Influence of activated carbon concentration on the dielectric, conductivity and impedance properties of TPU composites

Abstract

This study examines the dielectric, electrical, and impedance properties of thermoplastic polyurethane (TPU) composites enhanced with activated carbon (AC) at concentrations ranging from 0 to 10% over a frequency range of 1 kHz to 10 MHz. The analysis includes capacitance, dielectric permittivity (ε′, ε′′), loss tangent (tanδ), alternating current conductivity (σ ac ), electric modulus (M′, M′′), and impedance spectroscopy (Z, R, X, θ) to assess charge transport, polarization effects, and relaxation behavior. Results show that increasing AC content enhances interfacial polarization and charge mobility, improving dielectric performance and influencing conductivity mechanisms. Among the investigative composites, AC7 achieved the best balance of properties, with a dielectric constant of 54.47 at 10 kHz, an ac conductivity of 0.0169 μS/cm, and a loss tangent of 0.054 at the same frequency. This composition exhibited high charge storage capacity, stable impedance, and low dielectric losses, making it ideal for wearable technology, embedded capacitors, and supercapacitors. Its optimized electrical properties also support applications in flexible sensors and electronic packaging, where controlled impedance is crucial. This study highlights the importance of optimizing filler concentration to develop TPU-based composites with improved dielectric properties and minimal energy loss, making them suitable for high-frequency and energy-efficient applications.