Differences between the detonation behavior of emulsion explosives sensitized with glass or with polymeric micro-balloons

The differences between the detonation behaviour of ammonium nitrate based emulsion explosives sensitized with polymeric and those sensitized with glass micro-balloons is presented and discussed. Expancel® are hollow polymeric micro-balloons that contain a hydrocarbon gas. The mean particle size of these particles is 30 m with a wall thickness of about 0.1 m. The detonation velocity and the failure diameter of the emulsion explosive sensitized with different amounts of these particles have been measured in cylindrical charges by optical fibers. The detonation velocity demonstrates non-linear behaviour in relation to density and reaches the maximum value for a density lower than that of the matrix. The detonation fails when the density approaches that of the matrix. The detonation in the emulsion explosives extinguishes itself at a porosity value that seems to be independent from the nature of the sensitizing agent. For low densities, the detonation velocity is almost independent of the charge diameter, and is close to the values predicted by BKW equation of state