Chemomechanical Systems: Study of Contraction and Mechanical Work of Poly(Acrylonitrile) Gel Fibers

Abstract

A fully predictive computer model SSEM (Single-Screw Extrusion Model) has been developed for the single-screw plasticating extruders (with conventional and mixing screws). The model takes into account five zones of the extruder (hopper, solids conveying, delay zone, melting zone, and melt conveying) and the die, and it describes an operation of the extruder-die system, making it possible to predict the mass flow rate of the polymer, the pressure and temperature profiles along the screw channel and in the die, the solid-bed profile, and power consumption. Moreover, the mixing degree, the temperature fluctuation, and the viscoelastic characteristic of the polymer are evaluated. The model also makes it possible to predict the morphological changes of the polymer blend during the compounding process in the single-screw extruder. The simulation parameters are the material and rheological properties of the polymer, the screw, hopper, and die geometry, and the operating conditions (screw speed and barrel temperature profile). Such a comprehensive approach to the modeling of extrusion creates a possibility of optimizing the process, for example, from the point of view of the quality of extrusion. The model has been verified experimentally on a 45-mm-diameter single-screw extruder.