Effect of acetophenone on the breakdown strength of polyethylene

With the wide application of high voltage and ultra-high voltage cross-linked polyethylene (XLPE) insulated cables and the increasing demand for operation stability, development of XLPE insulation materials with high dielectric strength has become one of the most popular research topics in recent years. In this paper, acetophenone/polyethylene (PE) composites with different contents of acetophenone are fabricated with the melt blending method in torque rheometer. The AC and DC dielectric breakdown strengths of PE and acetophenone/PE composites are tested at room temperature. A theoretical calculation is performed at the B3LYP/6-311+G (d, p) level to investigate the energy barrier variation of keto-enol tautomerism of acetophenone. The experimental results show that the AC and DC breakdown strengths can be increased by 48.5% and 30.4% respectively when an appropriate amount of acetophenone is added into PE. This is because the potential energies of keto-enol tautomerism of acetophenone are lower than the average C-C bond energy of PE. As a result, the energy of hot electrons can be dissipated by this reaction without causing any rupture of PE molecular chains, thus significantly improving the breakdown strength of PE. Addition of acetophenone derivatives with specific functional groups is a promising method to develop high-performance XLPE insulation materials for high-voltage AC and DC cables.