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Fluid-fluid pinch-off in presence of polymeric surface agents

Fluid-fluid pinch-off in presence of polymeric surface agents. Matthieu ROCHÉ (1), Hamid KELLAY CPMOH, Universite Bordeaux 1, France (1) Now at Complex fluids group MAE – Princeton University APS DFD Meeting November, 22 2009 Minneapolis. Motivation. Polymers inside. [1,2]. [3].

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Fluid-fluid pinch-off in presence of polymeric surface agents

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  1. Fluid-fluid pinch-off in presence of polymeric surface agents Matthieu ROCHÉ (1), Hamid KELLAY CPMOH, Universite Bordeaux 1, France (1) Now at Complex fluids group MAE – Princeton University APS DFD Meeting November, 22 2009 Minneapolis

  2. Motivation Polymers inside [1,2] [3] A viscous fluid in another viscous fluid Polymeric fluids in air What happens if polymers are added to the outer fluid? [1] J. R. Lister and H. A. Stone, Phys. Fluids 10, 2758-2764 (1998). [2] I. Cohen, M. P. Brenner, J. Eggers, and S. R. Nagel, Phys. Rev. Lett. 83, 1147 (1999). [3] Y. Amarouchene, D. Bonn, J. Meunier, and H. Kellay, Phys. Rev. Lett. 86, 3558-3561 (2001).

  3. Main observations • With polymers lying at the interface between the fluids, we observe that: • Polymers in the outer phase modify the shape of the neck • Polymers in the outer phase modify the thinning dynamics • Structures analogous to those observed with bulk polymeric fluids (polymers inside the fluid led to break-up) arise during the thinning • We can obtain a good measurement of the surface viscosity induced by the presence of polymers

  4. Set-up Black: continuous outer phase (aqueous solutions of surface agents) White: to-be-dispersed inner phase (5CB liquid crystal) Polymers in the outer phase only

  5. Polymers in the outer phase modify the shape of the neck [SDS] = 0.1 CMC No PVA [SDS] = 0.1 CMC [PVA] = 1 wt% Average Mw = 105 Da t = tc-t, time away from singularity tc: pinch-off time

  6. Similarities between our experiments and the pinch-off of bulk polymeric fluids a: M. S. N. Oliveira and G. H. McKinley, Phys. Fluids 17, 71704 (2005). Polymers inside the neck b: R. Sattler, C. Wagner, and J. Eggers, Phys. Rev. Lett. 100, 3-6 (2008). Polymers inside the neck c: our experiment. Polymers outside the neck

  7. Polymers in the outer phase modify the thinning dynamics hmin tsd = 3.89 ms Qout=2 mL/h t = tc-t, time away from singularity tc: pinch-off time

  8. Comparison between the thinning slowdown for bulk polymeric fluids and the slow-down we observed Exponential tendency Y. Amarouchene, D. Bonn, J. Meunier, and H. Kellay, Phys. Rev. Lett. 86, 3558-3561 (2001).

  9. The slow down is well fitted by an exponential function tsd = 3.89 ms [SDS] = 0.1 CMC [PVA] = 1 wt% Qout=2 mL/h t = tc-t, time away from singularity tc: pinch-off time

  10. Observations for a silicone oil in a PVA outer solution : purely viscous effect e ~1140 s-1 Effect not related to the properties of the liquid crystal

  11. Surface viscosity induced by polymers lying on the interface hs on the order of a few 10-6 to a few 10-5 kg/s Good order of magnitude compared to values reported in the literature 5CB in a 1 wt% PVA solution Deflate Inflate

  12. Conclusion • Surface effects induced by polymers in the outer phase of a liquid-liquid system led to break-up • Growing structures analogous to those observed with bulk polymeric fluids, where polymers are inside the liquid led to break-up • Thinning dynamics for the neck similar to those observed with bulk polymeric fluids • Good agreement with reported values for surface viscosity of polymers

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