Fiber Reinforced Layered Dielectric Nanocomposite. (8th May 2019) - Rahman, Muhammad M.
Abstract: Polymer dielectrics find applications in modern electronic and electrical technologies due to their low density, durability, high dielectric breakdown strength, and design flexibility. However, they are not reliable at high temperatures due to their low mechanical integrity and thermal stability. Herein, a self‐assembled dielectric nanocomposite is reported, which integrates 1D polyaramid nanofibers and 2D boron nitride nanosheets through a vacuum‐assisted layer‐by‐layer infiltration process. The resulting nanocomposite exhibits hierarchical stacking between the 2D nanosheets and 1D nanofibers. Specifically, the 2D nanosheets provide a thermally conductive network while the 1D nanofibers provide mechanical flexibility and robustness through entangled nanofiber–nanosheet morphologies. Experiments and density functional theory show that the nanocomposites through thickness heat transfer processes are nearly identical to that of boron nitride due to synergistic stacking of polyaramid units onto boron nitride nanosheets through van der Waals interactions. The nanocomposite sheets outperform conventional dielectric polymers in terms of mechanical properties (about 4–20‐fold increase of stiffness), light weight (density ≈1.01 g cm −3 ), dielectric stability over a broad range of temperature (25–200 °C) and frequencies (10 3 –10 6 Hz), good dielectric breakdown strength (≈292 MV m −1 ), and excellent thermal management capability (about 5–24 times higher thermal conductivity) such as fast heat dissipation. Abstract : A thermally conductive dielectric nanocomposite with mechanical flexibility and robustness and temperature stability is developed by integrating 1D polyaramid nanofibers and 2D boron nitride nanosheets for next‐generation electronic device and electric power systems.