Abstract
Here, we report on the dielectric properties of polyvinyl-formaldehyde (PVF) foam doped with 1 wt%, 2 wt%, and 4 wt% multi-walled carbon nanotubes (MWCNTs). The samples were investigated in the frequency range from 0.1 to 20 MHz at −50 to 150 °C. The dielectric properties of the PVF foam were significantly influenced with increasing MWCNTs content. The 4 wt% PVF/MWCNTs shows high dielectric constant (ε′) value of 165 and low loss tangent (tan δ) value of 0.2 at 50 °C and 50 Hz. In addition, the real part of electric modulus (M′), the imaginary part of electric modulus (M″), and the ac conductivity (σac) were investigated. The appearance of conductivity-relaxation peak in the frequency dependence of M″ proves that the foams exhibit behavior of ionic materials where ions can move from long range to short range mobility. The correlated barrier hopping (CBH) is the dominant mechanism for conduction in the PVF/MWCNTs foams.
•Foams of PVF/MWCNTs as high dielectric constant and low dielectric loss nanocomposites were prepared.•The 4 wt% PVF/MWCNTs foam showed a high dielectric constant of 165 and 0.2 electric loss at 100 Hz and 50°C.•The electric modulus (M″) showed typical behavior of ionic materials.•Correlated barrier hopping was the dominated conduction mechanism for all samples.•The 4 wt% PVF/MWCNTs foam is a promising design for flexible, light weight, high dielectric constant, and low electric loss material for high performance dielectric capacitors.