Wyniki wyszukiwania - BazTech

1

Electric Spark Sensitivity of Polynitro Arenes. Part II. Aspects of the Molecular Structure with Utilization of the Net Charges of Nitro Groups

Zeman S., Friedl Z., Kočí J.

Central European Journal of Energetic Materials

|

2007

|

Vol. 4, nr 4

23-31

EN

An ESZ KTTV instrument of a new, relatively simple construction has been applied to the determination of electric spark sensitivity (EES) of 31 polynitro arenes and their derivatives. Results obtained are compared with the theoretical DFT B3LYP/6-31G(d,p) Mulliken net charges of nitro groups, QNO2, which primarily react in the initiation by the spark. On the basis of analysis of the results obtained it is shown that intermolecular interaction plays in this initiation a considerable role. However, generally accepted presumption, that most positive QNO2 value represents a sensitivity of the given molecule, is not valid without reserve. If the polynitro aromatic molecule contains several potential reaction centres, the proper initiation might then be realized selectively (depending on the kind of initiation impulse).

2

Electric Spark Sensitivity of Polynitro Arenes Part I. A Comparison of Two Instruments

Zeman S., Majzlík J., Kočí J.

Central European Journal of Energetic Materials

|

2007

|

Vol. 4, nr 3

15-24

EN

An ESZ KTTV instrument of a new, relatively simple construction has been applied to determination of electric spark sensitivity (EES) of 34 polynitro arenes and their derivatives. Results obtained are compared with those from measurements by means of older RDAD instrument. The analysis of relationship between the EES values obtained by measurements on the two instruments revealed that the relationship is not unequivocal. It is possible to come to the conclusion that the mechanisms of spark energy transfer into the reaction centre of molecule should be different in measurement on the two alternative instruments. Measurement by means of the ESZ KTTV system is more sensitive to molecular structure of the studied polynitro compounds.

3

A Relationship between 15N NMR Chemical Shifts and Detonation Characteristics of Polynitro Derivatives of Arenes and Polyazaarenes

Zeman S., Pešková M.

Central European Journal of Energetic Materials

|

2005

|

Vol. 2, nr 3

71-84

EN

The 15N NMR chemical shifts of eighteen polynitro arenes have been determined. The relationships were found and discussed between the characteristics of detonation and thermal decomposition, on the one hand, and 15N NMR chemical shifts of nitrogen atoms of the primarily split off nitro groups, on the other hand. Also the relationships are specified between the 15N NMR chemical shifts in the solid state of some polynitro derivatives of aminopyridines and aminopyrimidines, on the one hand, and squares of their detonation velocities, on the other. It has been stated that the chemical micromechanisms of primary fission processes of molecules of the studied compounds in the initiation by shock should be the same as in the case of their low-temperature thermal decomposition. Also mentioned is relevance of the modified Evans-Polanyi-Semenov relationship. On the basis of the findings presented it also has been stated that the detonation transformation itself of these polynitro compounds should be preceded by an induction period.

4

Relationship Between Electronic Charges at Nitrogen Atoms of Nitro Groups and Onsets of Thermal Decomposition of Polynitro Arenes

Zeman S., Friedl Z.

Central European Journal of Energetic Materials

|

2004

|

Vol. 1, nr 1

3-21

EN

Thermal stability of twenty-five polynitro arenes has been examined by means of non-isothermal differential thermal analysis (DTA), and it was expressed as an onset of thermal decomposition, TD. Electronic charges, qN, at nitrogen atoms of the polynitro arene molecules were calculated by means of the ab initio DFT B3LYP/6-31G** method. The relationship was confirmed between the onsets TD and squares of the qN values for the nitro groups that are primarily split off. In the sense of this relationship, the compounds studied fall into five groups. The reason of this diversification and principle of the relationship existence are discussed. It is stated that stabilising influence of the crystal lattice of the studied polynitro arenes can be evaluated by DTA of solutions of these compounds in 1,3,5-trinitrobenzene (TNB).