Competitive relationship between electrical degradation and healing in self-healing dielectric polymers

The concept of self-healing dielectric polymers has been heatedly discussed, with the expectation of high damage resistance and longer service time. However, there is still a lack of analysis on the competitive relationship between electrical degradation and self-healing. The authors discussed this relationship in two stages: the design of self-healing strategies and the operation of self-healing polymers. Since the requirements for excellent insulating or mechanical properties are not consistent with the demands for high self-healing capability, trade-offs are necessary during the design of self-healing polymeric systems. In the operation stage of dielectric polymers, some key factors that affect the service lifetime of non-autonomous self-healing dielectric polymers are analysed, including the efficiency and repeatability of self-healing, and the frequency of healing maintenance. For autonomous self-healing dielectrics, the simultaneous processes of ageing and healing are investigated using a self-healing epoxy resin based on microcapsules and in situ-generated radicals. A quicker recovery of insulating properties, in terms of partial discharge magnitude, was observed under appropriate healing voltages. However, the self-healing ability might vanish when the voltage was too high, verifying the competitive relationship between electrical degradation and self-healing.