On-line Measurement of Residence Time Distribution in a Twin-screw Extruder

Abstract A simple optical on-line residence time distribution (RTD) measurement technique has been developed. Changes in extrudate light transmittance are monitored by a photomultiplier. A He-Ne laser is the light source with carbon black as the tracer. The RTD of a ZSK-30 twin-screw extruder was measured using this technique. The effects of feed rate, screw speed, and melt viscosity on the RTD were studied. Also, the effect of the presence of an in-line rheometer on RTD was examined. The advantages and disadvantages of the technique are discussed.