Understanding the space charge variation in silicone rubber with different low molecular weight siloxanes

The low molecular weight (LMW) siloxanes play major role in Silicone Rubber (SR) insulators to get better hydrophobicity and hydrophobicity recovery characteristics over contaminated surface of the insulators in outdoor environment. The surface and bulk properties of the n-hexane treated SR composites were analyzed by various experimental studies. The reduction in hydrophobicity of SR samples after n-hexane treatment was observed due to extraction of LMW siloxanes. The higher contact angle was observed in filler SR samples after extraction due to strong interfacial regions between filler and polymer matrix, where the loss of LMW siloxanes were less. From the FTIR studies, a small reduction in methyl and siloxanes functional groups was observed after n-hexane treatment, resulting in the reduction of hydrophobicity of the specimens. The enhanced space charge accumulation was observed after n-hexane treatment compared to untreated one, where the least increment of space charge density is observed in S3 sample.