Synergistic Enhancement of Thermal Conductivity and Dielectric Properties in Al(2)O(3)/BaTiO(3)/PP Composites

Multifunctional polymer composites with both high dielectric constants and high thermal conductivity are urgently needed by high-temperature electronic devices and modern microelectromechanical systems. However, high heat-conduction capability or dielectric properties of polymer composites all depend on high-content loading of different functional thermal-conductive or high-dielectric ceramic fillers (every filler volume fraction ≥ 50%, i.e., f(filler) ≥ 50%), and an overload of various fillers (f(thermal-conductive) (filler) + f(high-dielectric) (filler) > 50%) will decrease the processability and mechanical properties of the composite. Herein, series of alumina/barium titanate/polypropylene (Al(2)O(3)/BT/PP) composites with high dielectric- and high thermal-conductivity properties are prepared with no more than 50% volume fraction of total ceramic fillers loading, i.e., f(fillers) ≤ 50%. Results showed the thermal conductivity of the Al(2)O(3)/BT/PP composite is up to 0.90 W/m·K with only 10% thermal-conductive Al(2)O(3) filler, which is 4.5 times higher than the corresponding Al(2)O(3)/PP composites. Moreover, higher dielectric strength (E(b)) is also found at the same loading, which is 1.6 times higher than PP, and the Al(2)O(3)/BT/PP composite also exhibited high dielectric constant ([Formula: see text] = 18 at 1000 Hz) and low dielectric loss (tan δ ≤ 0.030). These excellent performances originate from the synergistic mechanism between BaTiO(3) macroparticles and Al(2)O(3) nanoparticles.