Wetting Kinetics of Polymer Solutions. Experimental Observations
It is known that the spreading rates of small liquid drops over a solid surface exhibit a strong dependence on the viscosity of the liquid. These observations have led us to study the spreading behavior of polymer solutions on high- and low-energy substrates to determine what role complex rheology plays in wetting kinetics. We did not observe any effects of non-Newtonian (nonlinear) behavior, nor were any obvious signs of viscoelasticity (memory) visible. Instead, we observed a most intriguing phenomenon that polymer solutions, despite having low surface energies, do not wet high-energy substrates. in addition, nonwetting drops spread to an equilibrium configuration by either one of two distinct mechanisms. in the first case, they spread as a wetting Newtonian liquid and then stopped, that is, equilibrated, abruptly. in the second, they equilibrated continuously. We offer some possible molecular and continuum arguments to explain the differences between these two mechanisms.
S. Nieh et al., "Wetting Kinetics of Polymer Solutions. Experimental Observations," Macromolecules, American Chemical Society (ACS), Jan 1996.
The definitive version is available at http://dx.doi.org/10.1021/ma950424r
Chemical and Biochemical Engineering
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© 1996 American Chemical Society (ACS), All rights reserved.