Study of thermal stability of HMX affected by 1,9-acetoxyl-2,4,6,8-tetranitro-tetraaza nonane

1,9-acetoxyl-2,4,6,8-tetranitro-tetraaza nonane (AcAn) is one of the major impurities of HMX production. It is important to study the thermal stability of HMX affected by AcAn. The geome-trical structure of AcAn is optimized at B3LYP/6-311+G** level and two stable structures are obtained. Bond decomposition energy (BDE) of N-NO₂ of AcAn molecular is calculated at B3P86/6-31G** level, and it is found that N-NO₂ bond adjacent to acetoxy group in the end of AcAn is easy to cleave. The thermal decomposition of AcAn and the thermal stability of HMX affected by AcAn are studied. It is found that the poor compatibility of HMX-AcAn is level 4.The HMX has good stability, but the AcAn has poor stability. The stability of AcAn-HMX mixture of 50wt% AcAn is the worse. HMX product mixed with AcAn has the worse thermal stability and performance. When the content of AcAn in the AcAn-HMX mixture is more than 50wt%, the change of performance of HMX is the biggest. The most probable mechanism function is deduced by double equal double step method, and the thermal decomposition mechanism function is chemistry reaction mechanism. The integral function is g(a)=1-(1-a)^1-n/(1-n), and the differential function is (a)=(1-a)ⁿ, n=2.