Campuses:

Polymeric threads: formation and instability

Thursday, October 15, 2009 - 3:30pm - 4:10pm
EE/CS 3-180
Jens Eggers (University of Bristol)
We report on recent experimental and theoretical work on
the
pinch-off of dilute solutions of flexible polymers. Owing to
the
strong extensional hardening of such solutions, pinch-off of a
liquid drop is delayed. Instead, long threads of uniform
thickness
form, whose radius decreases exponentially in time. We derive a
relationship between the thread radius and the extensional
viscosity.
When the thread radius has decreased to about 10 microns, the
thread
becomes unstable to the rapid growth of small blisters.
Observations
are in strong disagreement with conventional models for dilute
suspensions.
The ensuing dynamics are very rich, and include iterated
instabilities and
periodic breathing. For sufficiently high polymer
concentrations,
the fluid never breaks, and a solid nanometer-sized thread is
left behind.

MSC Code: 
82D60
Keywords: