Investigation of Surface Alteration of Microplastics by Using UV Irradiation

Abstract

Microplastics are formed by the degradation of plastic wastes under the action of physicochemical mechanisms in environment, existing as contaminants of emerging concern in recent years due to their adverse impact on living organisms and the environment. When common polymers are exposed to the environment are adversely affected by solar radiation (primarily ultraviolet (UV) UV-B), which initiates photooxidative degradation leading to polymer chain breakdown, causing though the deterioration of their mechanical properties after an unpredictable time. In the present study, to improve understanding of characteristics and mechanism of microplastics, four of the most widely used polymers covering a wide spectrum of applications, due to their excellent chemical inertness and high processability such as low-density polyethylene (LDPE), high-density polyethylene (HDPE), polypropylene (PP) and polystyrene (PS) in the form of thin films were exposed to UV radiation at 254 nm with constant temperature for several times. After exposure (5, 10, 20, 30, 45 and 60 days), the films were removed from the chamber and UV irradiation influence was evaluated by using FTIR (Fourier-Transform Infrared) Spectroscopy, DSC (Differential Scanning Calorimetry), XRD (X-Ray Diffraction), Py-GC/MS (Pyrolysis-Gas Chromatography/Mass Spectroscopy), SEM (Scanning Electron Microscopy), while their mechanical properties were also evaluated.