Melt Rheology during Extrusion of Polypropylene Composites Filled with Diatomite Particles

Abstract

The melt volume flow rate (MVR) is an important parameter for characterization of flow properties of polymer. The MVR of the polypropylene composites filled with diatomite particles was measured by means of a MVR instrument to investigate the effects of the filler content, particle size and extrusion conditions (temperature 210—230°C, load 5.0—12.5 kg) on the melt flow properties of the composite systems. The results showed that the MVR of the composites increased as a quadratic function with the increase of load, while decreased nonlinearly with the increase of filler particle diameter. The MVR was a linear function of temperature. The MVR decreased quickly when the filler volume fraction (φ f ) was <5%, and then reduced slightly with an increase of φ f . In addition, the melt shear flow obeyed roughly power law under the experimental conditions, and the influence of particle size on the temperature sensitivity of the melt shear viscosity is insignificant at low filler concentration.