TNT in ammunition shells: an investigation of chemical integrity after
artificial aging using Fourier-transform infrared spectroscopy and gas
chromatography–mass spectrometry
Abstract
Rationale: Industrial TNT contains substances other than
2-4-6-trinitrotoluene that are of primary interest for military
applications. The degradation of industrial TNT by aging and by contact
with steel surfaces, which represent real situations of use of the
material, was investigated. There is practical knowledge about this
degradation, but the literature lacks details of this process. Methods:
Small steel samples used in military ammunition were covered with TNT
and heated at 75 ºC for 30 days under vacuum. Some of the samples were
previously painted with a red alkyd paint coating that protects the
metallic surface. After aging, the TNT was scraped off the metal pieces
and analyzed by scanning electron microscopy, Fourier-transform infrared
spectroscopy and gas chromatography-mass spectrometry. Results: The
results showed in detail how the integrity of the TNT is maintained even
under thermal stress and in contact with the steel surface. Although
some changes were observed in the surface appearance of the TNT, all the
analyses indicated the maintenance of the chemical integrity of the
industrial TNT. The only change in composition identified is related to
the contamination with degradation products of the alkyd paint coating
and not with the degradation processes of the TNT itself. Conclusions:
Our results indicated that although there are many TNT degradation
processes reported in the literature, for cases involving thermal stress
degradation of TNT in solid phase in contact with metal, these processes
are irrelevant. Thus, it is possible to elucidate the safety of TNT when
packaged in steel artifacts, which represent the majority of military
ammunition.