Investigation of the structural, dielectric and elasto-mechanical properties of tamarind, coir, and mesta fibres.

This study investigates the potential of few natural fibres such as Tamarind, Coir, and Mesta as sustainable alternatives to synthetic fibres. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and dielectric analysis were employed to evaluate their elasto-mechanical and dielectric properties. Rietveld refinement provided detailed insights into the crystal structures, revealing distinct polysaccharide, lignin, cellulose, and lignocellulosic components in Tamarind, Coir, and Mesta fibres. Crystallite sizes were determined using the Scherrer equation to analyse spatial variations. Elastic properties characterized with Treloar's Principle and ELATE demonstrated significant anisotropy: Tamarind exhibited high stiffness, Coir showed variable stiffness and shear resistance, and Mesta displayed the highest stiffness. SEM analysis revealed Tamarind's rough, densely packed structure, Coir's coarse, interwoven network, and Mesta's uniform fibrous arrangement. EDS analysis shows Mesta has the highest C/O ratio at 1.18, compared to 0.86 for Coir and 0.91 for Tamarind. Dielectric studies showed varying dielectric constants, impedance, and conductivity across frequencies. Coir had the highest dielectric constant at lower frequencies, Tamarind showed the highest impedance at low frequencies, and all fibres exhibited increased conductivity with frequency, with Tamarind showing the most significant rise. The study findings demonstrate the significant potential of these fibres in sustainable food chemistry, particularly for biodegradable packaging, processing, and bio-composites in academic and industrial sectors.