Radiation-modified atactic polypropylene as a sensitizer for photodegradation of polyethylene

Abstract

Atactic polypropylene (APP) was dissolved in CCl/sub 4/ and irradiated with /sup 60/Co gamma rays in various gas atmospheres (air, O/sub 2/, N/sub 2/, and Cl/sub 2/). A small amount of the irradiated APP was blended with polyethylene (PE) as a sensitizer for photodegradation of PE. There was no significant acceleration of decrease in yield strength of PE with uv exposure when oxidized APP or chlorinated APP was used. On the contrary, the use of the APP which was both oxidized and chlorinated caused a considerable acceleration of decrease in both yield strength and elongation. From the fact that the amount of carbonyl groups formed in the matrix PE with uv light exposure was closely related to both the amount of carbonyl groups and the amount of C-Cl bonds existing in the APP before the uv exposure, it was concluded that the combined action of carbonyl groups and C-Cl bonds in the sensitizer is important in the promotion of the photodegradation of the matrix polymer.