Properties of Intrinsic Self-Healing Epoxy Insulating Materials Based on Dynamic Disulfide Bond

The concept of self-healing material provides a possibility for prolonging the life of electrical equipment. Epoxy resin with self-healing function is the research hotspot of insulating materials. However, most of the existing researches on epoxy resin self-healing system are based on external self-healing, and there is still a large gap in the research on the performance of epoxy resin intrinsic self-healing. In this paper, epoxy insulating materials with self-healing ability were prepared based on disulfide bond self-healing system, and thermal, mechanical and electrical properties of the prepared self-healing epoxy resin were studied to explore the effect of raw materials, ratio and other factors on the performance of self-healing epoxy insulating materials. The optimal preparation scheme of self-healing epoxy insulating material based on disulfide bond was determined based on relevant properties, which provided material and technical support for the development of electric power equipment. Firstly, in order to prepare self-healing epoxy insulation material of disulfide bond, 4,4'-Dithiodianiline (4-AFD) and matrix-1,2-bis(4-(oxiran-2-ylmethoxy)phenyl)disulfane (BGPDS) were selected as the epoxy resin matrix and curing agent, respectively, to introduce the disulfide bonds required for self-healing. Based on fusion polymerization method, self-healing epoxy resin with disulfide bond and control group without disulfide bond were prepared according to preset ratio. Then, Fourier infrared characterization tests were carried out for the prepared self-healing epoxy resin, which proved that the prepared epoxy material met the expected target. Finally, the influence rule of disulphide bond on the basic properties of epoxy resin was obtained through the methods of thermogravimetric analysis, dynamic thermomechanical analysis, tensile testing and electrochemical comprehensive analysis, and the optimal material ratio was determined based on the surface mechanical repair test, which provided data and theoretical support for further exploring the application of intrinsic self-repair technology in epoxy insulating materials. The following conclusions can be reached from test analysis: (1) Based on the introduction of disulfide bonds into epoxy resin matrix and hardener, the self-healing epoxy resin is prepared. From the perspective of its mechanical properties and dielectric properties, the influence of disulfide bonds in matrix on the basic characteristics of epoxy resin is greater than that of disulfide bonds in hardener. (2) The introduction of disulfide bond can improve the chemical structure, crosslinking density and molecular weight of epoxy resin, which has adverse effects on the mechanical properties of epoxy insulating materials, but is conducive to the improvement of dielectric properties. (3) The content of disulfide bond has significant influence on the mechanical properties, electrical properties and self-healing effect of epoxy resin. Low content of disulfide bond leads to poor self-healing effect of the material, high content of disulfide bond leads to obvious decline in basic properties of the material. DBF0%, DBF20% and DBD40% are more suitable for the self-repairing research of epoxy resin with disulfide bond under the condition that the basic characteristics are slightly changed. © 2024 China Machine Press. All rights reserved.