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 reported for two grades of linear low density polyethylene. Numerical simulation of the flow is presented and the magnitudes of surface stress concentrations established. The onset of experimentally observed surface instabilities is then correlated with the magnitude of the surface stress concentrations at the exit and also with the melt strength of the polymer.