Nanoscale composite energetic materials (CEMs) based on oxidizer and fuel have potential advantages in energy adjustment and regulation through oxygen balance (OB) change. The micro- and nanosized fibers based on nano nitrocellulose (NC)-ammonium dinitramide (ADN) were prepared by the electrospinning technique, and the morphology, thermal stability, combustion behaviors, and mechanical sensitivity of the fibers were characterized by means of scanning electron microscope (SEM), transmission electron microscopy (TEM), differential scanning calorimetry (DSC), gas pressure measurement of thermostatic decomposition, laser ignition, and sensitivity tests. The results showed that the prepared fibers with fluffy 3D macrostructure were constructed by the overlap of micro/nanofibers with the energetic particles embedded in the NC matrix. The first exothermic peak temperature (T_p) of the samples containing ADN decreased by 10.1 °C at most compared to that of ADN, and the pressure rise time of all the samples containing ADN moved forward compared to that of the sample containing NC only. Furthermore, ADN can decrease the ignition delay time of NC-based fibers under atmosphere at room temperature from 33 ms to 9 ms and can enhance the burning intensity of NC-based fibers under normal pressure. In addition, compared to the single high explosive CL-20 or RDX, the mechanical sensitivities of the composite materials containing high explosive CL-20 or RDX were much decreased. The positive oxygen balance of ADN and the intensive interactions between ADN and NC can reduce the ignition delay time and promote the burning reaction intensity of NC-based composite fibers, while the mechanical sensitivities of composite fibers could be improved.

The initial interaction mechanism is very important for the design and safety of nano-scale composite energetic materials composed of ammonium dinitramide (ADN) and nitrocellulose (NC). The thermal behaviors of ADN, NC and an NC/ADN mixture under different conditions were studied by using differential scanning calorimetry (DSC) with sealed crucibles, an accelerating rate calorimeter (ARC), a self-developed gas pressure measurement instrument and a DSC-thermogravimetry (TG)—quadrupole mass spectroscopy (MS)—Fourier transform infrared spectroscopy (FTIR) combined technique. The results show that the exothermic peak temperature of the NC/ADN mixture shifted forward greatly in both open and closed circumstances compared to those of NC or ADN. After 585.5 min under quasi-adiabatic conditions, the NC/ADN mixture stepped into the self-heating stage at 106.4 °C, which was much less than the initial temperatures of NC or ADN. The significant reduction in net pressure increment of NC, ADN and the NC/ADN mixture under vacuum indicates that ADN initiated the interaction of NC with ADN. Compared to gas products of NC or ADN, two new kinds of oxidative gases O₂ and HNO₂ appeared for the NC/ADN mixture, while NH₃ and aldehyde disappeared. The mixing of NC with ADN did not change the initial decomposition pathway of either, but NC made ADN more inclined to decompose into N₂O, which resulted in the formation of oxidative gases O₂ and HNO₂. The thermal decomposition of ADN dominated the initial thermal decomposition stage of the NC/ADN mixture, followed by the oxidation of NC and the cation of ADN.

To investigate the influence of the cubic crystal morphology on the thermal properties and sensitivity of 2,6-bis(picrylamino)-3,5-dinitropyridine (PYX), cubic PYX (CPYX) crystals were prepared using the antisolvent method. Scanning electron microscopy (SEM), laser particle size analysis, X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) were used to characterize the morphology, particle size and structure of the prepared products. The thermal behavior, thermal decomposition kinetics, thermal safety parameters and thermal decomposition mechanism of CPYX were investigated by differential scanning calorimetry–thermogravimetry–mass spectrometry–Fourier transform infrared spectrometry (DSC-TG-MS-FT-IR) and in situ FT-IR experiments. Meanwhile, the mechanical sensitivity of CPYX was determined by means of the explosion probability method. The results showed that the product had a smooth cubic morphology and small crystal aspect ratio with an average particle size (d₅₀) of 10.65 μm, but it had no distinct differences from the crystal structure of raw PYX (RPYX). The thermal decomposition peak temperature, the self-accelerating decomposition temperature and the critical temperature of the thermal explosion of CPYX increased by 7.2 °C, 6.1 °C and 10.4 °C, respectively, compared to RPYX. Similarly, the apparent activation energy increased by 15%. Besides these, the impact sensitivity and friction sensitivity of CPYX decreased by 36% and 20%, respectively, compared to RPYX. The decomposition process of CPYX contains two stages. The first stage involves the breakage of N-H bonds and -NO₂ groups with the release of CO₂, N₂O, NO, HCN and H₂O, followed by the thermal decomposition of the resulting intermediate and the release of CO₂, N₂O and HCN in the second stage.

In order to assess the risk of nitrocellulose (NC) package atuo-ignition in warehouse, the three kinetic parameters of thermal decomposition of NC were calculated based on DSC curves using commercial software AKTS-kinetic module. On this basis, effects of ambient temperature (Ta), initial temperature of the package (T0) and cylinder diameter of package on time to ignition (τ) were studied using AKTS-thermal safety module. Results showed that as Ta and/or T0 increases the τ decreases exponentially, but the τ at different package dimensions is related to the Ta. More importantly, for a certain Ta, the τ doesn’t always change monotonously with the dimension, there is a dangerous dimension which are easier to ignite. It indicates that big risks exist when trying to predict the safe status of a certain NC package by extrapolation.

The fluffy fibers based on nitrocellulose (NC)/ammonium dinitramide (ADN) with high explosives have been fabricated by electrospinning technique. The morphology, thermal stability, combustion behaviors and mechanical sensitivity of NC/ADN-based composite fibers were characterized by means of scanning electron microscope (SEM), transmission electron microscopy (TEM), differentialscanning calorimetry (DSC), gas pressure measurement of thermostatic decomposition, laser ignition and sensitivity test, respectively. The results showed that the prepared fibers with fluffy 3D macrostructure were constructed by the overlap of mirco/nanofibers with the energetic particles imbedded in NC matrix. The addition of ADN can accelerate the thermal decomposition with the peak temperature (T_p) decrease by 10.1 ^oC and the pressure rise time moving forward. Furthermore, ADN can decrease the ignition delay time of NC-based fibers under atmosphere at room temperature from 33 ms to 9 ms, and enhance the burning strength of NC-based fibers under normal pressure. In addition, the impact sensitivities were reduced from 100–56% for NC-based fibers containing CL-20 and from 88–56% for NC-based fibers containing RDX; the friction sensitivities were reduced from 100–64% for NC-based fibers containing CL-20 and from 84–60% for NC-based fibers containing RDX, respectively.