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International audience; Polyimide is one of the most used polymer for electrical insulation in severe environment. For future aircrafts, polymer electrical insulation will be exposed to thermal constraints that can affect its physic- ochemical structure. Effects of thermal ageing are studied through their impact on the relaxational be- haviour. Thermal degradation impairs first the aromatic entities and lately the carbonyls. It is responsible for the strong acceleration of mobility observed for both localised βand γrelaxation modes. Both DMA and swelling test exhibit an acceleration of localized molecular mobility. However, as the local mobility is accelerated, the increase in heterogeneities visible through the evolution of the MWS polarisation brings up to light a change in the charge transport mechanism. The chain scission degradation mechanism, leads to a decrease of the density of deep traps. It explains the evolution of both the value of DC conductivity and its activation energy upon ageing.

Real time detection of intermittent or permanent faults which could appear on wired networks becomes a critical issue. Fault detection and localization methods are often based on reflectometry techniques but they need the implementation of dedicated devices. Furthermore, since they often use a wide frequency band, problems related to their electromagnetic compatibility with the environment may occur. If a power line communication is already implemented in the network, the objective of this paper is to study the proof of concept of a fault detection only based on the statistical properties of the received signals. Even without precise information on fault location, results of this approach could be interesting to decide to carry out a maintenance operation.