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Analyse des mécanismes de dispersion élémentaires et globaux de charges minérales dans les polymères : influence de la rhéologie et de la structure de la matrice

Abstract : The objective of this study is the analysis of the dispersion of mineral fillers within a polymer matrix. This work aims is to increase the fire resistance of a polyolefin by dispersing magnesium hydroxide mineral filler. High amounts of magnesium hydroxide are needed to reach a significant performance of the fire resistance. The high loads induce a degradation of the mechanical properties of the material. In order to obtain a good dispersion and to improve the mechanical properties, a high viscosity matrix may be used. However, this causes problems during the manufacturing of the composite by extrusion because high pressures induced by a highly filled viscous matrix might block the machine. To solve this issue a less viscous matrix can be used to facilitate the processing by extrusion. Two matrices having the same physico-chemical properties but very different viscosities have been used to disperse the filler. The first part of the study concerns the identification and analysis of the elementary mechanism of dispersion, i.e. how an individual agglomerate is dispersed. Then, extrapolation to highly filled systems is carried out. The global mechanism of dispersion has been conducted in an internal mixer and characterization techniques such as scanning electronic microscopy with X-ray detection, tensile test, fractal dimension and dynamic rheometry in the melt have been used. A rheological model relating dynamic rheological measurements and the state of dispersion has been developed. The last part of the study is concerned with the optimization of the fabrication process and the dispersion of filers by twin screw extruder
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https://tel.archives-ouvertes.fr/tel-00673116
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  • HAL Id : tel-00673116, version 1

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Béatriz Olalla. Analyse des mécanismes de dispersion élémentaires et globaux de charges minérales dans les polymères : influence de la rhéologie et de la structure de la matrice. Autre. Université Jean Monnet - Saint-Etienne, 2010. Français. ⟨NNT : 2010STET4003⟩. ⟨tel-00673116⟩

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