High-performance polyarylate nanofiber membranes with ultra-thin structure, multi-environmental tolerance, and recyclability for advanced electrical insulation

Polymer fiber-based insulating paper is widely utilized in electrical equipment for insulation and protection. However, with the miniaturization of electrical systems, conventional insulating paper struggles to balance space constraints and performance, limiting its application in high-performance devices. This study introduces polyarylate (PAR) nanofibers, fabricated via melt spinning and mechanical disintegration, followed by scalable hot pressing to produce ultra-thin PAR nanofiber membranes with a thickness of 30 μm, which is 40 % thinner than commercial aramid paper. The high orientation and dense inter-fiber network of PAR nanofibers effectively mitigate electric field distortion, resulting in a breakdown field strength of 71.46 kV/mm, which is 251.5 % higher than commercial aramid paper. Notably, the PAR nanofiber membranes exhibit exceptional structural stability under multi-physical environmental conditions. After prolonged thermal aging (250 °C for 24 h), UV exposure (365 nm for 48 h), repeated folding, and multiple kneading cycles, they retained breakdown strengths of 17.73 kV/mm, 25.19 kV/mm, 15.86 kV/mm, and 13.8 kV/mm, respectively. In contrast, commercial Aramid paper exhibited a marked decline, with breakdown strength decreasing to 11.32 kV/mm, 14.8 kV/mm, 7.75 kV/mm, and 9.97 kV/mm under the same conditions. Moreover, the thermoplastic nature of PAR nanofiber membranes enables closed-loop recycling, reducing material waste while preserving performance and presenting a sustainable and scalable approach for next-generation high-performance insulating materials.