Open siphon of PEO/silica suspensions

D. D. Joseph

University of Minnesota, January 2005


Open siphon is an unusual phenomenon observed in polymeric liquids. After a small initial thread of the polymeric liquid is drawn over the side of the beaker, the flow will continue upon the influence of the gravity and upon the cohesive forces which prevent the column of liquids in the legs of the siphon from breaking under its own weight.

The liquids in our open siphon experiments are aqueous Poly(ethylene) Oxide (PEO) solution laden with silica nanoparticles. The molecular weight of PEO is 8 million g/mol. The beaker holding the PEO/silica suspensions is tilted first for 15 so that a small portion of the liquid spills out of the beaker.

If the liquid is Newtonian, the flow stops when the liquid surface levels with the edge (see movie 1 where the fluid is glycerin).

Movie 1. Glycerin

For the PEO/silica suspensions, the flow can continue to empty the beaker partially or even completely. Please click on the picture to see the movie.

Movies

PEO wt%

silica wt%

silica size (nm)

0.5

0.5

10 - 20

0.5

1

10 - 20

0.5

2

10 - 20

0.5

2

45 - 60