Surface structural changes of naturally aged silicone and EPDM composite insulators

Modeling hydrophobic recovery of electrically discharged polydimethylsiloxane elastomers

“…Extensive studies [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] suggest that the superior electrical performance of silicone insulator over inorganic materials is due to its ability to recover the hydrophobicity. The hydrophobic recovery of electrically discharged silicone rubbers is significantly affected by discharge intensity, humidity, preexisting fluid and other factors; but, there is enough evidence [18][19][20][21][22] to suggest that the recovery process is dominated by the diffusion of in situ produced low molecular weight (LMW) species from the bulk to the surface of the polymer. This result has motivated researchers to estimate the diffusivity of the LMW silicone fluid in the silicone elastomer by measuring the absorbed amount of a silicone fluid in a sheet of a silicone polymer as a function of time [23][24][25][26][27].…”

Hydrophobic Recovery of Polydimethylsiloxane Elastomer Exposed to Partial Electrical Discharge

“…It is well known that 1 To whom correspondence should be addressed. the hydrophilic surface created by partial discharge regains its hydrophobicity partially or fully over time (5)(6)(7)(8). This change from a hydrophilic surface to a hydrophobic surface, often referred to as "hydrophobic recovery," is usually explained by the following mechanisms (9): (a) reorientation of polar groups from the surface to the bulk phase or reorientation of nonpolar groups from the bulk to the surface, (b) diffusion of LMW silicone fluid from the bulk to the surface, and (c) condensation of the surface hydroxyl groups.…”

Evaluation of surface degradation of silicone rubber using gas chromatography/mass spectroscopy

“…Silicone high voltage sheds are gaining market share as a result of improved tolerance to pollution, ease of handling and installation, and resistance to vandalism [3], [4]. However, the surface of silicones, and especially filled silicones, is subject to long-term degradation during outdoor use [5], [6]. In general, surface degradation of polymer insulators is caused by environmental attack related to weather conditions and electrical activity.…”