Diagnosis of hydrophobic condition of silicone rubber using dielectric measurement and image analysis

Abstract

Dielectric measurement and image analysis are used to evaluate the hydrophobic condition of silicone rubber surface. Hydrophobicity of silicone rubber surface was studied by using image data analysis of sprayed water droplets on the sample surface. Hydrophobicity class, HC from 1 to 7, is evaluated by the analyzed image data indices. The water droplets on the sample surface are digitized and the image indices such as size and shape factor of the droplets were evaluated. After this evaluation, 3D mapping technique is used to evaluate the HC value. The hydrophobic condition of the sample surface was also determined by measuring dielectric property of silicone rubber using a pair of inter-digital electrodes. The dielectric properties were detected by using unbalanced operation of Current comparator type Capacitance Bridge. The changes in dielectric loss current and the capacitive current by the change in hydrophobic condition were measured for every one cycle of ac applied field. Comparing of these results can define the degradation of hydrophobicity of polymer insulator more accurately.

Hydrophobicity classification of polymeric materials based on fractal dimension

“…Some researchers have proposed digital image analyses to classify the hydrophobicity of the electrical insulators. Circular factor 11,12 , goniometric measurement using Hough transformation 13 , segmentation, scaled entropy and histogram analyses 14 and surface energy 15 were some of the proposed methods, but neither of them were able to obtain a mathematical relationship which may define HC. This paper presents a new approach where this HC identification is possible using the fractal dimension as a parameter to quantify the texture of the images and classify the HC.…”