Effect of Antioxidant on Thermal Stability of Shielding Material for High-voltage Cable

Semi-conductive shielding layer is a crucial component of high-voltage cable, and its thermal stability is essential for ensuring the safety and reliability of cable operation. The shielding material is composed of base resin, conductive carbon black, crosslinking agents, antioxidants and other additives. The antioxidants formulation can affect the comprehensive physical properties of shielding material. However, the structure-activity relationship between the formulation and material performance remains understudied. In this paper, a series of samples are prepared by regulating the antioxidant content in high-voltage cable semiconductive shielding materials. The samples are characterized in terms of cross-linking degree, rheological property, crystallization characteristics, scorch resistance, mechanical properties, thermal properties, resistive characteristics, thermal expansion properties, and the distribution of conductive carbon black. The results indicate that increasing the antioxidant content can achieve the synergistic improvement in both scorch resistance and electrical conductivity of semi-conductive shielding materials. However, it also affects the cross-linking degree and carbon black distribution to some extent. In addition, the temperature stability of the volume resistivity of semi-conductive shielding materials is influenced by the spacing and uniformity of carbon black distribution. At higher temperatures, poor uniformity of carbon black distribution leads to a sharp increase in the volume resistivity of the samples. This article explores a technical approach for improving the thermal stability of semi-conductive shielding materials by adjusting the antioxidant formulation, which contributes to the advancement of independent research and development of semi-conductive shielding material for high-voltage cables.