Physico‐Mechanical, Thermal, and Microstructural Insights Into Waste Sheep Wool Reinforced Bio‐Composites: An Experimental Analysis

ABSTRACT This study investigates coarse sheep wool fibers as a sustainable reinforcement for high‐performance polymer composites produced via Vacuum‐Assisted Resin Transfer Molding (VARTM). Composite panels were fabricated with two to five nonwoven fiber layers of coarse sheep wool (CSW2–CSW5), yielding fiber volume fractions of ~22%–29%. The mechanical (tensile, flexural, compressive, and impact strength; Interlaminar Shear Strength (ILSS) and hardness), physical (density and void content), and thermal properties of the material were thoroughly assessed. Thermal stability and viscoelastic behavior were evaluated using thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA). CSW4 (~27% fiber) achieved the highest tensile (39.96 MPa), flexural (97.43 MPa), ILSS (6.95 MPa), and impact strength (14.87 kJ/m 2 ), surpassing CSW2 by ~24%, 10%, 60%, and 44%, respectively. DMA confirmed superior stiffness and damping via elevated storage and loss moduli, while TGA indicated enhanced thermal stability with delayed degradation onset and higher char yield. SEM analysis revealed improved fiber–matrix interfacial bonding in CSW4, correlating with its performance. These results highlight the importance of optimal fiber content and uniform dispersion for maximizing mechanical integrity, viscoelastic response, and thermal endurance. The findings validate coarse sheep wool as a viable bio‐based reinforcement, offering potential for sustainable thermal insulation and semi‐structural composite applications.