Effect of Doping Microcapsules on Typical Electrical Performances of Self-Healing Polyethylene Insulating Composite

Youyuan Wang,Yanfang Zhang,Zhanxi Zhang,Yudong Li

doi:10.3390/app9153039

Abstract

Polyethylene cables, as important transmission equipment of modern power grid, would inevitably be slightly damaged, which seriously threatens the safety of the power supply. This paper has pioneered the preparation and typical performances of a self-healing polyethylene insulating composite. The self-healing performance to structural damage was verified by tests of electrical and mechanical damage. The effect mechanism of doping microcapsules on the electrical performance of polyethylene was emphatically analyzed. The results show that in appropriate conditions (such as 60 °C/30 min), the composite can not only repair the electrical tree and scratches, but also restore the insulation strength of damaged area. The effect of doping microcapsules on the electrical performances of polyethylene, such as breakdown strength, volumetric resistivity, dielectric properties, and space charge characteristics, are mainly related to impurity and the interface of microcapsule. Polarization and ionization of impurities can reduce the electrical performance of polyethylene. The interface not only improves the microstructure of polyethylene (such as how the heterogeneous nucleation effect increases the number of crystal regions, and the anchoring effect enhances the stability of amorphous regions), but also increases the charge traps. Moreover, the microstructure and charge trap can affect the characteristics of carrier transport, material polarization, and space charge accumulation, thus improving the electrical performance of polyethylene. In addition, the important electrical performance of the composite can meet the basic application requirements of polyethylene insulating material, which has good application prospects.

Highlights

Polymer composites are increasingly used as the main components in various engineering applications
The results showed that the microcapsules can repair the damaged area, and delay the development of electrical trees, but the change rules and mechanism of typical performances are still insufficient
The morphological characteristics of the scratches was observed by optical microscope (OM)

Summary

Introduction

Polymer composites are increasingly used as the main components in various engineering applications. Micro structural defects are the major damage form of polymer composites, and the damage is usually formed deep within the material, where detection and repair are difficult [1,2,3]. In the field of electrical insulating materials, reliable and durable insulating polymers are required for high voltage transmission in the power grid [4]. Cross-linked polyethylene (XLPE) insulated cables have been widely used in modern power grids due to their excellent electrical performances. The XLPE cable has become the main transmission equipment of urban power grid [5,6,7]. In the process of manufacture, laying, and operation, damage can inevitably occur in the polyethylene insulation layer, resulting in structural defects, such as micro-cracks and micro-holes [7,8,9]. The outer surface of polyethylene at the joint is scratched [9]

Methods

Results

Conclusion