Investigation of Co-Extrusion Using a Coat Hanger Die with Different Feedblock Cross-Section

Abstract

When using the coat hanger die method for co-extrusion, the biggest challenges often involve maintaining the uniformity of the velocity distribution at the outlet of the die and ensuring the stability of the interface plane. This paper investigates the effect of different cross-section of feed channels connected to the coat hanger die on the velocity and pressure distribution of the flow at different parts of the die. Co-extrusion of LLDPE (Linear Low Density Polyethylene) and HDPE (High Density Polyethylene) polymers is simulated using ANSYS software 2020 R2 for coat hanger die design with rectangular and circular cross-sections inlet geometry; the results are compared for Carreau-Yasuda model to observe the result differences between rectangular and circular coextrusion channels connected to coat hanger die. Our results showed that rectangular cross-section feedblock generated higher values for pressure in comparison with the pressure generated by the circular cross-section feedblock. The maximum velocity generated in the circular feedblock is lower than that generated in the rectangular one, nevertheless there is more uniformity in velocity distribution in circular than rectangular cross-section.