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Academic literature on the topic 'Composites – Aspect environnemental'
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Dissertations / Theses on the topic "Composites – Aspect environnemental"
Lacoma, Vincent. "Évaluation environnementale des procédés composites pour l'analyse multicritère des systèmes de production : méthodologies, outils et applications." Electronic Thesis or Diss., Ecole centrale de Nantes, 2023. http://www.theses.fr/2023ECDN0020.
Full textIn the current context of environmental transition, this thesis aims to participate in the reduction of environmental impacts related manufacturing of composite parts, which has been a growing sector for several years. To this purpose,an environmental assessment methodology dedicated to composite manufacturing processes is fundamental to develop and evaluate strategies forreducing environmental impacts. To be applicable in the industry, these strategies must respect the technical and economic imperatives of companies.To carry out environmental assessments, the standardized Life Cycle Assessment (LCA) method can be used. However, the general nature of this approach leaves latitudes on its application which have not been yet the subject of a scientific consensus in the case of composite manufacturing.Thus, our work proposes details for each step of the LCA method to build a model of the environmental impacts of the manufacturing process which depend on its parameters, such as the forming temperatures and the consolidation efforts. A similar approach is also developed for the evaluation of economic indicators based on the same parameters. Finally, multi-criteria decision-making tools are offered to find solutions to the objective of reducing environmental impacts and manufacturing costs while ensuringc ompliance with the technical specifications of the parts produced. In this thesis, the case of thermostamping of polyphenylene sulfide reinforced with carbon fibres (C/PPS) parts is studied to support the construction and presentation of the proposed methodologies
Al-Mohamadawi, Ali Abdullah Hassan. "Contribution à l'étude de l'impact de l'environnement vis-à-vis d'éco-matériaux lignocellulosiques." Thesis, Amiens, 2016. http://www.theses.fr/2016AMIE0040/document.
Full textDue to their low cost, lightness and thermal properties, lignocellulosic byproducts received a particular attention, in the recent years, for manufacturing lightweight concretes. However, these byproducts are not fully compatible with the cement matrix, leading to setting delay, significant dimensional variations, and low mechanical strengths of the composites elaborated. To avoid such drawbacks, a coating process of flax shives using different substances has been adopted in this study. It leads to a reduction in treated shive water absorption compared to raw shives. The composites obtained exhibit significant improvements in hydrous behavior and mechanical strengths with moderate increase in the apparent bulk density and thermal conductivity. The phenomena of moisture transfer in the produced composites can significantly influence the durability and performance of them. In fact most of the materials used in the building area are porous, containing water as vapor or liquid. Therefore the water vapour permeability, sorption isotherms and moisture buffering capacity have been determined. The results obtained show the good hygric performance of the eco-composites elaborated. Three leaching tests have been proposed in this study to identify the chemical speciation of the materials and to evaluate their releasing into the environment. The experimental conditions of the leaching tests have been chosen to simulate different states of our composites in external environments in service or end of life. The leaching behaviour of the cement-based products elaborated differs little according to flax shive treatment and the leaching of toxic substances has not been identified
Nasiri, Aida. "Development of Safe-by-Design Nano-composites for Food Packaging Application." Thesis, Montpellier, 2017. http://www.theses.fr/2017MONTT076.
Full textThe market of nanotechnologies is dominated by the food packaging area which amounts more than 20% of the total nanotechnologies market in 2015. However, the wide-scale use of nanomaterials raises important questions about environmental and safety issues that could hinder their development. In the case of plastics intended to be in contact with food, the risk of contamination concerns not only the nanoparticles but also all the chemical additives added during the material processing. The presence of nanoparticles is susceptible to modify the interactions between polymer and the additives with a possible change in their transport properties and therefore the food contamination.The present work aims at identifying the relationship between the structural characteristic and the transport properties (diffusivity and solubility) of nanoparticles and chemical additives incorporated in nanocomposites. In this regard, it is necessary to fill the gap of knowledge in 3D nanostructure characterization and a multi-scale modeling of mass transfer properties of nanocomposites in real usage conditions.In this way, polyethylene and nanoclay were selected based on the best compromise between real potential applications and the scientific knowledge previously published and eventually the nanocomposites were synthesized with LLDPE, Cloisite20 and a compatibilizer by melt intercalation method.The nanocomposite structure was characterized using TEM, X-ray nanotomography, TGA and XRD then submitted to migration tests undertaken in contact with different food simulants which represent various types of food (aqueous, acid, alcoholic) following the recommendation of the European regulation on the food contact material. To evaluate the positive or adverse effects of the nanomaterials on the contamination of the food by chemical additives which are usually incorporated with the plastic packaging, the virgin polymer and nanocomposite material were spiked with a mixture of the additives exhibiting various volatility, polarity and molecular weight. Then, the transport properties (i.e inertia) of nanocomposite structure was distinctively investigated on kinetic (apparent diffusion coefficient) and thermodynamic (partition coefficient) considerations.The results indicated that nanoclay addition in plastic materials favorably reduced the migration of additives by modifying both their diffusivity in the polymer and their partition between the polymer and the food simulant. However, while the partition coefficient of additives increases in nanocomposite in comparison to pure LLDPE for the samples in contact with all types of food simulants, the reduction of diffusion coefficient is significantly dependent on the nature of the food simulant in contact. Hence, it can be concluded that the major role in the migration of additives is not played by the imposed tortuosity path, but by the factors such as the affinity between the base polymer and simulants as well as the effects of simulants on swelling and crystallinity of the samples. Moreover, the effect of additive-related parameters and the structural parameters were assessed and put in perspective with their impact on the transport properties of nanostructures. Integrating the results of characterization and transfer properties led to an improved understanding of the influence of structure of nanocomposites on their mass transfer properties and therefore on the suitability of using them as food contact materials
Seghini, Maria Carolina. "Mechanical Analysis and Fibre/Matrix Interface Optimization for Next Generation of Basalt-Plant Fibre Hybrid Composites." Electronic Thesis or Diss., Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aérotechnique, 2020. http://www.theses.fr/2020ESMA0003.
Full textGlobal awareness of environmental issues has resulted in the emergence of “green” composites, in which natural fibres are used to replace synthetic ones. However, in semi-or structural applications, it can be inconvenient to use composites based on natural fibres. A possible solution to this problem is the development of hybrid composite materials, combining together plies of natural and synthetic fibres. In this framework, the aim of this research project was to develop basalt-flax fibre hybrid composites with a view to obtaining more environmentally friendly composites for semi-structural applications. Hybrid composites were produced through vacuum infusion molding with epoxy matrix.For comparison purposes, 100% flax fibre composites and 100% basalt fibre composites were also manufactured. A quasi-static and dynamic mechanical characterization showed that the hybridization allows the production of a composite with intermediate mechanical performances compared to those possessed by flax and basalt composites. However, the damage analysis has revealed the need to optimize the fibre/matrix interface adhesion quality, in order to increase the mechanical properties of the resulting hybrid composites. For this reason, different surface modification treatments have been specifically designed and investigated for flax and basalt fibres. Flax and basalt fibres were treated by the physical process of Plasma Enhanced Chemical Vapor Deposition. Flax fibres were also subjected to two chemical treatments using enzymatic species and supercritical CO2. The effects of the surface modification treatments on the thermal stability, morphology and mechanical properties of flax and basalt fibres have been investigated. The degree and extent of fibre/matrix adhesion were analyzed by micromechanical fragmentation tests on monofilament composites. The adhesion quality between fibres and both epoxy and vinylester matrices has been assessed in terms of critical fragment length, debonding length and interfacial shear strength. High-resolution μ-CT has been used to support the analysis of the damage mechanisms during fragmentation tests. For both flax and basalt fibres, the best results were obtained after the plasma polymer deposition process. This process was able to produce a homogeneous tetravinylsilane coating on the surface of basalt and flax fibres, which resulted in a significant increase in the fibre/matrix adhesion, thus paving the way for the next generation of more environmentally friendly hybrid composites for semi-structural applications
Perrot, Yves. "Influence de la matrice sur le comportement mécanique de matériaux composites verre/polyester utilisés en construction navale de plaisance : cas des résines polyester limitant les émissions de styrène." Lorient, 2006. http://www.theses.fr/2006LORIS074.
Full textThe work performed in this study is concerned with the characterization of glass/polyester composites for the pleasure boat industry. In particular the properties of polyester resins limiting styrene emissions have been evaluated. Physico-chemical and mechnanical tests were first performed in order to understand the roles played by the constituants (matrix, fibres and fibre/matrix interface). Then a study of damage mechanisms, delamination and impact resistance, was carried out on composite specimens. Durability and the influence of the marine environment was also examined through two parameters, temperature and sea water aging. Finally the transfer from material to structure was illustrated through three aspects : the influence of fabrication (over-lamination), the behaviour of panels subjected to uniform pressure loading, and the design rules. The results of the study show that a multi-disciplinary approach, including investigation at different scales, is necessary to understand the specific characteristics of these composite materials
Diouf-Lewis, Audrey. "Elaboration et évaluation d'additifs verts pour polymères et composites respectueux de l'environnement." Thesis, Université Clermont Auvergne (2017-2020), 2017. http://www.theses.fr/2017CLFAC028/document.
Full textThis thesis work falls within the identified context of the need to develop new polymers that are more environmentally friendly. We are convinced that the development of these "green" materials requires the use of "green" additives during formulation. To develop environmentally friendly additives capable of stabilizing the polymer, with respect to the life cycle, and paying special attention to biomass valorization, three approaches have been studied. The first is an innovative way of using a mixture of polyphenols from winery by-products and tea industry. The second way is the valorisation of a molecule from the major by-product of the wheat industry. The third is a recent route of innovation, which proposes the use of layered double hydroxides nanocomposites (LDH) functionalized with bio based stabilizers. The evaluation of their stabilizing properties is carried out in polyolefins, against thermo- and photo-oxidation processes. The very promising results of the project highlight the strong potential of bio based molecules and composites to maintain polymers properties under conditions of use
Tlijani, Mohamed. "Contribution à la caractérisation thermophysique de matériaux bio-isolants : valorisation des déchets de bois de palmier." Thesis, Paris Est, 2016. http://www.theses.fr/2016PESC1157/document.
Full textThe growing interest in new concrete and their use in many fields of civil engineering was that we wanted to bring a new approach to the design of a new product consisting of a reinforced concrete with basel end frond palm fibers. This led us to conduct the experimental study of thermal properties of natural fibers of date palm (Phoenix dactylifera L.). The analysis of experimental results showed that the essential factors affecting the thermal conductivity are the variety of date palm and the fiber orientation and that the basel end of the frond palm is the most interesting part as thermal insulation. However, the main problem encountered when using plant fibers as reinforcement is cohesion, bonding with the matrix and dimensional instability so the composite loses its mechanical properties. In this context, an alkaline pretreatment of palm fibers was envisaged to clean and modify the fiber surface to address the problems of dimensional stability of the fibers and degradation before their use as reinforcement in the cement matrix. We also studied the influence of chemical treatment with sodium hydroxide on the mechanical properties of processed samples, they were subjected to the tensile test to estimate the fracture strength for each treatment concentration, the Young's modulus and elongation at break corresponding. Subsequently, we conducted experimental and theoretical research on the thermal conductivity of different formulations of basel end palm wood concrete composite. The study of the theoretical apparent thermal conductivity was based on an approach that relies on a process whereas the material consists of a solid matrix combined with a fluid phase (air). Finally, we performed a numerical simulation of heat transfer phenomena to assess the thermal conductivity of basel end frond palm concrete composite and validate subsequently the theoretical prediction model selected. The results showed that the numerical approach based on the isotropic orientation of the particles in the composite coincides and approaches the physical reality
Pradal, Nathalie. "Synthèses, mise en forme et caractérisations de luminophores nanostructurés pour une nouvelle génération de dispositifs d'éclairage sans mercure." Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2012. http://tel.archives-ouvertes.fr/tel-00775908.
Full textSaib, Mahdi-Salim. "Construction d'une méthode de caractérisation des inégalités territoriales, environnementales et sociales de santé." Thesis, Amiens, 2015. http://www.theses.fr/2015AMIE0003/document.
Full textThe objective of this thesis is to explore spatial indicator crossing-analysis techniques in order to characterize the accumulation and the interrelations of the territorial, environmental and social health (TESHI).This analysis implies to set up integrated approaches based on data representativeness, techniques adapted to specificities of aggregated data, and relevant modeling of the characterized phenomena. A specific aspect of this work is the development of a tool allowing the integration of spatial phenomena at different levels (local, regional and loco-regional). In this project, a pilot study is presented on the Picardy region. The tool has been tested for the analysis of TESHI, thus validating the methodology feasibility and the adaptation of approaches implemented while providing additional keys of interpretation to the relative limits of direct appropriation of the results by the managers
Magniont, Camille. "Contribution à la formulation et à la caractérisation d'un écomatériau de construction à base d'agroressources." Toulouse 3, 2010. http://thesesups.ups-tlse.fr/980/.
Full textThe main aim of this work was to contribute to the development of an innovative building material that complies with legislations and users actual requirements concerning environmental and health impacts as well as thermal or hygroscopic comfort. An original pozzolanic matrix has been formulated while conventional admixtures, reinforcement fibres and aggregates were substituted by renewable raw materials. Hardening mechanisms and long term behaviour of that binder (mix of metakaolin and hydraulic lime) have been explored. The benefits of incorporating two organic admixtures on early age properties and long term behaviour of the pozzolanic binder have been explained by the identification of interaction mechanisms between mineral and organic species. A comparative study has been realised on flexural reinforcement of this matrix by vegetable fibres of flax, hemp and yucca and on the durability of these different composites. Finally, the compatibility of this matrix with vegetable aggregates (hemp chènevotte and sunflower stem pith) has been checked and demonstrated in order to formulate self-supporting insulation ecomaterial