Dielectric and Repairable Properties of Epoxy Resin Based on Dynamic Polythiourethane Bonds

Developing epoxy resin covalent adaptive network with repairable properties is proposed to be an effective way to achieve the sustainable development of power equipment. In this paper, dynamic polythiourethane bonds are introduced into the epoxy resin by a sequential double curing method. As a result, excellent mechanical strength, dielectric properties, and damage self-healing properties are co-achieved in this repairable epoxy resin. Additionally, the rigid benzene ring structure introduced along with the dynamic polythiourethane bond gives the material excellent mechanical and dielectric properties. The elastic modulus exceeds 1.2 GPa and the volume resistivity is more than 10¹⁶ Ω·cm. Dissociation of poly-thiourethane bonds could be thermally stimulated, leading to topological network rearrangement and the corresponding mechanical damage repair and electrical breakdown recovery capabilities. The electrical damage repair efficiency could reach up to 90%. Therefore, with excellent mechanical strength, dielectric properties, and damage repairability, it is expected to be a new generation of eco-friendly insulating material.