Study on the Effect of Nano-SiO₂ on the Electrical Properties of XLPE

The insulation performance of cross-linked polyethylene (XLPE) cables is crucial for ensuring the longterm safe and reliable operation of power transmission systems. To enhance the electrical properties of XLPE, surface-modified silicon dioxide (<tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{SiO}_{2}$</tex>) nanoparticles were meltblended with the polymer matrix. To investigate the effect of different concentrations of silica on the dielectric properties of XLPE by means of differential scanning calorimetry, dielectric properties, volume resistivity and breakdown field strength tests. The results indicate that the sample containing <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$0.8 \text{wt} \% \text{SiO}_{2}$</tex> exhibits the most significant improvement in DC breakdown strength, with a 17.7 % increase compared to pure XLPE. Acting as a heterogeneous nucleating agent, nano- <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{SiO}_{2}$</tex> promotes the formation of higher-density crystalline structures within XLPE, thereby increasing its overall crystallinity. This structural modification reduces the mobility of charge carriers and improves the electrical properties of the nanocomposite material.