Determining heats of detonation of non-aromatic energetic compounds without considering their heats of formation

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Abstract

A new procedure is introduced for calculating heats of detonation of non-aromatic energetic compounds through ratios of oxygen to carbon and hydrogen to oxygen as well as the contribution of some structural parameters. There is no need to use heats of formation of non-aromatic energetic compounds that are usually needed by the other methods. Moreover, this much simple method does not use any experimental and computed data of energetic materials. Predicted heats of detonation for 28 non-aromatic energetic compounds have a root mean square (rms) of deviation of 0.54 kJ/g from experiment, which show good agreement with respect to measured values. The new method is the simplest procedure for predicting heats of detonation and provides reliable results which are comparable with the other methods.

Introduction

Detonation parameters such as detonation velocity, pressure and temperature can be determined by computer codes or empirical methods. A complicated computer code, e.g. CHEETAH [1], can be applied for explosives when their heats of formation and densities are known and the equations of state such as Becker–Kistiakosky–Wilson (BKW) [2] for the detonation products are assumed. Various empirical methods have been used to complete the computer output for desk calculations of factors related to various aspect of energetic materials [3]. As representative example, different procedures have been recently introduced for simple evaluation of detonation velocity of explosives using heat of detonation at loading density greater than 1 g/cm3 [4], [5] or any loading density [6], approximate detonation temperature [7], gas phase heat of formation [8] and structural parameters [9].

Detonation energy or heat of detonation has been regarded as one of the principal measures of performance of detonating explosives for many years. It will raise the temperature of gases detonation because decomposition of an explosive is extremely fast, which will in turn cause them to expand and work on surroundings. It can be determined from heats of formation of the reactants and the products of detonation through the relation [4]:QΔHf(detonation products)ΔHf(explosive)formula weight of explosive

The condensed phase heat of formation of the explosive and the standard heats of formation of detonation products can be use to predict the heat of detonation of an energetic material. To obtain a greater release of energy upon detonation and an improvement in performance, a positive heat of formation (per unit weight) is favorable for an energetic compound.

The calculated heats of detonation can also be used to determine detonation pressure and velocity of explosives [10], [11]. However, predicting fairly accurate heats of detonation, by simple empirical methods, are highly desired for calculating the various detonation parameters of energetic compounds. Moreover, their calculated values are useful in comparing the relative heat releasing of one explosive with another. The purpose of this work was to obtain the simplest method for estimating heats of detonation of non-aromatic energetic compounds without using their heats of formation. This work assumes that heat of detonation can be related to some structural parameters of explosive. There is no need to estimate the composition of detonation products and their thermochemical properties. The results will be also compared with two empirical methods for 28 non-aromatic energetic compounds. The new method is also simple in form and easy to use in a practical sense.

Section snippets

New procedure for predicting heats of detonation of non-aromatic energetic compounds

Heat of detonation is an important detonation parameter which can be used as the energy available to do mechanical work and estimating potential damage to surroundings [12]. The Kamlet and Jacobs [4] introduced N2, H2O, CO2 (but not CO) as the important products of decomposition reaction for calculating heat of detonation through Eq. (1). Rice and Hare [12] also used the predicted product concentrations by the CHEETAH 2.0/JCZS for computing heat of detonation using quantum mechanical

Conclusions

The effectiveness of an energetic compound depends on the amount of energy available in it and the rate of release of available energy when decomposition occurs. It is proposed here that the heat of detonation as one of the important detonation parameters can most appropriately be expressed as ratio of oxygen to carbon, ratio of hydrogen to oxygen and some structural parameters.

There is a continuing need to obtain better theoretical models of behavior of energetic materials and an improved

Acknowledgements

I would like to thank the research committee of Malek-ashtar University of Technology (MUT) for supporting this work. This research was supported in part by Institute of Chemical and Science Technology-Tehran-Iran Research Council Grant (No. ICST-8I03-2138).

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