Weathering of recycled photo‐degraded polyethylene

Abstract

AbstractThe increased use of recycled plastics in a wide range of outdoor applications depends on the long‐term performance of the material. However, to date most research has been concerned with the effects that recycling has on the immediate mechanical properties of the polymer. The following paper examines the effects that recycling photo‐degraded polymer has on the long‐term photo‐stability of the recycled material. Two identical high‐density polyethylene wheelie‐bins were used in this study, one of which had been kept in a controlled indoor environment and the other kept outdoors for 12years in the United Kingdom. Material removed from each wheelie‐bin was reprocessed and molded into specimens, which were artificially weathered in a Xenon arc chamber. Infrared spectroscopy and nanoindentation revealed that although the properties of each set of specimens were similar immediately after reprocessing, those that had been subjected to outdoor exposure prior to reprocessing degraded more rapidly. This accelerated degradation is believed to be due to the photo‐degraded products in the recycled material accelerating the degradation process. The consequences of this accelerated degradation raise issues regarding the vulnerability of recycled material to the long‐term effects of outdoor exposure. POLYM. ENG. SCI., 2008. © 2007 Society of Plastics Engineers