Degradation and Stabilization Issues of Polyethylene in Open air Applications
74In this study, degradation behavior of Low density polyethylene (LDPE) pipes which are unstabilized and stabilized against light has been taken under investigation in the course of ultraviolet (UV) light exposure. Commercial light stabilizers have been used for the production of real irrigation pipes. Thus the pipes with hindered amine light stabilizer (HALS) and carbon black (CB) as well as without UV light stabilization agents were produced and exposed to natural and artificial weathering processes. The influence of the stabilizers on UV degradation behavior of LDPE pipes has been investigated by monitoring the changes in chemical, structural, and mechanical properties of the pipes. The oxidative degradation of PE was determined in terms of oxidation index (OI) through fourier transform infrared (FTIR) spectroscopic analysis and oxidation induction time (OIT) assessment, utilizing differential scanning calorimetry (DSC). The assessment of crystallinity change was performed by means of DSC and X-ray diffraction (XRD) analyses. Mechanical properties of the pipes were analyzed through hydrostatic pressure resistance test (HPRT) as well as hardness measurement and tensile tests. Scanning electron microscopy (SEM) pictures were taken from the broken surfaces after the tensile tests to illuminate the structural changes due to the aging of pipes.