Dynamic and steady state viscoelastic behavior and morphology of MAPP treated PP/sisal composites

The present paper summarizes an experimental study on the molten viscoelastic behavior of PP/sisal composites under steady and dynamic state. Variations in melt viscosity and die swell of the composites with an increase in shear rate, fibre loading and coupling agent concentration have been investigated using capillary rheometer. It was observed that with the addition of sisal fibers and MAPP, the melt viscosity of the composites increased due to improved fiber-matrix interfacial adhesion. Further the dynamic viscoelastic behavior measured, employing parallel plate rheometer revealed an increase in the storage modulus (G') indicating higher stiffness in case of fibre filled composites as compared with the virgin matrix. Time temperature superposition was applied to generate various viscoelastic master curves. The fiber-matrix morphology of the extrudates was also examined using scanning electron microscopy, which corroborated the findings of the rheological properties. The extrudate cross sections of the composites displayed uniform distribution of fibers within the PP matrix with lesser surface irregularities at high shear rates. (c) 2006 Elsevier B.V. All rights reserved.