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Department of Mathematical Sciences

Seminar Archives

On this page you can find information about seminars in this and previous academic years, where available on the database.

Biomathematics Seminar: Nematic Dumbbell Model: Applications and Flow Instabilities

Presented by James Adams, Surrey University

10 November 2015 14:00 in CM105

iquid crystalline polymers (LCPs) are complex fluids that can be
constructed in a variety of molecular architectures. In the limit of
rod-like molecules their rheology show flow tumbling behaviour where
the director continuously rotates under shear. In the flexible polymer
limit the director tends to align with the flow direction. LCPs have a
complex director texture in the polydomain state, and show
orientational banding of the director in response an external shear
strain. Orientational banding is observed when LCPs are crosslinked
into a liquid crystalline elastomer (LCE). When LCEs are stretched
perpendicular to their director they form a striped
microstructure. They behave as active solids as the liquid crystalline
phase is changed e.g. by photoactuation or temperature cycling.

Experimental work on high molecular weight polymers has shown that
these materials form shear bands (spatial variation in the shear rate)
in response to a simple shear. Here we try and understand the
orientational band formation in a simple model of LCPs in terms of
transient shear banding.

Maffettone and Marrucci developed the nematic dumbbell model to
describe flow aligning LCPs. We will analyse this model to understand
its flow instabilities. We will use it to model a new application for
Liquid crystalline elastomers -- a switchable pressure sensitive

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