J. Kim et al., The mechanisms of hydrophobic recovery of polydimethylsiloxane elastomers exposed to partial electrical discharges, J COLL I SC, 244(1), 2001, pp. 200-207
Silicone elastomers exposed to electrical discharges can be rendered hydrop
hilic, and the loss of water repellency is related to the energy level and
number of the discharge pulses on the surface. However, the silicone surfac
e has the unique ability to recover the hydrophobicity and enhance the perf
ormance of a polymer insulator. Most of the studies of the loss and recover
y of hydrophobicity on elastomer surfaces have been carried out at high dis
charge energies experienced under severe service conditions. Despite numero
us studies, the mechanisms contributing to the loss and recovery of hydroph
obicity under lower energy partial discharges are not fully elucidated. The
current study was done with partial discharge pulses in the range 10-10000
pC and by using a needle-to-plane electrode configuration. At very low lev
els of energy pulses, the recovery is primarily caused by the migration of
preexisting fluids from the bulk to the surface of the elastomer. At higher
levels of partial discharges, the fluids no longer play the same role, but
the dominant mechanism in the recovery becomes the migration of in situ pr
oduced low molecular weight (LMW) species in the elastomer. These studies w
ere done under dry and wet conditions. (C) 2001 Academic Press.