Abstract: Using Polyflow software, a 3D transient simulation of the melt pressure field and melt mass flow at front and rear sections of screw during continuous extrusion of microcellular plastics was carried out. Different locations of gas injection, melt viscosity, screw speed were considered. It was found that along the axial direction, the distance from 640 to 670 mm constituted the best location for supercritical gas injection. At this location, the melt pressure varied weakly along the radial direction, therefore as long as the pressure of injected supercritical gas was slightly larger than the melt pressure, the injection of gas could be readily completed. The polymer melt mass flow increased with increasing screw speed, and thus controllable.

Key words: polymer, melt, screw, gas injection port, simulation analysis