Yvo Dirix

Loss and recovery of hydrophobicity of novel hydrophobic epoxy resins

Polymeric insulation for outdoor use has become increasingly important and is expected to dominate in the near future HV-outdoor applications. However, there are still some outstanding questions regarding aging of polymers under climatic and electrical stresses. Utilizing behaviors like hydrophobicity can extend the lifetime of these insulators. Therefore the long-term ageing stability of these properties has to been proven. Beside silicones, epoxy resins with intrinsic hydrophobicity seem to be a favorable material. The performance of such new epoxies is compared with the performance of silicones, epoxies and PUR. The loss of hydrophobicity was evaluated by aging with UV-radiation, humidity and temperature. To evaluate the recovery behavior, samples were aged with corona discharges.

Stability of novel hydrophobic epoxies exposed to UV-radiation, high humidity and temperature

Since 1999 novel epoxies with enhanced hydrophobic properties are marketed for HV-insulation. Beside this commercial products several research activities still improve this new class of epoxy resins, which combine the mechanical excellence of epoxies with the outstanding outdoor behavior of silicones. In the past the insufficient resistance of epoxies against UV-radiation was a drawback for outdoor use of these materials. This paper qualifies the hydrophobic epoxies regarding their UV-stability under the combined stresses of radiation, humidity and elevated temperature.