Reaction of gas-phase radicals from combustion with radical scavengers

The reaction of apparently long-lived, oxygen-centered gas-phase free radicals, which may cause damage to a living body, from combustion smoke of poly(methyl methacrylate) with typical radical scavengers, diphenylamine and 2,6-di-t-butyl-4-methylphenol has been studied. ESR spectra of the spin adducts of gas-phase radicals were observed in the presence of both radical scavengers. Results show that gas-phase radicals in combustion smoke do not react with these radical scavengers directly, but undergo complicated reactions like induced decomposition. In the case of diphenylamine, it was observed that radical concentrations increased with exposure. It is suggested that this increase may be caused by the reaction of organic peroxides or hydroperoxides in the combustion smoke with diphenylamine.