Study of Die Swell of Gas-assisted Extrusion of Polymer

The research on die swell in the gas-assisted extrusion processes of polymer was conducted on a self-made gas-assisted extrusion device.The comparison between typical and gas-assisted extrusion showed that die swell could be greatly reduced in gas-assisted extrusion.The influence of the rotation speed of screw,gas pressure and flux of gas on the die swell was studied.The speed field and pressure field of polymer in the die during gas-assisted extrusion were obtained with the CFD software FIDAP.The result indicated that the speed and pressure of different points across section of extrudated product at the outlet of die were respectively identical,which could reduce the internal stress and deformation of the product during the extrusion,being of benefit to the improvement of processing accuracy of product.