Buoyancy-Induced Convection Driven by Frontal Polymerization

In this Letter, we study the interaction between a self-sustaining exothermic reaction front propagating in a direction perpendicular to that of gravity and the buoyancy-driven convective flow during frontal polymerization (FP) of a low-viscosity monomer resin. As the polymerization front transforms the liquid monomer into the solid polymer, the large thermal gradients associated with the propagating front sustain a natural convection of the fluid ahead of the front. The fluid convection in turn affects the reaction-diffusion (RD) dynamics and the shape of the front. Detailed multiphysics numerical analyses and particle image velocimetry experiments reveal this coupling between natural convection and frontal polymerization. The frontal Rayleigh (Ra) number affects the magnitude of the velocity field and the inclination of the front. A higher Ra number drives instability during FP, leading to the observation of thermal-chemical patterns with tunable wavelengths and magnitudes.

Automated summary

This study examines the interaction between a self-sustaining exothermic reaction front and buoyancy-driven convection flow during frontal polymerization. The thermal gradients generated by the polymerization front cause natural convection of the fluid, which in turn affects the reaction-diffusion dynamics and the front shape. Numerical analyses and experiments reveal the coupling between natural convection and frontal polymerization, showing that the frontal Rayleigh number influences the velocity field and front inclination. Higher Ra numbers lead to instability during polymerization, resulting in thermal-chemical patterns with tunable wavelengths and magnitudes.