Polythiophene Coated Cellulose Fiber/High Density Polyethylene Composites for Capacitor Applications

Abstract

Conducting composites with enhanced flexibility and tunable electrical properties are highly desirable for applications in flexible electronics, wearable sensors, and actuators. In this study, polythiophene-coated banana stem fibers (PCFs) and high-density polyethylene (HDPE) were used to develop conducting composites. The PCFs, prepared via oxidative polymerization, exhibited a conductivity of 1.0 S/m. It was introduced into HDPE through a melt-mixing process, followed by compression molding. The composites were characterized for mechanical, morphological, thermal, electrical, and dielectric properties. Morphological analysis revealed poor interfacial adhesion between the polar PCFs and the nonpolar HDPE matrix, leading to decreased tensile strength and elongation at break with increasing fiber content. However, tensile modulus and thermal stability improved which was attributed to the formation of a network of PCFs and the protective effect of the polythiophene coating. Electrical conductivity increased significantly at fiber loadings above 20 phr, although moisture retained in the fibers and dopant migration partially limited conductivity. Dielectric properties improved with fiber content. The composites showed high dielectric constant and comparatively low dielectric loss. The study demonstrates the potential of polythiophene-coated natural fibers as flexible, conductive fillers in thermoplastic matrices, to develop efficient capacitors.