About New Approaches in the Study of the Initiation Reactivity of Nitramines
Institute of Energetic Materials, Faculty of Chemical Technology
University of Pardubice, The Czech Republic
Extemporary short intermolecular distances of nitro groups in the crystal lattice of polyniro compounds led towards invocation of activities in the research of free spaces (free volumes, DV) in crystals of EMs and of their influence on impact sensitivity of the mentioned energetic compounds. The first published papers from this area have awoke our interest also in verification of the mentioned influence not only on impact, friction and electric spark sensitivities, and thermal reactivity, but also on crystal densities and performance, which is demonstrated on 24 nitramines.
The relationships between sensitivity and the crystal lattice free space per molecule, DV, in the nitramine crystals are described by equations which are divided into a number of sub-relationships, each of them with a strong limitation by the molecular-structural characteristics of such compounds. With exception of the impact sensitivity, increasing DV values leads mostly to decreasing of initiation reactivity of the nitramines studied. In the case of impact sensitivity it is not possible to say uniquely that increasing of the DV values leads to its increasing or decreasing; this is differet from published opinion. Several little exceptions from the mentioned trends have analogies in other relationships of sensitivity, for example “spark energies – bond dissociation energies” or in the case of impact sensitivity in relation “impact sensitivity – volume heat of explosion”.
More detailed analysis of a mutual dependence of volume heat of explosion, rQ, on the crystal lattice free volume, DV, shows that their courses are relatively tight but they are not unequivocal. Partial linear relationships for the rQ values mostly show increase of this characteristic with increasing the DV values, but here also some opposite trends exist. A similar situation is in semilogarithmic relationship between the crystal density, r (important characteristics for detonation and performance), and the DV values of the nitramines studied; here the studied substances are as if divided into a group derived from dimethyl nitramine and a group derived from 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (HNIW). All the analyzed dependencies confirm that in the non-ionic nitramines maximal density and detonation parameters are limited by values which are peculiar to e-HNIW.
The found relationships for the impact and friction sensitivities confirm the disorder in distribution of the forces in the crystal lattice of the “common” quality of e-2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaaza-isowurtzitane (CL-20), in comparison with its RS (reduced sensitivity) or chemically pure analogue; these relationships allow also to speculate, which of the nitro groups in the CL-20 molecule might have a main participation in the intermolecular interactions for its particular kind.
The talk will be given in English
Sun, 04-06-2017, 16:00Meeting Hall 203, 2nd floor, Fine Rocket Propulsion Center, Aerospace Engineering
Light refreshments will be served before the lecture