Usability of Relationship between Activation Energies of Low-Temperature Thermal Decomposition and Heats of Explosion or Squares of Detonation Velocities in Study of Initiation of Energetic Materials

摘要

Activation energies of thermal decomposition of individual energetic materials, obtained under at comparable conditions, correlate with the respective detonation heats or squares of detonation velocities through a relation which reminds the Evans-Polanyi-Semenov equation (modified EPS equation). The attention is paid also to analogous relationships of the energies of electric spark, required for 50 percent initiation probability. These correlations indicate that the primary fragmentation processes during low-temperature thermal decomposition or initiation by electric spark are the same as those controlling the detonation reaction. This is valid also for explosive mixtures in which one from their component determines their initiation reactivity. In this case it was stated that initiation of the detonation of explosives based on mixtures of a fuel and /or high explosive with an ammonium nitrate oxidizing system proceeds primarily through decomposition of this system. However, if mechanism of the primary thermal decomposition of the given energetic material is not identical with the primary fission in its detonation, the modified EPS equation is not valid for such system. The last statement is documented by means of the mixtures on the basis of 1,3,5-trinitroso-1,3,5-triazinane (TMTA) with 1,3,5-trinitro-1,3,5-triazinane (RDX), 2,4,6-trinitrotoluene (TNT) and 1,3,5-trinitrobenzene (TNB) (i. e. TNT/TMTA, TMTA/RDX, TNB/TMTA, and TNB/TMTA/RDX). It is documented that the EPS equation can be derived also from relationships between the ~(15)N NMR chemical shifts of the nitrogen atoms of primarily leaving nitro groups and characteristics of initiation reactivities of polynitro compounds. By means of these shifts the key atoms in reaction centers of molecules of the said compounds can be specified. On the basis of the findings presented it also has been stated that the detonation transformation itself of the energetic materials should be preceded by an induction period.