EFFECT OF IRRADIATION ON THE DEGRADABILITY OF POLYPROPYLENE IN THE NATURAL-ENVIRONMENT

In order to understand the accelerated degradation of waste plastics i n natural environments, the effect of irradiation on the degradation o f polypropylene (PP) and PP with a nucleating agent (NA) during storag e has been investigated. Relatively low doses in the range 10-30 kGy l ed to considerable degradation during storage when samples were placed on the roof. The original Mn of 4.49 x 10(4) (before irradiation) of PP was reduced to 2.8 x 10(4) on electron beam irradiation of 100 kGy and further reduced to 3.8 x 10(3) during five months' storage. It was confirmed by chemiluminescence that the degradation during roof stora ge after irradiation is due to oxidation, NA resulted in the disappear ance of elongation of PP by irradiation before storage testing, but th e reduction of molecular weight during storage after irradiation was s maller in PP with NA than without NA. This is due to the fact that NA greatly changes the morphology of PP. From these findings, it was demo nstrated that the degradation of PP during outdoor storage is accelera ted by irradiation. Accordingly, it was concluded that the acceleratio n in the degradation of irradiated polymer in the natural environment should contribute to the reduction of the load on the environment.