Origin of non-universal percolation/scaling and universal non-Debye relaxation in PVDF/MWCNT polymer nanocomposites

Abstract

Polymer Nanocomposites (PNC) comprising polyvinylidene fluoride (PVDF)/Multi-walled Carbon Nanotubes (MWCNT) were studied. The structural composition and thermal stability were confirmed from XRD and DSC/TGA data, respectively. The extent of distribution of MWCNT in the PNC increases and the clustering of MWCNT also increases with an increase in the volume fraction of MWCNT ([Formula: see text], as confirmed by FESEM. The PNC shows an insulator-to-metal transition (IMT), with both non-universal percolation threshold [Formula: see text] of [Formula: see text] and scaling exponents [Formula: see text], respectively, attributed to adhesiveness/cold pressing and the higher aspect ratio/conductivity of MWCNT. Modulus spectroscopy confirms a non-Debye type universal relaxation behavior [Formula: see text] only for the percolative sample due to Maxwell–Wagner–Sillars/interfacial polarization, while only dipolar relaxation was probed or the samples below [Formula: see text]. The [Formula: see text] with static effective dielectric constant [Formula: see text] and low tan [Formula: see text] may be suitable for charge storage applications.