Simulated recycling of post-consumer high density polyethylene material

Post-consumer high density polyethylene (HDPE) was examined by a test proce dure consisting of repeated cycles of alternating extrusion and subsequent accelerated thermo-oxidative ageing. The material studied was collected fro m a real waste stream of HDPE bottles. The effect of addition of a commerci al re-stabiliser was also studied. The material was evaluated in terms of m echanical and chemical properties, such as elongation at break, tensile str ength, melt flow rate, oxygen induction temperature and molar mass distribu tions. The results show that after simulated recycling the HDPE material st ill has considerable resistance against thermal degradation. Upon an additi onal period of accelerated ageing the stability of the material was still h igh. The presence of re-stabiliser. introduced during extrusion in the simu lated recycling procedure, increased the resistance to subsequent thermo-ox idative ageing. However, significant crosslinking and/or molecular enlargem ent were found. (C) 2000 Elsevier Science Ltd. All rights reserved.