Multiscale Analysis of the Polymeric Insulators Degradation in Simulated Arid Environment Conditions: Cross-Correlation Assessment

The aim of this study is to highlight the joint evolution of the chemical, morphological, thermal and dielectric behaviors upon the UV weathering of an industrial ethylene-propylene-diene monomer (EPDM) rubber. This latter is used as a housing of composite high voltage insulators which are installed in the Algerian desert. This material was submitted to photochemical aging by irradiating UVA rays (lambda=340 nm) at a temperature of 45 degrees C in order to simulate the witnessed site conditions. It was shown that the degradation process leading to the formation of oxygenated species and the depolymerization of the material are responsible of the coupling which may appear between the realized measurements. Using Kendall rank correlation analysis, joint evolution models were established. Those models introduce a novel assessment approach of the chemical and morphological status of the aged rubber using electrical and dielectric measurements.