Tailoring electromagnetic interference shielding, electrical and thermal properties of poly(vinylidene fluoride) based hybrid nanocomposites with carbon nanofiber and magnetite nanoparticles†

To develop flexible conducting polymer composite (CPC) based microwave absorbers, tuning the electrical conductivity of the composite to a higher value by improving the dispersion of fillers in the polymer matrix is important. Therefore, the present study aims at improving the dispersion of carbon nanofiber (CNF) and magnetite nanoparticles (Fe₃O₄) in poly(vinylidene fluoride) (PVDF) matrix, by incorporating 1 wt% poly(vinylpyrrolidone) (PVP) as the compatibilizer to achieve enhanced electrical and electromagnetic interference shielding properties of hybrid nanocomposites. The enhanced dispersion of nanofillers in the PVDF matrix was confirmed by high-resolution transmission electron microscopy (HRTEM), field emission scanning electron microscopy (FESEM) and impedance analyses. The hybrid nanocomposites contain predominantly the electroactive gamma phase of PVDF as confirmed by X-ray diffraction (XRD), Fourier transform infra-red spectroscopy (FTIR) and differential scanning calorimetry (DSC) analyses. The solution blended, 0.1 mm thick PVDF–9 wt% CNF–3 wt% Fe₃O₄ hybrid nanocomposite film exhibits an electromagnetic interference shielding effectiveness (EMI SE) of 17.1 dB at 10 GHz dominated by absorption phenomenon. Additionally, the onset and main chain degradation temperatures of PVDF in the hybrid nanocomposites (with 1 and 3 wt% Fe₃O₄) are increased by more than 40 °C compared to PVDF–9 wt% CNF nanocomposites with 1 wt% PVP. The storage modulus of the hybrid nanocomposites was increased to about 164.2% at 40 °C in comparison to neat PVDF film with PVP as evidenced by dynamical mechanical analysis (DMA). Thus, the solution blended PVDF–CNF–Fe₃O₄ hybrid nanocomposite film with improved electrical, mechanical, thermal and EMI shielding properties can be used for microwave absorption application.