COMPARATIVE RHEOLOGICAL STUDIES ON JUTE-FIBER-FILLED AND GLASS-FIBER-FILLED POLYPROPYLENE COMPOSITE MELTS

An experimental study of the melt rheological properties of composites of isotactic polypropylene (IPP) filled with chopped jute-fibers (JF) and glass-fiber (GF) is reported. Fiber concentration is 5-20 wt %. Variation of shear stress with shear rate at constant temperature indicates increase in shear stress with shear rate and fiber loading. Shear stress values for IPP/GF melts are higher at the same shear rate and temperature. Variation of melt viscosity and melt elasticity with fiber concentration and shear stress or shear rate are also illustrated. Melt viscosity increases with fiber loading, while melt elasticity parameters such as die-swell and first normal stress difference decrease for both systems. For IPP/GF composite melts the viscosity values are higher, the die-swell and first normal stress difference values are lower compared to IPP/JF composites melts. Processing temperature of the filled IPP composites increase with respect to the nonfilled polymer, being a little higher in case of IPP/GF composites.