Fabrication and characterization of pineapple fibre reinforced vinyl ester composites toughened with fish skin collagen: analysis of shear, wear, and fatigue behavior

The present study evaluated the shear, wear, and fatigue performance of vinyl ester composites fabricated via hand lay-up and reinforced with untreated and silane-functionalized pineapple fibers (comprising 70–85% cellulose, 7% hemicellulose, and 8% lignin), along with varying concentrations of collagen.Among the fabricated specimens, the composite CFT1 comprising silane-functionalized pineapple fiber and 3 vol.% collagen exhibited superior mechanical behavior, recording an shear strengths of 93 MPa (In-plane shear), 40 MPa of V-notch shear strength, and fatigue life counts of 29,917 at 25% ultimate tensile strength (UTS), 27,618 at 50% UTS, and 25,817 at 75% UTS. On the other hand, the CFT2 composite (silane-functionalized pineapple fiber and 5 vol. % collagen) demonstrated excellent wear resistance, with a low specific wear rate of 0.008 mm³/Nm and a coefficient of friction of 0.31. Additionally, the 5 vol.% collagen content provided optimal matrix reinforcement by filling microvoids and increasing surface hardness without leading to agglomeration. This well-balanced microstructure enhanced durability and minimized material removal under wear conditions. These findings were further supported by morphological evidence from scanning electron microscopy (SEM). Given their multifunctional performance, these composites hold potential for applications in sectors such as marine, automotive, drone components, and packaging.