Enhanced mechanical and dielectric properties of Aramid fiber/Mica-nanofibrillated cellulose composite paper with biomimetic multilayered structure

The application of Aramid/mica composite paper in high-voltage electric insulation is hampered by its limited breakdown strength and mechanical robustness. In this work, Aramid fiber/Mica-NFC composite papers with varied amount of nanofibrillated cellulose (NFC) were fabricated by vacuum-assisted self-assembly process, wherein NFC was used as carrier/adhesion polymer. The Aramid fiber/Mica-NFC composite papers exhibited high mechanical strength (~ 29.04 MPa), superior dielectric properties (~ 14.87 kV/mm) and good thermal stability (~ 300 °C). Importantly, NFC acts as interfacial layer since the physical properties of NaOH-Urea treated Aramid/Mica-NFC composite significantly decreased. Based on visualization of NFC by fluorescence tracking, the addition of NFC favors the formation of biomimetic multilayer structure. Furthermore, the co-continuous double-network-like multilayer structured composite achieved an integrated strong and tough character. Therefore, our work shed light on the importance of constructing rational-designed microstructures for the preparation of high-performance composite papers.