Efforts in the quest for greener alternatives to ammonium perchlorate (AP) as a solid rocket propellant oxidizer have intensified due to the associated health and environmental concerns. AP exceptional performance in propulsion is accompagnied by its environmental concerns, necessitating the exploration of greener alternatives. Ammonium nitrate (AN) has emerged as a promising substitute, offering cleaner combustion products and cost-effectiveness. AN-based propellants face challenges such as hygroscopicity and structural instability. This study aims to reconcile the latter challenges by employing a co-crystallization process that embodies a synergistic association of AP and AN, culminating in a novel molecule that harmonizes their distinct advantages and mitigates their individual shortcomings. Optimizing the solvent/antisolvent co-crystallization process through a variation of the antisolvent temperature and antisolvent-to-solvent ratio allows to assess their impact on the co-crystallization process of AP and AN and to attain the desired and optimal co-crystal formation conditions. Various characterization techniques were applied to gain deep insights into the co-crystal formation mechanism, its thermal behavior, morphological and structural features together with its thermal decomposition kinetics. Maintaining a low and a high ( = 15 °C, = 11) yielded the design of AP/AN that demonstrates typical indications of the cocrystal formation. The AP/AN cocrystal formation elevated the decomposition temperature by about 18 °C compared to the physical mixture. Furthermore, the combination of AP and AN demonstrates a non-negligible decrease in the HTD temperature compared to that of pure AP by about 110 °C. The kinetic study demonstrated a 50 kJ/mol increase in the activation energy of the AP/AN cocrystal compared to that of the physical mixture. The present research addresses the critical gap in the literature by investigating the co-crystallization of AP and AN that not only improves the safety and environmental impact of solid propellants but also enhances their overall performance and stability.

中文翻译：

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共结晶法在固体火箭推进剂用高氯酸铵/硝酸铵氧化剂生产中的应用

由于相关的健康和环境问题，人们加大力度寻找高氯酸铵 (AP) 作为固体火箭推进剂氧化剂的绿色替代品。 AP 卓越的推进性能伴随着其环境问题，因此需要探索更环保的替代方案。硝酸铵 (AN) 已成为一种有前途的替代品，可提供更清洁的燃烧产品和成本效益。 AN基推进剂面临吸湿性和结构不稳定等挑战。本研究旨在通过采用体现 AP 和 AN 协同作用的共结晶过程来解决后一个挑战，最终形成一种新的分子，可以协调它们的独特优势并减轻它们各自的缺点。通过改变反溶剂温度和反溶剂与溶剂的比例来优化溶剂/反溶剂共结晶过程，可以评估它们对 AP 和 AN 共结晶过程的影响，并获得所需的最佳共晶形成条件。应用各种表征技术来深入了解共晶形成机制、其热行为、形态和结构特征及其热分解动力学。保持低温和高温 (= 15 °C, = 11) 产生的 AP/AN 设计展示了共晶形成的典型迹象。与物理混合物相比，AP/AN 共晶的形成使分解温度提高了约 18 °C。此外，与纯 AP 相比，AP 和 AN 的组合的 HTD 温度降低了约 110 °C，不可忽略。动力学研究表明，与物理混合物相比，AP/AN 共晶的活化能增加了 50 kJ/mol。本研究通过研究 AP 和 AN 的共结晶，填补了文献中的关键空白，不仅提高了固体推进剂的安全性和环境影响，而且还提高了其整体性能和稳定性。