A density- and composition-aware model for detonation propagation in the TATB-based explosive PBX 9502

PBX 9502 is an insensitive high explosive (HE) containing 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) as the HE crystal bonded with the copolymer Kel F-800 in a nominal weight ratio of 95% TATB and 5% Kel F-800. Multiple batches, known as lots, of PBX 9502 have been manufactured since its introduction. The detonation diameter effect, which measures steady detonation speed versus inverse charge radius in a cylindrical rate-stick configuration, varies significantly between the different lots. Here, we show that the diameter effect variation can be explained by differences in the initial pressing density, weight percentage of TATB, and percentage of TATB that is virgin or recycled in each lot (recycled lots have a larger weight percentage of fine TATB particles than virgin lots). Incorporating these properties into a detonation shock dynamics model, we show that the diameter effect data for the lots examined collapse onto a single curve at a given reference state. Novelty and Significance PBX 9502 is an important TATB-based insensitive high explosive, which has been extensively studied due to its unique combination of safety and performance properties. Since its introduction, multiple batches of PBX 9502, known as lots, have been manufactured. PBX 9502 shows significant lot-to-lot variations in detonation speed that have not been satisfactorily explained. In this work, we show that the variations are due to a combination of differences in pressing density, weight percentage of TATB, and weight percentage of fine TATB particles. The work provides a new capability for how detonation propagation in PBX 9502 can be modeled without extensive experimentation.