Water tree morphology

Water tree morphology as revealed by oxygen plasma etching of water trees in low-density polyethylene is reported. Water trees sectioned by freeze fracturing are found to be virtually invisible until treated by plasma etching. Etching attack is localized and produces either a pitted or a channeled structure, depending on the water tree growth conditions. The spatial distribution of the pits or channels is reminiscent of water tree void distribution. Secondary electron photomicrographs of trees grown under varied conditions are presented. >