Effect of temperature on the evaluation of hydrophobic condition of polymer surface

Hydrophobicity of polymer surface is one of the degradation indices of polymer insulator material and is usually evaluated by using an image of sprayed water on the sample surface. Surface free energy of both solid and liquid have negative temperature dependence. The decrease of surface free energy of solid increases the hydrophobic property; however, the decrease of the one of liquid decreases the hydrophobic property. In this study, the hydrophobic condition of the sample surface was measured at 5, 22 (Room temperature), and 50degC. During the temperature equalization to the room temperature, changes in the hydrophobic condition were measured. Comparing of these results can define the degradation of hydrophobicity of polymer insulator more accurately.