Wu Junying, Wu Jiaojiao, Li Junjian, Shang Yiping, Chen Lang
State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081, China.
ACS Omega. 2023 May 16;8(21):18851-18862. doi: 10.1021/acsomega.3c01160. eCollection 2023 May 30.
The addition of binders to energetic materials is known to complicate the thermal decomposition process of such materials. To assess this effect, the present work studied the thermal decomposition of cyclotrimethylene trinitramine (RDX)/hydroxy-terminated polybutadiene (HTPB) mixtures and of pure RDX over the temperature range of 2000-3500 K by combining the classical reaction and first-principles molecular dynamics methods. The incorporation of HTPB as a binder was found to significantly reduce the decomposition rate of RDX. At 3500 K, the decay rate constant of RDX in the RDX/HTPB system is 2.0141 × 10 s, while it is 2.7723 × 10 s in the pure RDX system. However, the binder HTPB had little effect on the initial decomposition mechanism, which involved the rupture of N-NO bonds to produce NO. The HTPB was predicted to undergo dehydrogenation and chain breaking. The free H resulting from these processes was predicted to react with low-molecular-weight intermediates generated by the RDX, resulting in greater equilibrium quantities of the final products HO and H being obtained from the mixed system compared with pure RDX. HTPB-chain fragments were also found to combine with the primary RDX decomposition product NO to inhibit the formation of N and CO.
已知向含能材料中添加粘结剂会使此类材料的热分解过程变得复杂。为评估这种影响，本研究通过结合经典反应和第一性原理分子动力学方法，研究了环三亚甲基三硝胺（RDX）/端羟基聚丁二烯（HTPB）混合物以及纯RDX在2000 - 3500 K温度范围内的热分解。发现加入HTPB作为粘结剂会显著降低RDX的分解速率。在3500 K时，RDX/HTPB体系中RDX的衰减速率常数为2.0141×10 s，而在纯RDX体系中为2.7723×10 s。然而，粘结剂HTPB对初始分解机理影响不大，初始分解机理涉及N - NO键断裂生成NO。预测HTPB会发生脱氢和断链。这些过程产生的游离H预计会与RDX生成的低分子量中间体反应，与纯RDX相比，混合体系中最终产物HO和H的平衡量更大。还发现HTPB链片段会与RDX的主要分解产物NO结合，抑制N和CO的形成。
