The effect of γ-ray irradiation on thermal oxidation of additive-free polypropylene pellets investigated by multichannel Fourier-transform chemiluminescence spectroscopy

Chemiluminescence emission spectra of polypropylene pellets pre-irradiated in air with γ rays were measured using a time-dependent multichannel Fourier-transform chemiluminescence spectrometer. Spectra were detected immediately after heating the irradiated polymer at 150 °C, which was not the case for the virgin material, and deconvoluted into emission bands by least-squares fitting using Gaussian curves. The peak intensity of the initial emission band around 490 nm rapidly increased and then decreased with a constant peak wavelength during the thermal oxidation time between 0 and 10 min. We have elucidated the emission mechanism from the dependence of γ-irradiation dose on the peak intensity.