Misting of liquids in forward roll coating is a problem under certain conditions. The relaxation time is known to influence misting but the fundamental mechanisms are not clear. A new mechanism for misting of dilute non-Newtonian liquids was proposed based on visualizations with a high-speed camera. With these liquids, filaments were created which sometimes transformed into beads-on-string structures and the beads were ejected as mist droplets when the structures broke. Misting was quantified by measuring sizes of the generated droplets, their count and mass concentration. The measurements were related to elasticity of the solutions through their relaxation times. Small levels of elasticity reduce the amount of misting, but higher levels lead to an increase.
Bibliographical noteFunding Information:
Financial support for this work was provided by the Industrial Partnership for Research in Interfacial and Materials Engineering (IPRIME) . We thank W.J. Suszynski for his help in capturing instabilities with the high-speed camera. Thanks are due to undergraduate research participants, Kris Hodgson, John Lund and Brian Kelly who gathered some of the data reported in this work.
- Boger liquids
- Dilute polymer solutions
- Forward roll coating