On the effect of temperature on the propagation of water trees in polyethylene

The effect of temperature on the growth of water trees in polyethylene was studied using injection-moulded laboratory specimens with water needle electrode. An increase in temperature form 25°C to 65°C was found to significantly decrease the growth rate of water trees. At 65°C the trees are more opaque. This reveals a higher intensity of the degradation inside the tree, which might play a role in the breakdown process. The annealing of the material during the test at 65°C is responsible for a large part of the observed temperature effect, pointing out the essential importance of the control of the material morphology when performing laboratory tests