Rheological Behavior of High Solid Content Propellant Substitutes in Extrusion Process Assisted with SC⁃CO2

In order to solve the problem of high viscosity of high solid content propellants,supercritical carbon dioxide(SC⁃CO2) has been used as a plasticizer to improve its rheological behavior. The in⁃line viscosity of the CA/CaCO3 solution was measured by a slit die rheometer during the extrusion process assisted with SC⁃CO2,and the Power law was used to describe the rheological behavior of CA/CaCO3 and CA/CaCO3/SC⁃CO2 solutions. Polyflow was utilized to model the dispersive mixing properties of the CA/CaCO3/SC⁃CO2 solutions. Results show that with the presence of SC⁃CO2,the viscosity and pressure of the CA/CaCO3 solu⁃ tion decreases significantly. And the viscosity coefficient of the CA/CaCO3 solution at 50°C decreases by 26.00%,while its non⁃Newtonian index increases by approximately 16.67%. As the extrusion temperature increases,the viscosity of the CA/CaCO3/ SC⁃CO2 solution decreases,and its shear viscosity is less sensitive to temperature at higher shear rate. According to this simulation results,when the CA/CaCO3/SC⁃CO2 solution is subjected to the maximum shear stress,the maximum probability density increas⁃ es by 20.63% at 50 °C,which confirms that SC⁃CO2 improves the dispersion mixing properties of the CA/CaCO3 solution.