Sharkskin melt fracture in high-performance hexene-lldpes

摘要

Several types of High-Performance Hexene (HPH)-LLDPE have been introduced in recent years for high-strength blown film applications, with substantial enhancement of film properties over conventional Ziegler-Natta LLDPEs. The present work is a study of the comparative behavior of the various types of LLDPEs under processign conditions designed to induce sharkskin melt fracture (SSMF). Both capillary rheology and blown film studies were conducted. The ability of capillary rheology to capture the difference between resins in terms of their relative tendency to sharksin melt fracture was investigated in parallel with blown film studies at different shear rates and die gaps. Film blowign is more effective in discriminating between resins and identifying melt fracture tendency. The influence of sharkskin melt fracture on the film propertie swas also quantified, showing the film impact strength to be affected most sensitively, and negatively, by the presence and severity of sharkskin melt fracture (SSMF).