Capturing the Efficiency of a Melt-Mixing Process for Polymer Processing

Abstract

Polymer blends and composite materials are often produced by a melt-mixing process, using equipment specially designed to mix high-viscosity fluids during laminar flow. The melt-mixing process can be classified into distributive and dispersive mixing. Distributive mixing includes stretching and folding of fluid elements and re-arrangement of dispersed materials. Dispersive mixing is size reduction of filler aggregates and/or liquid droplets in a matrix fluid. To optimize the design of a melt-mixing equipment, the evaluation of distributive and dispersive mixing is essential. In this paper, we consider fundamental aspects of melt-mixing, and experimental and computational approaches that have been reported in the literatures. Experimental observation of melt-mixing, by and large, provides rather limited information on the mixing process inside a equipment. Although a mixed material can be obtained under a specified condition and its physical properties can be directly measured, the mixing mechanism behind the final result is hardly inferred.Computational fluid dynamics complements this situation. Numerical simulation of a mixing process provides a non-invasive and detailed data in a equipment so that the quantitative measures for distributive and dispersive mixing can be obtained. we consider various quantitative measures that have been previously proposed to characterize distributive and dispersive mixing.