Effect of the Dispersion State on the Dielectric Properties in High Energy Density Polymer-Based Nanocomposites

Polymer composites with PVdF-HFP matrix and BaTiO3 nanoparticles were prepared with different dispersion states to evaluate the impact of the dispersion state of the nanoparticles on dielectric properties. We observe that the dispersion state has two effects: first, the overall dielectric permittivity is a little higher in aggregated systems than in well-dispersed systems; Second, conductivity, together with a capacitive contribution, increase at low frequencies in aggregated systems as compared to well-dispersed systems. We propose that polarization couplings may enhance the effective permittivity in aggregated systems, and that Maxwell-Wagner-Sillars polarization may also contribute at low frequencies due to local percolation of the particles.