Distributive mixing profiles for co-rotating twin-screw extruders

Distributive mixing was experimentally measured during polymer melt blendin g along the length of a co-rotating twin-screw extruder. A mixing limited i nterfacial reaction between two reactive polymer tracers was employed to ga in direct evidence of the generation of interfacial area. Model reactions w ere performed to validate this novel experimental method. In particular, th e conversion was a direct indicator of the interfacial area available for t he reaction. Specially designed sampling ports were used to obtain polymer samples along the length of the extruder during its continuous operation. T he mixing capabilities of conveying sections and kneading blocks were compa red over a wide range of operating conditions. In conveying sections, distr ibutive mixing was controlled by the fully filled fraction. The mixing in k neading blocks depended on the combination of the operating conditions and the stagger angle. (C) 2001 John Wiley & Sons, Inc.