A dynamic model for multiple steady states in reactive extrusion

The existence of multiple stationary values of the fully, filled length in reactive extrusion is studied on the basis of a mathematical model describi ng dynamic extruder behavior The extruder is modelled as a plug flow type o f reactor Through the introduction of travel time for a fluid element in th e extruder, time dependent viscosity models following from rheokinetics can be used. Special attention is paid to ionic and radical polymerization rea ctions. Hysteresis behavior for stationary values of the fully filled lengt h exists when die resistance and rotational speed are varied. The effects o f reaction rate, viscosity, levels and degree-of-fill on stable operation a t high conversions are studied. The mathematical dynamic model presented he re can account for some of the experimentally, observed dynamic phenomena i n the reactive extrusion of radical polymers.