Wavelength sensitivity of photooxidation of polypropylene

The wavelength sensitivity of polypropylene photooxidation was studied by using a cut-off filter technique. Both xenon are lamp and sunlight were used as irradiation sources. Carbonyl absorption and tensile strength of samples were measured to determine the degradation degree. Activation spectra of polypropylene were obtained. Results showed that in the experimental period of the accelerated test, radiation with wavelength longer than 400 nm contributed little to the degradation. In the energy range of solar exposure, radiation with wavelength longer than 360 nm made negligible contribution to the degradation. In the activation spectra of the accelerated test, the most effective spectral region was 300-350 nm at the beginning. When the irradiation time surpassed 68 h, it was 335-360 nm. Compared with other wavelength regions, the degradation effect of radiation in the 335-360 nm spectral region rose fastest with the irradiation time in the accelerated photooxidation.