Study on Dielectric Properties of Nanoclay-Modified Disulfide-Containing Polyurea Composites

Area of Science:

• Materials Science
• Electrical Engineering
• Polymer Chemistry

Background:

• Transmission lines face frequent faults due to extreme environments and limitations of conventional insulating materials.
• Existing insulators suffer from insufficient dielectric properties and poor interface compatibility.

Purpose of the Study:

• To develop a novel composite material for enhanced transmission line insulation under extreme conditions.
• To synthesize and characterize a disulfide-containing polyurea (DPU) modified with functionalized Halloysite nanotubes (HNTs).

Main Methods:

• Synthesis of HNTs modified with aminopropyltriethoxysilane (APTES) and DPU.
• Characterization using FTIR, SEM, and DSC.
• Performance evaluation including contact angle, breakdown strength, arc resistance, dielectric constant, and tower gap breakdown tests.

Main Results:

• APTES modification of HNTs ensured uniform microstructure and improved interface compatibility.
• HNTs/DPU exhibited superior thermal stability (higher Tg) and hydrophobicity compared to commercial polyurea (CPU) and commercial insulating sheath (CIS).
• The composite demonstrated enhanced breakdown strength, dielectric constant, and arc resistance, with optimal insulation at 4 mm thickness in tower gap tests.

Conclusions:

• HNTs/DPU presents a viable new solution for transmission line insulation protection in harsh environments.
• The material shows significant performance advantages over existing insulating materials.
• Dynamic covalent bonds in DPU and functionalized HNTs contribute to the improved properties.