Improved thermal conductivity of epoxy composites prepared with a mixed filler of multiwalled carbon nanotubes and aluminum nitride particles

The thermal conductive filler/epoxy resin (EP) composites were prepared by a casting method. The effects of the multiwalled carbon nanotubes (MWCNTs), aluminum nitride (AlN) particles, and their compounds on the microstructure and thermal conductivity of the composites were investigated, in addition to the thermal properties. The results indicated that compounds of MWCNTs and AlN particles exhibited a remarkable synergistic effect to improve the thermal conductivity properties of the composites. The one-dimensional MWCNTs with superb thermal conductivity bridged the AlN particles to form an excellent network, which provides a faster and more effective pathway for phonon transport in the composites. The thermal conductivity of the 0.6 vol% MWCNTs/3.4 vol% AlN/EP composite is 0.53 W (m K)(-1). In addition, the thermal conductivity of the MWCNTs/AlN/EP composites with 0.4 vol% MWCNTs and 3.4 vol% AlN is 0.48 W (m K)(-1) (which is twice the value of 0.24 W (m K)(-1) for the pure EP) which was much higher than the 0.4 vol% MWCNTs/EP composites (0.27 W (m K)(-1)) and the 3.4 vol% AlN/EP composites (0.28 W (m K)(-1)). Bruggeman's equation is identified to fit quite well to the experimental results of the AlN/EP composites in the entire range of volume percentage of AlN; however, the MWCNTs/EP composites coincided better to the Russell equation. The volume resistivity of the MWCNTs/AlN/EP composites (approximately 1.8-2.6 x 10(12) m) exhibited only a slight compromise in comparison to the pure EP (2.5 x 10(14) m), which manifested the excellent insulation characteristic of these composites.