Electrical treeing performance of silicone rubber filled with plasma-treated nanoparticles

Abstract

Nanocomposites have gained wide interests as insulating materials due to their excellent ability to resist electrical discharges such as corona discharges, partial discharges, electrical treeing and water treeing. However, surface incompatibility between polymer and nanoparticles is one of the main issues that may reduce their performances towards discharge resistances. Processing techniques of these nanoparticles such as coupling agent and intercalation methods showed excellent performance, but those techniques involved chemical processes. Recently, plasma treatment was introduced as an improved technique to enhance the dispersion of nanocomposites in electrical applications. However, electrical treeing studies on the electrical performance of plasma-treated nanocomposites are lacking. This study presents an investigation on the electrical tree growth performance as well as the effect of nanoparticles concentration of silicone rubber (SiR) filled with silicon dioxide (SiO2) nanoparticles treated with Atmospheric Pressure Plasma (APP). The treatment of the SiO2 nanoparticles’ surfaces with APP is to enhance SiO2 compatibility with SiR matrix. Besides, untreated and silane-treated nanocomposites were also studied for comparison purpose. Constant AC voltage was applied to these untreated, silane and plasma-treated nanocomposites with different nanoparticles concentration of 1, 3 and 5 wt% to investigate their electrical performances i.e. tree initiation time, tree propagation time, growth rate and tree breakdown time. Morphological analysis as well as chemical characterization of the nanoparticles were analyzed using Field Emission Scanning Electron Microscope (FESEM), Energy Dispersive X-ray spectroscopy (EDX) and X-ray Photoelectron Spectroscopy (XPS) while, the dispersion of the nanoparticles-polymer matrix were analyzed using FESEM. Results show that plasma-treated SiO2 nanoparticles dispersed uniformly in the SiR polymer matrix. The plasma-treated nanocomposites were able to resist electrical treeing better than untreated and silane-treated nanocomposites. The increase in nanoparticles concentration in all three different treatments has enhanced the electrical tree performance of the nanocomposites. Overall, the result from this study reveals that the plasma-treated nanocomposites showed better efficacy in inhibiting electrical tree growth by as much as 64% as compared to silane-treated nanocomposites that showed an efficacy in electrical tree growth rate reduction by as much as 29%. This indicates that plasma treatment could be an alternative technique to improve surface incompatibility of nanocomposites, and hence, resisting electrical treeing growth.