Interfacial, Mechanical and Thermal Properties of Coir Fiber-Reinforced Poly(Lactic Acid) Biodegradable Composites

Abstract

Abstract The poly(lactic acid) (PLA) biodegradable composites reinforced with short coir fibers were developed and studied. The effect of fiber mass content varying from 10 to 50% on mechanical and thermal properties of coir/PLA composites have been studied in terms of tensile properties, thermal stability and thermal expansion.The effect of alkali treatment on interfacial shear strength (IFSS), mechanical and thermal properties of coir/PLA composites was investigated. The coir fibers which are soaked in 5% sodium hydroxide solution at room temperature for 72 h showed the highest IFSS at 72.8% higher than untreated coir fibers. Alkali treatment of coir fibers enhanced the tensile properties of coir/PLA composites. The best tensile strength of coir/PLA composite was achieved at fiber mass content of 20% in this study. Below about 370°C, the coir/PLA biodegradable composites are found to have much higher thermal stability compared to coir fiber, but lower than that of PLA resin. Alkali-treated coir/PLA composites having improved fiber–matrix adhesion resulted in stable composites with better thermal stability than untreated coir/PLA composites. The thermomechanical stability of PLA resin is significantly improved by the addition of reinforcing coir fibers.The fractured surface morphology of the composite specimens exhibited an improvement of interfacial fiber–matrix adhesion in the composites reinforced with alkali-treated coir fibers.