Die design assisted by CFD for extrusion foam of starch-based mixtures

Polymer foams with complex cross-sectional shapes are used in a multitude of different applications (including transportation, construction, packaging, food, extraction and separation) thanks to their low mass allowing efficient energy transport, optimal acoustic absorption, catalytic, impact, and cushioning properties. Dimensional accuracy of the final foamed product, obtained through a die, is one of the biggest challenges for the engineering of a stable foam extrusion process. Nowadays, the design of dies is considered an art and, usually, it involves several experimental runs, wherein a die with an approximate shape is manufactured and iteratively modified based on the quality of the extrudate. This method is time and money consuming. Herein, the design is tackled using Computational Fluids Dynamics (CFD) reducing the trial-and-error process. We present the modelling of the rheological behavior of starch-based mixtures and the results of the CFD simulations on the slit die geometry.