▎ 摘　　要

A flexible three-phase composite material with enhanced dielectric permittivity was prepared with both graphene and BaTiO3 nanoparticles as fillers and polyimide (PI) as matrix. Studies on the dielectric properties of PI-graphene-BaTiO3 composite materials in the frequency range from 10(2) to 10(6) Hz show that they possess excellent dielectric permittivity (epsilon = 170.39) and lower dielectric loss thanks to their unique dimensional structure. In consideration of the percolation theory and microcapacitor model, a percolation threshold of 1.11 vol% was calculated and the mechanism of the enhancement of the dielectric permittivity of the composite material was discussed. (C) 2014 Elsevier B.V. All rights reserved.