Synthesis and characterisation of carbon nanofiber-wrapped polyaniline and polypyrrole sensory films in polyester resin for strain sensing

Abstract

ABSTRACT Nanomaterials hold promise as flexible sensor elements due to their enhanced flexibility and efficiency compared to conventional sensors. This study explores Carbon Nanofibers (CNF) in strain-sensing applications, synthesised with Polyaniline (PANI) and Polypyrrole (PPy) via a chemical oxidative technique. These composites form sensory layers on flexible Polyester resin substrates using a layer-by-layer technique. Characterisation through Fourier-Transform Infrared (FTIR) Spectroscopy and Powder X-ray Diffraction (PXRD) reveals strong interactions within CNF/PANI/Polyester and CNF/PPy/Polyester configurations, with heightened crystallinity in CNF/PANI, indicating enhanced electrical conductivity. Stress-strain analysis shows a significant 25% elongation with a corresponding 15% change in resistance across all samples. Calculated gauge factors exhibit substantial improvements: Polyester/PPy (12.96), Polyester/PANI (13.54), Polyester/CNF wrapped PPy (58.62), and Polyester/CNF wrapped PANI (95.8). Notably, CNF-wrapped PPy and CNF-wrapped PANI demonstrate superior gauge factors compared to conventional strain sensors, with Polyester/CNF-wrapped PANI displaying the highest sensitivity at 95.8%. This research underscores the potential of CNF-based composites, particularly CNF-wrapped PANI within a Polyester matrix, for advanced strain-sensing applications.