Ningning Zhao

Molecular structure and thermal behavior of N-Benzoyl-3,3-dinitroazetidine

N-Benzoyl-3,3-dinitroazetidine (BDNAZ) has been synthesized and characterized by elemental analysis, FT-IR spectroscopy, 1H NMR and X-ray single crystal diffraction technique. BDNAZ crystallizes in the monoclinic space group P21/c. Its thermal behavior was studied under a non-isothermal condition by DSC and TG/DTG methods, the value of Ea and A of the exothermic decomposition reaction of BDNAZ are 143.19 kJ mol−1 and 1014.34 s−1, respectively. The specific heat capacity of BDNAZ was determined with a continuous Cp mode of micro-calorimeter and theoretical calculation. The adiabatic time-to-explosion was evaluated as 109.9–124.4 s.

Molecular structure, quantum chemical investigation, and thermal behavior of (DNAZ-CO)2

Bis-(3,3-dinitroazetidinyl)-oxamide ((DNAZ-CO)2) is an acyl derivative of 3,3-dinitroazetidine (DNAZ). It is prepared and its crystal structure is determined. The crystal is orthorhombic, Fdd2 space group, a = 13.136(14) Å, b = 19.48(3) Å, c = 10.326(14) Å, V = 2642 (6) Å3, Z = 8. A density functional theory (DFT) method of the Amsterdam Density Functional (ADF) package is used to calculate the geometry, frequencies, and properties. The optimized geometry, frontier orbital energy, and main atomic orbital percentage are obtained. The thermal behavior is studied under a non-isothermal condition by DSC and TG/DTG methods. The apparent activation energy (Ea) and pre-exponential factor (A) of the exothermic decomposition reaction of (DNAZ-CO)2 are 164.10 kJmol−1 and 1013.38 s−1 respectively. The critical temperature of thermal explosion is 272.20°C. The values of ΔS≠, ΔH≠, and ΔG≠ of this reaction are 6.44 Jmol−1·K−1, 163.76 kJmol−1 and 160.34 kJmol−1 respectively.

Thermal behavior of nitrocellulose-based superthermites: effects of nano-Fe2O3 with three morphologies

Superthermites or metastable intermolecular composites (MIC) are well-known for their excellent combustion characteristics in propellants. Herein, superthermites with three Fe2O3 morphologies (rod-like, polyhedral, and olivary) were synthesized. The effects of Al/Fe2O3 on the thermal decomposition property of nitrocellulose (NC) were investigated in detail via differential scanning calorimetry (DSC). The results indicate that the catalytic performances of the superthermites are highly relevant to the specific surface area of their corresponding Fe2O3. Al/Fe2O3 containing rod-like Fe2O3 (Fe2O3(r)) shows a much improved performance compared with other morphological samples. The values of apparent activation energy (Ea) and thermal ignition temperature (Tbeo) of NC-Al/Fe2O3(r) were the lowest. This study could provide some directive reference data for the thermal behavior of nitrocellulose-based superthermites.

Combustion Catalyst: Nano‐Fe2O3 and Nano‐Thermite Al/ Fe2O3 with Different Shapes

In order to enable the energetic materials to possess a more powerful performance, adding combustion catalysts is a quite effective method. Granular, oval, and polyhedral Fe2O3 particles have been prepared by the hydrothermal method and used to fabricate Al/Fe2O3 thermites. All the Fe2O3 and Al/Fe2O3 thermite samples were characterized using a combination of experimental techniques including scanning electron microsco‐ py (SEM), energy dispersive spectrometer (EDS), X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscope (TEM), and high‐resolution TEM (HRTEM). The non‐isothermal decomposition kinetics of the composites and nitrocellulose (NC) can be modeled by the Avrami‐Erofeev equation f(α)=3(1–α)[–ln(1–α)]1/3/2 in differential form. Through the thermogravimetric analysis infrared (TG‐IR) analysis of decomposition processes and products, it is speculated that Fe2O3 and Al/Fe2O3 can effectively accelerate the thermal decomposition reaction rate of NC by promoting the O‐NO2 bond cleavage. Adding oxides or thermites can distinctly increase the burning rate, decrease the burning rate pressure exponent, increase the flame temperature, and improve the combustion wave structures of the ammonium perchlorate/hydroxyl‐terminated polybutadiene (AP/HTPB) propellants. Among the three studied, different shapes of Fe2O3, the granular Fe2O3, and its corresponding thermites (Al/Fe2O3(H)) exhibit the highest burning rate due to larger surface area associated with smaller particle size. Moreover, Al/Fe2O3(H) thermites have more effective combustion‐supporting ability for AP/HTPB propellants than Fe2O3 structures and the other two as‐prepared Al/Fe2O3 thermites.

3,3-Dinitro-azetidinium chloride.

In the title gem-dinitroazetidinium chloride salt, C3H6N3O4 +·Cl−, the cations and anions lie on a mirror plane. The azetidine ring is virtually planar, with a mean deviation from the plane of 0.0569 Å. The dihedral angle between the two nitro groups is 90.00 (5)°. In the crystal, the ions are linked by N—H⋯Cl interactions, forming a chain along the c-axis direction, and C—H⋯O interactions, forming a layer parallel to (010).