The alignment of AlN platelets in polymer matrix and its anisotropic thermal properties

Abstract

The thermal conductivity of polymer composites can be enhanced by the vertical alignment of anisotropic aluminum nitride (AlN) platelet fillers in polymer matrices. The AlN platelets in polymer matrix were aligned in the direction of in-plane and out-of-plane by using the doctor blading and the lamination process. The alignment of AlN plates in the out-of-plane or the in-plane direction has been confirmed by XRD and FE-SEM investigations. The polymer composite with the out-of-plane aligned AlN platelets showed almost 1.5 times or 2 times higher thermal conductivity than those with the AlN spheres or the in-plane aligned AlN platelets at the same filler content, respectively. This result could be attributed to the improvement of thermal pathway generated along the plane of platelets and the decrease of interfaces between the filler and the polymer. Keywords: Thermal conductivity, Aluminum nitride plate, Polymer composite, Alignment, Out-of-direction, In-plane direction