Thermal decomposition of chemical warfare agent simulants diisopropyl methylphosphonate and tributyl phosphate

Sanderson, Patrick
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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 P􀀀O 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 Cs􀀀1 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 Cs􀀀1 with a liquid ejection velocity of approximately 20ms􀀀1. 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.

chemical warfare, DIMP, pyrolysis, simulant, spectroscopy, TBP