ABSTRACT
Recycling of polymer material has attracted increasing interest and activity. One of the basic problems is to develop an understanding of the changes in properties during recycling, in order to predict the product performance during subsequent life-cycles. Our investigations have mainly concerned the effects of combined extrusion and thermo-oxidative ageing on properties of LDPE. The effect of combined injection moulding and ageing has also been studied to a minor extent. Several techniques has been used for evaluation. The study strongly supports the assumption that neither repeated processing, nor ageing alone can be used to predict the quality of a recycled LDPE. Instead, the results show that combined extrusion and ageing should be used. After three cycles of combined extrusion and ageing of a low-stabilized LDPE, the elongation at break was reduced to one sixth of the original value, while the reduction due to ageing or extrusion alone was significantly smaller.
