In‐line Rheological Behaviors of Gun Propellant Substitute Assisted with Supercritical CO2 in Extrusion Processing

To improve the rheological behaviors of gun propellants, SC‐CO2 was injected into the gun propellant substitute in extrusion processing. A slit die rheometer was used to investigate the in‐line rheological behaviors of CA solution. A Power model was applied to describe the rheological behaviors of CA/SC‐CO2 mixtures. The viscosity and pressure of CA solution obviously decrease with the assistance of SC‐CO2. The viscosity of CA solution reduces by 16.64 % at 55 °C and 10 s−1 with the presence of SC‐CO2. Increasing the processing temperature makes the viscosity of CA/SC‐CO2 mixture decrease remarkably, but it weakens the plasticization of SC‐CO2 to CA. Although the increasing solvent content improves the flow of the CA/SC‐CO2 mixture, it lowers the strength of CA/SC‐CO2 mixture, which is not in favor of the quality of product. The investigation of the in‐line rheological behaviors of CA/SC‐CO2 mixture is fundamental and important for the safe extrusion of gun propellants assisted with SC‐CO2.