Numerical Simulation of Phase Distribution in Recycled Immiscible Polymer Blends*

Understanding phase distribution in immiscible polymer blends is crucial for enhancing material properties, especially with recycled polyethylene (PE) and isotactic polypropylene (iPP). Our study examines phase distribution under various flow conditions using numerical simulations with the Navier-Stokes equation and the Oldroyd-B fluid model, combined with a finite volume-front tracking method. We analyze phase distribution in pressure-driven flow with varying volume fractions. Results show that low volume fractions form drops in the continuous phase, while comparable fractions result in a co-continuous structure. In pressure-driven parallel flow, the mixture forms a film of the continuous phase near the walls, maintaining a uniform distribution in the bulk. The average velocity profile for different Weissenberg numbers (Wi) indicates that intermediate Wi values reduce the flow rate compared to Newtonian and high Wi flows. These findings highlight the impact of volume fraction and viscosity contrast on phase distribution. Future research will incorporate temperature dependence to study cooling and solidification, guiding the design of higher-quality recycled polymer blends for more sustainable and efficient material usage.