Dynamic Cross-Linked Polyethylene Networks with High Energy Storage and Electrical Damage Self-Healability

Abstract

Dielectric polymers that exhibit high energy density U e , low dielectric loss, and thermal resistance are ideal materials for next-generation electrical equipment. The most widely utilized approach to improving U e involves augmenting the polarization through increasing the dielectric constant ε r or the breakdown strength E b . However, as a conflicting parameter, the dielectric loss also increases inevitably at the same time. In addition, due to the long-term work under a strong electric field or high potential, dielectric materials often produce electrical damage (electrical tree), which is one of the main factors affecting the reliability and service life of electrical equipment. To address these problems, we herein develop dynamic cross-linked polyethylene materials (PE-MA-Epo) by polyethylene-graft-maleic anhydride (PE-MA) and polar epoxy monomers, which showed high ε r (>7), low dielectric loss (<0.02), high U e (5.16 J/cm 3 at 425 MV/m), and outstanding discharge efficiency (97%). The performances of the materials are adequate to rival biaxially oriented polypropylene (BOPP) films. Moreover, the excellent self-healing capability of PE-MA-Epo enables the total recovery of ε r and tan δ after electrical tree healing. After two cycles of electrical breakdown healing, E b remained at 80%, which improves the durability and reliability of dielectric polymers. Therefore, PE-MA-Epo shows great potential for applications in advanced electronic power devices.

Largely Improved Creep Resistance and Thermal-Aging Stability of Eco-Friendly Polypropylene High-Voltage Insulation by Long-Chain Branch-Induced Interfacial Constraints

“…The thermoset cross-linked polyethylene (XLPE) insulated power cable is in increasing demand due to the continued development of urbanization. However, the thorny problems, including high energy consumption during fabrication and recyclability after retirement, limit the sustainability of cable insulation. − Therefore, replacing thermosets with recyclable thermoplastics, such as polypropylene (PP) with superior insulating performance, has been proposed as an effective method to achieve the target. − Nevertheless, brittleness and low toughness make it difficult for PP to be directly used as a cable insulation. Although the problems can be solved by introducing elastomers, the sharp interface between the matrix and the rubber phase always leads to serious decline in the resistance against deformation and aging during its long-term operation at high temperatures. − …”