NUMERICAL PREDICTION OF EXTRUDATE SWELL OF A HIGH-DENSITY POLYETHYLENE - FURTHER RESULTS

We investigate the effect of temperature and of the second normal stre ss difference on the extrudate swell of a high-density polyethylene at high shear rates with the use of a Wagner model. We find that the flo w is indeed non-isothermal but that temperature has little effect upon the swelling ratio. However, the second normal stress difference prod uces major effects on the swelling ratio. We conclude that any realist ic prediction of extrudate swelling requires an accurate measurement o f the second normal stress difference.