Advances in characterization and modelling of polymer ageing applied to electrical cables [12]

TeaM Cables Winter School – November 2021

This presentation deals with the kinetic analysis and modelling of hydrocarbon polymers in a nuclear environment. As an introduction, the general methodology for kinetic modelling using analytical equations is briefly recalled. It consists in breaking down the course of oxidation in two successive stages: polymer stabilization and oxidation, and therefore in applying two successive sets of kinetic modelling tools. Of course, the boundary conditions between the two sets of tools need to be carefully chosen. Then, the presentation is devoted to the application of this methodology. The different simplifying hypotheses made to access analytical equations are recalled. A particular attention is paid to two practical cases, coming from the TeaM Cables European project: the stabilization of crosslinked polyethylene (XLPE) with distearyl thiodipropionate, then the (thermal and radio-thermal) oxidation of XLPE. As the final objective is to predict the lifetime of XLPE insulation (based on embrittlement considerations), the consequences of oxidation on the macromolecular skeleton are also modelled. Numerous and complementary experimental criteria are used to check the reliability of the kinetic modelling tools: antioxidant depletion, hydroperoxides build-up, oxygen consumption, carbonyls build-up, concentrations in elastically active chains and lifetime.

TeaM Cables has received funding from the Euratom research and training programme 2014-2018 under grant agreement No 755183