Effect of Antioxidants on Mechanical, Electrical, and Thermal Oxidative Properties of Polypropylene-based Semiconducting Screen

The potential of using eco-friendly thermoplastic polypropylene (PP)-based semiconducting screen (SC) for high voltage direct current (HVDC) cable has been widely investigated. Considering a long service life (>30 years) under high temperature and high electrical stress is required for HVDC cables, investigations on the effect of antioxidant (AO) concentration and thermal oxidative stability, mechanical, and electrical properties of PP-based SCs were conducted in this work. Experimental results showed that an appropriate combination and amounts of AOs were critical for achieving high thermal stability and maintaining mechanical properties of SC after ageing in a harsh environment (150 °C, with Cu, in air, 7 days). Although higher amount space charges were observed in SC/PP/SC samples with higher AO concentrations, the impact on space charge behaviors was suppressed after ageing, suggesting that ageing (or operating at high temperature) led to significant microstructure evolution in SCs and can be potentially used for suppressing space accumulation in PP-based insulating materials.