Thermal Decomposition of Energetic Materials 70: Kinetics of Organic Peroxide Decomposition Derived from the Filament Control Voltage of T-Jump/FT-IR Spectroscopy

Abstract

An evaluation is made about whether T-jump/FT-IR spectroscopy can be used to determine the decomposition kinetics (Arrhenius E_a and ln A parameters) of energetic organic peroxides at high temperature following very rapid heating. Polystyrene peroxide (PSP) and benzoyl peroxide were investigated, but PSP was chosen for detailed study because of its known, simple, decomposition process. The shape of the control voltage trace of the Pt filament yields kinetic constants which are reasonable for O–O bond homolysis as the rate-determining step: E_a = 39 kcal/mol, ln (A, s⁻¹) = 45.9. These Arrhenius parameters differ from values measured by other methods, but it is found that an isokinetic temperature of 400 ± 20 K exists for all measurements. Thus, all the kinetic measurements appear to reflect the same dominant process (O–O homolysis), but their differences make extrapolation of the rates from the temperature range of measurement to another range inaccurate.