NH_3、ClO_3对β-HMX初始热解的影响

Effects of NH_3 and ClO_3 on Initial Pyrolysis of β-HMX

在密度泛函理论(DFT)的B3LYP/6-31g(d)水平上,优化得到了环四甲撑四硝胺(β-HMX)及其与高氯酸铵(AP)裂解产物NH3、ClO3分别形成复合物的稳定构型,计算了常压、4 MPa及6 MPa高压下β-HMX及各复合物的N—NO2键解离能。结果发现,复合物中β-HMX构型变化不是很大。β-HMX与NH3、ClO3结合后其N—NO2键解离能与HMX相比均变化不大,NH3和ClO3的存在不影响β-HMX的N—NO2键裂解E位优先于A位的顺序;但一旦复合物裂解,生成的NO2极易与NH3发生反应,放出大量热,从而可引发HMX的后续裂解反应。高压环境不改变NH3和ClO3对HMX初始裂解机理的影响。

The geometries of β-octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine（β-HMX） and its complexes with the pyrolysis products（NH3,ClO3） of ammonium perchlorate（AP） were optimized using density function theory（DFT） at the B3LYP/6-31g（d） level.The bond dissociation energies for N—NO2 in β-HMX and its complexes at normal,4 MPa and 6 MPa pressures were obtained.Results show that the geometrical configuration of HMX complexes with NH3 and ClO3 are similar to β-HMX structure.It indicates that,the equatorial nitryls of NH3—,ClO3—complexes are also prior to the axial nitryls in its pyrolysis process and there are trivial changes on the N—NO2 bond dissociation energies when β-HMX combines with NH3 or ClO3.However,once the complexes decompose,the product NO2 can react with NH3 more easily.This exothermic reaction may induce the subsequent pyrolysis process of HMX.The high pressure has no influence on the effects of NH3 and ClO3 on the initial pyrolysis mechanism of β-HMX.