Improved disposal security of 2,6-bis(picrylamino)-3,5-dinitropyridine via recrystallization

The crystal appearance of industrial grade 2,6-bis(picrylamino)-3,5-dinitropyridine (PYX) was mostly needle-shaped or rod-shaped with an average aspect ratio of 3.47 and roundness of 0.47. To improve the loading density and pressing safety, the crystal shape of PYX was optimized by cooling crystallization method. After recrystallization, the aspect ratio decreased from 3.47 to 1.28, and the roundness value increased from 0.47 to 0.78. XRD data showed that there is no crystal pattern change before and after recrystallization. The friction sensitivity of the explosive decreases from 88% to 56%, and the impact sensitivity decreases from 76% to 12%. Differential scanning calorimeter (DSC) was used to study the thermal decomposition of PYX. The thermal decomposition peak temperature of the samples after recrystallization was 4~7℃ higher than that of raw PYX. The adiabatic induction time (TMRad) and self-accelerating decomposition temperature (SADT) were calculated with AKTS software. In the same adiabatic induction time, the initial temperature of recrystallization PYX is about 30℃~40℃ higher than that of the raw PYX. The SADT is increased by about 50℃~60℃. The thermal safety of recrystallized PYX is improved.