Significantly improved dielectric properties of multiwall carbon nanotube-BaTiO3/PVDF polymer composites by tuning the particle size of the ceramic filler

RSC Advances Pub Date: 2019-07-29 DOI: 10.1039/C9RA04933A

Abstract

The effects of different BaTiO3 sizes (≈100 nm (nBT) and 0.5–1.0 μm (μBT)) on the dielectric and electrical properties of multiwall carbon nanotube (CNT)-BT/poly(vinylidene fluoride) (PVDF) composites are investigated. The fabricated three-phase composites using 20 vol% BT with various CNT volume fractions (fCNT) are systematically characterized. The dielectric permittivity (ε′) of the CNT-nBT/PVDF and CNT-μBT/PVDF composites rapidly increases when fCNT > 0.015 and fCNT > 0.017, respectively. The former is accompanied by the dramatic increase in the loss tangent (tan?δ) and conductivity (σ), but surprisingly, not for the latter. At 103 Hz, the low tan?δ and σ values of the CNT-μBT/PVDF composite are about 0.06 and 6.82 × 10?9 S cm?1, while its ε′ value is greatly enhanced (≈154.6). The variation of the dielectric permittivity with fCNT for both composite systems follows the percolation model with percolation thresholds of fc = 0.018 and fc = 0.02, respectively. With further increasing fCNT to 0.02, ε′ is greatly increased to 253.8, while tan?δ ≤ 0.1. Without μBT particles, the ε′ and tan?δ values of the CNT/PVDF composite with fCNT = 0.02 are as high as ≈240 and >103, respectively. Greatly enhanced dielectric properties are described in detail.

Graphical abstract: Significantly improved dielectric properties of multiwall carbon nanotube-BaTiO3/PVDF polymer composites by tuning the particle size of the ceramic filler
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