Reference : Etude de propriétés dynamiques linéaires et non-linéaires de deux liquides colloïdaux...
Dissertations and theses : Doctoral thesis
Physical, chemical, mathematical & earth Sciences : Physics
Etude de propriétés dynamiques linéaires et non-linéaires de deux liquides colloïdaux modèles par rhéologie: DGEBA/Al2O3 et DGEBA/SiO2
Thomassey, Matthieu [University of Luxembourg > Faculty of Science, Technology and Communication (FSTC) > Physics and Materials Science Research Unit >]
University of Luxembourg, ​Luxembourg, ​​Luxembourg
Docteur en Physique
Sanctuary, Roland mailto
[en] rheology ; nanoparticles ; DGEBA/Al2O3 - DGEBA/SiO2 ; linear and non-linear dynamical properties ; relaxation processes ; glass transition ; shear-thinning / shear-thickening ; surface instability / volume instability
[en] The dynamic mechanical behaviors of two model colloidal suspensions are compared in order to highlight microstructural changes in the suspensions. differentiate between the topological and physico-chemical impact of nanoparticles. For both systems the matrix material consists of the technologically relevant epoxy resin diglycidil ether of bisphenol A (DGEBA). The suspended nanoparticles are hydrophilic alumina and hydrophobic silica respectively. It will be shown that beside the classical α process an additional low-frequency relaxator exists whose qualitative frequency behavior is attributed to the pure presence of nanoparticles. The fine structure of the low-frequency relaxator depends on the physico-chemical surface properties of the nanoparticles. Similar to the α process the additional low-frequency relaxator shows cooperative behavior. Astonishingly, on the lines of the pure resin DGEBA, both colloidal suspensions show terminal behavior at very low frequency excitations. The nanoparticles are also shown to be responsible for non-linear dynamic and flow behaviors as well as for the emergence of free surface and volume instabilities. The transient character of flow is induced.

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