ANALYSIS OF PHOTOOXIDATION OF POLYMER MATERIALS BY PHOTOACOUSTIC FOURIER-TRANSFORM INFRARED-SPECTROSCOPY

Photoacoustic (PAS) FTi.r. spectra of photooxidized polypropylene samples have been recorded and the samples have also been analysed using transmission micro-FTi.r. analysis of cross-sectioned layers. The oxidation profiles monitored were shown to arise from oxygen diffusion limitation and also from the heterogeneous absorption of light by the TiO2-Pigmented samples. The intensity of the carbonyl absorbance measured by PAS-FTi.r. has been determined and it is shown that the front layer degradation monitored by both techniques (PAS-FTi.r. and micro-FTi.r.) has identical values. This rapid and non-destructive technique may thus be applied to quantitatively measure the surface degradation of aged polymers.