Pulse radiolysis studies of poly(ethylene terephthalate) film

Complete text of publication follows. Poly(ethylene terephthalate), PET is a thermoplastic material that is widely used in the form of fibres and films. The absorption spectrum of 6 MeV electron irradiated PET at 77 K represented two bands with maxima at ∼ 370 nm and ∼ 530 nm. The latter one can be tentatively attributed to the negative charge trapped on benzene ring. This spectrum is stable at 77 K. The increasing of temperature up to 115 K led to decrease of both transient bands and simultaneously the new absorption in the range 400-450 nm started to grow up in the case of 1 μs pulse irradiated PET film. At room temperature strong transient absorption band with λmax at ca 430 nm was only observed with shoulders at 370 nm and 530 nm. The transient absorption with λmax ∼ 430 nm can ben attributed to the ester radical anion. In the presence of air transient absorption events were observed too but the experimentally detected absorbances were much weaker. The pulse irradiated (17 ns pulse) PET film at room temperatures generated shortlived emission in the range 325-450 nm with maxima at 340 nm and 370 nm (weak shoulder at 410 nm). Such emission was detected for PET samples photoexcited by 300 nm light. The lowering of temperature down to 115 K led to substantial increase of the emission intensity mainly in the range ∼ 340 nm which can be attributed to the monomer units in the chain backbone radiative deactivation. The more detailed mechanism of the reactions will be proposed