MODELING OF INDUSTRIAL NYLON-6,6 POLYCONDENSATION PROCESS IN A TWIN-SCREW EXTRUDER REACTOR - I - PHENOMENOLOGICAL MODEL AND PARAMETER ADJUSTING

This article describes a mathematical model for the finishing stage of nylon-6,6 polycondensation in a twin-screw extruder reactor. In the m odel, the extruder is conceptually divided into two regions. The first one is the partially filled degassing zone, which is operated under l ow pressure and where the evaporation of water from the polymer takes place. The rate of evaporation is considered to depend on an overall m ass transfer coefficient and is limited by the water-polymer physical equilibrium. In the second region, which is fully filled, the polymer flow is assumed to be plug-flow and, in this region, the reversible po lycondensation reaction occurs, as well as degradation reactions. A co mparison with experimental data obtained in an industrial plant shows fairly good agreement with model predictions after optimal fitting of the rate coefficients. (C) 1998 John Wiley & Sons, Inc.