Effect of the Dimension of the Imposed Radial Flow on the PDMS Behavior

The rates of industrial extrusion processes are usually limited by the appearance of extrudate instabilities, which can mark the surface or the whole volume of the extruded material. By using a capillary rheometer, this work aims to compare the effect of the diameter of the annular geometry introduced upstream the die and the effect of the gap of the radial flow (distance between the upper plane of the die and the bottom extremity of the rod (annular geometry)) on the rheological behavior of a polydimethylsiloxane (PDMS). Experiments show no significant effect can be remarked consequently to the change of the rod diameter. However, gross melt fracture instability can be delayed when the gap of the radial flow is smaller.