Hybrid biocomposite-based vinyl resin/green microcrystalline cellulose/carbon nanotube material: Electrical and dielectric relaxation analysis

Abstract

In this work, we investigate the electrical properties of a ternary biocomposite material based on a vinyl resin (VR) matrix filled with two types of fillers, namely green microcrystalline cellulose (MCC) and carbon nanotubes (CNT), over a frequency range of 10⁻¹ to 10⁷ Hz and a temperature range from 10 to 130°C. Thermal analyses were carried out using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), which revealed significant changes in the glass transition and degradation temperatures of the biocomposite, respectively. The electrical measurements were analyzed using two formalisms: (i) Electrical conductivity, which showed the presence of two distinct low-frequency behaviors associated with quasi-dc conductivity below the glass transition temperature and dc conductivity above it, along with high-frequency dispersion, which allows determining the ac conductivity mechanisms using Jonscher’s power law, and (ii) Electric modulus, which revealed a low-temperature relaxation originating from water dipole polarization and two high-temperature dielectric relaxation processes. The first high-temperature relaxation, observed at low frequencies, was attributed to the Maxwell–Wagner–Sillars (MWS) effect, while the second, appearing at high frequencies, was associated with the α-relaxation. These relaxations were modeled using Bergman’s equation. Furthermore, the temperature dependence of the relaxation time and dc conductivity were analysed using an Arrhenius representation.