An Annular Rotating-Die Technique in Extrusion Process: Effect of Mandrel Rotating Speed on Extrudate Swell Behavior of HDPE Parison

Abstract

Abstract This work aims to propose an annular rotating-die technique which is specifically designed and constructed in order for the mandrel to rotate in the stationary barrel during extrusion. The annular rotating-die was employed to study the effect of the mandrel rotating speeds on the extrudate swell behavior of HDPE parison in single screw extruder at a test temperature of 210°C. The results of experiment found that rotation of mandrel caused significant change in dimension of HDPE parison after it flowed out from the annular rotating-die. It was also found that at the same apparent shear rate, the diameter swell decreased with increasing mandrel rotating speed whereas the thickness swell yielded opposite results. These results could be explained by the change of flow direction during the flow of HDPE melt in the annular rotating-die. Furthermore, the annular rotating-die technique proposed in this research could be applied in adjusting size of diameter and thickness and in predicting thickness of HDPE parison during extrusion with no need to change any production parameter in the polymer extruder.