Enhanced high-temperature dielectric performances of polyetherimide-based composites via surface functionalized silicon carbide whiskers

In this work, 3-aminopropyltriethoxysilane (AMEO)/polyurea (PUA)-modified silicon carbide whiskers (SiCw) were firstly fabricated and then incorporated into polyetherimide (PEI) to prepare the dielectric composites toward high temperature application. The results show that the introduction of amino/urea polar groups can effectively promote dielectric constant and suppress the dielectric loss of composites at room and high temperatures owing to the strong interfacial adhesion and deep trap effect of polar groups. Specifically, the variations of dielectric properties are also greatly dependent upon the surface functionalization of SiCw. SiCw-PUA endows the composites with relatively better comprehensive dielectric performances (dielectric constant of 18.3 and dielectric loss of 0.020) at room temperature while SiCw-AMEO has more apparent role in maintaining the dielectric performances (dielectric constant of 17.0 and dielectric loss of 0.029) at high temperature of 150 ?. Furthermore, the composites also exhibit high thermal conductivity with the maximum thermal conductivities of 1.41 and 1.37 W m(-1) K-1 for the SiCw-AMEO/PEI and SiCw-PUA/PEI at filler loading of 15 wt%, respectively. The excellent reinforcement effect of the surface functionalized SiCw also endows the composites with more application probability. This work on functionalization of SiCw could be applicable for integration of dielectric, thermally conductive and mechanical properties.