Effect of aluminum nanoparticles on rheological behavior of HTPB-based composite rocket propellant

The aim of this article was to understand the rheology of composite propellant containing aluminum nanoparticles, as it is a highly filled mixture of solids and is difficult to process. Aluminum nanoparticles utilized as a filler were characterized using X-ray diffraction spectroscopy, scanning and transmission electron microscopy. It was confirmed that the material was pure aluminum, spherical in shape and nano-sized (96.8 nm). The effects of shear stress, shear rate, strain, aluminum nanoparticles concentration, and shear time on rheology were investigated thoroughly, which confirmed a non-Newtonian, time-dependent, shear-thinning, and viscoplastic flow behavior. The composition which had 0% nanoparticles showed the lowest thixotropy index of 50.86 Pa/s, and the difference was almost minimal for compositions containing 0% and 6% nanoparticles. The propellant containing 6% nanoparticles did not yield, as compared to the compositions. The results indicate that nanoparticles have a considerable effect on the rheology of the composite propellant.