Teses / dissertações sobre o tema "Composites polymères – Propriétés thermiques – Propriétés mécaniques"
Crie uma referência precisa em APA, MLA, Chicago, Harvard, e outros estilos
Veja os 50 melhores trabalhos (teses / dissertações) para estudos sobre o assunto "Composites polymères – Propriétés thermiques – Propriétés mécaniques".
Ao lado de cada fonte na lista de referências, há um botão "Adicionar à bibliografia". Clique e geraremos automaticamente a citação bibliográfica do trabalho escolhido no estilo de citação de que você precisa: APA, MLA, Harvard, Chicago, Vancouver, etc.
Você também pode baixar o texto completo da publicação científica em formato .pdf e ler o resumo do trabalho online se estiver presente nos metadados.
Veja as teses / dissertações das mais diversas áreas científicas e compile uma bibliografia correta.
Fournier, Jérôme. "Contribution à l'étude des matériaux composites conducteurs à matrice époxyde : application à la non linéarité électrique". Lyon 1, 1997. http://www.theses.fr/1997LYO10336.
Sibold, Nathalie. "Elaboration et caractérisation de nanocomposites à base de polyéthylène et de montmorillonite". Caen, 2005. http://www.theses.fr/2005CAEN2011.
Chausson, Sophie. "Synthèse et utilisation de matériaux hybrides lamellaires pour l'élaboration et la caractérisation de nanocomposites polymères". Caen, 2009. http://www.theses.fr/2009CAEN2047.
The aim of this work is to elaborate original lamellar hybrid materials and disperse them in a polymer matrix to obtain nanocomposites. They have been prepared using two different matrixes, one apolar (polyethylene) and one polar (polyamide-12). The two lamellar hybrid systems have been dispersed in these matrixes and studied as part of the hybrid nature. The first one, the lamellar oxide KTiNbO5, has been chemically modified with alkylamines having different carbon chain lengths in order to be compatible with the different polymer matrixes. The dispersion of such materials has allowed improving several properties like thermal stability, mechanical resistance and fire resistance. The second family studied is the copper alkylphosphonate one. They have been prepared with different alkyl chain lengths. The aim of this study is to prepare a hybrid material with a transition metal and to disperse it in the polymer matrixes. A deep structural study of the homologue series has revealed two types of compounds: hydrated for the short alkyl chains (number of carbon atoms≤10) and dehydrated for the alkyl chains with n≥10. These two structural types have shown different magnetic behaviours. Finally, the incorporation of these fillers in polyethylene and polyamide-12 has revealed that the chemical nature of the bond which links the organic part to the inorganic one of the hybrid does not allow obtaining an efficient exfoliation mechanism
Rul, Alicia. "Compréhension et amélioration du nano-renforcement des élastomères silicone". Caen, 2011. http://www.theses.fr/2011CAEN2040.
Silicon rubbers exhibit very good thermal properties. Unfortunately, their mechanical properties are too weak and must be improved. Silica minerals are generally used to improve the silicon matrix properties via physical interactions. The aim of this work is to understand and improve the silicon rubbers physical behavior by using nanofillers. In depth studies of mechanical behavior and thermal degradation of silicon nanocomposites allowed us to well-understand reinforcement mechanisms. Thanks to hybrid organic/inorganic nanoparticles, we managed to increase the rubber’s crosslink density and to improve the dispersion of nanofillers in the matrix blends. Chemical modifications through hydrosilylation reaction and morphological modifications of these particles, allowed us to enhance significantly the thermal, mechanical and dynamic properties of silicon rubbers. In this work, we have found a new way of reinforcement by creating covalent bonds between tailored nanofillers and the silicon rubber matrix. This new way of reinforcement of silicon rubber properties allows simultaneously improving thermal behavior, reduce Payne effect, and increase elastic modulus
Borchani, Karama. "Développement d'un composite à base d'un polymère biodégradable et de fibres extraites de la plante d'Alfa". Thesis, Lyon, 2016. http://www.theses.fr/2016LYSES010/document.
This study is a contribution to the search for new composite material from vegetable natural resources. It aims at the exploitation of natural fibers extracted from the Alfa plant with a bioplastic of the Mater-Bi® type in order to develop biocomposites. Three kinds of short fibers extracted from Alfa plant were prepared; untreated, 1% and 5% alkali treated. The various techniques used for fibers characterization showed an increase in the roughness, cellulose level, crystallinity index and thermal stability after the alkali treatment. The composite materials were prepared by twin screw extrusion flowed by an injection operation by varying the fiber contents of 0 to 25%. Thermal analysis showed significant increase of the crystallization rate with the incorporation of Alfa fibers and enhancement of thermal stability by alkali treatment. Modulus and tensile strength of biocomposites also improved whereas toughness and elongation at break decreased upon increasing the fibers fraction. Scanning electron microscopy (SEM) on fractured surfaces indicated good adhesion between the matrix and the treated or untreated Alfa fibers. The study of crystallization kinetics of biocomposites showed strong nucleating effect of treated or untreated Alfa fibers
Honoré, Mathilde. "Mise au point de nouveaux bio-composites verts innovants à base de roseau commun Phragmites australis : applications en plasturgie et en éco-construction pour le bâtiment". Thesis, Lorient, 2020. http://www.theses.fr/2020LORIS572.
The use of plant fibres, both in the field of plastics processing and in the building industry, makes it possible to reduce greenhouse gas emissions and therefore the environmental impact of mankind. Interest in biocomposites using plant fibres such as hemp, wood, flax and also miscanthus reed is increasing. Nowadays, there is very little work on the reed phragmites australis. However, as it does not use cultivated areas, this invasive plant is independent of agricultural issues and does not require any chemical inputs. The reed harvest is therefore part of a wetlands management approach while enhancing the value of a material with multiple properties. This work is devoted to the characterisation of the raw material phragmites australis and to the study of its eligibility as a substitute material of three reference materials, wood, miscanthus and hemp shiv, widely used as reinforcements in plastics processing and eco-construction. Composite formulations using two polymer matrices (polypropylene and polybutylene succinate) with different rates of plant fillers and coupling agent were characterised from the point of view of their mechanical properties by Charpy tensile, flexural and impact tests. The water ageing of these composites was also studied and correlated to the hydrophobic character of the reed. For the construction application, formulations based on reeds of different origins and using different binders (lime, plaster and earth) were tested in compression and with thermal conductivity measurements in order to evaluate the behaviour of the reed as a material for building use
Hamdi, Khalil. "Fonctionnalisation de matériaux composites à renfort carbone et matrice thermoplastique par adjonction de nanocharges : élaboration et étude du comportement". Thesis, Compiègne, 2017. http://www.theses.fr/2017COMP2388/document.
To extend the use of composites in more varied application (smart applications, multifunctional issues), one of the actual barrier is their poor electrical and thermal conductivities. In the case of carbon fiber reinforced composites, organic matrix are in charge of the insulating properties of the resulting composite. One of the solutions to enhance conductivities of materials is the use of conductive nanofillers. Improving the electrical and thermal properties of nanofilled polymers has been investigated in several studies. However, studiing the properties of continuous carbon fiber nano-filled composites is less approached. This work tends to fabricate and characterize carbon black and carbon nanotubes nano-filled composites. First of all, special interest was given to the delicate phase of manufacturing. As mentioned before, processing continuous fiber reinforced nanofilled polymers implies issues related to nanofillers agglomeration and inhomogeneous dispersion in the final composite. To resolve these problems, the choice of the thermoplastic (Polyamide6) matrix seemed preferable. In fact, the dispersion of nanofillers was made by twin screw extrusion which is known as one of the most effective agglomeration separation ways. Adding to this, the fabrication method based on Polyamide 6 shects called film stacking, ensure a homogeneous partition at the beginning of the process. SEM observations were performed to localize the nano-particles. It showed that particles penetrated on the fiber zone. In fact, by reaching the fiber zone, the nano-fillers created network connectivity between fibers which means an easy pathway for the current. It explains the noticed improvement of the electrical conductivity of the composites by adding carbon black and carbon nanotube. This test was performed with the 4 points electrical circuit. It shows that electrical conductivity of 'neat' matrix composite passed from 20S/cm to 80S/cm by adding 8wt% of carbon black and to 15S/cm by adding 18wt% of the same nano-filler. For carbon nanotubes, with '2.5wt% the conductivity was around 150S/cm. For the thermal properties, tests based on Joule's effect were performed. The rise of temperature was recorded using IR camera. Results obtained are in agreement with the electrical conductivity ones, showing enhancement of the thermal behavior in presence of nanofillers. Thanks to these results, the use of these composites as a damage-monitoring tool was possible. By the way, the electrical resistance change method was performed. Nanofilled materials showed better sensitivity to damage. Results were compared with classical damage monitoring tools. At the end, several 'smart' applications were tested such as graded functionalities composite and stitched nanofilled materials
Miranda, Campos Bernard. "Copolymer-based PLLA matrix composites produced by TP-RTM". Electronic Thesis or Diss., Université de Lille (2022-....), 2023. http://www.theses.fr/2023ULILR042.
The present study experimentally investigated the production of poly(L-lactide)-based matrix composites by Thermoplastic Resin Transfer Molding (TP-RTM). In this process, the in-situ ring opening polymerization of L-lactide (L-LA) and ε-caprolactone (ε-CL) was performed in a single step to achieve composites with a biodegradable poly(L-lactide-co-ε-caprolactone) (PLCL) matrix in one step synthesis. The incorporation of ε-CL in the matrix was aimed at reducing the brittleness of PLLA. The resulting PLCL matrix was reinforced with glass or carbon fabrics. Different L-LA / ε-CL molar ratios were tested, leading to the development of composites with various chemical, thermal, and mechanical properties. The TP-RTM parameters were optimized to produce composites with reduced voids. Subsequently, these composites were characterized to evaluate monomers conversions, molecular weights and thermal properties of the matrices, as long as the mechanical properties of the resulting composites. It was found that PLCL / glass fabric composites exhibit higher impact resistance compared to their PLLA-based counterparts. On the other hand, PLCL / carbon fabric composites display remarkable lightweight properties with high bending strength. The fractures of the composites after mechanical tests were studied to identify the failure type during these experiments. In a more sustainable approach, fully biodegradable PLLA / flax composites were produced using TP-RTM, and their chemical, thermal, and mechanical properties were also studied. Furthermore, the impact of accelerated aging, i.e under temperature and UV irradiation, was studied on all composites. After aging, a relationship between crystallinity, matrices molecular weights and bending properties was established
Bardash, Liubov. "Synthesis and investigation of nanostructured polymer composites based on heterocyclic esters and carbon nanotubes". Thesis, Lyon 1, 2011. http://www.theses.fr/2011LYO10174/document.
The thesis relates to synthesis and investigation of nanostructured polymer composites based on oligomers of cyanate esters of bisphenol a (DCBA) or cyclic butylene terephthalate (CBT) and multiwalled carbon nanotubes (MWCNTS). Catalytic effect of mwcnts in process of DCBA polycyclotrimerization as well as in cbt polymerization has been observed. Significant increase in crystallization temperature of nanocomposites based on polybutylene terephthalate (cPBT) with adding of MWCNTS is observed. The effect of processing method of cpbt/mwcnts nanocomposites on its electrical properties has been found. It has been established that the additional heating of the samples (annealing) at temperatures above melting of cPBT leads to reagglomeration of MWCNTS in the system. It is established that reagglomeration of MWCNTS results in increase of conductivity values of nanocomposites due to formation of percolation pathways of MWCNTS through polymer matrix. In the case of polycyanurate matrix (PCN), it is found that addition of small mwcnts contents (0.03-0.06 weight percents) provides increasing tensile strength by 62-94 percents. It has been found that addition of even 0.01 weight percents of MWCNTS provides significant increase in storage modulus of cPBT matrix. This is explained by effective dispersing of small amount of the nanofiller during in situ synthesis of pcn or cpbt matrix that is confirmed by microscopy techniques. It has been established that the properties of the nanocomposites based on heterocyclic esters and MWCNTS can be varied from isolator to conductor and has low percolation thresholds (0.22 and 0.38 weight percents for cPBT and PCN nanocomposites respectively). The conductivity of samples is particularly stable on a very large range of temperature from 300 to 10 degrees Kelvin that make these materials perspective for practical applications in microelectronics, as parts of aircraft and space constructions
Blivi, Adoté Sitou. "Effet de taille dans les polymères nano-renforcés : caractérisation multi-échelles et modélisation". Thesis, Compiègne, 2018. http://www.theses.fr/2018COMP2431/document.
The work presented in this paper aims to highlight and to understand the size effect of nano-reinforcements on nanocomposite properties With an experimental approach. Nanocomposites of PMMA and silica particles With different sizes (15nm, 25nm, 60nm, 150nm and 500nm) and volume fractions (20/0, 4 0/0 and 60/0) were manufactured. Multiscale analysis (MET and DRX-WAXS) have shown that the characteristic parameters of the microstructure of nanocomposites vary With the size of the nanoparticles. Indeed, the decrease in the size of nanoparticles at a given volume fraction implies a decrease of the intermolecular distance. This decrease has induced a densification of the matrix and a decrease of the matrix chain mobility. Mechanical tests (tensile, DMA) have shown that the young (E) and the conservation (E') moduli of the nanocomposites increase With the decrease in the size of the nanoparticles With a constant volume fraction. And the increase of E l is kept when temperature growing. An increase in glass transition (Tg) and degradation temperature (Td) was also observed With the DSC, DMA and ATG tests. Experimental elastic properties of the nanocomposites were used to assess the relevance of size effect micromechanical models, particularly the Hashin-Shtrikman bounds With interface effects proposed by Brisard. The modeling has shown that to reproduce the experimental elastic moduli of nanocomposites, the elastic coefficients of the interface must be dependents on particle sizes. And the state of dispersion of particles must be taken into account
Roiron, Coline. "Contribution à la caractérisation thermomécanique d’un polyéthylène auto-renforcé et de ses « recyclats » : Effet des paramètres du procédé de moulage par compression". Electronic Thesis or Diss., Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aérotechnique, 2022. http://www.theses.fr/2022ESMA0004.
Reducing energy consumption is an essential issue for today's society. In order to achieve a sustainable energy transition, especially in the field of transportation, new and more demanding regulations are being implemented. The keywords are to increase the proportion of recycled and recyclable materials and lightening structural parts.The use of polymers can be a solution. However, to guarantee good mechanical resistance, the use of self-reinforced composites(SRP) is a lever for action. They are composed of a polymer or a family of polymers in two physical states, one to form the matrix and the second for the reinforcement. They present a low density, interesting mechanical behavior, and increased recyclability. To understand the behavior of a self-reinforced polyethylene and to be able to consider the use of this material for a given application,it is essential to understand the behavior of each of its components. If the behavior of more conventional composites, such as glass or carbon fiber reinforced thermoplastic matrix composites, is well understood, using thermoplastic reinforcements such as UHMWPE (Ultra-High Molecular Weight PolyEthylene) within the composite makes the understanding of the behavior of SRP more complex. The impact of temperature and time on the mechanical response of the reinforcements is then examined in a first step, and the observations are related to microstructural considerations. A test protocol has been proposed and validated before hand. A solid-phase transition is highlighted around 49°C and generates an abrupt behavior change.These UHMWPE reinforcements are integrated into composites. A compression molding process is suggested to process them in a single step from a matrix in granular form. The effect of different process parameters is evaluated to propose an optimal combination.The short and long-term mechanical response in tension and creep is then analyzed, and the interest of the SRPE thus designed is highlighted. Indeed, the benefit of its use is evident, especially at low temperatures. Moreover, the presence of thermoplastic reinforcements seems to introduce additional parameters that affect the behavior of the composites and, in particular, in creep. The precise characterization and the knowledge of the transition temperatures of the latter appeared then determining, mainly since the transitions depend on the microstructure of the reinforcement and thus on the type of stretching and the applied conditions. Finally, the recyclability of the implemented composites is studied since it constitutes a driving force for the development of SRP on the market
Guigon, Camille. "Vieillissement par cyclage thermique de composites interlocks 3D à matrice polymère". Thesis, Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aérotechnique, 2015. http://www.theses.fr/2015ESMA0004.
The introduction of composite materials in critical structural parts for aircrafts represents a real technological breakthrough and requires specific studies to understand their behavior and durability. This work aims to characterize and understand the ageing mechanisms incarbon/epoxy 3D interlock composites when they are submitted to thermal cycling.For this purpose, a thermal cycle test (-55°C/120°C), whose heat and gaseous environment istotally mastered, was set up for the ageing of composite samples of elemental interlock pattern dimensions. Analysis of induced degradation mechanisms was achieved by i/ the development ofa 3D quantitative characterization method of the evolution of microcracks during cycling, basedon observations by microtomography RX and the development of a specific image processing procedure, ii/ the development of an in situ thermal cycle test under synchrotron light, coupled to a digital volume correlation technique, and iii/finite elements simulations taking into account the actual mesoscopic architecture of the samples and the thermo-viscoelastic behavior of thematrix.The results reveal complex thermo-chemo-mechanical couplings that are linked to four important parameters: time (and the number of cycles), the interlock architecture, the matrix toughness andits sensitivity to thermo-oxidation
Fedosse, Zornio Clarice. "Ionic liquids as multifuncional additives for poly(methyl methacrylate)-based materials". Thesis, Lyon, 2017. http://www.theses.fr/2017LYSEI041/document.
The large array of cation/anion combinations, and the excellent intrinsic properties of ionic liquids (ILs) open a large range of possibilities in their use as additives to polymer materials. Thus, the main objective of this work is to explore the role of both the cation and anion of a series of ILs on the properties of poly(methyl methacrylate) (PMMA)-based materials. In a first approach, low amounts of imidazolium and ammonium-based ILs were incorporated as additives to PMMA in the molten state. Morphological and structural characterizations were developed in order to understand the impact of the presence of such ILs on the thermal and mechanical properties of the resulting materials. Then, in the following section, the ability of the same imidazolium and ammonium-based ILs as physical modifiers of silica surface was evaluated. In such an approach, ILs were supposed to act as interfacial agents. Sub-micron and nanosize silica particles were used to prepare PMMA composites. Thus, the extents of each IL improve the interfacial interaction between PMMA and silica particles were discussed. In addition, supercritical carbon dioxide (scCO2) was used as foaming agent to produce foamed PMMA-based composites. In such a case, the combined effect of the presence of ILs and silica particles was analyzed regarding the morphology of the foamed structures. In the last section, scCO2 was used as reaction medium, in an environmental friendly approach, to chemically modify silica nanoparticles using a series of imidazolium IL-functionalized silanes (with different alkyl chain lengths). Thermogravimetric analysis (TGA) was used to highlight the effect of the working pressure and the content of such ILs in the reaction medium. The effect of the alkyl chain length on the grafting density of the resulting nanoparticles was also discussed. Finally, novel PMMA-based nanocomposites were prepared by the incorporation of such grafted nanoparticles. Transmission electron microscopy (TEM) and small-angle neutron scattering (SANS) analyses were used to evaluate the state of dispersion of the particles into the polymer matrix. Moreover, the thermal, rheological and mechanical properties of the materials were studied
Raud, Christophe. "Fissuration des composites carbone à matrice thermostable en traction isotherme et cyclage thermique". Cachan, Ecole normale supérieure, 1993. http://www.theses.fr/1993DENS0013.
Chabert, Emmanuelle. "Propriétés mécaniques de nanocomposites à matrice polymère : approche expérimentale et modélisation". Lyon, INSA, 2002. http://theses.insa-lyon.fr/publication/2002ISAL0011/these.pdf.
This work aims to analyse the mechanical properties of polymer based composites reinforced by spherical nanofillers. The role of each component has been investigated: the polymer matrix, the filler and the interphase (matrix-filler, filler-filler). Firstly, the mechanical behaviour of polymer has been analysed through the molecular approach (“quasi point defect theory”) developped in GEMPPM laboratory. Based on an new formalism, a original method leading to the determination of physical parameters has been proposed. We have then validated this method for various polymers (PMMA, PET and P(S-ABu)). In a second step, the effect of grafted reactive surfactant on mechanical properties of latex films has been investigated. The comparison of self made model systems with grafted and non grafted surfactant has suggested that the grafting of surfactant affects slightly both the small and the large mechanical properties of latex films. On the contrary, the nature of the surfactant might affect the microstructure of complex latex, and in this way their mechanical properties. The last part is devoted to the effect of nanofillers. We have studied the role played by different parameters (concentration, filler nature (organic or mineral), filler/filler interactions) on the elastic mechanical properties. To model these properties, we have developped a discrete numerical approach taking into account the microstructure and the local contact (filler-filler and matrix-filler). The variation of contact caracteristics has thus enabled us to describe the different experimental results below and above the geometric percolation threshold. Finally, the analysis of tensile strain properties has suggested a rupture of the filler network from the first percent of elongation
Franbourg, Alain. "Influence d'un traitement à l'état fondu sur la structure cristalline et les propriétés mécaniques du poly(oxymethylène) et du poly(éther éther cétone) : relations : mise en oeuvre par injection/structure/propriétés". Lille 1, 1990. http://www.theses.fr/1990LIL10091.
Mulle, Matthieu. "Eprouvettes technologiques instrumentées à cœur par réseau de Bragg pour l'analyse du matériau composite dans la structure". Toulouse 3, 2007. http://www.theses.fr/2007TOU30242.
Vladkov, Mihail. "Modélisation des effets d'interface sur les coefficients de transport: propriétés mécaniques des polymères, propriétés thermiques des nanofluides". Phd thesis, Université Claude Bernard - Lyon I, 2007. http://tel.archives-ouvertes.fr/tel-00176186.
Nous avons développé une méthode d'étude locale de la dynamique dans un fondu de polymère. Ceci a permis d'expliquer les mécanismes impliqués dans la réponse d'un fondu pur à une excitation mécanique externe. Dans le cas d'une interface paroi polymère nous avons montré que la présence de chaînes greffées ralentit localement la dynamique et augmente la densité d'enchevêtrements dans une couche interfaciale de l'ordre de la taille des chaînes. En absence de greffage et pour une surface plane la dynamique est accélérée et la densité d'enchevêtrements diminue. L'étude d'un fondu enchevêtré chargé par des particules de taille inférieure à celle des polymères a montré que l'attraction charge polymère mène à une augmentation effective de la densité d'enchevêtrements à travers des réticulations créées par les charges. Ces phénomènes expliquent le renforcement dans les polymères chargés mesuré à haute température en absence d'effets vitreux.
Par l'étude des effets d'interface sur les transferts thermiques dans un nanofluide nous avons établi une méthode de mesure de la résistance thermique particule-fluide. Nous avons montré que la conductivité est bien prédite par un calcul de milieu effectif. L'effet du mouvement brownien est négligeable et l'augmentation de la conductivité de ces fluides est due à des effets collectifs (agrégation) des particules.
Bour, Yves. "Matériaux composites à fibres courtes : Relation entre facteur d'orientation et propriétés mécaniques et thermiques". Metz, 1999. http://docnum.univ-lorraine.fr/public/UPV-M/Theses/1999/Bour.Yves.SMZ9906.pdf.
The behavior of short fibers composite materials depends strongly of the orientation of the fibers. Using magnetic fields, anisotropic composite materials have been elaborated which contained up to 20 vol% of carbon fibers. One aim was to gain a better understanding of the process of orientation in the magnetic field. A model has been formulated to describe the movement of a single fiber which is exposed to a static and an oscillating magnetic field. Other parameters such as viscosity of the liquid polymer, temperature and fiber length were examined as well. The degree of anisotropy of the materials is measured by microscopy coupled to an optical imaging system, this work leading to define a procedure of filtering the image in order to obtain precisely the fiber orientation distribution (function). As well as the thermal conductivity was measured which is related to the three-dimensional orientation. The results from optical and thermal measurements correlate well, but the theoretical models to interpret the thermal conductivity are not yet reliable enough to allow the degree of orientation to be reduced from the measurements. Regarding the mechanical properties the increase of the YOUNG's modulus was measured and correlated with the fiber orientation distribution. Between the mechanical models tested some are found to agree well with the experiments
Marceau, Sandrine. "Architecture multiéchelle et propriétés mécaniques de nanocomposites". Chambéry, 2003. http://www.theses.fr/2003CHAMS012.
The purpose of this study is to improve the understanding of the mechanisms leading to reinforcement effects in nanocomposite materials. To do this, "model" systems were fabricated using an amorphous polymeric matrix reinforced by colloidal silica nanoparticles. The optical, physicochemical and mechanical properties of these materials were linked to their morphology. The morphological analysis of the nanocomposites showed that the silica nanoparticles were in form of dispersed aggregates for filler fractions lower than 6 %, whereas for higher fractions a percolating network of silica was evident. The study of the molecular mobility of the polymer chains showed that the nanoparticles did not induce any variation of the global mobility of the chains. The linear viscoelastic behaviour showed that the variations with temperature of the real part of Young's modules and the damping factor tan d were connected to the underlying structure of the nanocomposites. The experimental results were then compared to those obtained using two different theoretical approaches. At the mesoscopic scale, we used an adapted micromechanical model to show that the presence of the percolating network of fillers could induce a strong reinforcement effect and a shift of the main relaxation towards lower temperatures for fractions of silica higher than the percolation threshold. At the atomic scale, we analysed a PBMA-silica system by molecular dynamics. Using this model, we could show the influence of the filler on the molecular mobility of the polymer and on the mechanical properties of the nanocomposites
Brouard, Yoann. "Caractérisation et optimisation d'un composite biosource pour l'habitat". Thesis, Tours, 2018. http://www.theses.fr/2018TOUR4024.
The purpose of this study was to compare hygrothermal acoustical and mechanical properties ot different materials based on vegetal aggregates and clay in order to characterize the performances of different biocomposites to provide building insulation solutions with a view to valorizing agricultural waste. We first analyzed the raw materials in order to get the density, thermal and hydric properties of the vegetal aggregates in one hand and the mineralogy and gravimetric data of the selected crude earth in the other hand. Thermal behavior of earth:vegetal aggregates mixes have been investigated at different humidity rates and different density ranges. Additionally, hydric properties have been measured to produce sorption and desorption curves and moisture buffer values (MBV) in one hand and capillarity of both aggregates and biocomposites on the other hand. One of the main interests of this study is to confirm that a wide range of locally produced vegetal byproducts could be used as - bioaggregates for concretes. Local biomaterials industries could therefore emerge depending on the locally available resources at country scale
Dang, Tan Tai. "Nanocomposites PVC/Montmorillonite : élaboration, morphologie et propriétés". Chambéry, 2005. http://www.theses.fr/2005CHAMS027.
The aim of this work is to process Poly (Vinyl Chloride)/Montmorillonite nanocomposites by new technologies developed in order to avoid any PVC therrnal degradation that is an important lirnitation of current methodologies. At first, special attention is focused on degradation of PVC/organomontmorillonite (organo-montmorillonite: quaternary aLkylamrnonium modified montmorillonite). The role of the quaternary alkylamrnonium is highlighted, and a "concerted quasi-ionic" mechanism is proposed. After this study, several methods which are supposed to avoid decomposition of PVC are explored. The parts II and IV deal with intercalation of montmorillonite and process study of nanocomposites processed by these methods. The part V deals with morphology, viscoelastic and mechanieal properties of the different familles of nanocomposites. Then a comparative study is realised between nanocomposites performed with commercial montmorillonite or with natural montmorillonite
Nony, Fabien. "Développement de nouveaux polymères hybrides polyarylacétyléniques : application à la réalisation de matrices pour composites thermostructuraux". Lyon, INSA, 2003. http://theses.insa-lyon.fr/publication/2003ISAL0058/these.pdf.
This study comes within the scope of developing new matrices for thermostructural composites. The particular interest of this work relies on the synthesis of hybrid poly(silylene-ethynylene-phenylene-ethynylene) polymers with the aim of combining the intrinsic thermal stability of inorganic elements with the processability and the specific mechanical properties of polymers. Characterization of these silicon-containing polymers have revealed outstanding heat-resistance but limited mechanical properties. The thermosetting mechanism has also been studied. All the results have been used to develop different polymers or thermosets modification paths. Poisoning the reactive groups implicated in a weakening process, lead to an obvious increase of all thermosets mechanical properties and the preserving of their thermal stability and processability. Fiber-matrix interactions have been investigated on model-composites. Carbon fiber-reinforced composites, made by RTM, have also been characterized
Probst, Nicolaus. "Etude des propriétés électriques et diélectriques des composites polymères - noirs de carbone : parallélisme entre propriétés électriques et mécaniques". Mulhouse, 1991. http://www.theses.fr/1991MULH0180.
Planche, Jean-Pascal. "Nouveaux polymères sulfonés dérivés du polynorbornène". Lyon 1, 1985. http://www.theses.fr/1985LYO10512.
Schmitt, Yves. "Approches rhéologiques et mécaniques des matériaux composites à fibres courtes". Metz, 1999. http://docnum.univ-lorraine.fr/public/UPV-M/Theses/1999/Schmitt.Yves.SMZ9905.pdf.
The aim of this work is to develop new composite materials on very short fibers which present at the same time good mechanical properties and a low viscosity of the liquid phase to be used for the molding of complex structures. To reduce the viscosity of the suspensions vacuum and treatment by ultrasound was used. It is shown, that the viscosity of a polymer material which exhibits shear thinning flow can be lowered substantially (up to 20%) by the addition of a small quantity of microspheres (<2%). The gain in fluidity is preserved for the mixtures studied. Consequently a material with higher content in fibers can be made having the same viscosity. For the applications of this discovery a patent was filed in 1997. The rheology of various mixtures with several resins had been studied. As a result two regions of different flow behavior are found : within the first regions the viscous flow essentially is determined by the matrix whereas in the second region the main contribution comes from the fiber-fiber interactions. Therefore a reduction of the viscosity of the matrix below a certain level does not yield a gain in fluidity of the suspension. Studies of the mechanical properties show that strong composites based on fibers of about 200μm only could be made if the matrix has an elevated Young's modulus. Twelve different epoxy resins (including 9 which were made especially for this study) are used in order to demonstrate the influence of the Young modulus and the strain of the matrix. Today based on the results mentioned above a composite material can be made from an epoxy resin and carbon fibers (30% in volume) which offers specific properties comparable to a standard aluminum : (Young's modulus – 28GPa ; ultimate strength – 220 Mpa; density – 1400 kgm-3)
Antar, Zied. "Éco-composites polymères conducteurs (CPC) pour la production d'énergie renouvelable". Lorient, 2012. http://www.theses.fr/2012LORIS283.
Owing to the finite supply of fossil fuels and the negative public opinion surrounding nuclear energy, alternative energy resources are the subject of considerable research on a global scale. The aim of this work is to develop a Conductive Polymer Composite for energy harvesting and storage. The first part of this work was dedicated to the development of solar absorber. In fact, CPCs were prepared by melt processing where conductive fillers (graphite and/or carbon nanotubes) were dispersed in an insulate polymer matrix (PLA and PA12). Indeed, thermo-optical properties were measured and the durability of the CPC was checked by controlling the evolution of their mechanical properties during a weathering test. In a second step, CPC with good thermoelectric power were prepared using two routes: melt blending process and solution in-situ polymerization. Various formulations have been tried and some rather interesting results were obtained by recording encouraging values of figure of merit ZT
Amici, Marco. "Hybrid Inorganic / Organic polymers based on methacrylate - polyhedral oligomeric silsesquioxanes (POSS®) : morphology and structure - properties relationships". Lyon, INSA, 2006. http://theses.insa-lyon.fr/publication/2006ISAL0004/these.pdf.
Novel hybrid inorganic/organic systems based on methacrylate and polyhedral oligomeric silsesquioxanes (POSS ®) have been synthesised and characterised. The synthesis has been performed via either thermally or UV free-radical polymerization. Chemical characterisation has been done with NMR, NIR and SEC. The POSS have been found to be polymerizable with the organic monomers once a good dispersion is ensured. Structure and morphology, characterised by means of SEM, TEM, AFM and WAXS, have been shown to be mainly dependent on the dispersion of the POSS in the organic matrix. Depending on the POSS grade and concentration, one could obtain a wide array of structure-morphologies, from micro-aggregates to a very fine dispersion, probably to the molecular level. In turn, these different morphologies have an influence on the properties of the final systems. Thermal, thermomechanical and mechanical properties have been analysed. The POSS have been shown to change the crosslinking density of the thermosetting networks, while, in thermoplastic systems, the properties of the hybrid systems have been largely influenced by the nature of the organic ligands borne by the POSS
Djato, Anani. "Identification rapide des propriétés diffuso-mécaniques de matériaux polymères et composites pour applications aéronautiques". Thesis, Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aérotechnique, 2018. http://www.theses.fr/2018ESMA0010/document.
The use of organic matrix composite materials (OMC) for the realization of "warm" aeronautical structures, may expose these materials to aggressive environments: wet or gaseous environments,high temperatures, which may promote severe aging and degradation phenomena related to species diffusion within the macromolecular network of the polymer matrices. The complexity of the OMC microstructure used for these applications can complicate the understanding of degradation phenomena : for example, species diffusion can be isotropic, orthotropic or anisotropic, depending on the texture of the fibrous reinforcement. Humid aging of OMC is of particular concern for the aeronautical industry ; the diffusion of water in the polymer matrix of the composite may promote hygroscopic swelling, changes in mechanical properties (stiffness, strength). Experimental methods exist for the characterization of these phenomena and for the identification of the associated parameters : these methods often recommend the use of moisture saturated specimens, which require long conditioning times, sometimes often a relevant number of samples (1 sample for each saturated state), high costs. The aim of this work is to establish protocols for fast identification of the diffusomechanical properties of polymers and polymer based OMC materials for aeronautical applications. The approach implemented in this thesis is organized in four chapters. The first chapter presents a bibliographic study on coupled diffuso-mechanics modeling tools and on methods of characterization/identification of diffuso-mechanical properties, more particularly for OMC for aeronautical applications. The bibliographic study allows specifying the framework of the present research, which foresees the employment of a weakly coupled diffuso-mechanical model, where water diffusion follows the Fick’s law and the mechanical behavior is linear hygroelastic, depending on water content. The second chap-ter presents the setting up and the development of a method for fast identification of anisotropic diffusion properties, suitable for OMC with complex architecture, such as for instance, 2D or 3Dwoven OMC. The method relies on mass-gain measures of OMC samples, the diffusion anisotropy ofthese materials is obtained by rotating the axes of orthotropy. The proposed method represents an extension of the "slope method" introduced by Shen and Springer in the 1970s for the identification of the diffusion properties of orthotropic materials (such as laminated composites), and is based onthe exploitation of gravimetric curves at short times. Through this method, the principal coefficients and the principal axes of orthotropy can be identified. A discussion about the transition from 3Dto 1D diffusion as a function of the sample geometry is also presented at the end of this chapter. The third chapter explores through a numerical study the possibility of identifying in a fast way the mechanical properties affected by moisture of polymeric materials by the use of mechanical tests on thin plates with water concentration gradients. Traction and bending tests are taken into account.For isotropic materials, in a hygroelastic setting, it is showed that this method allows identifyng the water concentration dependent Young’s modulus and the Poisson’s ratio with a remarkable time gain compared to tests on moisture saturated samples. Finally, the last chapter proposes through a numerical study a method for fast identification of the diffuso-mechanical properties of isotropic materials based on the use of plates loaded by an asymmetric water concentration field. The identification is thus carried out from the monitoring deflections generated by the concentration fields. The moisturedependent hygroscopic expansion coefficient and Young’s modulus can be identified during the test,by exploiting the transient state of conditioning, with a remarkable time gain compared with moisture saturated samples
Hajji, Philippe. "Etude des relations synthèse-morphologie-propriétés mécaniques de nano composites hybrides polymère-silice : application au renforcement mécanique des verres". Lyon, INSA, 1999. http://www.theses.fr/1999ISAL0002.
This work deals with the study of synthesis-morphology-mechanical properties relationships of polymersilica nanocomposite hybrid materials and their application as coating to reinforce glass substrates ( e. G. Bottles). Two types of nanocomposites, exhibiting the same chemical composition, have been prepared. Type 1 systems were obtained by the bulk free-radical polymerization of 2-hydroxyethyl methacrylate (HEMA) in the presence of HEMA-functionalized silica nanoparticles (13 nm in diameter). Type 2 systems were obtained by the simultaneous polymerization of HEMA and tetraethoxysilane (TEOS). In this case, a silica rich phase results from classical acid catalyzed reactions, involving hydrolysis and condensation of TEOS (sol-gel process). Both types of hybrids, which can contain up to 30 wt% of silica, are optically transparent. Type 1 nanocomposites exhibit particle-matrix morphology where silica nanoparticles tend to form aggregates. Type 2 systems are molecular composites exhibiting a finer morphology that consists in a very open mass fractal silicate structure which is believed to be bicontinuous with the organic phase. Such morphology differences lead to very different mechanical behaviors. Type 2 materials exhibit higher levels of hardness and rubbery rigidity whereas Type 1 materials possess higher damping efficiency and plastic deformation ability. A mechanical model, based on a self-consistent scheme and taking into account local inversions of phase connectivity, has been proposed and applied to the description of the viscoelastic behavior of both types of nanocomposites. Finally, practical applications have been developed in the field of glass strengthening, by using such hybrid systems as coatings. These coatings, whose thickness remains below one micrometer, lead to important reinforcements of substrates, which can be explained by a healing mechanism of glass surface flaws
Capsal, Jean-Fabien. "Elaboration et analyse des propriétés physiques de nanocomposites hybrides ferroélectriques". Toulouse 3, 2008. http://thesesups.ups-tlse.fr/835/.
The piezoelectric activity of a hybrid ferroelectric nanocomposite, i. E. Polyamide 11/ Barium Titanate (BT), has been investigated for different loadings of BT particles. The BT volume fraction (phi) was ranging from 0. 024 to 0. 4 with a particle size of 50 nm, 100 nm, 300 nm and 700 nm. The influence of polarization mode on the piezoelectric behaviour has been studied. The magnitude of the poling field used in this study is in the same order of magnitude of the one used for bulk BT i. E. Significantly lower than for piezoelectric polymers. The optimum piezoelectric coefficient is reached when the amorphous phase of the polymeric matrix is in the liquid state i. E. ; for a polarization temperature higher than the glass transition and for time constant allowing macromolecular mobility. The composite piezoelectric activity decreases for particles size lower than 300 nm due to the loss of the tetragonal phase. The nanotexture of these particles has been investigated by TEM and HRTEM. A core shell structure has been observed. An increase of the longitudinal piezoelectric strain coefficient d33 with the raising of BT volume fraction was shown. Contrary to inorganic piezoelectric ceramics, the dielectric permittivity of hybrid composites remains moderate although the piezoelectric voltage coefficient of composites is bigger than ceramics
Osmani, Hocine. "Rupture des composites céramique-céramique à fibres". Lyon, INSA, 1989. http://www.theses.fr/1989ISAL0059.
Gomez, Jean-Paul. "Caractérisation mécanique de composites à matrice d'alliages d'aluminium et renforts particulaires SiC ou Al2O3 (influence des traitements thermiques,études des contraintes résiduelles)". Toulouse, INPT, 1996. http://www.theses.fr/1996INPT032G.
Aussedat, Yahia Eve. "Comportement et endommagement du composite tisse Carbone/PMR15 soumis à des chargements mécaniques et thermiques". Paris, ENMP, 1997. http://www.theses.fr/1997ENMP0748.
Liu, Yu. "Elaboration et étude des propriétés mécaniques des mousses d'aluminium et des métaux poreux polymères composites". Troyes, 2007. http://www.theses.fr/2007TROY0007.
The objectives of this work consist to manufacture new metal porous polymeric composites (MPPC) with interpenetrated structure and to characterize their mechanical behaviors under statical and dynamic loading. Firstly, we developed a technique of infiltration under a negative pressure to manufacture the open cell aluminium foams and MPPC. The optic observations were carried out in multi-scale. The characterizations of materials were carried out under uniaxial compression. The influences of the structural parameters on the compressive behaviors were clarified by SEM observations during compression. The elastic module was compared with the analytical models. These results obtained are completely restructed between the boundaries proposed in the literature. Secondly, the behaviors of indentation were studied. The relations between the response of indentation and the size and the geometry of plunger tip were illustrated. The size and the shape of the densification zone were observed and modelled by analytical models and the finite element simulation. Finally, the behaviour of impact was studied. The influences of experimental conditions and structural parameters on the behaviors of impact were illuminated
Planès, Émilie. "Influence des charges sur l'évolution des propriétés mécaniques des EPDM chargés lors de leur vieillissement par irradiation". Lyon, INSA, 2008. http://theses.insa-lyon.fr/publication/2008ISAL0089/these.pdf.
The understanding of the evolution of mechanical properties and the prediction of the lifetime of mate rials in industrial environnement is a recurring problem. This question is very important to develop polymer formulations used for electrical cables in nuclear power plants. Thus it is important to know the evolution of materials when they are submitted to usual conditions in nuclear power plants. The re are in litterature some studies concerning the ageing by gamma irradiation of unfilled elastomer but the addition of fillers in the material can have consequences on the evolution of the mechanical properties during irradiation. Thus this work concerns the study of the ageing by gamma irradiation of filled rubbers and the identification of the role of fillers in the degradation mechanisms. The studied matrix, which commonly used for this type of application is EPDM. The fillers are : nanoscopic silica and aluminum tri hydrate. Their surfaces have been treated in order to understand the role of filler-matrix interfaces du ring ageing. To evaluate the influence of fillers on the degradation mechanisms and on the evolution of the mechanical properties, the evolution during ageing of these materials filled or not has been studied for an ageing by irradiation : they have been physico-chemically, microstrcuturally and mechanically characterized at various levels of ageing
Reynaud, Emmanuelle. "Etude des relations Structure : Propriétés mécaniques de thermoplastiques renforcés par des particules inorganiques nanoscopiques". Lyon, INSA, 2000. http://theses.insa-lyon.fr/publication/2000ISAL0070/these.pdf.
The works aims to correlate some morphological parameters and the mechanical properties in composite systems based on polymer matrix reinforced by submicronic inorganic fillers. The thought process lies on the study of three distinct filled polymer systems, their internal structure being all the more complex. The first system consists of a polymethyl methacrylate matrix filled with silica nanoparticles. The second system has polyamide 6 as a matrix and silica as fillers. The last system results from the clay introduction to polyamide 6/ First a morphological investigation enables to get insight into the filler influence on the surrounding polymer matrix. It also enlightens the various filler dispersion states (and its possible orientation within the sample geometry) with respect to the composite nature (in particular the inorganic particle size or its surface treatment) and its elaboration route. Then the study focuses on the role played by various morphological parameters (filler fraction, aspect ratio and dispersion state) on some mechanical properties, both elastic and plastic (through an investigation around the yield point). The latter properties were analysed on the various studied systems and compared. The experimental data were further confronted to some mechanical approaches, in order to better identify the morphological parameters leading to the observed macroscopic behaviours. Eventually, on the composites based on PA6, a possible sequence of the damage mechanisms occurring with increased elongation at room temperature was proposed, thanks to complementary experimental observations (through scattering and volume changes measurements). Given the involved parameters, each system was found to be characterised by a particular sequence of events
Droval, Guillaume. "Élaboration et caractérisation de composites polymères conducteurs électrique et thermique". Lorient, 2006. http://www.theses.fr/2006LORIS068.
Focusing on further application in the field of ohmic heating, the aim of this work is to improve the thermal conductivity of heating systems (based on biphasic conductive polymer composites (CPC) – immiscible blend) without significantly altering electrical properties to ensure that the temperature gradient within the material decreases since that could, in a long run, damage the system. The applied approach allowed to study and control in an independent way the thermo-physical properties of each phase: an electrically conductive phase (high density polyethylene (HDPE) matrix with carbon black (CB) fillers) and a thermally conductive phase (syndiotactic polystyrene (sPS) matrix filled with various thermal micro particles such as aluminium oxide (Al2O3), aluminium nitride (AlN), talc or even boron nitride (BN) among others). The novel feature obtained from this study is the synergy of the electrical and thermal properties of the two phases. These new formulas maintain a self regulating capability (increase of the electrical resistivity as the temperature rises (Positive Temperature Coefficient – PTC effect) and double the heat dissipation. Finally, the thermo-electrical behaviour of optimized CPC in working process has been studied through experimental data and simulation models on benchmarks of pilot tests. These results are fully satisfying in the purpose of developing and designing these materials as self regulating heating elements
Bugnicourt, Elodie. "Development of sub-micro structured composites based on an epoxy matrix and pyrogenic silica : mechanical behavior related to the interactions and morphology at multi-scale". Lyon, INSA, 2005. http://theses.insa-lyon.fr/publication/2005ISAL0113/these.pdf.
Les réseaux époxys présentent des propriétés insuffisantes pour certaines applications, en particulier à cause de leur fragilité. L'objectif de ce travail était de développer des composites à matrice époxy-amine et charges de silice pyrogénée afin d'améliorer les propriétés mécaniques des époxys pour des utilisations comme revêtements, adhésifs ou matériaux de structure. La silice pyrogénée a été fréquemment employée pour renforcer des élastomères ou dans un but de modification rhéologique, mais peu d'études traitent de l'addition de silice pyrogénée dans des réseaux thermodurcissables. Contrairement aux additifs conventionnels (organiques ou micro-charges), les charges sub-microniques permettent généralement d'augmenter à la fois la rigidité et la ténacité des matériaux polymères, tendance qui a été vérifiée dans ce travail pour la silice pyrogénée. En faisant varier la nature des comonomères époxy-amine et de la modification chimique de la surface de la silice, la nature des interactions développées au sein du système a pu être modulée (liaisons covalentes vs. Interactions physiques) et l'influence de la silice pyrogénée a pu être étudiée à la fois sur des réseaux dans l'état caoutchoutique et vitreux à température ambiante. Un des principaux défis de cette étude était le contrôle de l'état de dispersion de la silice grâce à l'optimisation de chaque étape du procédé. Les morphologies ont été caractérisées à de multiples échelles tout au long de la mise en œuvre par diverses techniques complémentaires. Une attention particulière a été portée aux interactions effectivement développées entre les charges et la matrice. Le comportement mécanique des matériaux a été caractérisé par analyse mécanique dynamique, test de traction et mécanique de la rupture. Les relations entre la structure et le comportement mécanique des composites époxy / silice pyrogénée ont enfin été discutées afin de comprendre les mécanismes de renforcement impliqués. L'effet de la silice a également été investigué sur les propriétés thermiques et la résistance au feu des réseaux époxys
Martin, Nicolas André Michel. "Contribution à l'étude de paramètres influençant les propriétés mécaniques de fibres élémentaires de lin : Corrélation avec les propriétés de matériaux composites". Thesis, Lorient, 2014. http://www.theses.fr/2014LORIS355/document.
This research study has been carried out during a CIFRE joint project between the Van Robaeys Frères Company, UBS and IFREMER. The work aims to improve understanding of the properties of both flax fibres and composite materials reinforced with flax.First, the influence of the degree of retting of flax fibers on the tensile properties of single fibers and short fiber/polypropylene composites has been shown.Then, the properties of scutched flax and flax tow were compared. We have shown that it is possible to reach similar tensile properties for unidirectional composite materials manufactured from the two products.Moreover, the influence of three different flax nonwoven reinforcements on the mechanical properties of thermoplastic matrix composites was studied. These materials were found to show anisotropy of tensile properties.Finally, the mechanical properties of the flax fibres processed by the Van Robaeys Frères Company were examined. A straightforward relationship was found between the tensile properties of the fibres and the tensile properties of unidirectional composite materials. The relationship is more complex for short fibre injected composites
Zhao, Hang. "Comportement multifonctionnel des composites comportant des nano/micro renforts". Thesis, Université Paris-Saclay (ComUE), 2015. http://www.theses.fr/2015SACLC020/document.
Due to the outstanding mechanical electrical and thermal properties, carbon nanotubes (CNTs) received worldwide attentions and intensive investigations in last decades. CNTs are greatly potential in applications such as energy storage and microelectronics. The one dimensional structure, high aspect ratio and low density, promote CNTs serving as the excellent fillers in composites field. However, due to the strong interactions, CNTs are usually difficult to be dispersed and aligned in a polymer matrix. Designing the CNTs construction reasonably is an effective way to ameliorate the dispersion states of CNTs in matrix. These specific hybrid constructions allowed CNTs arrays synthesized vertically onto the substrates through catalyst chemical vapor deposition method. These CNT arrays effectively overcome the problem of CNTs aggregation and promote the interconnection among CNTs, leading to a considerable improvement of multi-functional properties of composites. Graphite nanoplatelets (GNPs) served as substrate make their synthesizing products-GNP-CNTs hybrids (GCHs) possess distinct merits of all-carbon composition, totally-conductive coupling structure and the low intrinsic density. These GCHs constructions provide a great improvement in the dielectric and electrical properties of composites. However, the relationship between GCHs organization and synthesizing conditions during CVD process and the influence of the addition of GCHs to internal conductive networks have not been reported in detail. These mentioned issues will be investigated and discussed in this thesis, which is divided into four chapters:The first chapter makes a general review of the structure, properties, application and synthesis of CNTs and GNP substrates, and the main procedures of fabricating composites and surface functionalization of CNTs. Moreover, a short introduction of the development of micro-nano hybrids applied to the functional composites is made. Most importantly, the developing electrical states and (di) electrical characteristics of composites with ever-increasing conducting filler loading are reviewed in detail at the last part.The second chapter discusses firstly the synthesis process through the CCVD approach and the relationship between CVD parameters and the corresponding construction of GCHs, where the temperature, gas composition and reaction time were controlled. The constructions CNT arrays are dependent on the synthesis conditions. Furthermore, the results obtained from analysis can provide a structural foundation for the huge application potential of GCHs constructions. The third chapter introduces the poly(vinylidene fluoride)-based nanocomposites containing GCH particles, the dielectric properties of which are improved more greatly than the ternary composites loading equivalent mixture of GNPs and CNTs. The composites achieved by dispersing GCH particles into matrix using the mechanical melt-mixing process, showing a strongly reduced percolation threshold (5.53 vol %) and the relatively high thermal stability. Their improved dielectric properties can be attributed to the formed microcapacitor networks and the change of crystalline formation of matrix, caused by well-designed CNT arrays constructions. The fourth chapter investigates the advanced GCHs/ polydimethylsilicone (PDMS) composites with high piezo-resistive performance at wide temperature range. The synthesized GCHs can be well dispersed in the matrix through the mechanical blending process. The flexible composite shows an ultra-low percolation threshold (0.64 vol%) and high piezo-resistive sensitivity (gauge factor ~103 and pressure sensitivity ~ 0.6 kPa-1). Particularly, the much improvements of electrical properties achieved in GCHs/PDMS composites compared with composites filled with equivalent CNT, GNP or mixture of CNTs/GNPs. Slight motions of finger can be detected and distinguished accurately using the composites film as typical wearable sensor
Chimeni, Yomeni Desire. "Effet des modifications de surface sur les propriétés morphologiques, mécaniques et rhéologiques de composites à base de fibres biosourcées et de polyéthylène". Doctoral thesis, Université Laval, 2017. http://hdl.handle.net/20.500.11794/27718.
This doctoral thesis focuses on understanding the effect of surface modifications of hemp fibers on the one hand (250 μm - 1 mm and 8% NaOH pretreated to increase the number of active sites on their surface) and cellulose (≤ 200 μm) on the other hand, on the properties of linear medium density polyethylene (LMDPE) based composites. Two different modification approaches (MAPE in a solution (hemp and cellulose) and catalytic polymerization (hemp)) not yet well known were investigated. The first two parts of this thesis focused on understanding the effect of solution modification of hemp fiber on LMDPE composite morphological and mechanical behavior, as well as a qualitative and quantitative analysis of their interface, with emphasis on the comparison between them, the direct use of MAPE and the combination of both methods (solution and direct modification). Then, the work focused on evaluating the effect of fiber type on the composite behavior. For this purpose, the cellulose powder (≤ 200 μm) extracted from wood (Aspen wood) was modified by MAPE in a xylene solution to improve the properties of LMDPE based composites. Finally, the last part focused on the modification of hemp fibers by catalytic polymerization. For the fibers (hemp and cellulose), the results showed that they were successfully modified by MAPE in solution, as well as by catalytic polymerization for hemp. This enhanced the quality of the corresponding fiber-matrix interface. The results showed that NaOH pre-treatment mainly controlled the wettability level (physical contact) of hemp fibers by the matrix, while the use of a coupling agent (directly or in solution) controlled the interfacial adhesion (chemical interactions). Compared to the composites with unmodified fibers, an increase of the tensile strength by 21% for solution modified fiber composite, 24% after the direct use of MAPE and 31% upon combining both methods, were observed. The direct use of MAPE also significantly improved the composite Young's modulus by about 17%, followed by the combination of both method with 6% improvement, while the solution modification did not significantly affect this property. The use of cellulosic fibers increased the tensile strength of both unmodified and modified fibers composite with a 29% improvement for the composite with modified fibers. Finally, hemp modification by catalytic polymerization resulted in a significant increase in Young's modulus and tensile strength of the corresponding composite by about 8% and 43% respectively, compared to the composite with untreated fibers.
Imbert, Claire. "Matériaux à propriétés mécaniques et thermiques améliorées sous pression hydrostatique en utilisation aquatique". Thesis, Montpellier 2, 2010. http://www.theses.fr/2010MON20019.
Materials nowadays used for thermal insulation in aquatic environment under hydrostatic pressure are either rubber flexible foams or rigid foams, especially syntactic foams, depending on depth. These flexible materials were analyzed through classical mechanical and thermal tests. However, methods and results were adapted to the final usage of the product, particularly to the aquatic environment at the surface and under depth. Relationships between structures and properties characteristics were studied to define appropriate properties within relevant criteria. Moreover, to underline thermal properties under hydrostatic pressure, a testing instrument has been developed: an innovating hyperbaric test chamber, dedicated to under water pressure thermal resistance and thickness measurements, from 0 to 50 m depth. Strengths and weak points of these classical materials have been clearly established. Results analysis lead to a new concept of composite material for the defined usage. This innovating material, a syntactic foam, has been developed. By varying the particle type added to a thermoplastic elastomer matrix, the cellular structure has been refined in order to obtain a similar behaviour in aquatic environment, at the surface like in depth. This material has been tested, parallel to its industrial production, to identify relationships between structures and properties
Roume, Chantal. "Synthèse de monomères multiépoxydes et de leurs dérivés acryliques à propriétés thermiques améliorées". Montpellier 2, 1991. http://www.theses.fr/1991MON20039.
Khaokong, Chuanpit. "Elaboration of electronic conductor composite materials : study of physical and electronic properties". Le Mans, 2008. http://cyberdoc.univ-lemans.fr/theses/2008/2008LEMA1018.pdf.
The hydroxytelechelic oligoisoprene was synthesized according to well-controlled degradation procedure which has been recently developed in our laboratory, followed by the reduction of carbonyltelechelic cis-1,4-polyisoprene (CTPI) into hydroxytelechelic cis-1,4-polyisoprene (HTPI). Telechelic oligomers were characterized by FTIR, 1H-, 13C-NMR and SEC. Linear and crosslinked polyurethane films were synthesized from hydroxytelechelic cis-1,4-polyisoprene and diisocyanates or triisocyanates using dibutyltin dilaurate as catalyst. The modification of main chain by epoxidation or hydrogenation allows us to modify the properties of films. In this work, we have studied the possibility to use these kinds of polyurethanes as the polyelectrolyte matrix. The incorporation of ionic liquids, 1-butyl-ÿ3-metylimidazolium hexafluorophosphate and trihexyltetradecylphosphonium chloride, in polymer films was done and the conductivity of films was measured by dielectric relaxation spectroscopy. The presence of epoxidation in the main chain of polyurethane allows us to incorporate more amount of ionic liquid in film. Type of ionic liquid has an effect on the compatibility and properties of polyurethane films. The thermal properties of films were determined by DSC and TGA. Moreover, the polyurethane films were used as supporting matrix in an electropolymerization of a conducting polymer. By this method, we can prepare the precise polyaniline spot according to the electrode on the polyurethane film support. In addition, new type chain extender containing pyrrole monomer unit was synthesized. Its structure was confirmed by NMR, mass spectroscopy and elemental analysis. Polyurethanes using this pyrrole derivative chain extender were prepared and the thermal properties were investigated. Finally, the electropolymerization of pyrrole unit in polyurethane structure was performed
Lavergne, Claudine. "Etude par spectroscopies diélectriques de matériaux composites à base polymère à finalité électrotechnique". Toulouse 3, 1992. http://www.theses.fr/1992TOU30012.
Rogier, Robert. "Matériaux composites à matrice d'aluminophosphate de calcium et à renforcement d'inclusions métalliques biocompatibles : étude des propriétés thermiques, élastiques et mécaniques". Montpellier 2, 1989. http://www.theses.fr/1989MON20202.
Naceri, Abdelghani. "Caractérisation du comportement mécanique de composites renforcés par tissus en traction uniaxiale à différents taux d'humidité". Lyon 1, 1991. http://www.theses.fr/1991LYO10104.
Périé, Thomas. "Dispersion de nanotubes de carbone dans les polymères : de la nanostructuration aux composites hautes performances". Phd thesis, Université Pierre et Marie Curie - Paris VI, 2011. http://pastel.archives-ouvertes.fr/pastel-00634552.
Zarrad, Turki Inès. "Valorisation des sédiments marins dans une matrice agrosourcée : caractérisation expérimentale des biocomposites et modélisation du comportement mécanique". Thesis, Amiens, 2016. http://www.theses.fr/2016AMIE0038/document.
In recent decades, many research activities at the international level have focused on biomaterials with one hand equivalent characteristics and sometimes even higher than that of fossil products and secondly renewability of resources is an asset environmental. In addition, the problem of marine and river sediments is a global problem. Dredged sediment management is thus a general concern because of the quantities produced and their potential nuisance. In this work, an experimental study is conducted on the development of marine sediments to percentages ranging from 0% to 20% as a mineral filler in an agro-sourced matrix and appreciate their influence on the physical-mechanical, thermal and Sustainability elaborate composite HESM (hemoglobin / Marine sediments). The results show that the compressive modulus, flexural, tensile and compressive strength were improved when the addition of marine sediments by against the tensile strength and the flexural strength were decreased compared the reference material. The microstructural study to justify the effect of the addition of sediments in the matrix on the mechanical properties. As for the thermal characterization of biocomposites, the results show the improvement in the thermal stability of the composite relative to the pure polymer. Regarding sustainability, the addition of marine sediments has not almost influenced the durability properties and the charged material or not should not be exposed to the elements without protection. The finite element modeling of the mechanical behavior in compression has yielded satisfactory results to develop this new biocomposite as a floor covering