DEMa) - São Carlos/SP, CEP: 13565-905. E-mail addreess: tomasi@power.ufscar.br.
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 FIBERS
L.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.
E-I11
COMPOSITE MATERIALS FOR BIOMEDICAL APPLICATIONS
6
L. Ambrosio, P.A. Netti, L. Nicolais - Institute of Composite and Biomedical Materials, CNR and
Interdisciplinary Research Centre on Biomaterials, University of Naples “Federico II”, Piazzale
Tecchio 80, 80125 Naples, Italy. Tel. +39.081.7682513; Fax: +39.081.2425932; Email:
Ambrosio@unina.it
The present research is aimed to study in a systematic and quantitative manner the effect of the 3D 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 collagenHA 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
CENTURY
Lawrence T. Drzal, University Distinguished Professor, A. K. Mohanty, Associate Professor, and
M. Misra, Visiting Associate Professor, Department of Chemical Engineering and Materials
Science, Composite Materials and Structures Center, Michigan State University, 2100 Engineering
Building, East Lansing, MI 48824, USA, e-mail: drzal@egr.msu.edu
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.
ORAL PRESENTATIONS
7
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
NANOCOMPOSITES
F.G.R. Filho, T. J. A. de Melo, L.H. de Carvalho, S.M.L. Silva, DEMa/CCT/UFCG, Caixa Postal
10034, CEP 58109-970, Campina Grande, PB, Brazil
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.
E-O3
MATHEMATICAL MODEL OF THE FUNCTION BETWEEN PARTICLES DISTRIBUTION
8
OF SiC IN ALUMINUM MATRIX AND THE COMPOSITE MATERIAL RESISTANCE
Z. M. Boari1; W. A. Monteiro1; C. A. J. Miranda1 - 1IPEN-CNEN, Material Science and
Technology Center, São Paulo; 2IPEN-CNEN, Nuclear Engineering - Structural Mechanics
Department, São Paulo.
This work deals with a composite material with SiC particles mixed in an aluminum matrix.
Qualitative analyses indicate that microstructural characteristics were very influenced by SiC
particulate distribution. Several studies have recognized the deviations from the periodicity of
reinforcement distribution can markedly influence the composite elastic and plastic deformation
characteristics. The composite overall response is influenced by the physical and geometrical
properties of the reinforcing phases. The finite element method, the Eshelby method and dislocation
mechanisms are usually employed in the formulation of the composite constitutive response. The
aim of this work is to study the relationship between the particle distribution and the metal matrix
composite resistance and to propose a mathematical model for the composite elastic behavior. The
proposed formulation was applied to establish the thermal stress field in an aluminum-SiC
composite due to its fabrication process – the mixing is done at 600oC and the material is supposed
to be used at room temperature. The analytical results, presented as stress probabilities, were
compared with the numerical ones, presented as stress distributions from the numerical model,
obtained with a commercial finite element code. Both results compare well with same trends and
very close average values of the thermal stresses. It is also shown that, if the Maxwell-Boltzmann
distribution law is used, it is possible to obtain the relationship between the distribution particles
and the material resistance through the Eshelby's thermal stress.
E-O4
STEAM CURING AND DELAYED ETTRINGITE FORMATION IN BRAZILIAN CEMENTS
G. Camarini, E L. F. Júnior - Departamento de Arquitetura e Construção Faculdade de Engenharia
Civil - Universidade Estadual de Campinas - Caixa Postal 6021 – Distrito Barão Geraldo –
Campinas – SP – CEP 13083-970.
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.
E-O5
REACTION-INDUCED PHASE SEPARATION IN EPOXY/POLYSULFONE/POLY (ETHER
9
IMIDE) SYSTEMS: 1. PHASE DIAGRAMS
M.I. Giannotti1; M.L. Foresti1; M.J. Galante1; P.A. Oyanguren1; J. B. Justo2; I. Mondragon 1
Institute 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, conversioncomposition 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
COMPOSITES
E.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 640 oC 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.
E-O7
SILICON NITRIDE/SILICON CARBIDE PARTICULATE COMPOSITES:
10
SINTERING
BEHAVIOR
Rumbao, A.C.S.C; J. C. Bressiani; A. H. A. Bressiani - IPEN - Instituto de Pesquisas Energéticas e
Nucleares- Centro de Ciências e Tecnologia de Materiais. Av. Prof. Lineu Prestes, 2242 – Cidade
Universitária. CEP: 05508-000 - São Paulo - SP – Brasil.
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 particulatereinforced 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 REPAIR
R.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, metalcomposite 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.
E-O9
REACTIVE MICROSPHERES AS ACTIVE FILLERS FOR EPOXY RESINS
11
C. Carfagna, V. Ambrogi, Department of Materials and Production Engineering, University of
Naples “Federico II”, Piazzale Tecchio, 80, 80125 Naples, Italy; G. Cicala, A. Pollicino, A. Recca,
Department of Physical and Chemical Methodologies for Engineering, University of Catania, Viale
A. Doria 6, 95125 Catania, Italy; G. Costa, IMAG-CNR, Via De Marini, 6, 16149 Genova, Italy.
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 T g 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 COMPOSITES
E. M. Araújo1; T. J. A. Mélo1; L. N. L. Santana1; G. A. Neves1; H. C. Ferreira1; H. L. Lira1; L. H.
Carvalho1; M. M. A`vila Jr2; M. K. G. Pontes2; I. S. Araújo2 – 1 DEMa/CCT/UFCG, C. Postal:
10034, CEP 58109-970, Campina Grande, Paraíba; 2 Student of the Materials Engineering/UFCG.
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.
E-O11
EVALUATION
OF
THE
MECHANICAL
12
PROPERTIES
OF
SISAL-POLYESTER
COMPOSITES AS A FUNCTION OF THE POLYESTER MATRIX FORMULATION
V. M. Fonseca1; V.J.Fernandes Jr.1; L.H. de Carvalho2; J.R.M.d’Almeida3 - 1DQ/UFRN, Caixa
Postal 1662, CEP 59078-970, Natal, RN, Brazil; 2DEMa/CCT/UFCG, Caixa Postal 10034, CEP
58109-970, Campina Grande, PB, Brazil; 3DCMM/PUC-RJ, Caixa Postal 38008, CEP 22453-900,
Rio de Janeiro, RJ, Brazil
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 METHOD
M.R.W.S. Abdala, E.M. Castrodeza, F.L. Bastian - Laboratory of Composite Materials,
COPPE/Federal University of Rio de Janeiro, CP 68505, 21941-972, Rio de Janeiro, Brazil.
Fiber-metal laminates (FMLs) are structural composites designed aiming to produce a damagetolerant 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.
E-O13
ENVIRONMENTAL EFFECTS ON THE INTERLAMINAR SHEAR STRENGTH OF
13
POLYMERIC COMPOSITES
J. A. P. Cunha1; M. L. Costa2, M. C. Rezende2, 1Departamento de Engenharia Mecânica,
ITA/SENAI – 12228-904-S. J. Campos/SP, Brazil;
2
Divisão 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 (88.111.9 MPa)
presented a decrease of 9% in the ILSS when compared with specimens non-conditioned
(97.65.2MPa). But the specimens submitted to the salt spray chamber (102.4  3.35MPa)
presented a small increase of the ILSS. These results suggest that the temperature cause more
damage than the moisture and the salt in the interlaminar shear properties.
E-O14
TEM STUDY OF HOT-PRESSED AL2O3-NBC COMPOSITE MATERIAL
W.Acchar1, C.A.A.Cairo2 and A.M.Segadães3 - 1 Departament of Physics
Federal University of Rio Grane do Norte, Natal-RN, Brazil, CEP:59072-970; 2 Divisão de
Materiais, Centro Técnico Aeroespacial, Instituto de Aeronáutica e Espaço, Praça Marechal do Ar
Eduardo Gomes 50, São José dos Campos –SP; 3 Departament of Galss and Ceramics, Univeristy
of Aveiro, Portugal.
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 Al 2O3TiC. 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.
E-O15
COMPARATIVE EVALUATION OF PROCESS PARAMETERS ON CORE MOVEMENT ON
14
HONEYCOMB SANDWICH PANELS CURED IN AUTOCLAVE
P. 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 COMPOSITES
C.T. Andrade, R.C.R.S. Rosa - Instituto de Macromoléculas Professora Eloisa Mano, Universidade
Federal do Rio de Janeiro, P.O. Box 68525-970, Rio de Janeiro, Brazil.
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.
E-O17
A
NUMERICAL
-EXPERIMENTAL
15
APPROACH
FOR
IDENTIFYING
ELASTIC
PARAMETERS IN COMPOSITE
F. Figueiredo1; M. Silva1; L. Borges1; F. Rochinha1; S. F. Bastos2 - 1LMS - Solid Mechanics
Laboratory - Department of Mechanical Engineering, EE/COPPE - Federal University of Rio de
Janeiro-UFRJ - Box 68503 – 21945-970 - Rio de Janeiro, RJ, Brazil; 2 SENAI – CETIQT; Dr.
Manoel Cotrim 195, Riachuelo. Rio de Janeiro, RJ, Brazil.
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 RayleighRitz 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 COMPOSITIONS
T. A. de O. Bouças1, C.R.G. Furtado1, L.L.Y. Visconte2, R.C.R Nunes2, E.B.A.V. Pacheco2 1
Instituto 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 butadienestyrene 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.
E-O19
CONTROLLED MICROSTRUCTURE MORTAR MATERIALS TO BENEFIT CREEP
16
PROPERTY FOR CIVIL CONSTRUCTION
M. A. Coimbra;M. R. Morelli, Department of Materials Engineering, Federal University of São
Carlos, PO BOX 676, São Paulo, Brazil.
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 STRUCTURES
Ghavami, K., Ph.D., FASCE.- Pontifícia Universidade Católica do Rio de Janeiro - Rua Marques
de São Vicente, n° 225, 22453 -900, Rio de Janeiro- Brazil
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.
E-O21
A QUANTITATIVE MODEL OF EGGSHELL GROWTH
17
P. Jeraldo, J. L. Arias, F. Lund, S. Maeckelberghe and D. Walgraef, Centro para la Investigación
Interdisciplinaria Avanzada en Ciencias de Materiales (CIMAT), Universidad de Chile, Santiago,
Chile.
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.
POSTER PRESENTATIONS
18
E-P1
MANUFACTURE OF THERMOPLASTIC / CARBON FIBER COMPOSITES BY AQUEOUS
SUSPENSION PREPREGGING
L. B. Nohara1; A. M. Kawamoto2; M. Wills3; M. C. Rezende4 - 1Departamento de Engenharia
Aeronáutica e Mecânica – ITA / CTA, Pça. Mal.-do-Ar Eduardo Gomes, 50, São José dos Campos,
12228-904, São Paulo, Brazil; 2Divisão de Química / Instituto de Aeronáutica e Espaço / CTA;
3Chemistry Department, Warwick University; 4Divisão de Materiais / Instituto de Aeronáutica e
Espaço / CTA.
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 ADHESIVES
R.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.
E-P3
MECHANICAL PROPERTIES OF PU/HESSIAN CLOTH COMPOSITES AS A FUNCTION OF
19
THERMAL AND HYGROTHERMAL AGEING
M.C.B. Costa & L.H. de Carvalho, DEMa/CCT/UFCG, Caixa Postal 10034, CEP 59109-970,
Campina Grande, PB, Brazil.
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.
E-P5
NATURAL RUBBER AND CARBON BLACK COMPOSITES CHARACTERIZED WITH
20
PRESSURE SENSORS
F.A. Oliveria; N. Alves; C.J.L.Constantino; J.A. Giacometti; A.E. Job - Depto. de Física, Química e
Biologia, FCT-UNESP, CP. 467, 19060-900, Presidente Prudente, SP, Brazil.
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 MODIFICATION
J.B.A. da Silva, J.C. Macedo, S.M.L. Silva, L.H. de Carvalho, DEMa/CCT/UFCG, Caixa Postal
10034, CEP 58109-970, Campina Grande, PB, Brazil.
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.
E-P7
WATER SORPTION OF JUTE AND JUTE/GLASS FIBER FABRIC UNSATURATED
21
POLYESTER COMPOSITES
W.S. Cavalcanti, CDEP/CCT/UFCG; L.H. de Carvalho; DEMa/CCT/UFCG, Caixa Postal 10034,
CEP 58109-970, Campina Grande, PB, Brazil.
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 COMPOSITE
V. P. e Silva; I. V. P. Yoshida; M. do C. Gonçalves; M. Rodrigues - Instituto de Química da
UNICAMP, Caixa Postal 6154, 13083-970, Campinas/SP, Brazil.
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).
E-P9
FRACTURE TOUGHNESS EVALUATION OF COMPOSITE MATERIALS FOR PIPELINE
22
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 RAM
L.C.Folgueras1, R. Faez2; M.C. Rezende3 - 1Instituto Tecnológico de Aeronáutica / CTA, Pça.
Marechal-do-Ar Eduardo Gomes, 50 – CEP: 12228-904 - S.J. Campos - SP, Brazil; 2IP&D /
UNIVAP, S.J. Campos – SP, Brazil; 3AMR/IAE/CTA, S.J. Campos, Brazil.
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
E-P11
CHEMISTRY COMPOSITION OF MICROSTRUCTURE OF SYSTEM SnO2-ZnO-WO3
23
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 5m, and high electrical resistence. The studied system
have ohmic character, which may be changed by doping with a increasing conductivity agent. The
samples were characterized by MET-EDS, and the chemistry composition of the microstructure
was observed the in grains, grains boundaries, triple points and precipitates. The tungsten is seem in
grain boundaries and precipitates increasing the resistivity.
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
E-P13
RADAR ABSORBING MATERIALS (8-12 GHz) BASED ON RUBBER SILICONE AND NiZn
24
FERRITE COMPOSITES
J.M.R.P.,Gonçalves1; J.C.N. Dutra2; I. M., Martin3; E. L., Nohara4; M. C. Rezende1 - 1Divisão de
Materiais / Instituto de Aeronáutica e Espaço / CTA, Pça. Mal.-do-Ar Eduardo Gomes, 50, São
José dos Campos, 12228-904, São Paulo, Brazil; 2Divisão de Química / Instituto de Aeronáutica e
Espaço / CTA; 3Departamento de Matemática e Física – Universidade de Taubaté / UNITAU;
4
Departamento 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
TEST
L. A. L. Franco1;G. M. Cândido2; M. C. Rezende1 - 1Centro Técnico Aeroespacial/Instituto de
Aeronáutica e Espaço/Divisão de Materiais; 2Centro Técnico Aeroespacial/Instituto de Fomento
Industrial. Praça Marechal-do-Ar Eduardo Gomes, 50,Vila das Acácias - CEP 12228-904 São José
dos Campos - SP – Brasil.
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
E-P15
FRACTOGRAPHIC ANALYSIS OF STRUCTURAL POLYMERIC COMPOSITES IN
25
COMPRESSION
L. A. L. Franco1;G. M. Cândido2; M. C. Rezende1 - 1Centro Técnico Aeroespacial/Instituto de
Aeronáutica e Espaço/Divisão de Materiais; 2Centro Técnico Aeroespacial/Instituto de Fomento
Industrial. Praça Marechal-do-Ar Eduardo Gomes, 50,Vila das Acácias - CEP 12228-904 São José
dos Campos - SP – Brasil.
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
COMPOSITES
E. C. Botelho, M. L. Costa, M.C. Rezende, L. C. Pardini - Divisão de Materiais – Instituto de
Aeronáutica e Espaço – CTA; CEP: 12228-904 – São José dos Campos – São Paulo – Brazil.
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
E-P17
HYGROTHERMAL AGEING INFLUENCE ON FRACTURE TOUGHNESS OF ARALL 2 3/2
26
FIBER-METAL LAMINATE
G.Q. Chaves1, E.M. Castrodeza2, F.L. Bastian2 - 1Materials Group, IPD, Av. das Américas, CP
23020, 28705, Rio de Janeiro, Brazil; 2Laboratory of Composite Materials, COPPE/UFRJ, CP
68505, 21941-972, Rio de Janeiro, Brazil.
Fiber-metal laminates (FMLs) are structural composites designed aiming to produce a damagetolerant 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 COMPOSITE
C. A. A. Cairo; M. Florian, M. L. A. Graça, N. G. Ferreira, Divisão de Materiais – Instituto de
Aeronáutica e Espaço – Centro Técnico Aeroespacial - CEP: 12228-904 – São José dos Campos –
São Paulo – Brazil.
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, microRaman spectra were recorded in backscattering configuration at room temperature employing the
argon-ion laser excitation line (514.5 nm).
E-P19
ELECTROSTATIC DEPOSITION OF NANOFIBERS FOR SENSOR APPLICATION
27
A. N. R. da Silva1,2,3, I. Ramos1, R. Furlan1, J. J. Santiago-Avilés1 – 1University of Puerto Rico at
Humacao, Puerto Rico USA; 2 LSI – EPUSP, São Paulo, Brazil; 3 FATEC-SP, Brazil
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 CAPACITORS
M. A. Soto-Oviedo; V. C. Nogueira; C. Longo; O. A. Araujo; M.-A. De Paoli - Laboratório de
Polímeros Condutores e Reciclagem, Instituto de Química, Unicamp. C. Postal 6154, 13083-971.
Campinas, SP, Brazil.
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.
E-P21
NANOCOMPOSITES EVOLVING TRANSPARENT POROUS GLASS AND CADMIUM
28
SULFIDE
R. 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) diethyldithiocarbamate, 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 STUDIES
R.D. Pinho, J.P. Soares, E.V.A. Oliveira, A.H. Shinohara, Laboratório de Tecnologia do Gesso,
DEMEC-CTG-UFPE, Av. Acad. Hélio Ramos, S/N, CDU, Recife-PE, Brazil; M.O.E. Schwartz,
CA-DQF-CCEN-UFPE, Recife-PE, Brazil; A.C. Inojosa, J. Inojosa Filho, Supergesso S.A. Ind. e
Com., BR316, Araripina-PE, Brazil.
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.
E-P23
FATIGUE BEHAVIOR OF INDUSTRIALLY MANUFACTURED LAMINATE COMPOSITES
29
R. C. S. Freire Jr1; E. M. F. de Aquino2 - 1 UFRN – CCET – PDCEM, Campus Universitário –
Lagoa Nova, Natal, RN, Brasil CEP: 59072-970; 2 UFRN-DEM/PPGEM - Centro de Tecnologia,
Campus Universitário - Lagoa Nova, Natal - RN - CEP: 59072 – 970.
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 NANOCOMPOSITES
M. R. O. Pinto1; S. M. L. Silva2, A. C. F. M. Costa2, L. H. de Carvalho2, 1DEQ/CCT/UEPB,
Campina Grande, PB, Brazil; 2DEMa/CCT/UFPB – C. Postal 10034 Cep 58109-970, Campina
Grande,PB, Brazil.
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.
E-P25
FRACTURE TOUGHNESS OF Si3N4 BASED CERAMICS USING THE IF, SEVNB AND CNB
30
METHODS
C. V. Rocha1; C. A. Costa2 – 1 Laboratório de Materiais Poliméricos, Centro de Tecnologia, Bl.
F/211, Cidade Universitária, CEP 21945-970, Rio de Janeiro, Brazil; 2Centro de Tecnologia, Bl.
F/210, Cidade Universitária, CEP 21945-970, Rio de Janeiro, Brazil.
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 COMPOSITES
M. O. H. Cioff1,2; H. J. C. Voorwald3; M. L. C. P. Silva4; G. L. J. P. Silva4 -1UNESP campus de
Sorocaba - Av. 3 de março CEP 18013/280 Sorocaba/SP. 2 Division of Materials-AMR / IAE /
CTA São José dos Campos / SP / BR-CEP:1288-904. 3UNESP campus de Guaratinguetá - Av.
Ariberto Pereira da Cunha, 333 CEP 12516-410, Guaratinguetá/SP. 4DEQUI/FAENQUIL Rodovia Itajubá - Lorena, Km 74,5 Campinho, cxp 116 Lorena.
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.
E-P27
SYNTHESIS OF SILICA-TUNGSTEN COMPOSITE FOR BRACHYTHERAPY PROCEDURE
31
Ana Maria M. Santos; Adelina P. Santos, Jaqueline M. Paulo, Vanessa A. Regis - Center of
Nuclear Technology Development/CNEN, Brazil, Rua Mário Werneck s/no - Pampulha, Belo
Horizonte, MG, CEP-31120-970 Brazil.
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 CYLINDERS
G. 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.
E-P29
OPTIMIZATION OF THE PROCESSING PARAMETERS OF CARBON FIBER FABRIC
32
/POLYAMIDE 6/6 COMPOSITE MATERIALS OBTAINED BY HOT COMPRESSION
MOLDING
E. C. Botelho, M. C. Rezende - Divisão de Materiais – Instituto de Aeronáutica e Espaço – Centro
Técnico Aeroespacial CEP: 12228-901 – São José dos Campos – São Paulo – Brazil.
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 METHOD
E. C. Botelho, L. C. Pardini, M. C. Rezende. - Divisão de Materiais – Instituto de Aeronáutica e
Espaço – CTA; CEP: 12228-901 – São José dos Campos – São Paulo – Brazil.
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
E-P31
ELECTRIC BEHAVIOR OF TIN OXIDE DOPED WITH ZnO AND Ta 2O5.
33
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 COMPOSITES
J. M. F. de Paiva, Mirabel Cerqueira Rezende - 1,2 Divisão de Materiais – AMR - Instituto de
Aeronáutica e Espaço – IAE - Centro Técnico Aeroespacial – CTA - Praça Marechal do Ar
Eduardo Gomes, 50 – Vila das Acácias; 12228-904 – São José dos Campos/SP – Brasil
Carbon fiber reinforced composites (CFRC) are very used in aeronautical industry to manufacture
several components as flaps, aileron, landing-gear doors and others. These components can suffer
mechanical damages mainly after moisture exposure. As a consequence, it is important to evaluate
the influence of this parameter on the mechanical behavior, for example, the compressive strength.
In this work were studied three types of composites combining the F155 epoxy matrix with carbon
fiber fabric styles Plain Weave (PW) and Eight Harness Satin (8HS) and F584 epoxy matrix with
8HS. These laminates were obtained by autoclave molding using prepregs and following an
appropriate curing cycle, i.e., heating rate at 2.5  2ºC/min until reaching isothermals at 116ºC
(60min) for F155 matrix and 177ºC (120min) for F584 matrix. In agreement with the supplier of
prepregs (Hexcel Composite) the F155 epoxy matrix was not modified and the F584 matrix was
toughened with rubber. After molding the laminates they were cut in twenty specimens attending
the ASTM D3410. These specimens were tested at room temperature and after hygrothermal
conditioning at 80  5C and 90  5% of humidity in accordance with ASTM D5229. The
conditioned sample weight became constant in eight weeks. The results showed that the
hygrothermal conditioning provoked the decrease of the compressive strength in, approximately, 820% depending of the laminate family. In sequence, the failure modes of the tested specimens were
evaluated showing good agreement with the literature.
Acknowledgements: FAPESP
E-P33
PREPARATION OF NYLON6/ORGANOCLAY COMPOSITES BY MELT INTERCALATION
34
METHOD FROM Na+ BENTONITE
E. M. Araújo1; T. J. A. Mélo1; L. N. L. Santana1; G. A. Neves1; L. H. Carvalho1; M. M. A`vila Jr.2;
E. Leal2; P. M. Silva2 – 1DEMa/CCT/UFCG – C. Postal 10034, CEP 58109-970, Campina Grande,
PB; 2 students of the Materials Engineering – UFCG.
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 PECVD
B. C. Trasferetti1; R. V. Gelamo1; F. P. Rouxinol1, M. A. Bica de Moraes1, C. U. Davanzo2, M. C.
Gonçalves2 - 1Laboratório de Processos de Plasma – IFGW/Unicamp, CP 6165, CEP – 13087-970,
Campinas–SP, Brazil; 2IQ/Unicamp, CP 6154, CEP – 13083-970, Campinas–SP, Brazil
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.
E-P35
STUDY OF GFRP COMPOSITES CURED BY ELECTRON BEAM
35
M. C. Évora1; G. Marinucci2; D. A. Sishitsuji3; L. G. Andrade e Silva4 - 1Instituto de Estudos
Avançados/CTA, São José dos Campos – SP, Brasil; 2Instituto de Pesquisas Energéticas e
Nucleares-IPEN São Paulo, Brasil;3Centro Tecnológico da Marinha em São Paulo-CTMSP/SP- São
Paulo, Brasil, 4 Instituto de Pesquisas Energéticas e Nucleares-IPEN - São Paulo, Brasil.
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 BLENDS
G. de Carvalho, Gil; M. P.R. da Silva; J. M. P. Machado - IPRJ –UERJ, Rua Alberto Rangel, sn
28614-970 Nova Frigurbo - RJ.
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.
E-P37
WATER SORPTION KINETICS AND EFFECTS ON THE MECHANICAL PROPERIES OF
36
PU/HESSIAN CLOTHS
L.H. Carvalho, G.S. Morais, DEMa/CCT/UFCG, Caixa Postal 10034, CEP 58109-970, Campina
Grande, PB, Brazil & O.L.S. Alsina, DEQ/CCT/UFCG, CEP 58109-970, Campina Grande, PB,
Brazil.
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 tailormade 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, nonhomogeneous 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.
E-P39
APLICATION OF THE FOURIER TRANSFORM INFRARED SPECTROSCOPY (FTIR) TO
37
THE STUDY OF THE CURE PROCESS OF PREPREG OF GLASS-PHENOLIC
R. S. Rosa1, M. L. Pontarolli1, D. Dibbern-Brunelli1, R. C. L. Dutra2 - 1Departamento de Química,
Instituto Tecnológico de Aeronáutica, Praça Marechal Eduardo Gomes, 50, Vila das Acácias, CEP
12228-900, São José dos Campos, SP, Brazil; 2Divisão de Química, Instituto de Aeronáutica e
Espaço, Praça Marechal Eduardo Gomes, 50, Vila das Acácias, CEP 12228-900, São José dos
Campos, SP, Brazil.
The objective of this work is: (a) determine the type of phenolic resin of a glass-phenolic preimpregnated (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 BLENDS
F. L. B. O. Oliveira1; M. C. A. M. Leite1; C. R. G. Furtado1; L. R. Bocayuva2, C. M. F. Oliveira2 - 1
Instituto de Química/UERJ, Rio de Janeiro, Brazil;2 IMA/ UFRJ, Rio de Janeiro, Brazil.
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.
E-P41
FINITE ELEMENT ANALYSIS OF INDENTATION IN WC-Co CERMETS
38
A. S. Dias1, G. C. Godoy2, P. R. Cetlin2 - 1 Mechanical Department, Federal University of São João
del-Rei, São João del-Rei P. J. Modenesi; 2Department of Metallurgical Engineering, UFMG, Belo
Horizonte, Minas Gerais, Brazil.
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 MATERIALS
I. C. Bigno1; P. F. Castro2 - 1 Instituto Militar de Engenharia - IME, Praça General Tiburcio 80,
Praia Vermelha, CEP 22290–270, Rio de Janeiro, Brasil; 2 Universidade Federal Fluminense - UFF,
Rua Passo da Pátria 156, Bloco. D, Sala 365, CEP 22240–240, Niterói, Rio de Janeiro, Brasil.
email: icbigno@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.
E-P43
MECHANICAL BEHAVIOR OF HIGH IMPACT POLYSTYRENE REINFORCED WITH
39
SHORT SISAL FIBERS
P. 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.
E-P45
MICROSTRUCTURAL CHARACTERIZATION OF Al2O3-ZrO2-SiC COMPOSITE AFTER
40
OXIDATION IN AIR AT HIGH TEMPERATURE
C. A. A. Cairo1, M. L. A.Graça1; W. Acchar2 - 1Divisão de Materiais – Instituto de Aeronáutica e
Espaço – Centro Técnico Aeroespacial; CEP: 12228-904 – São José dos Campos – São Paulo –
Brazil; 2 Universidade Federal do Rio Grande do Norte.
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 MATERIAL
R. S. Biscaro1, E. C. Botelho2, R. Faez3, M. C. Rezende2 - 1Depto de Engenharia Aeronáutica e
Mecânica – ITA – CTA; 2Divisão de Materiais – Instituto de Aeronáutica e Espaço – CTA, CEP:
12228-904 – São José dos Campos – São Paulo – Brazil; 3 Instituto de Pesquisa &
Desenvolvimento - Universidade do Vale do Paraíba, São José dos Campos – São Paulo – Brazil
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
E-P47
INFLUENCE OF SYNTHESIS CONDITIONS ON THE STRUCTURAL FEATURES OF
41
SILOXANE-PMMA SOL-GEL DERIVATIVE NANOCOMPOSITES
V.H.V Sarmento1, M.R. Frigério1, K. Dahmouche1 C.V Santilli1 S.H Pulcinelli1 A.F. Craievich2 1
Instituto 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 FIELD
J. M. F. de Paiva 1, S. Mayer 2 , M. C. Rezende 1 - 1 Divisão de Materiais – AMR - Instituto de
Aeronáutica e Espaço – IAE - Centro Técnico Aeroespacial – CTA - Praça Marechal-do-Ar
Eduardo Gomes, 50 – Vila das Acácias, 12228-904 – São José dos Campos/SP – Brasil, 2 Embraer
– Empresa Brasileira de Aeronáutica.
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
E-P49
EFFECTS OF THERMAL HISTORY ON CRYSTALLIZATION OF POLY(ETHER ETHER
42
KETONE) (PEEK) AND POLY(PHENYLENE SULFIDE) (PPS)
A. Moura1; L. B. Nohara2; E. L. Nohara3; M. C. Rezende1 - 1Divisão de Materiais / Instituto de
Aeronáutica e Espaço / CTA, Pça. Mal.-do-Ar Eduardo Gomes, 50, São José dos Campos, 12228904, São Paulo, Brazil; 2Departamento de Engenharia Mecânica e Aeronáutica – ITA / CTA;
3
Departamento 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 COMPOSITES
R.L.Ferreira1; C.R.G. Furtado1; M.F. Rosa2; A.A.L. Furtado2; R.C.R Nunes3; L.L.Y. Visconte3;
J.L.Leblanc4 - 1Instituto de Química/UERJ, Rio de Janeiro, Brazil; 2EMBRAPA, Brazil;
3
IMA/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
E-P51
MICROSTRUCTURAL ANALYSIS OF SIC-SIC COMPOSITE OBTAINED BY CONVERSION
43
REACTIONS IN DIFFERENT TEMPERATURES
M. Florian1; C.A.A. Cairo2 - 1-Depto de Engenharia Aeronáutica e Mecânica – ITA – CTA, Pça
Mal. Eduardo Gomes, 50, 12228-901 - São José dos Campos/SP, Brazil; 2-Divisão de Materiais –
Instituto de Aeronáutica e Espaço – CTA, Pça Mal. Eduardo Gomes, 50, 12228-904 São José dos
Campos/SP, Brazil.
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 1400 oC 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 1600 oC, 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.
E-P53
EFFECT OF ADDITION OF FELDSPAR AND TALC ON THE MECHANICAL PROPERTIES
44
OF EPOXY ADHESIVES
A. N. Sousa; R. T. Fujiyama; J. R. Albuquerque; F. L. Bastian -Laboratório de Materiais
Compósitos, PEMM/COPPE/UFRJ- Caixa Postal: 68505 Cep: 21941-942 - Rio de Janeiro- Brasil.
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 INTERCALATION
T. J. A. Mélo; E. M. Araújo; M. P. Baracuhy, L. H. Carvalho – Departamento de Engenharia de
Materiais, Universidade Federal de Campina Grande, Av. Aprígio Veloso, 882, Bodocongó, Caixa
Postal 10034, 58109-970, Campina Grande, Brazil.
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.
E-P55
INFLUENCE OF THE INTERFACE ON THE TENSILE AND IMPACT PROPERTIES OF
45
CARBON FIBER REINFORCED POLYPROPYLENE MATRICES
C. L. Nogueira1,2, J. M. F. de Paiva2, M. C. Rezende2 - 1 Departamento de Engenharia Aeronáutica e
Mecânica / ITA; 2 Divisão de Materiais/IAE/CTA – Centro Técnico Aeroespacial - Pça. Marechal
do Ar Eduardo Gomes, 50, São José dos Campos – SP, CEP: 12228-904.
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 NANOCOMPOSITES
E. S. Lima1; P. L. Brandão1; C. A. Costa2; L. H. L. Louro1 - 1IME, Programa de Ciência dos
Materiais, Praça General Tibúrcio 80, Rio de Janeiro; M. A. P. Santos, IPqM, Grupo de Materiais,
Rua Ipirú (sem numero), Ilha do Governador, Rio de Janeiro; 2 PEMM/COPPE/UFRJ, Centro de
Tecnologia, Cidade Universitária, Rio de Janeiro.
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 + ZrO 2, 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.
46