Polymer Processing Additives and Melt Fracture in Blown Film: Die Geometry, 2005 PLACE Conference
The die geometry was investigated to gain a better understanding of the polymer processing additive (PPA) coating mechanism in a blown film extrusion process. In particular, the land length of the die, the extrusion throughput rate, the width of the die gap, and the apparent shear rate at the die wall were systematically varied to identify optimal processing conditions and die geometry configurations for rapid PPA conditioning. The results show that PPA efficiency improves as the length-to-gap ratio of the die increases, particularly at low shear rates. This is consistent with a coating mechanism based on PPA migration from the melt to the die surface.