Fluid-motion effects on the dynamics of thermal frontal polymerization

Thermal frontal polymerization (FP) is a process that rapidly converts liquid monomer solutions into solid polymers via self-sustaining exothermic reaction fronts. It is a promising method for polymer manufacturing because it is fast and energy-efficient. However, it is susceptible to chemical and thermo-convective instabilities that degrade product quality. In extreme cases, such instabilities can even quench the entire process. Typically, FP is modeled via a system of single-phase reaction-diffusion equations. However, our current understanding of the effects of fluid motion remains incomplete. In order to bridge this gap, we recently developed a two-phase flow model for FP based on a mixture-theoretic formalism. It treats the liquid reactants and the solid polymer as two separate interacting continua and accounts for fluid motion via a dynamic momentum-balance law.

In this talk, we present a numerical study of FP based on this model. First, we outline the governing equations and provide results from validation tests. Then, we present numerical results from 1D and 2D simulations. Our discussion focuses on the effect of fluid motion on the evolution of the front instabilities and the advancement of the polymerization process. According to our simulations, fluid motion alters considerably the key properties of the front such as propagation speed, amplitude of temperature oscillations, conversion rate to solid polymer and others.