A Mussel‐Inspired Strategy for Synergistically Enhancing Thermal and Electrical Properties of <scp>ACFs</scp> / <scp>PPS</scp> Composite Paper With h‐ <scp>BN</scp> ‐Modified Mullite Nanofibers

ABSTRACT The inherent porosity defects and limited thermal conductivity of aramid insulating paper substantially compromise its insulation performance and thermal stability under high electric field strength and power density operating conditions. Herein, inspired by the mussel byssal, we used the γ‐glycidoxypropyltrimethoxysilane (KH560) to bond hexagonal boron nitride (h‐BN) to mullite nanofibers, thereby fabricating an h‐BN‐modified mullite (BNM) nanofiber. Upon incorporation into aramid chopped fibers (ACFs)/polyphenylene sulfide (PPS) composite paper, these modified fibers not only effectively filled the pores but also established highly efficient thermal conduction pathways facilitated by boron nitride. Consequently, the thermal dissipation capacity of the composite paper was significantly enhanced, mitigating the detrimental effects of thermal stress on its insulating properties. At a BNM fiber loading of 40 wt%, the resultant composite paper exhibited a breakdown strength of 71.5 kV/mm, representing a 1.1‐fold enhancement compared to the ACFs/PPS composite paper. Notably, owing to the synergistic effects of porosity reduction and h‐BN incorporation, the through‐plane thermal conductivity of the composite paper reached 0.577 W/mK, corresponding to a 3.9‐fold increase relative to the ACFs/PPS composite. Furthermore, the BNM fiber‐reinforced composite paper demonstrated exceptional thermal stability, maintaining superior performance even under extreme conditions such as elevated temperatures and ultraviolet irradiation. These attributes position ACFs/PPS/BNM composite paper as a promising candidate for next‐generation advanced insulating materials.