Journal Article

FZJ-2015-06739

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Convective Cage Release in Model Colloidal Glasses

Jacob, A. R. ; Poulos, A. S. ; Kim, S. ; Vermant, J. ; Petekidis, G. (Corresponding author)

2015
APS College Park, Md.

This record in other databases:      

Please use a persistent id in citations: http://hdl.handle.net/2128/9484  doi:10.1103/PhysRevLett.115.218301

Abstract: The mechanism of flow in glassy materials is interrogated using mechanical spectroscopy applied to model nearly hard sphere colloidal glasses during flow. Superimposing a small amplitude oscillatory motion orthogonal onto steady shear flow makes it possible to directly evaluate the effect of a steady state flow on the out-of-cage (α) relaxation as well as the in-cage motions. To this end, the crossover frequency deduced from the viscoelastic spectra is used as a direct measure of the inverse microstructural relaxation time, during flow. The latter is found to scale linearly with the rate of deformation. The microscopic mechanism of flow can then be identified as a convective cage release. Further insights are provided when the viscoelastic spectra at different shear rates are shifted to scale the alpha relaxation and produce a strain rate-orthogonal frequency superposition, the colloidal analogue of time temperature superposition in polymers with the flow strength playing the role of temperature. Whereas the scaling works well for the α relaxation, deviations are observed both at low and high frequencies. Brownian dynamics simulations point to the origins of these deviations; at high frequencies these are due to the deformation of the cages which slows down the short-time diffusion, while at low frequency, deviations are most probably caused by some mild hydroclustering.

---

Contributing Institute(s):

1. Neutronenstreuung (ICS-1)
2. Neutronenstreuung (Neutronenstreuung ; JCNS-1)

Research Program(s):

1. 551 - Functional Macromolecules and Complexes (POF3-551) (POF3-551)
2. 6G4 - Jülich Centre for Neutron Research (JCNS) (POF3-623) (POF3-623)
3. 6215 - Soft Matter, Health and Life Sciences (POF3-621) (POF3-621)

Appears in the scientific report 2015

---

Database coverage:
; ; ; Current Contents - Physical, Chemical and Earth Sciences ; IF >= 5 ; JCR ; NCBI Molecular Biology Database ; SCOPUS ; Science Citation Index ; Science Citation Index Expanded ; Thomson Reuters Master Journal List ; Web of Science Core Collection

---