| Delayed luminescence after UV-B irradiation of polyamide 12 (PA12), poly(ethylene terephthalate) (PET) and poly(buthylene terephthalate) (PBT), before and after ageing was investigated. Polymers were ageing at various pH of the water environment. Molecular oxygen, hydrogen peroxide and hydroxyl radicals, generated in a Fenton reaction, were used as ageing species. Light sums and kinetic curves of luminescence from PA12, PET and PBT were measured. The decay of luminescence was described as I(t) = (Aj+kjt)-1/2 in both time periods (from 0 to 180 s) and (from 180 to 600 s) respectively. Changes of all kinetics parameters during ageing were observed. Luminescence spectra of the investigated polymers were also measured using cut-off filters. The spectra show three bands with maxima at 460 nm, 500 nm, and 590 nm. These findings suggest that excited carbonyl containing compounds and molecular oxygen in its singlet state formed during termination reactions involved in the polymers oxidation are the main emitters of delayed luminescence. |
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