In‐line Rheological Behaviors of Gun Propellant Substitute Assisted with Supercritical CO 2 in Extrusion Processing

To improve the rheological behaviors of gun propellants, SC‐CO 2 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‐CO 2 mixtures. The viscosity and pressure of CA solution obviously decrease with the assistance of SC‐CO 2 . The viscosity of CA solution reduces by 16.64 % at 55 °C and 10 s −1 with the presence of SC‐CO 2 . Increasing the processing temperature makes the viscosity of CA/SC‐CO 2 mixture decrease remarkably, but it weakens the plasticization of SC‐CO 2 to CA. Although the increasing solvent content improves the flow of the CA/SC‐CO 2 mixture, it lowers the strength of CA/SC‐CO 2 mixture, which is not in favor of the quality of product. The investigation of the in‐line rheological behaviors of CA/SC‐CO 2 mixture is fundamental and important for the safe extrusion of gun propellants assisted with SC‐CO 2 .