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Keywords:

  • polyethylene (PE);
  • photooxidation;
  • stabilization;
  • HALS;
  • mechanical properties

Abstract

The increasing use of products from recycled polymers, or from blends with recycled polymers exposed to the outdoors, implies the need for good weathering resistance. This is particularly important when the recycled material comes, in turn, from products exposed during their lifetime to the sun. In this case the presence of C[DOUBLE BOND]O groups in the macromolecular chains strongly increases the photooxidative degradation kinetics of these secondary materials. In this work the change of the photooxidative degradation of blends of virgin and photooxidized polyethylene was evaluated as a function of the C[DOUBLE BOND]O content present in the material. As expected, the presence of the C[DOUBLE BOND]O groups strongly increases the photooxidation kinetics, as revealed by the increase of the carbonyl compounds, and by the decrease of the elongation at break. It was confirmed that the increase of C[DOUBLE BOND]O groups is dependent on the content of the same groups, whereas this is not true for the mechanical properties. The use of UV stabilizer strongly improves the weathering resistance of these materials, which become almost insensitive to the initial amount of C[DOUBLE BOND]O groups. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2244–2255, 2004