Effect of Sebastiana Rostrata Fiber Loading on the Tribological Behaviour of Polycaprolactone Biocomposite

This study investigates the tribological behaviour of Sesbania rostrata fiber (SRF) reinforced polycaprolactone (PCL) biocomposites using a pin-on-disc wear couple. The stationary SRF/PCL composite specimen interacted with a rotating EN31 steel disc (64 HRC), establishing the sliding wear interface in accordance with ASTM G99 standards. Composite laminates containing 10, 20, and 30 wt% SRF were evaluated at a sliding velocity of 1 m/s over a fixed distance of 1000 m under varying normal loads. The incorporation of SRF significantly enhanced the wear performance relative to neat PCL, with 20 wt% fiber loading achieving the lowest coefficient of friction and specific wear rate due to improved load transfer, stronger interfacial adhesion, and a more uniform laminate structure. In contrast, the 30 wt% composite exhibited fiber agglomeration, reduced homogeneity, and weakened fiber–matrix interactions, resulting in increased wear. SEM microstructural analysis confirmed the formation of a continuous polymer transfer film and uniform fiber distribution at 20 wt%, whereas 30 wt% showed non-uniform fiber orientation and clustering that negatively influenced tribological stability. These results demonstrate that optimized SRF loading significantly improves the load-bearing capacity and surface durability of PCL biocomposites, supporting their potential for wear-critical automotive, orthopaedic, and biodegradable engineering applications.