Effect of hindered phenolic antioxidants on crosslinking characteristics of low-density polyethylene initiated by peroxide

Hindered phenolic antioxidants are the most prevalent antioxidants used in crosslinked polyethylene (XLPE) insulating materials of high-voltage (HV) cables. Doping antioxidants is conducive to delaying the low-temperature pre-crosslinking, but decreases final crosslinking degree. In order to comprehensively reveal the effect of hindered phenolic antioxidants on the crosslinking characteristics of XLPE insulating materials, four kinds of insulating materials doped with different hindered phenolic antioxidants are studied by experiment and simulation methods. The results demonstrate that antioxidant 300 is better for delaying low-temperature pre-crosslinking of insulating materials, but negative for maintaining high crosslinking efficiency and degree. Although insulating materials with antioxidant 1010 have higher crosslinking degree, it is poor to delay the low-temperature pre-crosslinking. Notably, antioxidant 245 with phenolic hydroxyl of lower bond dissociation energies can delay the low-temperature pre-crosslinking to some extent, meanwhile, crosslinking efficiency and degree of XLPE are still higher. Notably, the crosslinking characteristics of XLPE insulating materials are closely related to molecular structure of antioxidants, including functional group and ortho-substituents. Comprehensively considering the demands of delaying low-temperature pre-crosslinking and maintaining high crosslinking degree of insulating materials, antioxidant 245 is the better choice. This study provides a theoretical guidance for the choice of hindered phenolic antioxidants used for HV cable insulating materials.