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2 Central European Journal of Energetic Materials

2 2020

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The Preparation and Properties of Low-Nitrogen Nitrocellulose by Alkaline Denitration

Tao Zhongan, Li Shiying, Ding Yajun, Xiao Zhongliang

Central European Journal of Energetic Materials

2020

Vol. 17, no. 4

535--551

Waste high-nitrogen nitrocellulose (NC) has always been disposed of as hazardous material for destruction, and has not been recycled as a resource. The present work describes how waste high-nitrogen NC may be converted to low-nitrogen NC via an alkaline denitration reaction between sodium hydrosulfide and the nitrate ester groups, in order to control and reduce the nitrogen content for industrial products. Scanning electron microscopy (SEM), infrared spectroscopy (FT-IR), 1H nuclear magnetic resonance spectroscopy (1H NMR) and X-ray diffraction (XRD) were used to detected the changes in the surface morphology and chemical structure of the NC samples. TG-DSC tests analyzed the decomposition temperature and the heat released on thermal decomposition, and the explosion heat was obtained by calorimetry. The results demonstrated that the denitration reaction does not destroy the skeletal structure of NC. Notably, the nitrogen content of NC may be reduced from 12.92 to 10.74%, generating the level for industrial products (N <12%). Moreover, NC samples with different nitrogen contents have similar decomposition trends and decomposition temperatures, but the heat released is gradually decreased and the explosion heat is significantly reduced, and confirms the successful partial removal of nitrate ester groups from NC. Therefore, the alkaline denitration affords a potential method for recycling waste high-nitrogen NC.

Microcellular Oblate Propellant with Skin-core Structure Deterred by Poly(neopentanediol adipate)

Ding Yajun, Ying Sanjiu, Xiao Zhongliang, Wu Wenlong, Li Chunzhi, He Yun

Central European Journal of Energetic Materials

2020

Vol. 17, no. 1

49--65

In order to solve the issues of high muzzle flash, smoke, residue, migration rate and carcinogenicity of double-base oblate propellants deterred by dibutyl phthalate (DBP), skin-core structure microporous oblate propellants to replace DBP deterring technology were fabricated in the present work by supercritical carbon dioxide (SC-CO2) foaming technology. Poly(neopentanediol adipate) (NA) was employed as the deterrent to modify the combustion properties because of ist lower migration rate in storage. Scanning electron microscopy (SEM) was used to observe the morphology of the microporous oblate propellants generated by different processing conditions, and the combustion properties were investigated by closed bomb tests. The SEM images indicated that the skin region displayed smaller cell diameters and lower cell density compared with cells in the core region. The closed bomb tests demonstrated that it was feasible to adjust the progressive combustion performance by controlling the skin-core structure and the NA deterred layer. The burning time values of the original, the microcellular, and the NA deterred samples were 3.45, 2.14, and 4.20 ms, respectively. Microcellular oblate propellants, with a skin-core structure foamed by SC-CO2 and deterred by NA, provides a novel and promising method to realize progressive combustion performance.