Thermal decomposition of chemical warfare agent simulants diisopropyl methylphosphonate and tributyl phosphate
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Abstract
The pyrolysis of chemical warfare agent simulants, diisopropyl methylphosphonate
(DIMP) and tributyl phosphate (TBP), were studied in a constant volume heated cell
using infrared spectroscopy (9:35 μm to 10:55 μm) over a temperature range of 50 C to
550 C. DIMP began decomposing at 130 C and was undetectable by 280 C. The ex-
pected decomposition products observed were propene, 2-propanol and methylphospho-
nic acid. One unexpected species, methanol, was observed, and isopropyl methylphospho-
nate was not observed. Tributyl phosphate began decomposing as low as 130 C and was
undetectable by 270 C. The pyrolysis of TBP had three distinct temperature regions
in which decomposition reactions occurred. The products of TBP decomposition ob-
served were cis-2-butene, methanol, and possibly ethylene. An unidentied species with
a PO group was also observed at high temperature. DIMP was further tested with a
high power, pulsed lament heater (T-jump) in an open atmosphere at heating rates of
greater than 300 103 Cs1 to simulate exposure to an explosive device. Time resolved
mid-infrared spectroscopy was performed simultaneously. The high heating rate creates
a vapor explosion at the lament surfaces, driving the majority of the liquid chemical
warfare agent simulant from suspension within the lament. As a result, a droplet eld is
created around the lament wire with no detectable decomposition spectra. High-speed
video of the explosion and droplet eld was taken at 50 kHz and heating rates on the
order of 3 106 Cs1 with a liquid ejection velocity of approximately 20ms1. Raman
scattering spectra were taken of DIMP from 50 C to 240 C in the constant volume cell to
characterize the major species composition. High temperature Raman scattering spectra
could not be taken due to strong scattering from smoke.