Evaluation of mechanical properties for Ricinus communis L plant fiber/epoxy composite

Abstract This research explores the mechanical properties of castor oil plant (Ricinus communis L) natural fiber‐reinforced epoxy composites, addressing the need for sustainable materials. Cortex and xylem fibers extracted from castor oil plant residue using a standardized method were used to fabricate unidirectional long fiber and short random fiber composites. Various fiber volume fractions (10 %, 20 %, 30 %, 40 %) and fiber lengths (5 mm to 40 mm) of cortex fibers were tested according to ASTM standards and results showed that fibers of diameters 275 μm to 325 μm, have superior tensile strength (290 MPa to 346 MPa) compared to xylem fibers (90 MPa to 140 MPa). Composites of 40 % volume fraction cortex fibers aligned longitudinally exhibited the highest tensile (76.35 MPa), flexural (121.45 MPa), and impact strength (6.99 kJ/m 2 ) significantly improved compared to the epoxy matrix. For short random cortex fiber composites, the optimal mechanical performance was achieved with 20 mm fibers and a 40 % volume fraction, resulting in the highest tensile strength (32.12 MPa), flexural strength (84.31 MPa), and impact energy (40 J/m). These results highlight the potential of castor oil cortex fibers to enhance the mechanical properties of epoxy composites for various engineering applications.