Effect of Freeze-Line Position and Stretching Force on the Morphology of LDPE-PA6 Blown Films

Abstract

Blends of low density polyethylene (LDPE) and polyamide-6 (PA6) are produced via blown film extrusion to study the effect of freeze-line position and stretching force on blend morphology. An experimental setup is designed to measure the stretching force as a function of draw ratio (DR) and freeze-line position for 4, 6, and 10 wt% PA6 in LDPE. Numerical simulations of the non-isothermal and viscoelastic process are in good agreement with the experimental data of film dimensions. However, as reported many times in the literature, the calculated stretching force is underestimated and can be predicted more precisely by using a simple correction factor. The results also show that the dispersed phase deformation increases with DR and decreases with freeze-line height.