AcAn对奥克托今热稳定性的影响研究

Study of Thermal Stability of HMX Affected by 1,9-acetoxyl-2,4,6,8-tetranitro-tetraaza Nonane

1,9-二乙酰氧基-2,4,6,8-四硝基-2,4,6,8-四氮杂壬烷(AcAn)是奥克托今(HMX)制备过程中产生的一种主要杂质,研究AcAn对HMX热稳定性的影响具有重要意义。基于B3LYP/6-311+G**水平全优化了AcAn的几何结构,得到船式和椅式两种稳定结构;在B3P86/6-31G**水平计算了AcAn中N—NO2键的键离解能(BDE),研究发现,AcAn两端与乙酰氧基相邻的硝胺N—NO2键容易断裂。采用差热分析(DTA)技术研究了AcAn的热分解及其含量对HMX热稳定性的影响,结果表明:HMX和AcAn的相容性差,为4级;HMX安定性最好,AcAn安定性差,AcAn含量为50%时,安定性最差;HMX产品中混有AcAn,使得HMX储存热稳定性变差,使用性能也变差;当AcAn含量高于50%时,HMX产品性能变化最大。根据双等双步法推导AcAn和HMX的最概然机理函数,热分解反应机理函数为化学反应RO(n)机理,积分函数形式为g(a)=1-(1-a)1-n1-n,微分形式为f(a)=(1-a)n,n=2.

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 geometrical structure of AcAn is optimized at B3 LYP /6-311 ＋ G＊＊ level and two stable structures are obtained.Bond decomposition energy（BDE） of N—NO2of AcAn molecular is calculated at B3P86 /6-31G＊＊ level,and it is found that N—NO2bond 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 mech-anism 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.