Degradation of Low-Density Polyethylene Film Exposed to UV Radiation in Four Environments

Abstract

Low-density polyethylene (LDPE) when exposed to ultraviolet (UV) radiation under different environmental conditions deteriorates to different extents. The objective of this study was to evaluate changes in the physical and chemical properties of LDPE strips under four different environmental conditions: air, double distilled water (DDW), and two salt solutions with ionic strengths of 0.017 M (corresponding to potable water) and 0.6 M (corresponding to sea water) by incubating them for 90 days at 30°C. LDPE samples were taken out at time intervals of 30, 60, and 90 days and analyzed for various mechanical (tensile strength, Young’s modulus, and percentage elongation), physical (surface roughness, texture, topography, morphology, and composition), and chemical properties. Photodegradation of LDPE was greatest in air, followed by DDW, 0.017 M aqueous salt solution, and, finally and least of all, in 0.6 M salt solution. Increasing salt concentrations resulted in the protection of LDPE strips from photodegradation due to the formation of salt crystals on film surface. The presence of oxygen was found to be the most important factor in the initiation of photooxidative degradation of LDPE film.