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Science and Technology of Energetic Materials

Vol.64, No.5 (2003)

Research paper

Synthesis and properties of alkali metal picrates
Makoto Matsukawa, Takehiro Matsunaga, Masatake Yoshida, and Shuzo Fujiwara
p.183-191

Abstract

Picric acid is known to react with metals to form highly unstable metallic picrates, which have caused serious explosive accidents. In this study, alkali metal picrates of lithium, sodium, potassium, rubidium, and cesium salts were synthesized, and the thermodynamic and initiation sensitivity were examined. Differential scanning calorimetry (DSC) results reveal that the decomposition of alkali metal picrates begins at a higher temperature than that of picric acid. The heat of decomposition of alkali metal picrates is found to be lower than that of picric acid. Thermal gravimetric analysis and Karl Fischer analysis confirm that alkali metal picrates contain crystalline H2O. Experimental results show that the amount of crystalline H2O in picrates is 1.0 hydrate for Li-picrate, and 1.0 hydrate for Na-picrate. However, K-picrate, Rb-picrate and Cs-picrate are anhydrate. Li-picrate mono crystal, which includes a full crystalline H2O condition, is 3.0 hydrate in the metastable phase. The results of thermogravimetry analysis show that crystalline water dehydration occurs between 350 K and 500 K. Activation energies at start of exothermic decomposition was analyzed by different heating rates of DSC analyses. Result of analyses were; Li-picrate 127.4 kJ, Na-picrate 151.3 kJ, K-picrate 207.9 kJ, Rb-picrate 204.9 kJ, and Cs-picrate 172.8 kJ. Drop-hammer test results show that alkali metal picrates demonstrate greater impact sensitivity than picric acid. Friction test results show that anhydrate picrates show more sensitivity than hydrate picrates.

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