The chemical and physical composition of water trees in XLPE

The arguments supporting a model of the composition of water trees are updated with additional information concerning inorganic salts in water trees. It is pointed out that water trees are in fact salt trees. Hydrophilic tracks (rather than channels) run through the amorphous phase of polyethylene. The hydrophilic groups are carboxylate salts chemically bonded to the polymer matrix and trapped (on the removal of the electrical field) inorganic salts. The polymer matrix may still be largely intact, but (severe) mechanical damage is possible