Bulg. J. Phys. vol.30 no.3-4 (2003), pp. 158-169
Photo-Oxidative Degradation of Recycled, Reprocessed HDPE: Changes in Chemical, Thermal and Mechanical Properties
J.H. Khan, N. Ahmed
Center for Refining and Petrochemicals, Research Institute, King Fahd University of Petroleum and Minerals, 31261 Dhahran, Saudi Arabia
go backCenter for Refining and Petrochemicals, Research Institute, King Fahd University of Petroleum and Minerals, 31261 Dhahran, Saudi Arabia
Abstract. Weathering degradation of thermally stabilized recycled and reprocessed high-density polyethylene (HDPE) was monitored by naturally exposing the HDPE dumbbells on the aluminum exposure racks. The HDPE dumbbells were prepared in the injection-molding machine using small percentage of anti-oxidants and slip agent to protect the thermo-oxidative degradation of the material. Four types of HDPE material were used under this study such as: virgin HDPE, 50/50 mixture of recycled and fresh HDPE, virgin HDPE with thermal stabilizers and recycled HDPE with thermal stabilizers. The performance characteristics of the weathered recycled HDPE material was monitored by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and the mechanical properties. The results clearly revealed the deterioration of virgin and recycled mixed HDPE formulations as compared to thermally stabilized recycled HDPE material under the hostile out door weather conditions of Dhahran, Saudi Arabia. A significant drop in the mechanical, thermal and the chemical properties was observed for all the exposed HDPE formulations in terms of drop in elongation, increase in the percent crystallinity and percent carbonyl index. The photostability of recycled and reprocessed HDPE materials can be enhanced by incorporating appropriate amount of photostabilizers in the base formulations.