Reactive antioxidants for peroxide crosslinked polyethylene

The results obtained showed that the presence of the graftable (r-AOs) antioxidants did not affect the level of crosslinking of the PEXa pipes which remained high (>85%) and that they were retained to a very high extent in the PEXa material after solvent extraction, and are very uniformly distributed across the length and thickness of PEXa pipes. The long-term stabilising performance of the graftable r-AOs in the PEXa material (in both laboratory prepared samples and in peroxide crosslinked pipes produced by commercial processes) was also examined using complimentary methods: oxidative induction time (OIT) before and after solvent extraction, physical embrittlement following oven ageing at 125 °C, as well as by a hydrostatic pressure tests conducted (with water inside and air outside) at 115 °C and 2.5 MPa pressure. The stabilising efficacy of the r-AOs was compared with that of conventionally stabilised PEXa material containing analogous antioxidant functions produced in the same way. The level of retention (in the pipes) of the graftable antioxidants and their long-term stabilising performance was shown to be significantly higher than that of the conventional AOs under all the test conditions used here.