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@INPROCEEDINGS{Lettinga:867478,
author = {Lettinga, M.P.},
title = {{Q}uantitative understanding of sheared colloidal rods and
the effect of length and stiffness},
reportid = {FZJ-2019-06117},
year = {2019},
abstract = {Soft matter materials are classically characterized by
rheological experiments, which probe the mechanical response
to shear flow. Knowledge of the microscopic structure in
flow is crucial to understand, predict, and tune flow
behaviour and therefore the macroscopic rheological response
of complex fluids. A simple example of such fluids are
dispersions of stiff particles, as alignment of the
particles will cause a huge drop in the viscosity of the
fluid. This ‘shear thinning’ can cause flow to be
unstable, causing gradient shear banding. It is yet unclear,
however, how this highly non-linear behaviour is linked to
microscopic features such as the stiffness and dimensions of
the particles. In this talk I will first show how we gained
full understanding of the shear thinning process of rods by
performing in situ rheology and Small-angle neutron
scattering experiments1 on a library of monodisperse viruses
with varying length2. The shear and length dependent
orientational order could be linked to the rheological
response, by extending the Doi, Edwards, Kuzuu theory. I
will also show, however, that even a length of 2 𝜇m for
the longest viruses is not sufficiently shear thinning to
yield the system unstable3. On the other hand, we could tune
dispersions of Xanthan4 and pnipam-grafted DNA dispersions
such that shear bands do form, using the ionic strength and
temperature, respectively. Finally, in situ microscopy
experiments on F-actin5 will be discussed to show how
systems where the persistence length is smaller than the
contour length relax in shear flow.},
organization = {(Japan)},
subtyp = {Invited},
cin = {ICS-3},
cid = {I:(DE-Juel1)ICS-3-20110106},
pnm = {551 - Functional Macromolecules and Complexes (POF3-551) /
DiStruc - Directed Colloidal Structure at the Meso-Scale
(641839)},
pid = {G:(DE-HGF)POF3-551 / G:(EU-Grant)641839},
experiment = {EXP:(DE-MLZ)KWS2-20140101},
typ = {PUB:(DE-HGF)31},
url = {https://juser.fz-juelich.de/record/867478},
}