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Evaporation Induced Rayleigh-Taylor Instability in Aqueous Polymer Solutions

ORAL

Abstract

Understanding the mechanics of detrimental convective instabilities in drying polymer solutions is crucial in many applications such as the production of film coatings. It is well known that solvent evaporation in polymer solutions can lead to Rayleigh-B{\'e}nard or Marangoni-type instabilities. Here we demonstrate another mechanism, namely that evaporation can cause the interface to display Rayleigh-Taylor instabilities due to the build-up of a dense layer at the air-liquid interface. We study experimentally the onset time ($t_p$) of the instability as a function of the initial polymer concentration ($c_0$) and molecular weight. In dilute solutions, $t_p$ shows two limiting behaviors. For high diffusivity polymers (low molecular weight), the pluming time scales as $c_0^{-2/3}$, while in the absence of diffusion, the pluming time scales as $c_0^{-1}$. Above a critical concentration, $\hat{c}$, viscosity delays the growth of the instability, resulting in $t_p$ scaling as $(\nu/c_0)^{2/3}$. These scaling results are not restricted to polymer solutions or evaporation induced instabilities, but are transferable to other binary systems undergoing gravity driven instabilities.

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Authors

  • Endre Joachim Mossige

    Chemical Engineering, Stanford University

  • Antara Bhattacharya

    SLAC National Accelerator Laboratory, Department of Physics, University of Nevada, Reno, 89557, USA, School of Mathematics and Physics, the University of Queensland, Brisbane, QLD 4072, Australia, University of California, Berkeley, National Institute for Materials Science, Lawrence Berkeley National Lab, Chemical Engineering, Stanford University, Santa Clara University, Lawrence Livermore National Laboratory, University of California San Diego, University of Nevada, Reno, Nihon University, Osaka U., LLNL, SLAC, U. of Nevada, Reno, California State University, Chico, Lawrence Livermore National Laboratory; UC, Irvine, Chemical Engineering and Materials Science, University of Minnesota Twin Cities, Physics, California Polytechnic State University, San Luis Obispo, Oak Ridge National Lab, Department of Physics, California Polytechnic State University, San Luis Obispo, CA 93407, USA, School of Chemical and Physical Sciences, Victoria University of Wellington, Wellington 6021, New Zealand, California Polytechnic State University, University of California, Santa Barbara, Department of Physics, California Polytechnic State University, Victoria University of Wellington, Palo Alto High School, Palo Alto, CA, Navy Children School, Mumbai, Maharashtra, India

  • Antara Bhattacharya

    SLAC National Accelerator Laboratory, Department of Physics, University of Nevada, Reno, 89557, USA, School of Mathematics and Physics, the University of Queensland, Brisbane, QLD 4072, Australia, University of California, Berkeley, National Institute for Materials Science, Lawrence Berkeley National Lab, Chemical Engineering, Stanford University, Santa Clara University, Lawrence Livermore National Laboratory, University of California San Diego, University of Nevada, Reno, Nihon University, Osaka U., LLNL, SLAC, U. of Nevada, Reno, California State University, Chico, Lawrence Livermore National Laboratory; UC, Irvine, Chemical Engineering and Materials Science, University of Minnesota Twin Cities, Physics, California Polytechnic State University, San Luis Obispo, Oak Ridge National Lab, Department of Physics, California Polytechnic State University, San Luis Obispo, CA 93407, USA, School of Chemical and Physical Sciences, Victoria University of Wellington, Wellington 6021, New Zealand, California Polytechnic State University, University of California, Santa Barbara, Department of Physics, California Polytechnic State University, Victoria University of Wellington, Palo Alto High School, Palo Alto, CA, Navy Children School, Mumbai, Maharashtra, India