Characterization of the rheological behavior of fiber‐filled polypropylene melts under steady and oscillatory shear using cone‐and‐plate and rotational parallel plate rheometry

Abstract Utilization of cone‐and‐plate and rotational parallel plate rheometry to characterize the rheological behavior of fiber‐filled polymer melts at low shear rates was evaluated. The effect of flow geometry and dimensions on the viscoelastic and viscometric functions was considered. Stress growth functions were found to be dependent on the dimensions of the flow channel. However, viscometric functions were not affected by the dimensions or the geometry of the flow channel. The initial state of orientation was found to be an important factor in determining the flow found to be an important factor in determining the flow behavior. Oscillatory shear tests yielded highly strain‐dependent loss and storage moduli even at very small strain amplitudes. However, the stress response was found to be sinusoidal in most cases, although the properties were strain dependent.