UDC 502.1:537.312.53
DOI 10.35776/VST.2025.12.04

Karmanov Ruslan, Егорова М. Д.

Effect of ultra violet exposure on polymer fragmentation in aqueous media

Summary

Studying microplastics distribution in aqueous media requires understanding polymer fragmentation processes effected by the natural factors. It is widely accepted that UV radiation is the most important factor resulting in (relatively) rapid degradation of polymers: the solar radiation initiates autocatalytic thermal oxidation that is the trigger of polymer degradation in the environment. Wind and additional mechanical stress cause molecular chains to break, which, in the presence of oxygen, leads to increased plasticity of the material (so-called chemico-mechanical degradation). Mechanical fragmentation can also accelerate if the material already bears the traces of aging due to other destructive factors. As part of the study, laboratory experiments were conducted to accelerate the «aging» of polymers by exposing them to UV radiation on water surface at an intensity of 1.16 W/m² until the first signs of fragmentation appeared on the polymer samples. Based on the obtained experimental data, the residence time of the target polymers – polyethylene (PE) and polypropylene (PP) – in the Izhevsk water bodies under the natural solar UV radiation conditions before the first signs of fragmentation appeared was calculated. The calculations show that while PE and PP entering the aqueous media being exposed to the natural UV radiation, the first signs of polymer fragmentation appear in 730 days in winter and 136 days in summer.

Key words

UV-irradiation , microplastic , plastic waste , polymers , degradation , fragmentation