Stress Relaxation Behavior of Banana Fiber-Reinforced Polyester Composites

Stress relaxation behavior of banana fiber-reinforced polyester composites were investigated with special reference to the effect of fiber loading, fiber treatment, hybridization with glass fiber and also as woven fabric composites. It was observed that incorporation of fiber in the polyester matrix reduces the rate of relaxation. The nature of the relaxation curve was found to depend on the quantity of fiber as well as the surface characteristics of fiber used as reinforcement. The decrease in stress relaxation modulus was greatest for the neat polyester sample whereas it was at a minimum for composites with 40% fiber loading. Chemical modification of the fiber surface was found to affect the degree of adhesion and thereby the nature of relaxation at the initial stages. Of the various chemical modifications chosen in the present study, the decrease in stress was found to be the lowest for composites made out of banana fiber treated with NaOH. Hybridisation of banana fiber with glass was found to decrease the rate of relaxation further. However, stress relaxation values of woven glass and banana gave even lower values.