Impact Sensitivity of Azide Polymer Composite Propellants

Abstract

Effects of azide polymers on the sensitivities and fragmentation mechanism were studied in this paper. Only fragmentation was observed at lower impact velocity, up to 172 m/s, even with an one-kilogram impactor. Most of the propellants showed linear relationship between an impact velocity and a fragmented fraction. The critical impact velocity, VCR, depended on the amount of the binder but not on the chemical structures. The propellants which had no particle oxidizers showed high VCR and their cracks were hard to grow into a piece of fragment. Nitramine-binder matrix dewetting caused by the deformation of the propellant was supposed to terminate the crack propagation and to damp the impact energy at a higher impact velocity. In AP-based propellants impact velocity dominated the initiation mechanism and impact energy did not control the ranking of the reaction. The friction energy played a more important role in the initiation than did the impact energy. There was no difference in the sensitivity to the card gap test between the azide polymer and HTPB binder.