Rheological Property of Double-base Propellant in SC-CO2 Assisted Extrusion Process
To partially substitute the organic solvents used in the extrusion process of propellant,supercritical carbon dioxide ( SC-CO2 ) was introduced into the extrusion process of propellant. Owing to its solvent properties that sharply changing near the critical point, SC-CO2 is rapidly removed from the product after plasticization, paving the way for the complete replacement of organic solvents by SC-CO2 .Shear viscosity is adopted as a parameter to reflect the rheological property, and an in-line slit rheometer is used to measure the shear viscosity of material and obtain the rheological curves to investigate the rheological properties of material under various process conditions. The results indicate that the rheological behavior of material in the extrusion process of SC-CO2 assisted double-base propellant can be described by power-law model. The viscosity of material decreases significantly due to the introduction of SC-CO2 . And the introduction of SC-CO2 decreases the viscous coefficient of double-base propellant by 17. 10％ at the content of 4. 67 wt％, reflecting the excellent plasticizing effect of SC-CO2 on the double-base propellant. The plasticizing effect provided by increasing the parameter values is limited as the process parameters such as SC-CO2 content, solvent content, and temperature increase.
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