The influence of temperature on the recovery of the hydrophobicity on silicone rubber surfaces

The surface hydrophobicity of silicone rubbers can decrease by the influence of partial discharges (corona) or by the pollution with hydrophilic layers. These phenomena can be simulated in a laboratory. In this paper methods for the application of corona discharges and for the evaluation of the transfer of the hydrophobicity are presented. The hydrophobicity of different silicone rubbers was investigated with these methods. The influence of additional low molecular weight silicone fluids (LMW) was also investigated. The evaluation of the hydrophobicity was realized by measuring the dynamic receding angles. It was found that the hydrophobicity of silicone rubber decreases by corona treatment in a short time. The recovery of the hydrophobicity and the hydrophobicity transfer were evaluated at different temperatures. It was found that the temperature strongly influences the recovery after corona treatment and also the hydrophobicity transfer. Pit temperatures approaching 0 degreesC the hydrophobicity recovery was significantly decreased.