Detonation Chemistry Studies

Blais, N. C., "Detonation Chemistry Studies of Energetic Materials Using Laboratory-Scale Samples," this conference. 

DETONATION CHEMISTRY STUDIES OF ENERGETIC MATERIALS USING LABORATORY SCALE SAMPLES... 

Later studies by the above authors (Ref 16) demonstrated that the detonability of heptane/ air mixts is greatly enhanced by the addition of about 20% of n-propylnitrate or n-propylnitrite. This further emphasizes that the chemistry of the fuel (or more properly fuel/additive) mixts... 

Processes at detonation fronts occur on such short time scales (subpicosecond) and length scales (subnanometer) that they are ideal for molecular dynamics simulations. Such simulations, which follow individual atomic trajectories, not only have the potential to probe how detonations are initiated but are also capable of studying the subsequent chemistry at the shockfront. The approach might also clarify how the discrete shock-induced chemistry relates to the continuum theory of detonations. 

We have further studied the problem of impact initiation in two dimensions by varying both the number of layers in the flyer plate and its impact velocity. Results from these simulations are shown in Fig. 13. In this figure the solid squares denote simulations where the detonation was sustained, while the open squares denote simulations where, if exothermic chemistry began at all, it was insufficient to maintain a detonation. The solid line follows the interface between these two regions. Figure 13 demonstrates that as the number of layers in the flyer plate is increased, the minimum impact velocity for initiation decreases, approaching an asymptotic value... 

Although these nitroimidazole derivatives were studied mainly for their pharmacological medicinal chemistry, they were seldom studied for their use in explosives and propellants application. However more recently these nitroimidazoles, as so-called high energy density materials , have attracted renewed attention due to their favorable detonation performances. 

We have measured sound velocities of various supercritical fluid systems. An attempt to carry forward such measurements on higher temperature isotherms of formic acid was frustrated by chemical reaction toward products that may include carbon dioxide, carbon monoxide, water, hydrogen and differentiated solid-like products at even higher temperatures and pressures. Nonetheless, the diamond anvil cell provides a unique opportunity to study the chemistry and kinetics of fluids under extreme conditions. We also find that CH2O2 is present during the detonation of some common explosives. 

The paper presents a brief survey of available results obtained from studies of the initiation micro-mechanisms of polynitro compounds from the point of view of organic chemistry. Attention is also paid to the basic mechanisms of low-temperature thermal deeomposition of these compounds. With consideration of these results, the relationships have been specified and analyzed between the characteristics of impact and electric spark sensitivities, detonation and thermal decomposition, on the one hand, and C and N NMR chemical shifts of polynitro compounds, on the other. In the ease of the impact sensitivity, the said relationships involve the NMR chemical shifts of the atoms carrying the most reactive nitro groups. In the case of the remaining stimuli studied, the N shifts of nitrogen atoms in the most reactive nitro groups themselves are involved. It has been stated that the chemical micro-mechanisms of primary fission processes of molecules of polynitro compounds in the initiation by mechanical stimuli (inclusive of the detonation course) and electric spark should be the same as in the case of their low-temperature thermal decomposition. 

Scientists have studied the African bombardier beetle extensively in order to understand its remarkable defense system. When attacked by predators, mostly ants, the beetle unleashes bursts of hot chemicals with audible detonations. The spray originates from a turret-like appendage under its abdomen, which the beetle maneuvers to achieve remarkable target accuracy. But the truly amazing thing is the chemistry of the spray. 

The results of the Excitonic model by Kuklja and Kunz [15,59,65-67] are in concordance with experimental findings obtained by low-temperature decomposition of polynitro compounds. The outputs from this model also correspond with results from the application of physical organic chemistry to the study of initiation reactivity of EMs (POC model). Both these models are also supported by the results obtained by Raikova and likholatov [118], who found that the Arrhenius parameters in both the detonation transform-... 

Zeman S (2003) A study of chemical micro-mechanisms of initiation of organic polynitro compounds. In Politzer P, Murray) (eds) Theor Comp Chemistry, vol 13, Energetic materials. Part 2, Detonation, combustion. Elsevier, Amsterdam, p 25 Zeman S (2006) J Hazard Mater A132 155... 

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