National Research Council of Canada. Automotive and Surface Transportation
National Research Council of Canada. Medical Devices
Antec 2015, March 25, 2015, Orlando, Florida, USA
The polymer extrudate swell phenomenon is studied to understand the effects of parameters such as past deformation history, die design characteristics, viscoelastic characteristics and process conditions. Accurate prediction of extrudate swell is very crucial in applications such as blow molding, extrusion and fiber spinning. The integral K-BKZ and differential PTT constitutive models are used to simulate the extrudate swell phenomena of a high molecular weight HDPE in capillary extrusion, under various geometric and operating conditions. The simulated swell results were further compared with experimental observations. It was found that the K-BKZ model overpredicts and the PTT model slightly under-predicts the experimental measurements. An attempt has been made to explain the discrepancy between swell predications using K-BKZ and PTT models by studying various material rheological functions using these rheological models.