A STUDY ON THE PERFORMANCE OF THE MADDOCK MIXING HEAD IN PLASTICATING SINGLE-SCREW EXTRUSION

An experimental and theoretical study was conducted on the performance of the Maddock mixing head in plasticating single-screw extrusion. For the experimental study, a low-density polyethylene was extruded in an extruder that had nine pressure transducers mounted, almost equally spaced along the extruder axis, on the wall of the extruder barrel. Two screws with the Maddock mixing head were used, namely: one screw to measure the pressure difference between the entrance and the exit of the mixing head in the down-channel direction, and the other screw to measure pressure variations in the cross-channel direction in the middle of the mixing head. Our experimental results showed both pressure decrease and pressure increase in the down-channel direction of the mixing head, depending upon the extrusion conditions employed. Using the flow analysis network (FAN) method, we predicted pressure variations in both the down-channel and cross-channel directions of the Maddock mixing head, which agree with experimental results.