Propellants and explosives

Hayes [52] used multidetector SEC to characterize proprietary plastic propellant compositions for forensic purposes. PL-gel (500-1- 100-h 100 -h 50A) with tetrahydrofuran eluent (1 mLmin ) gave partial separation of the components, which gave very different UV (288 nm) or infrared (6.15 or 5.75 pm) detector responses, allowing clear distinction of plastic explosives from different sources. 

We must not, however, suppose that all multiple bonds are necessarily inert. In fact, the data of Table 2.3 imply that this is a special feature of triply bonded dinitrogen, since the N=N bond is rather weak. Acetylene, for example, reacts readily with hydrogen gas (especially if catalyzed) to form ethane because the energy required to reduce the triple C=C bond to a single C—C bond and to break two H—H bonds is more than compensated by the formation of four new heteroatomic bonds  

Further information on issues raised in Sections 2.6 to 2.10 may be obtained from standard texts.  

For an explosion to occur, the first requirement is that the decomposition or combustion of the explosive—a substance or mixture of substances 

A substance is classed as a deflagrating explosive when a small amount of it in an unconfined condition suddenly ignites when subjected to a flame, spark, shock, friction or high temperatures. Deflagrating explosives burn faster and more violently than ordinary combustible materials. They burn with a flame or sparks, or a hissing or crackling noise. 

On initiation of deflagrating explosives, local, finite hotspots are developed either through friction between the solid particulates, by the compression of voids or bubbles in the liquid component, or by plastic flow of the material. This in turn produces heat and volatile intermediates which then undergo highly exothermic reactions in the gaseous 

The rate at which the surface of the composition burns, linear burning rate , can be calculated using Equation 3.1, where r is the linear burning rate in mm s-1, P is the pressure at the surface of the composition at a given instant, fi is the burning rate coefficient and a is the burning rate index. 

For example, if the linear rate of burning for a typical propellant at atmospheric pressure (9.869 x 10 2 N mm-2) in an unconfined state is equal to 5 mms 1 and the burning rate index is 0.528, then the value of equals 16.98 mm s 1 (N mm 2)1/0 528 as shown in Equation 3.2. 

On burning the propellant inside a gun barrel, the pressures increase by 4000 times and the linear burning rate is raised to 399 mm s 1 as shown in Equation 3.3  

Kirk-Othmer Encyclopedia of Chemical Technology (4th Edition) 

A substance is classed as a deflagrating explosive when a small amount of it in an unconfined condition suddenly ignites when 

For example, if the linear rate of burning for a typical propellant at atmospheric pressure (9.869 x 10 N mm ) in an unconfined 

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EXPLOSIVES AND PROPELLANTS - EXPLOSIVES] (Vol 10) -substitution for hydrogen [NITRATION] (Vol 17)... 

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