The Melt Shear Viscosity of Polypropylene/Glass Bead Composites at High Extrusion Flow Rates

The effects of filler content and its surface treatment with silane coupling agent on the melt shear viscosity of glass bead-filled polypropylene (PP) composites have been investigated using a capillary rheometer at a wide shear rate scope of 150 to 7200 s and temperature range of 160 to 200 C. The melt flow obeys power law, but the slopes of the flow curves have transitions at the shear rate of about 500 s. The melt shear viscosity of the coated glass bead-filled system is somewhat higher than that of the uncoated glass bead-filled system when both were subjected to the same conditions. The dependence of the melt shear viscosity on temperatures can be described with Arrhenius relationship, and the temperature sensitivity of the composite melts is greater than that of pure PP. The melt shear viscosity (ηw ) increases with the volume fraction of the fillers (φf ) at lower shear rates, while the dependence of ηw on φf decreases with the increase of shear rates.