Studies on Curing Time and Curing Temperature of AP-HTPB-Based Composite Solid Propellant

The curing process plays a crucial role in solidifying composite propellants, which consist of hydroxyl-terminated polybutadiene (HTPB) as a binder and ammonium perchlorate (AP) as an oxidizer. This paper examines and discusses the impact of curing time and temperature on solid propellant samples, considering factors such as burn rate, mechanical properties, FTIR characterization, and thermal decomposition analysis. Through experimental methods, it was observed that all the aspects were positively influenced. Specifically, increasing the curing temperature led to an enhanced propellant burn rate. Similarly, the mechanical properties such as Young’s modulus, hardness, and elongation at break for the sample with 60 and 70 °C curing temperature lie in the standard range, whereas the rest of the samples are beyond the range due to a higher curing temperature which makes the sample brittle. FTIR analysis revealed changes in the strength of the isocyanate functional group, indicating the formation of allophanate linkage at a curing temperature of 100 °C. Moreover, the thermal decomposition of samples with 60, 70, 80, and 90 °C curing temperatures indicated three major peaks, but in the sample with 100 °C curing temperature, one more peak was detected at around 370 °C shows that the decomposition process of oxidizer and binder has divided into two different peaks. Considering the overall perspective, it was evident that an increase in curing temperature significantly affected the propellant and its burn rate, mechanical properties, FTIR analysis, and thermal decomposition.