Some Specific Decomposition Pathways

The various structure-sensitivity relationships mentioned above typically treat different classes of compounds separately. Nitramines, for example, are not expected to fit on the same correlations as nitroaromatics or nitroheterocycles. Even within a given class, however, a variety of decomposition mechanisms may be operative. Indeed, Kamlet and Adolph found it necessary to establish two oxidant balance correlations for nitroaromatics [16], one being only for molecules having a CH—containing substituent alpha to a nitro group, 3  

Evidently the a-H is likely to be involved in the early stages of the decomposition process [16], perhaps moving to an adjoining nitro group to form a nitronic acid tautomer, 4 [35,45,46]. These are known to be reactive and unstable [47], The transfer or loss of a proton to yield a nitronic acid or a nitronate (aci) anion has also been invoked as the initial step in the decompositions of other energetic molecules, e.g. picric acid [35,48] and amine-sensitized nitromethane [49-51]. 

A particularly interesting compound is TATB, 5, which shows a remarkable lack of sensitivity [10,16], The decomposition of TATB proceeds, in its early stages, through furazan and furoxan intermediates [52,53], e.g. 6, the 

It should be apparent from even this very brief discussion that impact and shock sensitivities can depend upon a variety of chemical and structural factors. Any generalizations should be made cautiously, and are likely to be subject to qualifications and limitations. 

RELATIONSHIPS BETWEEN IMPACT SENSITIVITIES AND MOLECULAR SURFACE ELECTROSTATIC POTENTIALS 

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Aluminium hydroxide has a Moh hardness of about 3 and a specific gravity of 2.4. It decomposes endothermically with the release of water at about 200 °C and this makes it a very useful flame retardant filler, this being the principal reason for its use in polymers. The decomposition temperature is in fact too low for many thermoplastics applications, but it is widely used in low smoke P VC applications and finds some use in polyolefins. For these applications low aspect ratio particles with a size of about 1 micron and a specific surface area of 4-10 m g are preferred. The decomposition pathway can be diverted through the mono-hydrate by the application of pressure, and this may reduce the flame retardant effect [97]. This effect can be observed with the larger sized particles. Although it is chemically the hydroxide, it has for many years been known as alumina trihydrate and by the acronym ATH. 

It is recognized that some degradation pathways can be complex and that under forced conditions, decomposition products may be observed that are unlikely to be formed under accelerated or long-term testing. This information may be useful in developing and validating suitable analytical methods, but it may not always be necessary to examine specifically for all degradation products if it has been demonstrated that, in practice, these decomposition products are not formed. 

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