On the role of ions in the formation of water trees in polyethylene cable insulation

This study is based on the measurements of the growth of water trees in polyethylene, using laboratory models, in accelerated conditions, and on the analysis of water trees by FTIR microspectroscopy. The influence of ions and different concentrations of electrolyte on the growth of water tree and on the penetration of electrolyte inside the water tree are examined. The results show that there is a constant ratio between the number of ions and the number of water molecules that penetrate into the polymer. Moreover, this ratio is independent of the ionic concentration of the initial solution.