2. 国家民用爆破器材质量监督检测中心,江苏 南京 210094
2. National Civil Blasting Equipment Quality Supervision and Testing Center, Nanjing 210094, China
有机叠氮化合物是一类广受关注的含能物质, 具有独特的作用和性能, 可用作含能粘合剂、含能增塑剂、含能氧化剂等[1-6]。然而, 有机叠氮化合物普遍存在密度小的问题。众所周知, 密度是评估高能化合物性能的一个重要的参数, 其大小影响并决定着化合物的爆轰性能, 故如何提高密度一直是含能物质研究中的热门话题。季戊四醇的衍生物——四叠氮甲基丁烷(TAPE), 密度仅为1.444 g·
运用Gaussian 03[16]程序包中的B3LYP[17-19]方法和6-31
在此基础上, 运用Kamlet-Jacobs (K-J)公式[21]计算爆速和爆压:
$\begin{eqnarray} D=1.01 (N \bar{M}^{1/2} Q^{1/2} )^{1/2} (1 + 1.30ρ) \end{eqnarray}$ | (1) |
$\begin{eqnarray} p=1.558ρ^{2} N \bar{M}^{1/2} Q^{1/2} \end{eqnarray}$ | (2) |
式中,
采用与以往研究相同的方法[22-24]由(3)式计算分子中较弱键的键离解能(
$\begin{eqnarray} E_{\text{BD}} (A-B)=E(A·)+E(B·)-E(A-B) \end{eqnarray}$ | (3) |
式中,A·和B·为A-B键解离产物,
由Peter Politzer等[25]提出的方法求比冲
$\begin{eqnarray} I_{\text{s}}=T_{\text{C}}~^{1/2}N^{1/2 } \end{eqnarray}$ | (4) |
$\begin{eqnarray} \text{Δ}H_{\text{C}}=C_{\text{p},\text{g}}(T_{\text{C}} -T_{0}) \end{eqnarray}$ | (5) |
$\begin{eqnarray} \text{Δ}H_{\text{C}}=∑\varDelta H_{\text{f},\text{R}}-∑\varDelta \text{H}_{f,P} \end{eqnarray}$ | (6) |
式中,
图 1给出了标题物优化后的几何构型以及部分键的键长和Mulliken集居数。Mulliken集居数[26]分析尽管有不足, 但对于反映系列分子中电子分布的变化趋势仍然是有意义的。一般而言, Mulliken键集居数越小, 表明该键越弱。从图 1可以看出, 对于分子中只含有叠氮基的TAPE而言, C—N键集居数(0.210)比—
根据统计热力学原理[27], 由优化所得结构和采用因子0.96校正后的频率[28-29], 计算了标题物在200~800 K温度范围的热力学函数, 所得结果列于表 1,热力学函数与温度的关系见图 2, 由图 2拟合得到的定量关系式见表 2。
由表 1和图 2可见, 标准摩尔热容(
计算所得HOF(
计算得到太安的
表 3给出了标题物的
根据键集居数结果, O—
一般来说,
(1) 叠氮基对生成热的贡献大于硝酸酯基, 而硝酸酯基对爆轰性能的贡献比叠氮基大。
(2) 对于取代基只有—
(3) PATN的稳定性和爆轰性能均接近于PETN, 且优于PDADN, 是一种有潜在研究价值的高能化合物。
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A systematic theoretical study was carried out on tetraazido pentaerythritol (TAPE), pentaerythritol triazido nitrate (PTAN), pentaerythritol diazido dinitrate (PDADN), pentaerythritol azido trinitrate (PATN) and pentaerythritol tetranitrate (PETN) to investigate their structures and properties, especially the pyrolysis mechanism by analyzing the bond dissociation energy (EBD) of the possible trigger bond and the activation energy (Ea) of the hydrogen transfer reaction.