Effect of taggant vapor adsorption and containment on the pedetonation detection of explosives

Abstract

Predetonation detection of explosives in realistic scenarios may be accomplished by detecting vapors emitted by the explosive. These vapors could be either the vapor emitted from the inherent compounds present in the explosive or the vapor emitted by a specific vapor taggant introduced into the explosive at the time of manufacture. The emitted vapor concentration in various detection scenarios can be diminished either by vapor adsorption onto adsorptive surfaces present in the scenario, e.g., clothing, curtains, rugs etc., or by enclosing the explosive in a relatively airtight enclosure, e.g., box, luggage, etc., which will impede the vapor emission into the detection scenario. These two effects are modeled to ascertain the magnitude of the vapor concentration reduction in various scenarios. Experiments have been performed to provide a necessary input parameter for the containment model and to confirm the predictions of the model. Seven potential vapor taggants were experimentally examined for their vapor concentration depletion by adsorption in a typical scenario. The potential vapor taggants are perfluorodimethylcyclobutane (PDCB), perfluoromethylcyclohexane (PMCH), perfluorodimethylcyclohexane (PDCH), perfluorodecalin (PFD), L-4412 (a 3M Company proprietary compound), decafluorobiphenyl (DFBP), octafluoronaphtalene (OFN), and octafluorotoluene (OFT). Six enclosures were examined experimentally for their ability to contain taggant vapors. Of these, amore » box filled with styrofoam packing, a suitcase, a heat sealed polyethylene bag, and an attache case provided no significant impediment to the release of the vapor taggant into the detection scenario, i.e., these enclosures had a negligible degree of airtightness. The remaining two examined enclosures, a paint can and a zip lock plastic bag, showed significant vapor containment and thus possibly could hinder the vapor detection of explosives which are placed in these enclosures.« less