Effect of layering pattern on dynamic mechanical properties of randomly oriented short banana/sisal hybrid fiber-reinforced polyester composites

Dynamic mechanical test methods have been widely employed for investigating the structures and viscoelastic behavior of polymeric materials to determine their relevant stiffness and damping characteristics for various applications. Randomly oriented short banana/sisal hybrid fiber-reinforced polyester composites were prepared by keeping the volume ratio of banana and sisal 1 : 1 and the total fiber loading 0.40 volume fraction. Bilayer (banana/ sisal), trilayer (banana /sisal /banana and sisal /banana /sisal), and intimate mix composites were prepared. The effect of layering pattern on storage modulus (E'), damping behavior (tan delta), and loss modulus (E '') was studied as a function of temperature and frequency. Bilayer composite showed high damping property while intimately mixed and banana/ sisal /banana composites showed increased stiffness compared to the other pattern. The Arrhenius relationship has been used to calculate the activation energy of the glass transition of the composites. The activation energy of the intimately mixed composite was found to be the highest. (C) 2005 Wiley Periodicals, Inc.