Alkali-Engineered Tobacco Stem Particles for Polyester Composites: Enhancing Physical, Mechanical, Thermal, and Dynamic Mechanical Properties

The increasing demand for eco-friendly materials has driven the development of sustainable biocomposites using renewable natural fibers. This study evaluates the mechanical, physical, tribological, and thermal properties of sustainable polyester biocomposites reinforced with treated tobacco stem particles (NTSPs). The NTSPs were treated with sodium hydroxide (NaOH) at concentrations of 2%, 5%, and 8% to enhance compatibility with the polyester matrix. Biocomposites containing 30% NTSPs by volume were fabricated via hot pressing at 105 °C and 75 Pa. Testing included tensile and flexural strength, thermal analysis, dynamic mechanical analysis (DMA), tribological evaluation, and scanning electron microscopy (SEM). The 8% NaOH-treated composite showed the best performance, with tensile strength of 48.53 ± 2 MPa, modulus of 2035.6 ± 77 MPa, and density of 1.22 ± 1.5 g/cm³. FTIR confirmed surface modification, while SEM revealed improved fiber–matrix bonding. The results demonstrate that treated tobacco stems particles are promising reinforcements for eco-friendly polyester composites, suitable for automotive interiors and semi-structural applications.