Study of the degradation of polyolefins by amplifying the heterogeneous photo-oxidised sites through grafting

Through grafting styrene onto UV irradiated polyolefins, the hydroperoxidised sites of the substrates were amplified. These grafted sites can be seen from scanning electron microscopy or detected by Raman micro-spectroscopy of fractured samples. The grafting spots are heterogeneous as observed in SEM images and in Raman maps where they appeared as 1-4 mum nodules attached to the substrates and distributed through the sample thickness in a profile consistent with diffusion control of photooxidation. Catalyst residues were also detected through Raman mapping and EDX. Their distribution is also heterogeneous but maxima in catalyst concentration are not coincident with the sites for grafted polystyrene. (C) 2001 Elsevier Science Ltd. All rights reserved.