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 str ength of samples were measured to determine the degradation degree. Ac tivation spectra of polypropylene were obtained. Results showed that i n the experimental period of the accelerated test, radiation with wave length longer than 400 nm contributed little to the degradation. In th e energy range of solar exposure, radiation with wavelength longer tha n 360 nm made negligible contribution to the degradation. In the activ ation spectra of the accelerated test, the most effective spectral reg ion was 300-350 nm at the beginning. When the irradiation time surpass ed 68 h, it was 335-360 nm. Compared with other wavelength regions, th e degradation effect of radiation in the 335-360 nm spectral region ro se fastest with the irradiation time in the accelerated photooxidation .