Case-II diffusion and solvent-polymer films drying: A meso-scale modelM. Souche and D. Long
Laboratoire de Physique des Solides, UMR 8502 CNRS/Université de Paris sud - Bât. 510, 91405 Orsay Cédex, France
received 28 August 2006; accepted in final form 12 December 2006; published February 2007
published online 25 January 2007
We propose a model for calculating a constitutive relation for the dynamics of solvent-polymer systems close to the glass transition. We do it by considering a layer of thickness of a few nanometers which is submitted to an arbitrary time varying solvent activity a(t). We show then how these constitutive relations allow to explain case-II diffusion in glassy polymers and provide a physical interpretation for the parameters of the Thomas-Windle model. Regarding the process of film drying, we show that films up to thick can be almost completely dried in an accessible experimental time, even at temperatures well below the polymer glass transition temperature. When drying a thicker film, we show that a glassy crust may appear on the free surface, as has been shown experimentally.
83.80.Rs - Polymer solutions.
66.20.+d - Viscosity of liquids; diffusive momentum transport.
61.41.+e - Polymers, elastomers, and plastics.
© Europhysics Letters Association 2007