Abstract:
Epoxy and its composites have expressed exceptional qualities for usage in high-voltage
outdoor insulation applications. However, the organic structure of epoxy based insulators
is deteriorated due to UV-A radiations in the outdoor environment. By fabricating three
sample compositions consisting of pristine epoxy (NEP), 15 weight percent epoxy
microcomposite (EPMC), and 5 weight percent epoxy nanocomposite EPNC, the
influence of UV radiations on the physiochemical properties of epoxy was studied. An
ultraviolet aging chamber was fabricated to conduct the aging of prepared samples. Inside
the chamber, 5mW/cm intensity of UV-A radiations was maintained. The performance
of the samples was analyzed with visual inspection, hydrophobicity classification by the
Swedish Transmission Research Institute’s (STRI) hydrophobicity classification,
Scanning Electron Microscopy (SEM), and Fourier Transform Infrared (FTIR)
spectroscopy. Physiochemical degradations were observed in the samples due to severe
oxidation which resulted in the formation of ester and carbonyl groups on the surface of
the samples. Color changes were observed due to surface oxidation. Hydrophobicity of
all the samples was degraded with neat epoxy, EPMC and EPNC expressing HC-3, HC-3
and HC-2 classes after 1000 hours of aging. SEM micrographs expressed holes and loss
of material. Filler exposure was also seen in micrographs however degree of filler
exposure was less in case of nanocomposite. Statistical analysis of results of FTIR
expressed decrease in absorption peaks of hydrophobic methyl groups due to chain
scission which consequently resulted in increment of carbonyl and ester groups’
absorption peaks. For NEP, EPMC, and EPNC, the FTIR peaks of carbonyl group at
1726 expressed an increase of 158 percent, 75.86 percent, and 33.33 percent,
respectively. Similarly C=C stretching at ~1606.52 increased by 56 percent, 37.25
percent and 5.12 percent for NEP, EPMC and EPNC, respectively. This demonstrates that
EPNC outperformed EPMC and NEP in terms of resistance against surface oxidation.
Fillers improved the chain integrity of the polymer, whereas nano fillers performed
significantly better due to their larger surface area and surface energy.
