Broadband Dielectric Spectroscopy on dry Poly(vinyl alcohol)/Poly(vinylidene fluoride) blends reinforced with Nano-Graphene Platelets at combined pressure and temperature

TL;DR

This study investigates the dielectric properties of dry Poly(vinyl alcohol)/Poly(vinylidene fluoride) blends with Nano-Graphene Platelets under varying temperature and pressure, revealing how absorbed water influences electron tunneling and conductivity.

Contribution

It provides new insights into the dielectric behavior of these polymer blends by isolating the effects of absorbed water through annealing and applying broadband spectroscopy under combined conditions.

Findings

Conductivity and relaxation follow fluctuation induced tunneling models.

Absorbed water significantly affects electron transport mechanisms.

Activation energies and volumes quantify water's impact on tunneling.

Abstract

Poly(vinyl alcohol)/Poly(vinylidene fluoride) blends at mass ratio 3:1 with Nano - Graphene Platelet fillers constitute mechanically and thermally stable systems, which are used for developing piezoelectric devices. Blends host a fraction of water molecules absorbed by the poly(vinyl alcohol) phase. Dc conductivity and dielectric relaxation occur via fluctuation induced tunneling of electrons. Electric charge transport is affected by the glass transition of the polymer matrix and the rotational and translational dynamics of absorbed water molecules. In the present work, absorbed water was subtracted by annealing and pumping and, subsequently, dry blends were characterized by employing Broadband Dielectric Spectroscopy at combined temperature and pressure states. Conductivity and relaxation obey fluctuation induced tunneling temperature dependencies. The corresponding activation energies and activation volumes reveal the role of absorbed polar water molecules on the tunneling current for macroscopic or localized electron transport.