With recent developments, polymer film capacitors become increasingly important for advanced power applications. In this work, dielectrical properties of polycarbonate (PC)/poly(vinylidene fluoride) (PVDF) multilayer films with a composition of 50/50 (vol./vol.) were compared between 32- and 256-layer films. It was observed that the 256-layer film with thinner PVDF and PC layers exhibited a lower breakdown strength, a higher electric conductivity, and a higher ion loss than the 32L film with thicker PVDF and PC layers. These differences in dielectric properties were attributed to the difference in the interfacial polarization due to permittivity and conductivity contrasts between PVDF and PC. Space charges at the PC/PVDF interfaces could serve as effective traps to prevent leakage current through the film, leading to enhanced electrical insulation. For the 256-layer film, the interfacial charges were much less than those in the 32-layer film with thicker PC, because thinner PVDF layers could not effectively block space charges. As a result, the 256-layer film was less insulating than the 32-layer film. The interfacial polarization in the 32- and 256-layer films was proved by thermally stimulated depolarization current (TSDC) spectroscopy.

Effect of interfacial polarization on electric insulation properties for multilayer polymer films

254th National Meeting (2017)

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