Diffusion in Evaporating Polymer Solutions: A Model in the Dissipative Formalism of Nonequilibrium Thermodynamics

TL;DR

This paper develops a thermodynamic model for solvent diffusion in evaporating polymer solutions, capturing heat-mass coupling effects and thermal diffusion phenomena during solution casting.

Contribution

It introduces a coupled heat and mass transfer model based on nonequilibrium thermodynamics with moving boundaries, advancing understanding of thermal diffusion in polymer solutions.

Findings

Model captures thermal diffusion effects in polymer solutions.

Numerical results show increased solvent concentration near warm substrates.

The approach improves upon previous models by incorporating complex heat-mass interactions.

Abstract

In this paper, diffusion in polymer solutions undergoing evaporation of solvent is modeled as a coupled heat and mass transfer problem with moving boundary condition within the framework of nonequilibrium thermodynamics. The proposed governing equations derived from the fundamental equation of classical thermodynamics using the local equilibrium hypothesis display more complex connection between heat and non-convective mass fluxes than what has been presented in the previous research works. Numerical computations, performed using an explicit finite difference scheme, indicate that the model is able to capture the effect of thermal diffusion in polymer solutions. This effect manifests itself as an increase in local concentration of solvent near warm substrates during solution casting process.