The Melt Flow Properties of Poly(propylene)/Glass Bead Composites

Abstract

The effects of filler content and its surface treatment on the melt flow properties of A-glass bead-filled poly(propylene) (PP) composites have been investigated using a capillary rheometer at a wide apparent shear rate scope of 150 to 7 200 s–1 and a temperature range of 160 to 200°C. It was found that the melt shear flow obeyed roughly the power law. The melt shear viscosity (ηw) of the treated glass bead-filled system with a silane coupling agent was somewhat higher than that of the raw glass bead-filled system when both the systems were subjected to the same test conditions. The increase of the resistance to flow and flow satiability for the former system can be attributed to the improvement of the compatibility and interfacial adhesion between the filler and matrix as well as the dispersion of the filler in the matrix due to the surface treatment of the glass beads. The dependence of ηw on temperatures can be expressed with an Arrhenius relationship. The temperature sensitivity of ηw for the composite melts is greater than that of the unfilled PP. Furthermore, ηw increases obviously with the volume fraction (ϕf) of the fillers at lower shear rates, while the dependence of ηw on ϕf decreases with the increase of shear rates. This is attributable to the increase of the ability of relative movement between the filler and matrix melt at high extrusion rates.