Fabrication of epoxy functionalized MWCNTs reinforced PVDF nanocomposites with high dielectric permittivity, low dielectric loss and high electrical conductivity

Nanocomposites of Polyvinylidene Flouride (PVDF) with Multi-walled Carbon Nanotubes (MWCNTs) possess excellent thermal, piezoelectric and conductive behaviors. However, the potential of MWCNTs as filler in polymer composites is hampered by their poor dispersion into the matrix, corresponding to the strong inter-tubular and weak inter tubular-polymer chain interactions. This issue is successfully overcome by utilizing di-glycidyl ether of bisphenol-A (DGEBA) grafted MWCNTs (DG-MWCNTs) as reinforcement in PVDF matrix. To synthesize the desired nanocomposites, the easier to manipulate, solution casting technique was employed. The resulting PVDF/DG-MWCNTs nanocomposites have different loadings of filler ranging from 1.0 wt% to 10 wt%, and have shown variation in the phase transformation from α-phase to β-phase along with improvements in thermal and dielectrical behaviors. It was revealed by the impedance spectroscopy (IS) that the reinforcement of PVDF with DG-MWCNTs leads to an increase in the dielectric permittivity. This increase was found higher enough to reach up to ∼5288 (at ∼100 Hz) and 214 (at ∼102 Hz) for filler loading of 10 wt %. The increase is several hundreds of magnitude i.e., ∼204 at ∼102 Hz higher than the PVDF matrix, while retaining a low level conductivity (4.18 × 10−6 S/cm). This enhancement in the dielectric permittivity is attributed to the strong interfacial interaction between PVDF and DG-MWCNTs, and was explained by the Maxwell-Wagner-Sillar (MWS) effect.