Comparative Analysis of Polyester Composites Reinforced with Local Plant Fibers: Stipa tenacissima Vs. Agave americana

This work presents a comparative investigation of unsaturated polyester composites reinforced with two local Algerian lignocellulosic fibers: Stipa Tenacissima and Agave americana. These fibers were harvested, water-retted, and subsequently characterized using Fourier Transform Infrared Spectroscopy (FTIR) and X-ray Diffraction (XRD). Single-fiber tensile testing, supported by Weibull statistical analysis, showed that Stipa Tenacissima fibers exhibit a higher Young’s modulus (~15.5 GPa) and lower elongation at break, whereas Agave fibers display lower stiffness (~6.7 GPa) but significantly greater ductility. Two unidirectional composites, unsaturated polyester/ Stipa Tenacissima and unsaturated polyester/ Agave Americana, containing each approximately 25 wt% fiber were fabricated using the vacuum-bagging process and cured at 70 °C for 2 h. Mechanical testing revealed substantial improvements compared to neat polyester. Stipa Tenacissima fiber composites achieved an increase of about 120% in tensile modulus and nearly 110% in flexural modulus. In contrast, Agave Americana fiber composites exhibited lower stiffness but superior strain-to-failure and toughness, with an enhancement of ~95% in flexural strength. Overall, the results confirm that both Stipa Tenacissima and Agave Americana are effective reinforcements for polymeric matrices: Stipa Tenacissima fibers primarily improve stiffness and strength, while Agave fibers enhance ductility and energy-absorption capability.