Key Laboratory of Light Field Manipulation and Information Acquisition, Ministry of Industry and Information Technology, and Shaanxi Basic Discipline (Liquid Physics) Research Center, School of Physical Science and Technology, Northwestern Polytechnical University, Xi'an 710129, China.
Science and Technology on Combustion, Internal Flow and Thermo-structure Laboratory, Northwestern Polytechnical University, Xi'an 710072, China.
ACS Sens. 2023 Jul 28;8(7):2664-2672. doi: 10.1021/acssensors.3c00521. Epub 2023 Jun 23.
Curing activity in the preparation of solid composite propellants determines the performance of solid rocket motors in operation. Limited by the lack of effective monitoring tools, the complete curing behavior and thermal-induced curing kinetics are rarely disclosed. It is still a challenge to monitor in situ and in real-time the physical and chemical cross-linking reaction during the curing of propellant. Herein, we demonstrate a promising approach based on optical fiber capable of being implanted inside the propellant to monitor the internal stress evolution during the curing process, by taking hydroxyl-terminated polybutadiene propellant as an example. Attributed to the strain and temperature sensitivity of a pair of optical fiber gratings, the thermal-assisted physico-chemical cross-linking states of curing process have been demonstrated in detail. By tracking the stress-induced wavelength shifts of fiber gratings and calculating the curing mechanism function, the complete curing roadmap, including the viscous flow stage, gel stage, hardening stage can be clearly revealed, and the curing completion times are obtained as 154, 81, and 40 h, at the curing temperatures of 60, 70, and 80 °C, respectively. The apparent activation energy of this curing system obtained by calculation is 73.88 kJ/mol. This flexible fiber-based sensor provides an effective tool for unraveling the cure kinetic mechanism, and paves a universal pathway to guide the preparation and applications of versatile composite materials for solid rocket motors.
固化活性在固体复合推进剂的制备中决定了固体火箭发动机在运行中的性能。由于缺乏有效的监测工具，完全的固化行为和热诱导固化动力学很少被揭示。在推进剂固化过程中实时原位监测物理和化学交联反应仍然是一个挑战。在这里，我们展示了一种有前途的方法，该方法基于光纤，能够植入推进剂内部，以监测固化过程中的内部应力演变，以端羟基聚丁二烯推进剂为例。由于一对光纤光栅的应变和温度灵敏度，详细展示了热辅助物理化学交联状态的固化过程。通过跟踪光纤光栅的应力诱导波长移动并计算固化机制函数，可以清楚地揭示完整的固化路线图，包括粘性流动阶段、凝胶阶段、硬化阶段，并获得在 60、70 和 80°C 的固化温度下，固化完成时间分别为 154、81 和 40 h。通过计算得到的该固化体系的表观活化能为 73.88 kJ/mol。这种基于灵活光纤的传感器为揭示固化动力学机制提供了有效的工具，并为指导各种用于固体火箭发动机的复合材料的制备和应用铺平了通用途径。
