Fabrication of thermoplastic polyurethane and polyaniline conductive blend with improved mechanical, thermal and excellent dielectric properties: exploring the effect of ultralow-level loading of SWCNT and temperature

Abstract

A novel multifunctional conductive blend and nanocomposites based on thermoplastic polyurethane (TPU), polyaniline (PANI) and carboxylic acid functionalized single-wall carbon nanotubes (SWCNT) with very high mechanical, thermal and excellent dielectric properties have been fabricated. The dispersion pattern and the interconnectivity of nanowire form of PANI and SWCNT in the TPU matrix are observed from HRTEM and FESEM photomicrographs. The interfacial interaction between the constituents in terms of hydrogen bonding has been confirmed from the FTIR and Raman spectra. The enhancement in tensile strength at 10 weight percentage (wt%) PANI loading explores the reinforcing nature of PANI on TPU matrix. The increase in thermal stability of the TPU/PANI blend in comparison with PANI again confirms the establishment of chemical linkages in the interface. The effect of PANI loading and temperature on the dielectric relaxation behavior has been explored in a wide range of frequency (1–106 Hz). The easiness in the polarization of the dipoles in PANI as well as in SWCNT has been confirmed from the improved value of dielectric permittivity (e′). The pronounced tunneling and hopping mode of conduction have reflected from conductivity (σac) and reduction in impedance (Z′ and Z″) value. The substantial improvement in e′ and σac of TPU/PANI/SWCNT nanocomposites at ultralow loading level of SWCNT (0.5wt %) in comparison with unfilled TPU/PANI blend is the uniqueness of this study. The effect of temperature on e′ and σac ensures the negative temperature coefficient (NTC) behavior of resistance of TPU/PANI blends.