Alkali treatment and its effect on tribological properties of naturally woven coconut sheath polyester composite

In the recent years natural fibres have drawn great interest for its bio-degradability, low cost and its availability in nature. Among different types of natural fibres, naturally woven coconut sheath fibres are one of the recently explored alternatives for synthetic fibres. These fibres are generally treated with alkali for enhancing mechanical properties and reinforcing characteristics. Tribological applications like gears, cams, bearings, etc. can be benefited from such composites. In most cases chemical treatment are done favouring the structural properties however, their influence on tribological properties are rather not considered. In the current research, hybrid composites (polyester resin with naturally woven coconut sheath (N) and glass fibres (G)) were tested against hardened steel counterface in a pin on disc configuration. Tests were performed at 40 N normal force and 3.5 m/s sliding velocity. From the results all hybrid combinations except (NNN) shows degrading wear properties with the alkaline treatment. The friction properties are modified by having low friction coefficients for all combinations except NGN and GGG hybrids. From the observed SEM images the surface morphology of NNN hybrid significantly differs from the rest of the combinations in both treated and untreated specimens. The partial removal of individual phase (resin) prevails in untreated specimen for which the fibres are highly visible. However, such phenomenon is not dominant in the alkali treated material showing better reinforcing behaviour complimenting low friction properties. The alkali treated specimen has reduced fibre size comparing the untreated specimen which results in low wear resistance. Compromise between friction and wear properties between each other the untreated fibres are best suited for tribological applications. Furthermore, investigations on treatment process and other treatments might have some influence in tribological behaviour

Exploration of tribological characteristics of naturally woven fiber composites

Natural fiber composites (NFC) being one of the new interventions in the composite industry, is given less importance for tribological applications. In the current research, an in-depth study is made to understand the influence of normal force and speed, affecting the tribological characteristics. Various forms of lignocellulosic fibers exist, out of which coconut fibers are advantageous due to its naturally woven state. Tribological characterization was performed using a ball on disc configuration. Online measurements of friction force elucidate that the friction characteristics of naturally woven coconut sheath reinforced polymer (CSRP) composite stabilize at increased speed. Moreover, the orientation of the fiber strongly influences mode of wear