Melt-processable aggregated boron nitride particle via polysilazane coating for thermal conductive composite

In this study, thermally conductive composite was fabricated using hexagonal and spherically aggregated boron nitride filler based on epoxy and polyphenylene sulfide (PPS) matrixes. The spherically aggregated BN (A-BN) particles were shown the outstanding thermal conductivity compared hexagonal BN (H-BN) in the epoxy matrix. However, A-BN is very weak to external forces and broken during PPS based melt processing, causing it to lose the advantage of its particulate shape. Therefore, we adopted a particle coating method for the A-BN to enhance its durability, using pre-ceramic polysilazane (PSZ) in solution. With the PSZ coating of A-BN, the spherical particle shape was retained after melt mixing. Moreover, the interfacial affinity between BN and PPS was enhanced by secondary interactions between the polar functional groups comprising PSZ, thereby increasing the through-plane thermal conductivity from 1.82 to 3.9 W m(-1) K-1 at 70 wt% of A-BN filler, because the spherical filler particles formed a three-dimensional heat flow path.