Raman spectral mapping of photo-oxidised polypropylene

Raman spectral mapping at a microscopic scale has been used to probe the he terogeneous photo-oxidation of unstabilised single particles and films of p olypropylene (PP). Analysis of resonance Raman spectra in conjunction with SEM/EDX data allowed determination of the distribution of polymerisation ca talyst residues throughout the polymer. However, the distribution of oxidat ion products was found not to correlate with the distribution of catalyst. Consequently, a conclusion was drawn that the catalyst residues, for the ty pe of PP studied, tend to stabilise the polymer in the immediate vicinity, but also form reactive species that diffuse away from the catalyst to initi ate oxidation (C) 2000 Elsevier Science Ltd. All rights reserved.