Enhancement of Isotropic Heat Dissipation of Polymer Composites by Using Ternary Filler Systems Consisting of Boron Nitride Nanotubes, h-BN, and Al₂O₃

In this researcharticle, a poly(dimethylsiloxane) (PDMS)-basedcomposite was postulated adapting an interactive ternary filler systemconsisting of Al2O3, hexagonal boron nitride(h-BN), and boron nitride nanotubes (BNNT) to construct a continuousthree-dimensional (3D) structure for thermal attenuation. Al2O3 was imposed as a main filler, while h-BN and BNNT wereassimilated to form interconnected heat conduction pathways for effectivethermal dissipation. The structured framework articulates a profoundimprovement in isotropic thermal conductivity considering both axialand radial heat dissipation. The presence of h-BN entails uniformheat distribution in a planar mode, eliminating the occurrence ofhotspots, while BNNT constructed a connecting phonon pathway in variousdirections, which insinuates effective overall thermal transport.The generated ternary filler composites attained an isotropic ratioof 1.35 and a thermal conductivity of 7.50 W/mK, which is a 36-fold(& SIM;3650%) increase compared to neat PDMS resin and almost 3-fold(& SIM;297%) that of the Al2O3 unary fillercomposite and & SIM;53% that of its binary counterpart, partakinginterfacial thermal gaps of & SIM;36.15 and & SIM;62.24% on practicalheating performance relative to its counterparts. Moreover, the incorporationof BNNT on a traditional spherical and planar filler offers an advantagenot only in thermal conductivity but also in thermal and structuralstability. Improvement in thermal stability is stipulated due to amelting point (T (m)) shift of & SIM;11 & DEG;C upon the assimilation of BNNT. Mechanical permeance reinforcementwas also observed with the presence of BNNT, showcasing a 31.5% increasein tensile strength and a 53% increase in Young's modulus relativeto the singular filler composite. This exploration administers a newinsight into heat dissipation phenomena in polymeric composites andproposes a simple approach to their design and assembly.