Squeeze flow rheometry for rheological characterization of energetic formulations

The rheological characterization and the determination of the parameters describing the shear viscosity and wall slip behavior of energetic materials is a challenge. Some of the conventional rheometers including various rotational rheometers are not capable of deforming typical energetic formulations with their gel binders and high degrees of particulate fill. Other available rheometers are not conducive to rheological characterization of energetic formulations in the vicinity of the manufacturing operation with the data to be used immediately for quality control. Squeeze flow provides significant advantages in safety of materials handling and exposure as well as providing easy data generation for routine quality control of energetic formulations being processed. Here the basic hardware is reviewed along with the methods for the analysis of raw data to determine the parameters of the shear viscosity and the wall slip of energetic formulations. It is suggested that appropriate analytical and numerical analyses can indeed provide the basic wherewithal necessary for the solution of the inverse problem of squeeze flows to characterize the shear viscosity and the wall slip parameters provided that the issues of uniqueness and stability are properly addressed.