ABSTRACT
The results obtained with polyethylene are overall similar to those obtained in PP; high molecular mass HAS can considerably enhance the thermooxidative stability of PE-HD, PE-LD, and PE-LLD. This is shown in Table 41 for PE-HD tapes. Here, the phenolic antioxidant already confers an impressive thermooxidative stability at 100°C. This is improved significantly by the addition of small amounts of the polymeric HALS-2 and HALS-3. The HAS are as effective in PE-HD films. This is shown in Table 42 for both Phillips-type and Ziegler-type high-density polyethylene. Table 42 shows that the results obtained with the two polyethylene types are comparable for the base-stabilized samples as well as for the samples containing in addition HALS-2 or HALS-4. Notably, with unstabilized samples, Phillips-type PE is much more prone to thermal oxidation than Ziegler-type PE (31). Data with PE-LD and PE-LLD films can be found in Chapter 2.
