Surface photo-oxidation and photostabilization of photocross-linked polyethylene

The surface photo-oxidation and photostabilization of photocross-linked pol yethylene (XLPE) have been studied by Fourier transform infrared spectrosco py (FTIR) and X-ray photoelectron spectroscopy (XPS). The FTIR and XPS data gave the evidence that the surface photo-oxidation of XLPE increases, appa rently, with increasing W-irradiation time. The main photo-oxidation produc ts have been identified as hydroperoxides and Various carbonyl compounds. T he photostabilization of XLPE can be carried out by suitable pre-irradiatio n of low-pressure mercury (LPM) lamp and by addition of hinder amine light stabilizers (HALS). The FTIR and XPS data also show that the optimum time o f pre-irradiation of LPM lamp is 10 s under the experimental conditions of the present study. The addition of HALS into PE resin can protect the XLPE efficiently from surface photo-oxidation in the photocross-linking process of PE. (C) 2000 Elsevier Science Ltd. All rights reserved.