New Mechanism For Slow Explosives | April 13, 2009 Issue - Vol. 87 Issue 15 | Chemical & Engineering News
Volume 87 Issue 15 | p. 44 | Concentrates
Issue Date: April 13, 2009

New Mechanism For Slow Explosives

Nitrogen-rich heterocycle formation interferes with shock reaction
Department: Science & Technology
Retardant
The formation of nitrogen-rich heterocycles, like the one shown, may help slow reactions of some high explosives (C = gray, N = blue, O = red).
Credit: J. Am. Chem. Soc.
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Retardant
The formation of nitrogen-rich heterocycles, like the one shown, may help slow reactions of some high explosives (C = gray, N = blue, O = red).
Credit: J. Am. Chem. Soc.

High explosives rich in carbon react far more slowly than those with less carbon—on the order of milliseconds, instead of nanoseconds. Scientists have believed that the detonation process is slower in the carbon-rich materials because of the formation of graphitic or diamond-like particles. But now, chemist M. Riad Manaa of Lawrence Livermore National Laboratory and colleagues have discovered an entirely different mechanism that may explain the relatively sluggish reaction of carbon-rich explosives (J. Am. Chem. Soc., DOI: 10.1021/ja808196e). Using both density functional-based tight-binding theory and molecular dynamics simulations, the group modeled the shock compression of a particularly insensitive explosive, 1,3,5-triamino-2,4,6-trinitrobenzene (TATB), and found that during the process, nitrogen-rich heterocyclic clusters form, slowing the reaction. These clusters remain intact for much of the simulation, which is "a testament to their resiliency toward further decomposition and further retardation of chemical activity," the authors write.

 
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