Permeation of Artificial Seawater into Polyurethane and Its Effect on the Performance of Potted Electrical Equipment

Measurements were conducted to quantify the permeation of artificial seawater into various polyurethanes and polyethylene as a function of time and temperature. Both weight gain from water absorption and an electrical current between pairs of wires embedded into the polyurethanes were measured over a period of several months at 50°C. Water was absorbed into all materials, including polyethylene, but there was no increase in the current between wire pairs embedded in the polyurethanes, indicating that the water that was able to permeate was pure water of high resistivity whereas the charged ions in the seawater were not able to permeate to the wires.