Phase transition and electrical spectroscopy of PVDF/MWCNT polymer nanocomposites

As purchased, PVDF and MWCNT were used to synthesise PD by varying the volume fractions of MWCNT (fMWCNT) into the polymer matrix through the novel cold-pressing method. The structure, microstructure and the electrical properties of the samples were obtained through XRD, FESEM, and Impedance analyzer. The microstructures of the PD show the presence of two components, such as the spherulites of PVDF (retained due to the novel cold-pressing) and the distribution of MWCNT into the PVDF matrix. The extent of distribution of MWCNT in the PD increases and the clustering of MWCNT also increases with increase of fMWCNT. The PD undergo an insulator to metal transition (IMT), with a non-universal low percolation threshold (fc) value of fMWCNT = 0.006, attributed to the high aspect ratio of MWCNT and the adhesiveness/method of preparation of the PD. The scaling equations hold good in the critical region around IMT, and the non-universal critical exponents [s = 0.36 ± 0.03, s` = 1.26 ± 0.1] were obtained. Impedance, Nyquist and Modulus spectra for the PD have been implemented to understand the relaxation behaviour/microstructure of the samples. For fc, a broad relaxation, understood by a modified Kohlrausch, Williams and Watts (KWW) function, showing a non-Debye type relaxation associated with the universal stretched coefficient of β = 0.54 is obtained. The σeff with frequency obeys universal Jonscher’s power law with exponent, k = 0.91 ± 0.01.