Influence of Density and Compacting Pressure

In both cases it is difficult to determine the exact density before the experiment. The only known (or reported) parameter is therefore compacting pressure. 

Very rare results have been obtained by Stmad [9] who used MF, LA, and DDNP of various specific surfaces, compressed them with defined pressures, and experimentally measured the resulting densities (Fig. 2.3). This allowed him to study the influence of the resulting density on the initiation efficiency. More on this issue will be addressed in detail later in this chapter but, to summarize, it can be stated that, in the case of MF, LA, and DDNP, an increase in density first leads to a decrease in the minimal necessary amount of explosive—and what happens subsequently is material specific. Some substances (e.g., DDNP, MF start to lose their ability to initiate secondary explosives, which is reflected in higher amounts needed for successful initiation, while other substances work in the same way, no matter how hard they are pressed (pure LA). 

The influence of compacting pressure on the mean minimal amount is shown in Fig. 2.4 for LA, Fig. 2.5 for DDNP, and Fig. 2.6 for MF. All three exhibit a decrease in the minimal amount by shght compression (9.8 MPa). Further increase of pressure 

The compacting pressure in Figs. 2.4, 2.5, and 2.6 can be converted to densities of the compacted material and the relationships then plotted as initiation efficiency as a function of density (Fig. 2.7, 2.8, and 2.9). The highest initiation efficiency is obtained for MF at 3.2 g cm (72% of TMD) and for DDNP at 1.2-1.3 g cm (73.6-80.2 TMD). Using higher pressures leads to an increase in the minimal necessary amount of the explosive, and at density 3.6 g cm MF and at 1.3-1.4 g cm DDNP became dead-pressed. The density at which dead pressing takes place is lower for material with higher specific surface. 

LA shows minimal necessary amount at density 2.7 g cm (58% of TMD). Further increase in the compacting pressure does not have any significant effect on the initiation efficiency. The only exception is LA with a very large specific surface ( 10,000 cm g ) which has high minimal amounts that, after exceeding optimal density, increase yet further (Fig. 2.9). 

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