Homogeneous explosives

Meat grinder Hobart chopper Polytron homogenizer Explosion-proof blender and jars... 

The theory of detonation has also been extended to study the process of initiation of reaction by the commonest means used in practice, namely, by the shock wave arising from another high explosive. Campbell, Davis and Travis have studied the initiation by plane shock waves of homogeneous explosives, particularly nitromethane. Initiation occurs at the boundary of the explosive after an induction period which is of the order of a microsecond and which depends markedly on initial temperature. During the induction period the shock wave has proceeded through the explosive and compressed it. The detonation initially in compressed explosive has a velocity some 10% above normal, but the detonation soon overtakes the... 

A thermal explosion is the third type of chemical explosion. In this case, no reaction front is present, and it is therefore called a homogenous explosion. Initially, the material has a uniform temperature distribution. If the temperature in the bulk material is sufficiently high so that the rate of heat generation from the reaction exceeds the heat removal, then self-heating begins. The bulk temperature will increase at an increasing rate, and local hot spots may develop as the thermal runaway proceeds. The runaway reaction can lead to overpressurization and possible explosive rupture of the vessel. 

Mader, "The Hydrodynamic Hot Spot and Shock Initiation of Homogeneous Explosives", LASL Rept LA-2703 (1962) PhysFluids 6,... 

J. Zinn R.N. Rogers, JPhysChem 66, 2646-53(1962) CA 58, 3262(1963) (Thermal initiation of expls) 40b) C.L. Mader, "The Hydrodynamic Hot Spot and Shock Initiation of Homogeneous Explosives ,... 

Mode d) is operative only at strong shock inputs and may be the main mode of initiation and propagation in homogeneous explosive liquids or defect-free explosive single crystals... 

Campbell et al (Ref 7) have successfully used Eq 5 to interpret their observations on the shock initiation of homogeneous explosives such as NM, liq TNT single crystal PETN... 

In order to achieve the maximum velocity of detonation for a homogeneous explosive, it is necessary to consolidate the explosive composition to its maximum density. For a crystalline explosive the density of compaction will depend upon the consolidation technique (i.e. pressing, casting, extrusion, etc.). The limiting density will be the density of the explosive crystal. The velocity of detonation can be calculated from the density of the explosive composition using Equation 3.5,... 

For some homogeneous explosives detonation performance is strongly influenced by the density and sound velocity of the charge casing. 

Table 22. Lead block excavation values. A. Homogeneous Explosives ...

The desirable situation for the occurrence and linear propagation of a detonation for homogeneous explosives exists in confined tubes or cylindrical shaped explosives, in which the system should not fall below the critical diameter (characteristic for every individual explosive) as it otherwise causes the wave front to be disturbed ( loss of energy to outside) and therefore the detonation velocity will be reduced. While for many secondary explosives one inch is a good tube diame-... 

As previously stated, this discussion is valid for homogeneous explosives, such as the ones used in the military, since their reactions are predominantly intramolecular. Such explosives are often referred to as ideal explosives, in particular when they can be described using the steady state model of Chapman and Jouguet. In heterogeneous explosives (non-ideal), which are currently used in civil applications, intermolecular (diffusion controlled) mechanisms are predominant for the air bubbles, cavities or cracks (etc.). As a general rule detonation velocities increase proportional to the diameter. 

Puszynski et al. (1987) have suggested the use of the homogeneous explosion criterion for the existence of constant-pattern propagation ... 

Zimmer [96] came to the conclusion that the LVD of nitroglycerine (1500-1600 m/s) could be manifested by a spiral mode of propagation. (It should be pointed out that T. Urbanski (97) expressed the view that non-homogeneous explosive mixtures can show a spiral way of detonation.) According to Zimmer the irregularities of the LVD arc caused by the interaction of incident and reflection waves forming Mach waves under certain conditions. An analogy can be drawn between the spiral way of detonation of gas-mixtures [98 102] and spiral w ay of detonation of solid-liquid systems. 

Anoihei experiment by T. Urbanski [33, 34] throws some light on the detonation of explosives, if the detonation was carried out in a plastic tube put concentrically inside another tube made of glass and suspended in air (Fig. 90). If the inner tube was filled with homogeneous explosive not a mixture, the... 

Additions of crystalline oxidizers such as ammonium nitrate or potassium nitrate to nitrate esters or energetic polymers form composite explosives whose physical structures are heterogeneous. In contrast to homogeneous explosives, the energy density of composite explosives is higher than that of homogeneous explosives. 

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