Interface Performance of Untreated Dracaena trifasciata Fibers in Epoxy Composites

This study evaluates the potential of Dracaena trifasciata (DT) fibers as reinforcement in epoxy composites by analyzing mechanical, thermal, and microstructural properties. Fibers underwent water-retting and drying, and were characterized via SEM and FTIR. Composites were fabricated by vacuum infusion with 55% fiber volume fraction and tested according to ASTM D638. Two epoxy systems were investigated: a rigid matrix (LY5052) and a flexible matrix (AR324). With LY5052, DT fiber incorporation led to a 101% increase in elastic modulus but caused a 26% reduction in tensile strength, attributed to stress concentration at the fiber–matrix interface and brittle matrix behavior. In contrast, composites with AR324 exhibited a 908% increase in stiffness and nearly 1000% improvement in tensile strength, enabled by superior strain compatibility between the flexible matrix and the fiber reinforcement. TGA analysis showed thermal stability above 400 °C and ~ 5% increase in residual mass due to inorganic components in DT fibers. SEM revealed predominant fiber pull-out, 40 µm voids, and resin penetration into the fiber lumen. These findings highlight the importance of matrix selection in maximizing the mechanical potential of natural fibers. DT/epoxy composites are promising for lightweight applications, particularly when paired with ductile matrices that mitigate premature failure mechanisms.