Structural, Mechanical, Thermal, and Preliminary Biological Characterization of Cymbopogon citratus Leaf Fibers for Sustainable Material Applications

The growing demand for sustainable bio-based materials has increased interest in underutilized plant fibers as environmentally friendly alternatives for engineering applications. In this study, Cymbopogon citratus (lemongrass) leaf fibers were extracted using an eco-friendly water-retting process and characterized by Fourier transform infrared spectroscopy (FTIR), tensile testing, thermogravimetric analysis (TGA), antibacterial assays, and confocal laser scanning microscopy (CLSM). FTIR analysis identified characteristic lignocellulosic functional groups, with absorption bands at 3360, 1403, 1141, and 873 cm−1 corresponding to cellulose, hemicellulose, and lignin. Tensile testing yielded a maximum tensile strength of 317.74 MPa, a Young’s modulus of 19.1 GPa, and a strain-to-failure of 0.017, indicating favorable stiffness and mechanical performance. TGA revealed a multistage degradation profile associated with moisture loss and the progressive thermal decomposition of lignocellulosic constituents under a nitrogen atmosphere. The aqueous fiber extract exhibited concentration-dependent antibacterial activity against Escherichia coli, producing inhibition zones of 13 ± 0.5 mm and 19 ± 0.8 mm at extract concentrations of 50 and 100 μg, respectively. CLSM observations qualitatively indicated reduced bacterial viability and altered biofilm architecture following treatment with the fiber extract. Therefore, the results demonstrate that C. citratus leaf fibers possess favorable structural, mechanical, thermal, and preliminary biological characteristics.