Theoretical study on the reaction mechanism in the UV radiation cross-linking process of polyethylene

Abstract

A theoretical investigation on the benzophenone-initiated UV radiation cross-linking reactions of polyethylene is accomplished at B3LYP/6-311+G(d,p) level for high-voltage cable insulation materials. The reaction potential energies of 9 reaction channels are identified in the T₁ state. The HOMO–LUMO energy gaps, ionization potentials, and electron affinities of the polyethylene, photoinitiator, voltage stabilizer, antioxidant, and by-products in the polyethylene insulation composite products are obtained. The results show that the by-products, photoinitiator, voltage stabilizer, and antioxidant can effectively increase the electrical breakdown strength. In addition, aromatic ketone voltage stabilizer and hindered phenol antioxidants of the studied molecule can be grafted to the polyethylene chain easily during the polyethylene UV radiation cross-linking process, and they have excellent compatibility with the polymer matrix. The investigation is expected to provide reliable information for optimizing the polyethylene UV radiation cross-linking process and for the development of insulation material for high-voltage cable for use at voltages exceeding 500 kV in real applications.