Processing conditions effect on dispersion evolution in a twin-screw extruder: polypropylene-clay nanocomposites

Abstract

Polymer-clay nanocomposites are often manufactured using twin-screw extruders. Processing conditions, namely screw speed and feed rate, are known to strongly influence the final dispersion levels attained. The effect of these parameters on the evolution of dispersion along the extruder for a system consisting of polypropylene, polypropylene grafted with maleic anhydride, and an organoclay is investigated. Inline near-infrared measurements were performed at various axial locations plus die outlet. At the same positions, local average mass temperature and minimum residence time were also monitored. In addition, samples were quickly removed from the extruder for subsequent offline characterization. Regardless of the processing conditions, dispersion develops rapidly upon melting, with a much slower pace downstream.