Revitalising DC-Aged Silicone Rubber Composites: Hybrid-Silica/Alumina Triumph Over Multi-Stress Ageing

Abstract

In this study, various concentrations of high-temperature vulcanised silicone rubber composites filled with nano/micro silica and alumina were manufactured. In this work, all test specimens were subjected to a variety of environmental stresses as well as DC voltage for 5000 h. Then, different diagnostic methods were used to look at the changes that happened on their surfaces and in their bulk properties. These included hydrophobicity classification, X-ray photoelectron spectroscopy (XPS) analysis, Fourier transform infrared spectroscopy (FTIR) analysis, thermogravimetric analysis (TGA) analysis, leakage current analysis and mechanical strength analysis. The composite with 2% nano silica and 10% micro alumina had the smoothest surface and the best hydrophobicity (HC-3). It also had the lowest leakage current (3.1 μA), the least amount of strength loss (31.3%), and good thermal stability compared to the other samples that were studied. Aged samples show a considerable increase in the concentration of the O element and a significant drop in the proportion of the Si component relative to the virgin specimen, which points to the oxidation of chemical bonds during HTV SR and their composites during ageing but with different concentrations. However, two samples (SP2 and SP3) showed comparatively lower concentrations of oxygen degradation in Si contents. This can be attributed to the strong molecular interaction between the fillers and the base matrix.