A Study on Hydrophobicity of Silicone Rubber Exposed to Corona Discharge

This paper describes the degradation of unfilled high temperature vulcanized silicone rubber (HTV-SR) resulting from corona discharges. In this study, corona stress was produced by a needle-plane electrode system, and the chemical and morphological structures at the surface layer of SR before and after corona discharge treatment were analyzed by using the techniques of scanning electron microscope (SEM), Fourier transform infrared (FT-IR), thermogravimetric differential thermal analysis (TG-DTA) and gas chromatography/mass spectrometry (GC/MS), respectively. It can be found that hydrophilic OH groups that are byproducts of ageing can be formed instead of hydrophobic CH₃ groups on the surface of aged SR and the corona discharge plays an important role on the temporary loss of hydrophobicity. GC/MS results show that low molecular weight (LMW) silicone fluid disappeared after corona ageing. Also, the endothermic dent appears in the DTA profile because of the occurrence of OH groups