Influence Factors Analysis On The Safety Characteristics Of PBT Solid Propellant

In order to investigate the safety characteristics of the new high-energy insensitive propellant,the thermal safety characters of typical formulation of PBT insensitive solid propellants were studied,and the low-vulnerability characteristics of two formulations(P01 and P02)were studied in accordance with MIL-ST-2015D.The thermal decomposition characteristics of P01 were studied by differential scanning calorimetry(DSC)and adiabatic acceleration calorimeter(ARC).The DSC test of BU showed that BU was the first decomposed component during the heating,and the initial decomposition temperature of BU was 192.9?,the activation energy of the BU was 137.8 kJ· mol-1.The activation energy of the first step thermal decomposition of P01 was 101.7 kJ ·mol-1.In the temperature range of 50? to 450?,the ARC test results showed that there were three exothermic stages in the decomposition of the P01.The first stage of the exothermic process was the decomposition of BU,the decomposition temperature was 121.7?,and the reaction system maximum temperature was 139.3?.The low temperature range ARC test,between 50? to 160?,was selected to prove the discrete decomposition character of P01.From the result,it can be concluded that thermal decomposition of BU didn't result in a subsequent reaction because of the low content.The response characteristics of P01 and P02 to thermal stimulation were studied by slow cook-off test and fast cook-off test.In the slow cook-off tests,the respond temperature of P01 was 133? and the response level was detonation,the respond temperature of P02 was 154.6? and the response level was combustion.Under the condition of small sample without package,the first decomposed component of P01 was BU,and the decomposition of BU couldn't cause the reaction of propellant.The response of the propellant was exacerbated when there was a package constraint in the slow cook-off test.It can be concluded that,the response level of slow cook-off test could be reduced if the package have a pressure relief design.In the fast cook-off test,the response level of P01 and P02 were all combustion.In general,it will be a more serious respond level in slow cook-off test than fast cook-off test.The response characteristics of P01 and P02 to mechanical stimulus and mixed stimulus were studied by using bullet impact test,fragment impact test,shaped charge jet test and sympathatic detonation test.The response level of P01 and P02 were all combustion in the bullet impact test,the fragment impact test and the sympathatic detonation test.In the shaped charge jet test,the response level of P01 was detonation,and the response level of P02 was combustion.Thus,HMX has a significant effect on the and low vulnerability of PBT insensitive solid propellants.