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Nanocomposites à matrice polypropylène renforcée par argile lamellaire - Etude de la relation procédé-structure

Abstract : This PhD focuses on the relationship between the preparation process and the structure of polypropylene/clay nanocomposites. First, the samples were prepared via an internal mixer. Scanning electron microscopy observations, completed by X-ray diffraction analysis and rheology measurements enabled us to characterize the clay dispersion state in the nanocomposite at different scales. Three organoclays were compared. It was shown that the chemical compatibility between the clay and the matrix was essential to ensure a good dispersion: Cloisite 20 and Dellite 67G showed good dispersion states at all scales, whereas Cloisite 30B did not. The influence of rotor speed and mixing time on the clay dispersion state was shown. The percolation threshold of the clay was determined. The link between dispersion state and crystallinity was also studied.The samples were then prepared via a twin-screw extruder. The influence of screw speed on the clay dispersion state was demonstrated, as well as the matrix degradation at high screw speed. The evolution of the dispersion state along the screw profile showed that intercalation was reached early in the screw profile, whereas exfoliation evolved linearly until the last mixing elements. A lower barrel temperature, as well as a more viscous matrix did not improve the clay dispersion state, and did not prevent the matrix degradation. Finally, the Ludovic© software allowed us to apprehend the thermomechanical phenomena involved during extrusion, but also to optimize the process.
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Submitted on : Thursday, January 25, 2018 - 10:36:29 AM
Last modification on : Wednesday, November 17, 2021 - 12:28:25 PM
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  • HAL Id : tel-01692446, version 1


Guillaume Normand. Nanocomposites à matrice polypropylène renforcée par argile lamellaire - Etude de la relation procédé-structure. Matériaux. Université Paris sciences et lettres, 2016. Français. ⟨NNT : 2016PSLEM053⟩. ⟨tel-01692446⟩



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