Thermal behavior and decomposition mechanism of three nitrate energetic materials: TNNP, TNOP and DNHM

Thermal decomposition of three new energetic materials，5-nitratomethyl-1,3,5-trinitrohexahydropyrimidine (TNNP), 5–methylnitrate-1,5–dinitrooxazine (TNOP) and 1,3-dinitrohexahydropyrimidine-5-nitrate (DNHM) was investigated by using TG–DTG, DSC, TG-FTIR, and TG-MS techniques. Results show that DNHM is more stable than TNNP and TNOP, while the decomposition process of TNNP and TNOP is more complicated than that of DNHM. TNNP starts to decompose at around 176.1 ºC and the peak temperature is 187.9 ºC with decomposition heat of − 1157.9 J·g⁻¹ at the heating rate of 2.5 ºC·min⁻¹. In comparison, the onset temperature and heat release of TNOP and DNHM are respectively 172.3 ºC, − 486.5 J·g⁻¹ and 180.8 ºC, − 1947.6 J·g⁻¹ at the same condition. The first decomposition step of TNNP follows first-order kinetics (F1) based on DSC data, while the decomposition of TNOP and DNHM follows the random chain scission model (L2) and the phase boundary controlled reaction (contracting area) model (R2), respectively. The main products of these three compounds during the decomposition process are N₂, CO₂, N₂O, CH₂O and NO from TG-FTIR and TG-MS.