(258b) Inference-Based Control of Reactive Extrusion Processes

Reactive extrusion processes are widely employed by polymer processing industries for the production and modification of commercial polymers (e.g. ethylene co-polymers, polyamides, etc.). Due to strongly interacting process mechanisms and unavailability of high frequency measurements of quality variables, ?q' (melt index, viscosity, density, etc), as well as product end-use properties, ?w' (toughness, UV/chemical resistance, etc.), it has been very difficult to guarantee acceptable end-use product performance for this class of processes. To achieve the challenging goal of assuring acceptable end-use performance, we propose a modeling and control framework for effectively controlling key product properties and meeting customer requirements on end-use performance. In this framework, an appropriate quantitative representation of the relationships between variables across the entire processing chain is realized through a modeling scheme consisting of a hierarchical network of judiciously selected models. These models constitute an integral part of a control scheme consisting of a fast model-based controller C1 for the inner loop between the manipulated variables, u, and the process variables, y, and a slower (model-based) controller C2, which translates the end-use performance objectives to set points for the process variables, y.

In this presentation, we will discuss the development of the overall control scheme and present some results on an experimental implementation involving the reaction of a functionalized ethylene co-polymer, ?Elvaloy? (ethylene/n-butyl acrylate/glycidal methacrylate terpolymer) with an acid co-polymer ?Nucrel? (ethylene/methacrylic acid copolymer) in a Coperion W&P ZSK-30mm co-rotating, intermeshing twin-screw extruder.