Conventional explosive performance

A comparison of the characteristics associated with propellant burning, explosive detonation, and the performance of conventional fuels (see Coal Gas, NATURAL Petroleum) is shown ia Table 1. The most notable difference is the rate at which energy is evolved. The energy Hberated by explosives and propellants depends on the thermochemical properties of the reactants. As a rough rule of thumb, these materials yield about 1000 cm of gas and 4.2 kj (1000 cal) of heat per gram of material. 

The chief advantages in NCN blasting agent use are related to economy, efficiency and safety. In certain applications, an overall cost saving of up to 75% over conventional NG expls has been reported. Where used.under well-controlled conditions, it is reported to perform as well as or better than Dynamites, and, by virtue of its greater gas production, may even give better fragmentation. It is safer to handle and use because its hazard sensitivity is low, and misfires are easily and safely resolved. One of its important virtues is that it is not classified as an explosive but when mixed in the correct stoichiometric proportions under preferred physical con-... 

Catalytic combustion experiments have been performed in a flow reactor operating below the lower explosion limits using HC/02/He mixtures. The product analysis was done by gas chromatography. FT-IR spectra have been recorded with a Nicolet Magna 750 instrument, using conventional IR cells connected with evacuation-gas manipulation apparatus. The powder was pressed into self-supporting disks, calcined in air at 773 K and outgassed at 773 K for 20 minutes before experiments. 

Gilbert and co-workers showed that the nitrolysis of 1,3,5-triacyl-1,3,5-triazacyclohexanes offered little benefit over the conventional synthesis of RDX via the nitrolysis of hexamine. This is not the case for HMX where its synthesis via the Bachmann process is far from perfect. This process and its modifications are expensive, requiring large amounts of acetic anhydride. The rate of production is slow and the maximum attainable yield is 75 %. In fact, HMX is five times as expensive as RDX to produce by this process and this prevents the widespread use of this high performance explosive. Many efforts have focused on finding more economical routes to HMX. 

Nitrotriazolone and TATB are explosives of relatively low sensitivity compared with conventional secondary explosives but their performance levels are not high. The VOD for NTO is 8510ms"1 and density is 1.91 gem 3 whereas for TATB, VOD is 8000 ms"1 and density is 1.94 gem 3. Further, NTO can easily be obtained in particle size much larger than TATB, that is, 300 pm to 500 nn (NTO) as against 9pm-3pm (TATB). 

The oxidation of butane (or butylene or mixtures thereof) to maleic anhydride is a successful example of the replacement of a feedstock (in this case benzene) by a more economical one (Table 1, entry 5). Process conditions are similar to the conventional process starting from aromatics or butylene. Catalysts are based on vanadium and phosphorus oxides [11]. The reaction can be performed in multitubular fixed bed or in fluidized bed reactors. To achieve high selectivity the conversion is limited to <20 % in the fixed bed reactor and the concentration of C4 is limited to values below the explosion limit of approx. 2 mol% in the feed of fixed bed reactors. The fluidized-bed reactor can be operated above the explosion limits but the selectivity is lower than for a fixed bed process. The synthesis of maleic anhydride is also an example of the intensive process development that has occurred in recent decades. In the 1990s DuPont developed and introduced a so called cataloreactant concept on a technical scale. In this process hydrocarbons are oxidized by a catalyst in a high oxidation state and the catalyst is reduced in this first reaction step. In a second reaction step the catalyst is reoxidized separately. DuPont s circulating reactor-regenerator principle thus limits total oxidation of feed and products by the absence of gas phase oxygen in the reaction step of hydrocarbon oxidation [12]. 

A number of conventional tests and calculation methods exist for determining the comparative performance of different explosives. The determinations of the detonation rate and density require no conventions, since they are both specific physical parameter. 

Figure 4.1 shows the influence of the oxygen balance on conventional CHNO-explosives. Usually (this is the case for very nitrogen-rich compounds as well) a good oxygen balance results in a greater (more negative) heat of explosion and therefore leads to a better performance of the explosive. 

In spite of the many years of research, there are limited possibilities to realize a substantial increase in performance from conventional C-H-N-0 explosives. Recent advances in energetics energy output have come in improved processing or inclusion of energetic binders to increase overall formulation energy, but limited success has been realized in the development of novel energetics. One reason for this is that conventional nitramine and nitroaromatic explosives such as TNT, RDX, HMX and other similar molecules share the same three limitations (Table 9.11) ... 

Despite these advances, it appears to be difficult to make significant improvements to the performance with conventional C/H/N/O explosives based on nitro and nitrato compounds. This is partly due to, the fact that classic explosives suffer from the following three limitations (Tab. 12.1) ... 

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