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

Date
2019-01-01
Authors
Sanderson, Patrick
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Mechanical Engineering
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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 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.

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