Influence of Halloysite Nanotube Fillers on Fracture, Mechanical, and Tribological Characteristics of Sisal Fibre Reinforced Composites

The need for structural materials that are sustainable has driven attention of the researchers towards natural fibre reinforced polymer laminates. This study examines the synergistic influence of halloysite nanotubes (HNTs) on the mechanical strength, tribological response, and fracture characteristics of sisal fibre reinforced epoxy composites. Composites containing 15 wt.% to 35 wt.% sisal fibre (SF) and 0.5 wt.% to 2.5 wt.% HNTs were fabricated using an optimized processing route to ensure uniform dispersion and low void content. Tensile, flexural, and impact tests revealed significant improvements in strength and stiffness, with a strength of 46.34 MPa in tensile mode and a strength of 76.4 GPa in flexural mode. The addition of HNTs up to a certain limit (1wt.%) to the composite with optimum wt.% of sisal fibre viz., 20 wt.% enhanced stiffness, achieving a Young’s (E) modulus of 1.43 GPa and a flexural modulus of 3.32 GPa, indicating improved load transfer efficiency. Tribological evaluation using pin-on-disc testing showed a 30% drop-in wear rate and a 25% reduction in coefficient of friction under lubricated conditions. Fractographic observations confirmed reduced fibre pull-out and delayed crack propagation. The results demonstrate the potential of SF–HNT composites for structures demanding integrity and improved resistance to fracture.