Microwave Dielectric Characteristics of Butyl Rubber- Barium Titanate Composites

Abstract

Butyl rubber-micron barium titanate (BR/BT) and butyl rubber-nano barium titanate (BR/nBT) composites were prepared by sigma mixing followed by hot pressing. The tensile tests show that both the composites were mechanically flexible. The microwave dielectric properties of both BR/BT and BR/nBT composites were investigated as a function of ceramic loading and were found to be improved with filler content. The butyl rubber has relative permittivity (εr) of 2.4 and loss tangent (tan δ) of 0.0017 at 5 GHz. At a filler loading of 0.24 volume fraction (vf) of micron sized barium titanate (BaTiO3) powder loading, the composite attained a εr of 7 and tan δ of 0.014 and for the same filler content of nano BaTiO3 the composite have εr of 8.9 and tan δ of 0.019 at 5 GHz. The thermal stability of the relative permittivity of both the composites was investigated. The experimental values of εr of both BR/BT and BR/nBT composites were compared with theoretical models.