Fragmentation, explosion phases

Another type of physical explosion can occur upon rapid vaporization of a liquid when contacted with a significantly hotter material (e.g., water added to vessel containing hot oil). This is also referred to as a rapid phase transition explosion. In addition to blast, physical explosions can also generate fragments when initially confined. 

Some substances can release significant heat if they decompose. Under certain conditions, this decomposition can cause a condensed-phase explosion, which can cause a failure of the containment system, creating blast as well as fragment effects. Some condensed-phase materials decompose in a denotative manner and are capable of producing blast effects even when not initially confined. 

This technique provides a method of initiating primacord—-and thus any explosive charge—if a regular blasting cap is not available. The device may be rigged as a booby trap with trip wire or it can be fired remotely by the operator. Since the technique does require the destruction of a usable rifle it likely would be used only when there is no other alternative. In addition, care should be taken in all phases of the preparation, because when the weapon is fired it will break into many fragments which would severely injure anyone holding the weapon or close to it. 

A vapour explosion can occur on contact between 2 liquids of differing temperatures if the temperature of the hotter liquid is above the b.p. of the cooler, and the explosion is due to extremely rapid vapour generation (phase transition) of the cooler liquid. Vapour generation must be preceeded by very good heat transfer by a fragmentation... 

While fragmentation is the dominant chemical reaction induced by core electron excitation of molecules in the gas phase, other reactions such as rearrangements can be expected, and this possibility needs to be investigated. The extent of a Coulomb explosion in a large molecule is not known, and the role of Coulomb localization in the chemistry of isolated molecules needs to be examined further. Electron-multiple ion coincidence experiments are essential in the study of the chemistry because it is necessary to relate specific electronic decay channels to particular fragmentation patterns as identified by the several ions that are produced. 

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