Preparation and properties of BaTiO3 filled butyl rubber composites for flexible electronic circuit applications

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 a relative permittivity (er) 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 er of 7 and tan δ of 0.014 and for the same filler content of nano BaTiO3 the composite have er of 8.9 and tan δ of 0.019 at 5 GHz. The thermal and mechanical properties of both the composites were investigated. The experimental values of er of both BR/BT and BR/nBT composites for different volume fractions were compared with theoretical models.