Electrical Treeing Degradation Characteristics of $\beta$-Nucleating Agent-Modified Polypropylene Cable Insulation Under Mechanical Tensile Stress

This paper investigates the effect of mechanical tensile stress on the electrical treeing degradation characteristics of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\beta$</tex>-nucleating agent-modified PP cable insulation. The results reveal that the incorporation of-<tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\beta$</tex> nucleating agents enhances the mechanical toughness of PP insulation, thereby effectively suppressing electrical tree degradation and partial discharge (PD) under mechanical tensile stress. With the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">${\beta}$</tex>-nucleating agent content increasing from <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$0 \text{wt} \%$</tex> to <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$0.2 \text{wt} \%$</tex>, the severity of electrical treeing degradation and the number of PD under mechanical tensile stress decreases progressively. However, increasing the-<tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\beta$</tex> nucleating agent content further to <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$0.4 \text{wt} \%$</tex> aggravates electrical treeing and PD compared with the samples modified with 0.2 wt% <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\beta$</tex>-nucleating agent. The sample containing 0.2 wt% <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\beta$</tex>-nucleating agent exhibits optimal performance, achieving a 59.18 % reduction in cumulative electrical tree damage area and a 1.05 V decrease in maximum <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$P D$</tex> amplitude relative to unmodified PP samples. This research provides theoretical insights for improving the stability of PP-based cable insulation under mechanical stress.