A Rheometer Made from a Screw Extruder and Abnormal Flow Properties of High Density Polyethylene Melt

In order to obtain the flow characteristics of polymer in melt state which are important in practical processing, we prepared a capillary rheometer. The rheometer is a screw extruder equipped with an overflow valve and direct detectors of pressure and temperature of melts. The flow properties of Staflen E605 (a grade of high density polyethylene) measured here showed to have two discontinuous regions. On the melt fracture region, a sudden increase of apparent fluidity was found, from which the existence of slip flow at the capillary wall was observed.