This research deals with the melt rheology of isotactic polypropylene (iPP) reinforced with short glass fibers (SGF) coated with electrically conductive polyaniline (PAn). Composites containing 10, 20, and 30 wt % PAn-SGF were studied. Moreover, a composite of 30 wt % PAn-SGF was also prepared with a blend of iPP and PP-grafted-maleic anhydride (iPP/PP-gMA). The composites showed linear viscoelastic regime at small strain amplitudes. The onset of nonlinearity decreased as the concentration of filler increased. The time-temperature superposition principle applied to all composites. The filler increased the shear moduli (G', G '') and the complex viscosity eta*. Steady-state shear experiments showed yield stress for the composites with 20 and 30 wt % PAn-SGF. Strikingly, the 10 wt % composite showed higher steady state viscosity than the 20 wt %. Rheo-optics showed that shear induced disorder of micro-fibers at a concentration of 10 wt %. However, at 20 wt % concentration shear aligned the microfibers along the flow axis, this would explain the anomalous steady state viscosity values. The viscosity exhibited a shear thinning behavior at high shear rates for all composites. Creep experiments showed that the filler induced greater strain recovery in the composites and that the amount of strain recovery increased as the PAn-SGF concentration increased. However, the enhancement of strain recovery (as well as shear viscosity) was more significant when using the iPP/PP-gMA blend, suggesting greater adhesion between this matrix and the filler PAn-SGF. (c) 2008 Wiley Periodicals, Inc.