High-performance insulation materials from poly(ether imide)/boron nitride nanosheets with enhanced DC breakdown strength and thermal stability

Environmentally-friendly polymers which can be recycled and reused at the end of life are urgently needed for the development of advanced high-voltage direct current (HVDC) systems. Polymer nanocomposites have attracted considerable attention owing to their unique features arising from synergistic combination of inorganic fillers and polymer matrices. Here we describe thermoplastic poly(ether imide) (PEI) nanocomposites that contain boron nitride nanosheets (BNNSs). It is found that the polymer nanocomposites exhibit simultaneous improvements in multiple physical properties, such as the DC electrical breakdown strength, volume resistivity, mechanical strength and thermal stability, along with substantial reduction in loss tangent, compared with neat PEI. A great improvement in thermal conductivity has been attributed to the presence of BNNSs in the composites, which improves heat dissipation in comparison with neat polymers. The composite approach provides a promising solution for alleviating temperature-gradient distribution and addressing heat accumulation issues in HVDC equipment, and enables broader applications of insulation materials in HVDC systems operated under high voltages.