Effect of Microcapsules on Dielectric Properties of Self-Healing Low Density Polyethylene Insulation Composites

The polyolefin materials play important roles in transmission equipment for their advantages. However, slight damage would happen inevitably, which is difficult to detect and repair, and threatens the power supply safety. It is a new research field for realizing the self-healing ability of polyolefin insulation materials by microcapsule technology. This paper explores the preparation scheme of low density polyethylene (LDPE)/microcapsule insulation material and focuses on its dielectric properties. Based on the verification of self-healing properties, how microcapsules of different concentrations affect the LDPE dielectric properties is analyzed by the crystallinity change. The results show that the composite has evident self-healing ability, and the mechanical damage of the LDPE matrix can trigger the self-healing behavior of microcapsules timely. When the microcapsule concentration increases, the dielectric constant decreases initially and then increases, and the dielectric loss factor tends to increase. In general, the 1 wt% microcapsule composite has better crystalline, dielectric properties, and self-healing ability. In summary, microcapsules affect the crystallinity and grain size of LDPE by changing its crystallization behavior and the proportion of the amorphous region. Meanwhile, the influence of microcapsules on the crystal structure, the introduction of impurities and interfaces affect the dielectric constant and loss factor. This study not only provides a potential new self-healing insulation material, but also promotes the fusion development of new solid insulation material and self-healing.