Dielectric analysis of VGCNF reinforced polyethylene composites

Dielectric analysis was performed on vapor grown carbon nanofiber reinforced high density polyethylene (HDPE) composites. The dielectric parameters (permittivity, loss factor, tan δ and ionic conductivity) of pure HDPE and composites were obtained in a frequency range of 0.01–105 Hz and temperature range of 35–120 °C. The dielectric properties of pure HDPE are slightly dependent on temperature and frequency. Permittivity values decreased slightly with frequency and temperature while changes in loss factor and dissipation factor (tan δ) were negligible. The dielectric properties of the composites showed a strong dependence on nanofiber content, testing frequency and temperature. Permittivity, loss factor and tan δ increased with the increase of nanofiber content and decreased with increasing temperature and frequency. Percolation phenomenon was observed in the dielectric analysis, similar to the percolation in electrical conductivity studies. The threshold value for permittivity and loss factor was ≈15 wt% VGCNF. The ionic conductivity of the composites increased with frequency.