Analysis of die drool phenomenon for metallocene based linear polyolefins

Abstract

Die drool phenomenon, occurring as a result of the viscoelastic behavior during the flow of the polymer melts, has been experimentally investigated for metallocene based LLDPE on the specially designed annular extrusion die with the capability to control the stress state at the end of the die by the help of specific type of cooling system. With the aim to understand the die drool phenomenon in more detail, the flow at the end of the die has been analyzed theoretically by the Finite Element Method (FEM) employing modified White-Metzner model as the constitutive equation. It has been revealed that the negative pressure occurs at the die lip area which seems to be driving factor for the die drool phenomenon.