Depuis des années, les polymères renforcés de fibres (PRF) sont de plus en plus utilisés, notamment dans le domaine du génie civil. Ces matériaux composites sont rigides, tenaces, légers et ils sont inertes face à la corrosion électrochimique, ce qui en fait d’excellents candidats pour de nombreuses applications, par exemple comme barres d’armature dans le béton ou en réhabilitation externe des structures. Récemment, la communauté scientifique s’est tournée vers l’utilisation des nanocomposites polymère (PNC), matériaux biphasés constitués d’une matrice polymère mélangée à des nanoparticules. La très grande surface spécifique de ces dernières augmente significativement les propriétés mécaniques, thermiques ou barrières des polymères. Ces PNC sont de bons candidats pour la réhabilitation et le renforcement des structures en béton. Cependant, les matériaux à matrice polymère soulèvent diverses questions, comme leur dégradation face à l’environnement d’application, humide et parfois alcalin, ou leur mauvaise interface fibre/matrice causée par les natures différentes des fibres hydrophiles et des matrices polymères hydrophobes. Pour répondre à ces problématiques, cette étude porte sur le nanorenforcement des PRF à matrice polymère thermodurcissable utilisés en génie civil. Des nanoparticules, dispersées dans les matrices polymères sous forme de feuillets, induisent un phénomène de tortuosité limitant la diffusion au sein du matériau, augmentant ainsi la durabilité. Ces feuillets peuvent être des argiles, comme les silicates, ou des graphites exfoliés, comme le graphène. Pour améliorer l’interface fibre/résine des PRF, des traitements de surface sur des fibres minérales et naturelles sont effectués pour améliorer leur affinité avec des matrices thermodurcissables. Les objectifs principaux du nanorenforcement sont de : (1) augmenter les propriétés barrières des vinylesters pour augmenter leur durabilité et (2) améliorer l’interface dans les PRF à matrice thermodurcissable. Les résultats montrent que l’intercalation de nanoargiles dans les vinylesters augmente sensiblement la durabilité du polymère, en limitant la diffusion d’humidité au sein du matériau, tout en stoppant l’hydrolyse de la matrice. L’addition de faibles fractions (0.5 % en poids) de graphène oxydé augmente ainsi de plus de 15% les propriétés en flexion du polymère, tout en diminuant l’absorption à saturation (- 8%). À l’interface fibre/matrice, le nanorenforcement réalisé avec de la fumée de silice ou des nanocristaux d’amidon augmente non seulement les propriétés en traction des fibres de basalte et de bambou (jusqu’à 20%), mais aussi leurs interfaces avec les matrices thermodurcissables (vinylester et bio-époxy), avec une augmentation de plus de 25% des propriétés mécaniques des PRF réalisés avec ces fibres modifiées.

Nanocellulose has gained lots of attentions in recent years due to the development of nanotechnology. Thousands of publications have been reported about the fabrication, characterization and application of nanocellulose, among which most of the nanocelluloses were fabricated from the microcrystalline cellulose (MCC) or pulp, and only two methods about the nanocellulose fabrication have been reported, i.e. sulphuric acid hydrolysis and mechanical treatment. The sulphuric acid method can only obtain low yield of nanocellulose and the mechanical treatment can not fabricate nanocellulose with high crystallinity index (CI) and well separation. These problems limit the scale up of nanocellulose to industrial area. Moreover, none of works has reported the application of nanocellulose for the modification of natural fibres and only a few works reported the reinforcement of epoxy with nanocellulose. In this this research, we fabricated nanocellulose directly from hemp fibres by employing oxidation/sonication method with the aim to solve the main problems of nanocellulose fabrication with sulphuric acid hydrolysis or mechanical. By using this method the yield of nanocellulose could up to 54.11 % and the crystallinity of nanocellulose was 86.59 %. In order to expand the application of nanocellulose, we investigated the modification of natural fibres (hemp) with nanocellulose and the fabrication of nanocomposite. Two-step modification, i.e. dodecyltrimethylammonium bromide (DTAB) pretreatment and nanocellulose modification, was used to modify hemp fibres. In this process, we systematically investigated the deformation of hemp fibres, revealed the mechanism of deformation on the mechanical property of single fibre by using Fourier transform infrared spectroscopy (FTIR) and investigated the effect of deformation on the hemp fibre modification with nanocellulose by using energy dispersive X-ray (EDX). The two-step modification increased the mechanical properties of hemp fibres significantly. Compared with raw hemp fibres, the modulus, tensile stress and tensile strain of the two-step nanocellulose modified hemp fibres increase by 36.13 %, 72.80 % and 67.89 %, respectively. Moreover, two-step modification facilitated the improvement of interfacial property of fibres. This novel natural fibre modification provides new clue to exploit nanocellulose as a green chemical agent for natural fibres modification. We modified nanocellulose by using curing agent of epoxy---diethylenetriamine (DETA). This modification could increase the dispersity of nanocellulose in epoxy and reinforce epoxy. Compared with epoxy, the modulus, tensile stress and tensile strain of the modified nanocellulose/epoxy nanocomposite increased 1.42 %, 15.44 % and 27.47 %, respectively.

Ένας συναρπαστικός τομέας της σύγχρονης επιστημονικής έρευνας είναι αυτός των νανοσύνθετων υλικών. Το πεδίο αυτό περιλαμβάνει τη μελέτη πολυφασικών υλικών, στα οποία μία ή περισσότερες από τις χωρικές διαστάσεις κάποιας φάσης βρίσκεται στην περιοχή νανομέτρων (10-9m). Αυτό που ξεχωρίζει τα νανοσύνθετα από τα άλλα συμβατικά σύνθετα υλικά είναι η ικανότητά τους να συνδυάζουν ιδιότητες, οι οποίες είναι απαγορευτικές για τα παραδοσιακά υλικά, αλλά και η λειτουργικότητα που παρουσιάζουν. Η εισαγωγή των νανοσύνθετων υλικών και οι πολλές επιστημονικές μελέτες που έγιναν τα τελευταία χρόνια στόχευαν και προσδοκούσαν σε μία δραματική βελτίωση των μηχανικών τους ιδιοτήτων, πράγμα που πολλές φορές δεν επαληθεύτηκε. Στις μέρες μας υπάρχει ένα αυξανόμενο ενδιαφέρον για τη μελέτη της διηλεκτρικής συμπεριφοράς και αγωγιμότητας των νανοσύνθετων πολυμερικής μήτρας με ανόργανα νάνο-εγκλείσματα. Τα νανοσύνθετα συστήματα πολυμερικής μήτρας – ανόργανων νάνο-εγκλεισμάτων αναμένεται να αποτελέσουν μια νέα γενιά υψηλού τεχνολογικού ενδιαφέροντος υλικών που θα επιδεικνύουν λειτουργικές ιδιότητες λόγω της μεταβαλλόμενης πόλωσης των κεραμικών νανοσωματιδίων. Η διασπορά κεραμικών εγκλεισμάτων στο εσωτερικό πολυμερικής μήτρας προσδίδει στα σύνθετα συστήματα βελτιωμένη μηχανική και ηλεκτρική συμπεριφορά. Τέτοιου τύπου συστήματα υλικών, που έχουν υψηλή ηλεκτρική διαπερατότητα (high-Κ materials) χρησιμοποιούνται σε ηλεκτρονικές εφαρμογές, καθώς μειώνουν τα ρεύματα διαρροής και παράλληλα λειτουργούν ως ενσωματωμένοι νανο-πυκνωτές εισάγοντας ένα νέο είδος νανο-διατάξεων για την αποθήκευση ενέργειας. Η ηλεκτρική απόκρισή τους, εκφράζεται κυρίως μέσω της ηλεκτρικής διαπερατότητας και μπορεί να ρυθμιστεί, ελέγχοντας τον τύπο, το μέγεθος και την ποσότητα της κεραμικής ενίσχυσης. Η ενσωμάτωση πιεζοηλεκτρικών κρυστάλλων, που επιδεικνύουν μεταβαλλόμενη πόλωση, σε μια πολυμερική μήτρα, όπως η εποξειδική ρητίνη –που εν γένει είναι ηλεκτρικός μονωτής- με χαμηλή ηλεκτρική διαπερατότητα και υψηλή διηλεκτρική αντοχή μπορεί να οδηγήσει στην ανάπτυξη ενός ευφυούς συστήματος. Σκοπός αυτής της εργασίας είναι η παρασκευή και ο χαρακτηρισμός σύνθετων πολυμερικών συστημάτων εποξειδικής ρητίνης – νανοσωματιδίων οξειδίου του ψευδάργυρου (ZnO) καθώς και σύνθετων υβριδικών συστημάτων εποξειδικής ρητίνης - νανοσωματιδίων οξειδίου του ψευδάργυρου (ZnO) και καρβιδίου του τιτανίου (TiC) ώστε να οδηγηθούμε σε ένα σύστημα υλικών με βέλτιστη συμπεριφορά. Τα δοκίμια που παρασκευάστηκαν χαρακτηρίστηκαν διηλεκτρικά, μορφολογικά και θερμικά. Τα νανοσύνθετα υποβλήθηκαν σε μορφολογικό και θερμικό χαρακτηρισμό. Η μορφολογία των δειγμάτων εξετάστηκε μέσω του Ηλεκτρονικού Μικροσκοπίου Σάρωσης (SEM). Από την εξέταση προέκυψε πως η διασπορά των νανο-σωματιδίων μπορεί να χαρακτηρισθεί ως, τουλάχιστον, ικανοποιητική και σε όλα τα συστήματα συνυπάρχουν νανοδιασπορές και συσσωματώματα. Η θερμική απόκριση των συστημάτων μελετήθηκε μέσω της τεχνικής της Διαφορικής Θερμιδομετρίας Σάρωσης (DSC). Από τα θερμογραφήματα προσδιορίστηκε η θερμοκρασία υαλώδους μετάπτωσης των συστημάτων. Η διηλεκτρική φασματοσκοπία (Broadband Dielectric Spectroscopy) έχει αποδειχθεί ως ένα ισχυρό εργαλείο για την έρευνα της μοριακής κινητικότητας, των αλλαγών φάσης, των μηχανισμών αγωγιμότητας και των διεπιφανειακών φαινομένων στα πολυμερή και τα σύνθετα πολυμερικά συστήματα. Η διηλεκτρική απόκριση των νάνο-συνθέτων εξετάστηκε στο εύρος συχνοτήτων 10-1-107 Hz και στο διάστημα θερμοκρασιών από 30οC έως 160οC. Από τα πειραματικά αποτελέσματα προκύπτει πως παρατηρούνται διηλεκτρικές χαλαρώσεις που οφείλονται τόσο στην πολυμερική μήτρα, όσο και στην ενισχυτική φάση. Τρεις διακριτοί τρόποι χαλάρωσης καταγράφηκαν στα φάσματα των συστημάτων που μελετήθηκαν και αποδίδονται στη διεπιφανειακή πόλωση (Interfacial Polarization) μήτρας/εγκλεισμάτων, στην μετάβαση από την υαλώδη στην ελαστομερική φάση (α- χαλάρωση) της πολυμερικής μήτρας και στην κίνηση πλευρικών πολικών ομάδων (β- χαλάρωση) των κύριων αλυσίδων. Τέλος, υπολογίστηκε η πυκνότητα ενέργειας όλων των συστημάτων με παραμέτρους τη συχνότητα, τη θερμοκρασία και την περιεκτικότητα σε πληρωτικό μέσο. Τα ενισχυμένα συστήματα παρουσιάζουν, εν γένει, μεγαλύτερη ικανότητα αποθήκευσης ενέργειας. Η λειτουργική συμπεριφορά των νανοσύνθετων εξετάσθηκε με χρήση της Συνάρτησης Διηλεκτρικής Ενίσχυσης (DRF). / The impact of nano-materials and nano-structured materials is well known and recognized in our days. Nano-composites consists an exciting modern field of scientific research. Nano-composites are multiphase materials where at least one of the dimensions of the reinforcing phases is in nano-scale. The main difference of nano-composites in comparison with conventional composites is their ability to achieve superior performance at a very low concentration of their filler. The introduction of nanocomposite materials was followed by many scientific studies which aimed to achieve a dramatic improvement of their mechanical performance. The latter, in many cases has not been verified. Recently, there is an increasing interest in studying the dielectric behavior and conductivity of polymer matrix – inorganic nano-filler composites. Polymer matrix nano-composites are expected to be useful in replacing conventional insulating materials providing tailored performance, by simply controlling the type and the concentration of nano-inclusions. Nanocomposite systems, which include inorganic nano-particles represent a novel class of materials which are expected to exhibit functional properties because of the varying polarization of the ceramic particles. Dispersing ceramic inclusions within a polymer matrix, results in systems with enhanced mechanical and electrical behavior. Such material systems are used in electronic applications, for the reduction of leakage currents, and as integrated nano-capacitors. The ceramic filler could be piezoelectric crystal particles. Their varying polarization can be combined with a polymer host, like an epoxy resin – which is, in general, electrical insulator – with low dielectric permittivity and high dielectric breakdown strength. This combination could lead in the development of a smart materials’ system. The aims of this work are the preparation and characterization of epoxy resin nanocomposites with embedded zinc oxide (ZnO) and nanoparticles and in tandem hybrid system of epoxy resin– zinc oxide (ZnO) and titanium carbide (TiC) nanoparticles. Furthermore, morphology, thermal and electrical response of the produced specimens was examined. The morphology of the specimens was checked for voids and clusters, by means of Scanning Electron Microscopy. Ceramic particles distribution is considered as satisfactory, although clusters co-exist with nanodispersions in all the examined systems. Thermal response was examined via Differential Scanning Calorimetry (DSC), and the obtained thermographs were used for the determination of glass transition temperature. Broadband Dielectric Spectroscopy (BDS) has been proved to be a powerful tool for the investigation of molecular mobility, phase changes, conductivity mechanisms and interfacial effects in polymers and complex systems. The dielectric response of nano-composites was examined via BDS in the frequency range 10-1-107 Hz and temperature interval from 30 oC to 160 oC. Experimental results include relaxation phenomena arising from both the polymeric matrix and the filler. Three distinct relaxation modes were recorded in the spectra of all systems. They were attributed to interfacial polarization, glass to rubber transition (α-relaxation) and motion of polar side groups (β – relaxation). Finally, the energy density for all the studied systems was calculated with parameters the frequency, temperature and filler content. Composites systems exhibit, in general, higher energy storage efficiency. The systems’ functionality was examined by employing the Dielectric Reinforcing Function (DRF).

Progress in the burgeoning field of organic electronics is enabling the development of novel technologies such as low-cost, printable solar cells and flexible, high-resolution displays. One exciting avenue of research in this field is nanostructured hybrid organics such as quantum dot (QD)-polymer devices. The incorporation of QDs can greatly improve a device’s efficiency and gives one the ability to tune its electrical and optical characteristics. In order for such technologies to be commercially viable, it is important to classify their mechanical integrity and reliability. Surprisingly little is known about the mechanical properties of QD-polymer thin films (<100 nm). This is in part due to challenges of: (1) isolating the mechanical response of a thin film from the underlying substrate, (2) obtaining a homogeneous dispersion of QDs in the film, and (3) the sensitivity of mechanical properties to the inherent rate dependence of polymer deformation (i.e., viscoelasticity). All of these challenges can introduce significant errors in the measurement of mechanical properties. Furthermore, the deformation mechanisms in nanocomposites are not well understood, so it is difficult to predict the effect of adding QDs on the mechanical behavior of films. In this thesis, these challenges are addressed for characterizing the mechanical properties of thin films of CdSe QD-poly[2-methoxy-5-2(2΄-ethylhexyloxy-p-phenylenevinylene)] (MEH-PPV) nanocomposites using quasi-static nanoindentation testing. Elastic modulus, hardness, and creep are measured as a function of QD concentration and loading and unloading rates. The QDs' ligands are removed by pyridine treatment prior to mixing with MEH-PPV to improve dispersion. The films are prepared via spin-coating onto glass substrates and subsequent annealing in air. Efforts are taken in the mechanical testing to minimize errors due to viscoelastic creep and interference from the substrate. Transmission electron microscopy reveals that the QDs are relatively well-dispersed in the polymer matrix. It is observed that adding QDs increases the elastic modulus (E) and hardness (H) of the films, while reducing the viscoelastic creep. Both E and H increase linearly with the volume percent of QDs. E ranges from 14.5 GPa to 52.7 GPa for pure MEH-PPV (0% QDs) and 100% QD films, respectively, while H ranges from 220 MPa to 1430 MPa for the same films, respectively. The films behave viscoelastically at lower QD loading, but assume a more granular character as the loading approaches 100%.

This thesis reports on the challenge of applying an innovative ‘soft-soft nanocomposite’ design strategy to establish synthesis parameters that affect the performance of coatings based upon water-borne latexes, which is driven by the environmental and legislative need to develop feasible alternatives to solvent-borne coatings. A framework emulsion polymerisation formulation to synthesise core-shell latexes with (poly[(butyl acrylate)-co-(butyl methacrylate)]) core and (poly[(butyl acrylate)-co-(butyl methacrylate)-co-(diacetone acrylamide)]) shell copolymer phases in a controlled manner was established, with high monomer conversions and approximately constant particle numbers. Retention of particle morphology in the films was confirmed using atomic force microscopy (AFM). The effect of adding adipic acid dihydrazide to the latex post-polymerisation to facilitate crosslinking of the shell phase during film formation was found to have a significant effect on the stress-strain properties of latex films. A core:shell mass ratio of 80:20 was found to be optimum in all crosslinked systems tested. Increasing the amount of crosslinking in the shell phase of the particles was found to have an effect on the large strain tensile properties of films, leading to strain hardening with reduced extension to break and higher failure stresses at higher crosslinker levels. Core phase copolymer Tg had a very significant effect upon the low strain mechanical properties, with Young’s modulus values of 5-180 MPa being accessible in the range of core Tg¬s from 5 – 25 oC, although little difference in mechanical behaviour was seen when varying the shell phase Tg from 5 – 15 oC. Adding 2 wt% methacrylic acid (MAA) to the shell phase copolymer gave an additional improvement in the low strain tensile region, with a Young’s modulus of 425 MPa being realised. However, it was found that additional amounts of MAA (up to 5 wt% in the shell phase) were deterious to film properties, with low Young’s modulus and poor extensibility. This was interpreted as being due to an increased concentration of ionomeric crosslinks restricting interparticle chain diffusion and keto-hydrazide crosslinking. Studies to evaluate the mechanical performance of soft-soft nanocomposite films compared to binder latexes used in commercial products were favourable, and showed that a high level of versatility with regards to mechanical properties is possible.

Compósitos são materiais híbridos que resultam de associações de, pelo menos, dois tipos deferentes de materiais. O desenvolvimento da sociedade humana somente atingiu o estágio atual utilizando-se de compósitos de todo o tipo de misturas de materiais. Além disso, o desenvolvimento de compósitos com partículas cada vez menores de fase reforçante com o passar das décadas, ou precisamente, dos séculos foram as principais razões do alcance do \"estado da arte\" da ciência dos compósitos. Com relação à ciência dos compósitos, os nanocompósitos são a grande descoberta do último meio século. Seguindo tendências dos estudos na área dos compósitos, este trabalho foca obter nanocompósitos de elastômero SBR (matriz elastomérica) com argilas tratadas e não tratadas. Além disso, a avaliação de propriedades mecânicas, térmicas, reológicas, de cura, em solução e propriedades de difração de raios-X são outro alvo deste trabalho. Os compósitos foram preparados com equipamentos tradicionais de processamento de elastômeros e, depois disso, suas propriedades foram avaliadas. Considerando propriedades em difração de raios-X, somente o compósito com Cloisite 20A mostrou estrutura intercalada. Os compósitos com argilas tratadas mostraram um melhor perfil geral de propriedades, com destaque novamente para o compósito com Cloisite 20A. Todos os compósitos com argilas tratadas mostraram um menor tempo de cura. Esse comportamento se deve à presença dos sais de tratamento orgânicos dos argilominerais que modificam a densidade de ligações cruzadas e a velocidade de cura. As melhores propriedades do compósito contendo Cloisite 20A, considerando que este foi o único a demonstrar estrutura intercalada, nos permitem concluir que um nanocompósito foi obtido nesta situação. / Composites are hybrid materials which result from associations of, at least, two different kind of materials. The human society development only achieved the current stage using composites of all type of materials mixing. Besides this, the achievement of composites with smaller particles of reinforcing phases along the decades or, precisely, along centuries were the main reasons to reach the current \"state of art\" of composites science. Regarded to composites science, the nanocomposites are the major breakthrough of the last half century. Following the trends of composites science study, this work is focused on obtain nanocomposites of SBR elastomer (rubber matrix) with treated and untreated clays. In addition to this, the evaluation of mechanical, thermal, reological, rubber cure, solution stability and X-Ray diffraction properties are other main target of this work. The composites were prepared with traditional equipments of rubber processing an after the properties were measured. Considering the X-Ray diffraction properties of obtained composites, only the composite with the organoclay Cloisite 20A showed an intercalated structure. The composites containing treated clays demonstrated the better mechanical, thermal and solution stability properties, with a special highlight to the composite containing Cloisite 20A. All composites obtained with organoclays showed lower cure time. This behavior is a result of organic treatment salts of organoclays presence that is able to modify crosslink density and the cure velocity. The better properties of composite containing Cloisite 20A, considering that this composite was the only one that showed intercalated structure, enable us to conclude that a nanocomposite was obtained in this situation.

The design methodology and realization of nanocomposite films aiming for mechanical (superhardness, toughness) and functional (optical, microelectronic) properties were discussed in this paper. Superhard TiCrCN and nc-TiN/a-SiNx films and super-tough nc-TiC/a-C(Al) films were prepared through co-sputtering method by optimal design of microstructure. The nanocrystalline silicon (nc-Si) passivated with a matrix of thermally grown silicon dioxide were prepared using implantation of Si into SiO₂ film, and showed improved photoluminescence and optical properties. Also discussed is the nano-composite design of thin film resistor with optimized temperature coefficient of resistivity. / Singapore-MIT Alliance (SMA)

<p>The aim of this study was to determine whether tooth bleaching agents alter the colour of stained direct composite resins.</p>

This research provides a new insight on various properties, such as rheological, mechanical, and flame-retarding properties, as well as the foaming behaviors of wood flour /plastic composites (WPCs) through the addition of a small amount of nanosized clay particles. Although WPCs have replaced natural wood in many applications, their industrial usage has been limited because of their weak modulus, low impact strength, low screwing-ability/nailing-ability, high density compared to natural wood, as well as their flammability compared to plastics. In this context, the incorporation of nanoclay and foam structure into WPC has been studied to dramatically alleviate these drawbacks. The melt blending method was used to prepare different types of clay-filled wood flour composites such as intercalated and exfoliated clay nanocomposites. The effects of key processing variables such as the mixing time, mixing temperature and screw speed on clay dispersion were investigated from the thermodynamic and kinetic point of view. Their nanostructure was determined by using X-ray diffraction (XRD) and transmission electron microscopy (TEM). Accordingly, effective strategies for controlling intercalation and exfoliation of polyolefin/clay nanocomposites were proposed and evaluated. Wood flour composites with high levels of clay dispersion were synthesized successfully using a general new route (i.e., maleated-polyolefin-based clay masterbatch and dilution). The effects of nanoclay particles on the rheological, thermal, and mechanical properties were identified. In addition, it was demonstrated that a small amount of well-dispersed nanoclay in WPC significantly improved flame retardancy of WPCs. The mechanism of improved flame-retarding effects on nanoparticles was elucidated as well. The relationship between the clay dispersion and the material properties were also clarified. Furthermore, the foaming behaviors of HDPE-based and PP-based wood flour/nanoclay composites were investigated using N2 as the blowing agent in an extrusion process. The cell nucleation and growth behaviors of wood flour/polyolefin/clay composite foams were elucidated while varying the temperature, pressure, wood flour content, clay content and dispersion degrees.

Nanocomposites are a new class of mineral-field plastics that contain relatively small amounts (&lt / 10%) of nanometer-sized clay particles. The particles, due to their extremely high aspect ratios (about 100-15000), and high surface area (in excess of 750-800 m2/g) promise to improve structural, mechanical, flame retardant, thermal and barrier properties without substantially increasing the density or reducing the light transmission properties of the base polymer. Production of thermoplastic based nanocomposites involves melt mixing the base polymer and layered silicate powders that have been modified with hydroxyl terminated quaternary ammonium salt. During mixing, polymer chains diffuse from the bulk polymer into the van der Waals galleries between the silicate layers. In this study, new nanocomposite materials were produced from the components of recycled thermoplastic as the matrix and montmorillonite as the filler by using a co-rotating twin screw extruder. During the study, recycled poly(ethylene terepthalate), R-PET, was mixed with organically modified quaternary alkylammonium montmorillonite in the contents of 1, 2, and 5 weight %. Three types of clays were evaluated during the studies. For comparison, 2 weight % clay containing samples were prepared with three different clay types, Cloisite 15A, 25A, 30B. The nanocomposites were prepared at three different screw speeds, 150, 350, 500 rpm, in order to observe the property changes with the screw speed. Mechanical tests, scanning electron microscopy and melt flow index measurements were used to characterize the nanocomposites. The clay type of 25A having long alkyl sidegroups gave the best results in general. Owing to its branched nature, in nanocomposites with 25A mixing characteristics were enhanced leading to better dispersion of clay platelets. This effect was observed in the SEM micrographs as higher degrees of clay exfoliation. Nearly all the mechanical properties were found to increase with the processing speed of 350 rpm. In the studies, it was seen that the highest processing speed of 500 rpm does not give the material performance enhancements due to higher shear intensity which causes defect points in the structure. Also the residence time is smaller at high screw speeds, thus there is not enough time for exfoliation. In general, the MFI values showed minimum, thus the viscosity showed a maximum at the intermediate speed of 350 rpm. At this processing speed, maximum exfoliation took place giving rise to maximum viscosity. Also, the clay type of 25A produced the lowest MFI value at this speed, indicating the highest degree of exfoliation, highest viscosity, and best mechanical properties.