In this work, Polyflow was applied to simulate the flow behaviors of gun propellant substitute in the extruder barrel during extrusion processing assisted with supercritical carbon dioxide (SC-CO2). The results demonstrate that the presence of SC-CO2 leads to the great reduction of pressure and viscosity of the fluid, which is beneficial for the safety in extrusion processing. The shear rate and viscosity appear the lowest values near the screw thread, and they increase higher in the screw channel. The high screw speed brings the high production, but it causes the high pressure distribution, enhancing the processing risk. Although both high processing temperature and solvent content are in favor of decreasing the pressure and improving the flow behaviors of CA/SC-CO2 solution, the excessive processing temperature or solvent content weakens the plasticization of SC-CO2 to CA solution. The pressure of CA/SC-CO2 solution at 45ºC is closed to the pressure of CA solution at 65ºC, which means that the extrusion processing can be reduced by almost 20ºC with the assistance of SC-CO2. Meanwhile, the solvent concentration can be reduced by SC-CO2 while the viscosity of CA solution is kept in the same level.
gun propellant, SC-CO2, extrusion, Polyflow, flow behaviors