Development of Boron Nitride Hydroxide/Aluminum Oxide/Epoxy Resin Spheres and Graphene Oxide‐Loaded L‐Ascorbic Acid Aerogel for Enhanced Thermal Conductivity and Insulation via Hot‐Pressing

ABSTRACT Polymer composites have easy processability, low cost, and wide applicability. Moreover, arranging fillers within such polymer composites to form a heat transfer path plays a crucial role in enhancing thermal conductivity. In this paper, composites were composed using boron nitride (BN), aluminum oxide (Al 2 O 3 ), reduced graphene oxide (r‐GO), L‐ascorbic acid (L‐AA), and epoxy resin (EP) (BN‐OH/Al 2 O 3 /EP/r‐GO@L‐AA). To create BN‐OH/Al 2 O 3 /EP spheres, Al 2 O 3 was used as the core, with a small amount of EP and BN‐OH surrounding it to form ceramic spheres. An r‐GO@L‐AA aerogel was formed by cross‐linking r‐GO and L‐AA, followed by freeze‐drying. The BN‐OH/Al 2 O 3 /EP/r‐GO@L‐AA composites were fabricated by hot‐pressing the BN‐OH/Al 2 O 3 /EP spheres and r‐GO@L‐AA aerogel. With the vertical alignment of the BNs arranged according to the r‐GO@L‐AA aerogel, the BN‐OH/Al 2 O 3 /EP/r‐GO@L‐AA composite achieved a high thermal conductivity of 4.632 W/m K, a tensile strength of 65 MPa, and insulating properties.