Effects of Multiwalled Carbon Nanotubes on Phase Transformation and Dielectric Properties in Poly(Vinylidene Fluoride-Hexafluoropropylene) Nanocomposites

Abstract

Poly(Vinylidene fluoride-hexafluoropropylene) [P(VDF-HFP)] nanocomposites filled with multiwalled carbon nanotubes (MWCNTs) were successfully fabricated by solution casting. The influence of MWCNTs on the phase structure, dielectric and mechanical properties of MWCNTs/P(VDF-HFP) nanocomposites were evaluated. FTIR spectra and X-ray diffraction show that the incorporation of MWNTs promoted the formation of γ phase crystal. The DSC curves demonstrated that the nanocomposites possess higher T_m and T_c than neat P(VDF-HFP), which can be explained by the increasing of the γ phase crystal and the heterogeneous nucleation effect respectively. In addition, the dielectric constant of the nanocomposites is enhanced remarkably with the increasing content of the MWNTs. The highest dielectric constant of the MWCNTs/P(VDF-HFP) nanocomposites was about 106 when the content of fillers was 1.3 vol% at 1 kHz. The percolation threshold of the nanocomposites was predicted at about 1.2 vol%. Moreover, The tensile strength and Young’s modulus of 1.2 vol% MWCNTs/P(VDF-HFP) nanocomposites reach to maximum.

Fig. 5 Dependence of dielectric constant and dielectric loss (tan δ) of composites on contents of MWCNTs measured at 1 kHz and room temperature.