Rheological Impact of Particle Size Gradation on GAP Propellant Slurries

[Image: see text] Over the years, widespread interest has been placed on rheological properties to reflect the processability of propellant slurries. Particle gradation technology plays an essential role in the improvement of the processability of propellant slurries. In this article, rheological properties of glycidyl azide polymer (GAP) propellant slurries were measured by dynamic rheological measurements with a rheometer. Submicron-sized (d(50) = 0.221 μm) and micron-sized (d(50) = 33.02 μm) CL-20 particles and ultrafine (d(50) = 2.40 μm) and micron-sized (d(50) = 341.69 μm) AP particles were utilized to investigate the influence of the addition of CL-20 and particle size gradation on rheological properties. The test results demonstrate that the LVE region remains almost invariable while the yield transition process is delayed when the relative content of submicron-sized CL-20 increases from 10 to 20%. The values of G′, G″, and |η*| increase with increasing submicron-sized CL-20. Despite this, the value of |η*| can be effectively reduced to about the same value as the slurries with bimodal AP by the size gradation of CL-20. In addition, particle porosity appears to be a suitable parameter to predict trends concerning the rheological properties of the GAP propellant slurries.