Melt‐Processing Strategy in Modulating Distribution Structure and Thermal Conductivity of PP / POE / hBN / Al 2 O 3 Composites

The developing trends of electrical and electronic devices in high‐power operation, densified installation, and structural miniaturization challenge the application of the composites with efficient thermal conductivity. In view of the manufacture technology of polyolefin materials, the melt‐processing strategy was designed to prepare the thermally conductive composites based on polypropylene/polyolefin elastomer (PP/POE) blend with hexagonal boron nitride (hBN) and alumina oxide (Al 2 O 3 ). By filling hBN and Al 2 O 3 separately into the co‐continuous PP/POE blend, the selectively distributed structure with hBN in the PP phase and Al 2 O 3 in the POE phase was revealed, and the thermal conductivity of the composites was improved with selective filler distribution. The processing scheme exerted distinct influences on the distribution structure and the thermal conductivity of the composites with the same filler content. A superior thermal conductivity of 0.80 W/(m K) was achieved with the individually distributed structure of BN and Al 2 O 3 together with the bridged interaction between PP/BN and POE/Al 2 O 3 phases. The reduction in interfacial thermal resistance contributed to the enhanced thermal conductivity according to the simulation with finite element analysis (FEA). The proposed strategy provides an efficient way to mass manufacture thermally conductive polypropylene composites.