Effect of Polymer Processing Aids (PPAs) on the Elimination of Sharkskin Defect in LLDPE Extrusion: Influence of Die Surfacing

摘要

Since more than twenty years, fluoropolymer-based processing aids (PPAs) are used to efficiently eliminate sharkskin defect in linear polyolefin extrusion. Fluoropolymer PPAs act by coating die surface, inducing wall slip (and thus simultaneously eliminating sharkskin defect) and reducing die pressure. However, their mechanisms of action are not still completely understood, especially the mechanism of deposition. In this paper, we study the influence of die surfacing on PPA kinetics during extrusion process.