SHOCK INITIATION OF A HEATED AMMONIUM PERCHLORATE-BASED PROPELLANT

Solid propellants containing ammonium perchlorate (AP), aluminum, and a carboxylterminated polybutadiene binder (CTPB) are known to burn rel iably and to be very insensitive to transition to detonation under amb ient conditions. In accident scenarios, these propellants may become m ore shock sensitive when they are subjected to heat and/or multiple im pacts. The shock sensitivity of one such propellant, ANB-3066, is dete rmined using embedded manganin pressure gauges at an elevated temperat ure of 170 degrees C. The measured pressure histories are modeled usin g the Ignition and Growth reactive flow model of shock initiation and detonation. The experiments clearly show that ANB-3066 is not signific antly more shock sensitive at 170 degrees C than it is at ambient temp erature. The Ignition and Growth reactive flow calculations indicate t hat less than 20% of the chemical energy of AP and CTPB reactions is r eleased at input shock pressures as high as 21 GPa. The aluminum compo nent does not reach the high temperatures required for it to react. Th ese results indicate that AP-based solid propellants are still extreme ly resistant to shock to detonation transition even when heated to tem peratures close to the thermal decomposition temperature of the propel lant formulation. The shock insensitivity of heated AP-based propellan ts is hypothesized to be due to the melting of the AP component during shock loading and the relatively low temperatures produced by the wea kly exothermic decomposition of AP and binder.