ABSTRACT
Energetic materials are typically gels or highly filled suspensions. The major factor that plays a role in the characterization of the energetic gels and highly filled suspensions is their viscoplasticity. This chapter presents the basic concepts of the maximum packing fraction, viscoelastic gel-like behavior, and the coupled viscoplastic and wall slip behaviour. A basic experiment in the characterization of the viscoelastic behavior of structured complex fluids, including energetic materials, is the step strain flow, which provides the relaxation modulus, as a function of time and strain. The wall slip of concentrated suspensions of rigid particles, incorporated into a Newtonian or non-Newtonian binder, occurs mainly on the basis of the apparent slip mechanism. Slit die rheometers with a series of pressure transducers installed flush with the channel wall are preferable over capillary rheometers. The rheological behaviors of gels and suspensions depend on the dynamics of their mixing process applied prior to their rheological characterization of the formulation.
