Zhang Jun, Zheng Wei, Yuan Zhifeng, Chen Junbo, Pei Jiangfeng, Xue Ping
College of Mechanical and Electrical Engineering, Beijing University of Chemical Technology, Chaoyang District, Beijing 100029, China.
Xi'an Modern Chemistry Research Institute, 168 Zhangba East Road, Xi'an 710065, China.
Polymers (Basel). 2025 Jul 22;17(15):2003. doi: 10.3390/polym17152003.
Currently, the shear-extrusion behavior of solid propellants (SPs), which comprise a significant volume fraction of micro-/nanoscale solid particles (e.g., octogen/HMX), nitroglycerin as a plasticizer/solvent, nitrocellulose as a binder, and other functional additives, is still insufficiently understood. While the rheology of highly filled polymers has been extensively documented, the rheological behavior of SPs within the practical processing temperature range of 80-95 °C remains poorly understood. This study investigated, in particular, the pressure dependence of the viscosity of SPs melts during steady-state shear flow. Steady-state shear measurements were conducted using a twin-bore capillary rheometer with capillary dies of varying diameters and lengths to explore the viscosity dependence of SPs. The results reveal that interface defects between octogen particles and the polymer matrix generate a melt pressure range of 3-30 MPa in the long capillary die, underscoring the non-negligible impact of pressure on the measured viscosity (). At constant temperature and shear rate, the measured viscosity of SPs exhibits strong pressure dependence, showing notable deviations in pressure sensitivity (β), which was found to be greatly relevant to the contents of solvent and solid particles. Such discrepancies are attributed to the compressibility of particle-particle and particle-polymer networks during capillary flow. The findings emphasize the critical role of pressure effect on the rheological properties of SPs, which is essential for optimizing manufacturing processes and ensuring consistent propellant performance.
目前，固体推进剂（SPs）的剪切挤压行为仍未得到充分理解，固体推进剂包含大量的微/纳米级固体颗粒（如奥克托今/HMX）、作为增塑剂/溶剂的硝化甘油、作为粘合剂的硝化纤维素以及其他功能添加剂。虽然高填充聚合物的流变学已有大量文献记载，但在80-95°C的实际加工温度范围内，固体推进剂的流变行为仍知之甚少。本研究特别考察了稳态剪切流动过程中固体推进剂熔体粘度对压力的依赖性。使用具有不同直径和长度毛细管模头的双孔毛细管流变仪进行稳态剪切测量，以探究固体推进剂的粘度依赖性。结果表明，奥克托今颗粒与聚合物基体之间的界面缺陷在长毛细管模头中产生3-30MPa的熔体压力范围，突出了压力对测量粘度的不可忽视的影响（）。在恒定温度和剪切速率下，固体推进剂的测量粘度表现出强烈的压力依赖性，在压力敏感性（β）方面存在显著偏差，发现其与溶剂和固体颗粒的含量密切相关。这种差异归因于毛细管流动过程中颗粒-颗粒和颗粒-聚合物网络的可压缩性。研究结果强调了压力效应在固体推进剂流变性能中的关键作用，这对于优化制造工艺和确保推进剂性能的一致性至关重要。
