In-line Rheological Behaviors of Gun Propellant Substitute Assisted with Supercritical CO sub(2) in Extrusion Processing

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