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Project

Investigating the Linear and Nonlinear Rheology of Model Polymer Melts

While the linear viscoelastic behavior of polymer melts has been deeply studied and is rather well understood, the nonlinear regime is still a matter of discussion and many questions remain unanswered. For example, despite the basic nature of the problem, there is no clear molecular picture to explain how the steady elongation viscosity of linear chains depends on the Hencky strain rate applied to the sample, and why this dependence is found to vary in function of the polymer concentration. While these questions are addressed at a fundamental level, they are also of great relevance for many applications related to polymer processing. The objective of this research project is to bring new insights to understand the elongational properties of polymer melts and solutions. To this end, we will investigate the elongational properties of model polymeric systems designed to help us to understand, at the fundamental level, the origin of strain hardening and the existence of a steady regime, as well as the role played by the molecular environment on the stretch state, strain hardening and relaxation behavior of a polymer chain. Typical systems are binary or tertiary blends of monodisperse linear chains, as well as monodisperse linear polymers diluted in solvent of different natures. In parallel to this first objective, this project also aims at validating and improving the Filament Stretching Rheometer of which there are currently very few instruments available in Europe. While it has already allowed significant progress in the understanding of elongation properties, there is still room to improve the instrument and extend its performance.

Date:2 Jun 2021 →  22 Nov 2023
Keywords:Non-linear Rheology, Polymer Physics, Filament Stretching Rheometer
Disciplines:Rheology
Project type:PhD project