In this study, nitrated bacterial cellulose (NBC) energetic binder was introduced to prepare NBC-based nanocomposite energetic materials (nEMs) through a combined simple and safe sol−gel method and the freeze-drying technology. A series of analytical and test methods were systematically conducted to characterize the structure, composition, thermal properties, and safety performance of the materials. The results indicated that the particles of nitramine explosives were dispersed and embedded homogeneously in the three-dimensional (3D) porous cross-linked construction of the NBC gel matrix; the crystal growth of the explosive particles was restricted, which led to nanometer-scale composites. The thermal analysis demonstrated that the peak temperature of the composite (e.g., NBC/CL-20: 224.8 °C) was reduced and produced substantial heat release (e.g., NBC/CL-20: 3346 J•g −1 ) during the process of decomposition. In addition, the mechanism of thermal decomposition was probed, and cyclic catalytic decomposition between the NBC gel and explosives may exist. The sensitivity decreased visibly because of the existence of the cross-linked structure of the gel matrix, which could act as a buffer system to mitigate the release stimulated from the surroundings. Accordingly, this investigation may provide the promising potential for NBCbased energetic composites used in explosives and propellants in the military, and further promote the methodology for manufacturing energetic nanocomposites.

No abstract

No abstract

In this work, nitrocellulose/hexanitrohexaazaisowurtzitane/carbon nanomaterials (NC/CL‐20/CnMs) nanoenergetic composite materials are synthesized by combining sol‐gel and vacuum freeze‐drying technology, wherein NC is chosen as the gel matrix to load CL‐20 particles and CnMs. The results indicate that the CL‐20 and CnMs are imbedded and homogeneously dispersed in the monolithic gel of NC matrix, and the polymorph of CL‐20 maintains the optimal ϵ form during the fabrication process. The thermal results reveal that the onset temperature and exothermic temperature are visibly advanced compared with physical mixing and CL‐20. In addition, the activation energy (Ea) of composites has also been calculated and exhibits lower Ea (110 kJ mol−1<) than that of raw materials (NC: 299.13 kJ mol−1, CL‐20: 157.93 kJ mol−1). Finally, the impact and frication sensitivities have been tested and present inspirational results that sensitivity is decreased greatly owning to buffer function of the monolithic gel of NC matrix. This fabrication strategy and conclusions will provide promising application for NC/CL‐20/CnMs used in propellants.

In order to investigate the thermal decomposition kinetics and mechanism of nitrocellulose (NC) based nitramine explosives nanocomposite energetic materials, this work prepares NC/RDX (cyclotrimethylenetrinitramine), NC/HMX (cyclotetramethylenetetranitramine), and NC/CL-20 (hexanitrohexaazaisowurtzitane) composites by a combined sol-gel and the freeze-drying technology. The structure is systematically investigated and the results reveal that the explosive particles are dispersed, filled, or embedded homogenously in the gel matrix of NC, thereby restricting the crystal growth of RDX, HMX, CL-20 particles to coarse and achieving submicron/nanometer. The thermal analysis of composites exhibits much lower peak temperature compared with raw explosive crystal, furthermore, the activation energy (E a ) of composites is also lower than that of both NC and explosives. Hence, the unique structure of NC gel matrix embedded explosives inside demonstrated different mechanism of decomposition. Concretely, the rupture of the H-NCO = O bond in the cross-linked structure is detected firstly, subsequently, the macromolecular chains' scission site of gel firstly occurs at -C-O-C-in the ring, and then the scission of -NO 2 (from NC or explosive crystals) bonds happened. Hence, this study may provide promising fabrication strategy and basic theory for the application of NC-based nanocomposite energetics in high-energy propellants and explosives.