Influences of HMX contents on potential reaction violence and fragmentation degree of PBT-propellants after impact load

The extent of damage that is developed during the production, transportation, storage, and handling of propellants after a low-velocity impact is an important factor in evaluating a dangerous threat such as deflagration-to-detonation transition. In this paper, a friability test was performed to evaluate the critical impact ignition velocity (CIIV), fragmentation degree, and potential reaction violence of four 3, 3-Bis(azidomethyl)oxetane (BAMO) and tetrahydrofuran (THF) copolymer-propellants (PBT-propellants) with various 3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) contents under impact at different velocities. The results showed that as the HMX contents increased, the CIIV decreased and changes of that also decreased. Simultaneously, the fragmentation degree increased with the increase in impact velocity, as it was judged by the initial dynamic activity ratio. Then, we calculated the maximum value of the initial dynamic activity ratio by fitting the data using Boltzmann, which were 27 (HMX = 0), 39 (HMX = 5%), 48 (HMX = 10%), and 56 (HMX = 15%). The ratios of the maximum value of the initial dynamic activity ratio between PBT-propellants containing HMX and those without HMX were 1.44, 1.78, and 2.07. The addition of HMX increased the maximum fragmentation degree of PBT-propellants under impact. The potential reaction violence increased as the impact velocity increased due to the increase in the fragmentation degree of PBT-propellants after impact. Similarly, we also obtained the maximum values of potential reaction violence, which were 62.39, 50.17, 41.89, and 34.65. The maximum value of potential reaction violence decreased with the increase in HMX contents, and the addition of HMX improved the safety of PBT-propellants burning after impact.