PHOTOOXIDATIVE DEGRADATION OF POLYETHYLENE GREENHOUSE FILM IN A HARSH ENVIRONMENT

Photo-oxidative reactions make a major contribution in reducing the lifetime of polymers. These reactions play a detrimental role in the decay of useful physical and chemical properties of polymers. In addition, high ultraviolet radiation, increased temperature and high humidity accelerate the degradation phenomenon in polymers. Natural weathering trials were conducted on samples of low density polyethylene greenhouse film in the harsh environment of Dhahran, Saudi Arabia. Greenhouse film with a thickness of 180 mu based on low density polyethylene and stabilized with hindered amine light stabilizer (HALS) and Ni-quencher was selected for this study. Samples were withdrawn monthly for a period of three years and the extent of the degradation was monitored by using Fourier Transform Infra-Red (FTIR) spectroscopy, Differential Scanning Calorimeter (DSC), Mechanical Testing, Gel Permeation Chromatography (GPC) and Scanning Electron Microscopy (SEM).