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To investigate the thermal decomposition mechanism between Poly(3-nitratomethyl-3- methyloxetane) (PNIMMO) and 2, 4, 6, 8, 10, 12-Hexanitrohexaazaisowurtzitane (CL-20), the thermal decomposition of PNIMMO, CL-20 and PNIMMO+CL-20 mixture under different conditions was studied using differential scanning calorimetry (DSC), thermogravimetric-differential scanning calorimetry-mass spectra-fourier transform infrared spectrometer (TG-DSC-MS/FTIR) and in-situ FTIR experiments. As a result, the exothermic peak temperature of the PNIMMO+CL-20 mixture shifts to lower values under both closed and open circumstances compared to CL-20. Different kinetic parameters and models were obtained for the three decomposition steps in the mixture. The first step follows the random chain scission model (L2) at α <0.5, and the phase boundary controlled reaction model (R3) at α >0.5. The second/third step is between the random chain scission model (L2) and the first-order reaction model (F1) at α <0.5, and conforms to the first-order reaction model (F1) at α >0.5. Thus, the decomposition of PNIMMO controls the initial speed, while the removal of the nitro group in CL-20 controls the later step. Combined with the analysis of gas products and condensed phase, PNIMMO speeds up the N—NO 2 bond breaking in CL-20 but doesn't alter its initial breakdown route. • The thermal decomposition mechanism between PNIMMO and CL-20 is investigated by various techniques. • PNIMMO+CL-20 mixture decomposes in three steps with different kinetic parameters and kinetic models. • PNIMMO doesn't change the initial decomposition pathway of CL-20. • PNIMMO can accelerates the N—NO 2 bond breaking in CL-20 due to incremental heat and H atoms. [ABSTRACT FROM AUTHOR]

Highlights • The bis(dinitromethyl) groups were firstly introduced into a single furazan ring. • The salt 5 achieved a high level of balance between high energetic density and low sensitivity. • The thermal behaviors of the potassium salt 1 and dihydroxylammonium salt 5 were described. • The neutral compound bis(fluorodinitromethyl)-furazan showed a high oxygen balance of 10.19%. Abstract In the field of energetic materials, the contradiction between energy density and sensitivity has long baffled the researchers in pursuing the high detonation-performance compounds with low sensitivity. The bis(dinitromethyl) and bis(fluorodinitromethyl) groups were introduced into a single 1,2,5-oxadiazole (furazan) ring for the first time to form a series of novel furazan-based energetic derivatives, which have been fully characterized by NMR, FTIR, elemental analysis and single crystal X-ray diffraction. The thermal decomposition behaviors were also investigated by multiple heating methods and TG-DSC. Interestingly, among these newly as-synthesized compounds, the dihydroxylammonium salt of bis(dinitromethyl)-furazan (5) possessed a high crystal density of 1.938 g cm−3 at room temperature and exhibited excellent detonation properties (v D = 9679 m s−1, P = 41.5 GPa), as well as moderate impact sensitivities (14 J), which achieved a high level of balance between high energetic density and low sensitivity to date for the furazan-based energetic salts. Furthermore, the neutral compound bis(fluorodinitromethyl)-furazan (11) showed a high positive oxygen balance of 10.19%, which also makes it a potential candidate for the high energetic oxidizer. Such fascinating properties demonstrate that the assembly of bis(dinitromethyl) groups with the single furazan ring is a favorable strategy for the design and synthesis of novel energetic materials with high energy and improved safety. [ABSTRACT FROM AUTHOR]

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 N 2 , CO 2 , N 2 O, CH 2 O and NO from TG-FTIR and TG-MS. • Thermal decomposition of TNNP, TNOP and DNHM was investigated by using TG-DTG, DSC, TG-FTIR, and TG-MS techniques. • The reaction model of TNNP, TNOP, DNHM was studied by combined kinetic method, which follows F1, L2 , R2 model, respectively. • Thermal decomposition temperatures, products and kinetic parameters have been provided for three novel energetic materials. [ABSTRACT FROM AUTHOR]