This paper deals with the experimental investigation of bubble-free film degassing in a partially filled twin-screw extruder. A systematic study of polymer devolatilization with a model substance system is carried out at ambient temperature with variation of rotational speed and degree of fill. The influence of the gas-side mass transfer is evaluated by a stripping flow of nitrogen at different gas flow rates. Experimental mass transfer values are compared to theoretical predictions based on penetration and surface renewal theory. Longer degassing zones lead to decreasing efficiency due to incomplete mixing. Degassing results from simplified devices may be used to predict the performance in more complex devolatilization equipment.
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