Acceleration of the thermal degradation of PETN in the microdroplets flow reactor

Thermal degradation of pentaerythritol tetranitrate (PETN) was investigated in microdroplets within a heated capillary used as a flow reactor. The thermal degradation was monitored by aerodynamic thermal breakup droplet ionization mass spectrometry. It was shown that the PETN degradation in microdroplets occurs much faster than the bulk reaction (by 4-5 orders of magnitude). The effect of the capillary material [stainless steel (Fe, Cr), copper (Cu), or fused quartz (SiO₂)] on the thermal PETN degradation in microdroplets of water or acetonitrile was studied next. The capillary material affected the rate of thermal PETN degradation much more weakly than did the use of microdroplets (pure Cu was most conducive to the degradation). Kinetic parameters (activation energy and the frequency factor) of the PETN degradation for all the studied materials of the flow-through reactor and the solvents were estimated under the assumption that the thermal degradation is a first-order reaction. Implications of the acceleration of PETN degradation in microdroplets are discussed.