Probing the dynamics of high-viscosity entangled polymers under shear using Neutron Spin Echo spectroscopy

6th European Conference on Neutron Scattering

Kawecki, M.^1 ; Gutfreund, P.^2 ; Adlmann, F.A.^1 ; Lindholm, E.^3 ; Longeville, S.^4 ; Lapp, A.^4 ; Wolff, M.^1

Department of Physics and Astronomy, Uppsala University, Box 516, SE, Uppsala, Sweden^1

Institut Laue Langevin, EPN Science Campus, Grenoble, France^2

Angstrom Workshop, Uppsala University, Box 516, SE, Uppsala, Sweden^3

Laboratoire Leon Brillouin, CEA Saclay, Gif-sur-Yvette, France^4

关键词: Conformational change;    Entangled polymer solutions;    Entangled polymers;    Entanglement-disentanglement transition;    Intermolecular interactions;    Neutron spin echo;    Neutron spin echo spectroscopies;    Scattered neutron;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/746/1/012014/pdf
DOI  :  10.1088/1742-6596/746/1/012014

来源: IOP

【 摘 要 】

Neutron Spin Echo spectroscopy provides unique insight into molecular and submolecular dynamics as well as intra- and inter-molecular interactions in soft matter. These dynamics may change drastically under shear flow. In particular in polymer physics a stress plateau is observed, which might be explained by an entanglement-disentanglement transition. However, such a transition is difficult to identify directly by experiments. Neutron Spin Echo has been proven to provide information about entanglement length and degree by probing the local dynamics of the polymer chains. Combining shear experiments and neutron spin echo is challenging since, first the beam polarisation has to be preserved during scattering and second, Doppler scattered neutrons may cause inelastic scattering. In this paper we present a new shear device adapted for these needs. We demonstrate that a high beam polarisation can be preserved and present first data on an entangled polymer solution under shear. To complement the experiments on the dynamics we present novel SANS data revealing shear- induced conformational changes in highly entangled polymers.