A methodology to investigate heterogeneous oxidation of thermally aged cross-linked polyethylene by ToF-SIMS

Artificial ageing of polymeric insulation jackets is routinely performed in order to assess end-of-life material characteristics. Practical constraints including high temperatures/short times ageing treatments lead to strong influence of diffusion-limited oxidation (DLO) resulting in unreliable life-time predictions. This study proposes a new experimental approach to the investigation of cable insulation ageing, exploiting analytical techniques capable of resolving chemistry at the length scale relevant for DLO (nano-micro scale). When studying the potential effects of DLO using Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS) sample preparation becomes crucial. This paper presents the development of a methodology to generate suitable specimens to investigate the DLO effect using ToF-SIMS. A reference polymeric material has been thermally aged in various DLO conditions. Cross-sections of aged samples were generated using three different methods. In order to assess the most suitable approach for this study, cross-sections topography were scanned using a profilometer and the surface chemistry was investigated using ToF-SIMS together with multivariate analysis methods. ; JRC.A.5 - Scientific Development