In the Brazilian Aerospace Program, even though all developed rocket motors are manufactured in the same plant of the Department of Aerospace Science and Technology, differences are observed in the magnitude of the masses applied in each motor. Thus, depending on the volume of the combustion chamber, it is common for the casting to carry out multi-batch processes when a required mass of solid propellant is greater than the maximum capacity of the reactor. In this context, the studies that systematically evaluate multi-batch processes on an industrial scale of composite propellants based on polyurethanes obtained from HTPB are incipient. Furthermore, each batch preparation of the casting process for large motors is carried out on different days, so that each of these has a different storage time until the day of the effective casting. As a result, this wait can generate changes in the properties of the propellant grain as a whole, which can modify the motor's performance. Thusly, through the analysis of data of multi-batch processes, the present study evaluated the influence of the storage time in the preparation of the propellant and on the final properties of the grain. It was concluded that the grain becomes softer with a reduction in its hardness, greater elongation at break, and less modulus for batches with longer storage times before casting.

中文翻译：

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在工业规模的多批次工艺中研究未固化推进剂的储存时间对复合材料最终性能的影响

在巴西航空航天计划中，尽管所有研制的火箭发动机都是在航空航天科技部的同一家工厂制造的，但在每个发动机上应用的质量大小不同。因此，根据燃烧室的容积，当所需固体推进剂的质量大于反应器的最大容量时，浇铸通常进行多批次工艺。在此背景下，以从 HTPB 获得的聚氨酯为基础的复合推进剂工业规模的多批次工艺系统评估研究刚刚起步。此外，大型电机的铸造工艺的每批准备在不同的日子进行，因此每个批次都有不同的存储时间，直到有效铸造之日。其结果，这种等待会导致整个推进剂药柱的特性发生变化，从而改变发动机的性能。因此，本研究通过对多批次工艺数据的分析，评估了储存时间对推进剂制备和谷物最终性能的影响。得出的结论是，对于铸造前储存时间较长的批次，随着硬度的降低、断裂伸长率的增加和模量的降低，晶粒变得更软。