Improved thermal conductivity and dielectric properties of flexible PMIA composites with modified micro- and nano-sized hexagonal boron nitride

A series of flexible poly(m-phenylene isophthalamide) (PMIA)-based composites with different sizes and mass fractions of hexagonal boron nitride (hBN) were successfully manufactured for the first time via the casting technique. The effects of modified hBN particles on microstructure, mechanical properties, dielectric properties and thermal conductivities of fabricated composites were investigated. The results indicate that modified hBN particles manifest good compatibility with the PMIA matrix. The Young’s modulus and T heat-resistance index of PMIA-based composites are increased with increasing the mass fraction of hBN particles. Due to additional thermal conductive paths and networks formed by nano-sized hBN particles, the K-m/n-hBN-30 composite displays the thermal conductivity of 0.94 W·m -1 ·K -1 , higher than that of the K-m-hBN-30 composite (0.86 W·m -1 ·K -1 ), and more than 4 times higher than that of neat PMIA. Moreover, the obtained PMIA-based composites also show low dielectric constant and ideal dielectric loss. Owing to the excellent comprehensive performance, hBN/PMIA composites present potential applications in the broad field of electronic materials.