Simulated recycling of post-consumer high density polyethylene material

Post-consumer high density polyethylene (HDPE) was examined by a test procedure consisting of repeated cycles of alternating extrusion and subsequent accelerated thermo-oxidative ageing. The material studied was collected from a real waste stream of HDPE bottles. The effect of addition of a commercial re-stabiliser was also studied. The material was evaluated in terms of mechanical and chemical properties, such as elongation at break, tensile strength, melt flow rate, oxygen induction temperature and molar mass distributions. The results show that after simulated recycling the HDPE material still has considerable resistance against thermal degradation. Upon an additional period of accelerated ageing the stability of the material was still high. The presence of re-stabiliser. introduced during extrusion in the simulated recycling procedure, increased the resistance to subsequent thermo-oxidative ageing. However, significant crosslinking and/or molecular enlargement were found. (C) 2000 Elsevier Science Ltd. All rights reserved.