Electrical conductivity and dielectric response of poly(vinylidene fluoride)–graphite nanoplatelet composites

• Published in: Synthetic metals 2010-09, Vol.160 (17), p.1912-1919
• Main Authors: Li, Y.C., Tjong, S.C., Li, R.K.Y.
• Format: Article
• Language: English
• Subjects: Applied sciences; Composites; Dielectric constant; Dielectric relaxation; Dielectric strength; Dielectrics; Electrical properties; Exact sciences and technology; Forms of application and semi-finished materials; Layered structures; Nanocomposites; Nanomaterials; Nanostructure; Polymer industry, paints, wood; Polymers; Polyvinylidene fluorides; Resistivity; Technology of polymers
• ISSN: 0379-6779; 1879-3290
• DOI: 10.1016/j.synthmet.2010.07.009

Poly(vinylidene fluoride)/graphite nanoplatelets (PVDF/GNP) composites were fabricated using solution mixing followed by compression molding. The electric conducting and dielectric behavior of such nanocomposites were determined over a wide frequency range from 10 2 to 10 7. The results showed that the electrical behavior of PVDF/GNP nanocomposites can be well described by the percolation theory. Both conductivity and dielectric constant were found to be greatly enhanced at the percolation threshold. A large dielectric constant of 173 and low loss tangent of 0.65 were observed in the PVDF/2.5 wt% GNP nanocomposite at 1 kHz. Moreover, dynamic mechanical analysis was also used to characterize the relaxations of polymers in PVDF/GNP nanocomposites. Dielectric and mechanical relaxations of PVDF/GNP nanocomposites showed strong dependence with frequency and temperature. The activation energy for glass transition determined from mechanical relaxation is considerably higher than that evaluated from the dielectric analysis. This resulted from different operating mechanisms for dielectric and mechanical relaxation processes.