Hydroxyl terminated polybutadiene resin (HTPB) based solid propellants are being currently used in solid rocket motors of launch vehicles. HTPB‐XT (HTPB blended with the hydrocarbon oil, Extol‐21) was developed to enhance the pot life of the propellant slurry and to overcome the problems in the propellant processing due to the shorter pot life of present HTPB propellants. The diffusion study of labile chemical species in HTPB and HTPB‐XT propellants (with low and high viscosity hydrocarbon oils) was carried out. Analog cartons simulating the propellant of the main motor were cast with 120 kg mix level propellant and subjected to an aging study at room temperature and an accelerated condition at different intervals over a period of 100 days. Samples from the cartons were subjected to Soxhlet extraction and analyzed for concentration of chemical species in insulation rubber as well as in propellant. The change in concentration of species from the insulation to interior propellant was also studied and compared with HTPB propellant. The diffusion of the other chemicals along with plasticizer was also observed in these studies. Nonax‐D, a solid ingredient also migrated due to its solubility in the propellant matrix but not due to the movement of solid particles. Due to the migration of propellant chemicals into insulation, there was a significant reduction in their initial concentrations in the propellant regions adjacent to the insulation surface. The rate of diffusion of the chemically unbound species was affected by temperature and time. The results of viscosity build‐up, mechanical, interfacial, ballistic properties for HTPB and HTPB‐XT propellants are presented and discussed.

中文翻译：

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不稳定化学物质在HTPB和HTPB-XT固体推进剂中的扩散及其对固体火箭发动机性能老化的影响-研究

基于羟基封端的聚丁二烯树脂（HTPB）的固体推进剂目前正在运载火箭的固体火箭发动机中使用。HTPB‐XT（与烃油共混的HTPB，Extol-21）的开发是为了提高推进剂浆液的适用期，并克服由于现有HTPB推进剂的适用期较短而导致的推进剂加工问题。进行了不稳定化学物质在HTPB和HTPB-XT推进剂（低粘度和高粘度烃油）中的扩散研究。用120千克混合水平的推进剂浇铸模拟主发动机推进剂的模拟纸箱，并在室温和加速条件下以不同的间隔进行100天的老化研究。将来自纸箱的样品进行索氏提取，并分析绝缘橡胶和推进剂中化学物质的浓度。还研究了从绝缘体到内部推进剂的物质浓度变化，并将其与HTPB推进剂进行了比较。在这些研究中还观察到其他化学物质与增塑剂的扩散。Nonax‐D（一种固体成分）也由于其在推进剂基质中的溶解性而迁移，而不是由于固体颗粒的移动而迁移。由于推进剂化学物质向绝缘体中的迁移，在与绝缘体表面相邻的推进剂区域中，其初始浓度显着降低。化学未结合物质的扩散速度受温度和时间的影响。粘度增加的结果，机械的，