The correlation of experimental surface extrusion instabilities with numerically predicted exit surface stress concentrations and melt strength for linear low density polyethylene

Experimental data on the onset and magnitude of surface instabilities are r eported for two grades of linear low density polyethylene. Numerical simula tion of the flow is presented and the magnitudes of surface stress concentr ations established. The onset of experimentally observed surface instabilit ies is then correlated with the magnitude of the surface stress concentrati ons at the exit and also with the melt strength of the polymer. (C) 2000 Th e Society of Rheology. [S0148-6055(00)01106-8].