SEM images of the three types of plastic pellets treated by different UV irradiation times in three different environments were obtained by using SEM.As shown in Fig. , three types of virgin plastic pellets exhibited relatively homogeneous and compact textures.In contrast, the weathered plastic pellets exhibited relatively rough surface texturesIn the case of the PE pellet, granular oxidation and flakes were found on PE pellet surfaces after 3 months of UV irradiation. Among these pellets, flakes were apparent after 1 month of UV irradiation, while granular oxidation appeared on PE pellet surfaces after 2 months of UV exposure.For the PP pellets, cracks and flakes were common patterns of degradation.Cracks were apparent after 1 month of UV exposure in all three different environments. However, PP cracks in the air environment were obviously thicker than those in the solution environments after 3 months of UV exposure, indicating that the level of chemical weathering of the PP pellets in the air environment was highest among the three different environments at the same UV exposure time.