Polymer dielectrics with excellent dielectric properties and energy storage performance under elevated temperature are urgently needed in electrical power systems. Polyetherimide (PEI), which is supposed to be the most promising candidate among polymer dielectric materials, has a limitation for high-temperature dielectric applications especially at high electric field owing to secondary relaxation. Herein, a series of self-cross-linkable oligomers are prepared by combining the advantages of PEI and phenylethynyl groups. Cross-linked polymer dielectric films with enhanced voltage resistance and low leakage current density are obtained by cross-linking under oxygen. The occurrence of β-relaxation is diminished by cross-linking, which makes polymer dielectrics exhibit desirable dielectric stability over a broad temperature and frequency range. Particularly, the dielectric loss of c-10%PEPA-PEI at 1000 Hz is 0.0037 and 0.0043 at room temperature and 150 °C, respectively. Simultaneously, the polymer dielectric maintains a still low dielectric loss (95.0%) and improved energy density (3.6 J/cm3 ) at 150 °C. The authors believe that these cross-linked films showing excellent dielectric performance have a promising future in high-temperature applications.

中文翻译：

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通过操纵弛豫行为，提高了聚合物电介质中高温下的放电效率和高能量密度

在电力系统中迫切需要具有优异的介电性能和在高温下的能量存储性能的聚合物电介质。聚醚酰亚胺（PEI）被认为是聚合物介电材料中最有希望的候选者，由于二次弛豫，对高温介电应用（特别是在高电场下）具有局限性。本文中，通过结合PEI和苯基乙炔基的优点制备了一系列可自交联的低聚物。通过在氧气下交联获得具有增强的耐电压性和低漏电流密度的交联聚合物介电膜。β-松弛的发生通过交联而减少，这使得聚合物电介质在较宽的温度和频率范围内显示出所需的介电稳定性。特别是，室温和150°C下c-10％PEPA-PEI在1000 Hz下的介电损耗分别为0.0037和0.0043。同时，聚合物电介质在150°C时仍保持较低的介电损耗（95.0％），并提高了能量密度（3.6 J / cm3）。作者认为，这些具有优异介电性能的交联膜在高温应用中具有广阔的前景。