Polymer Processing Institute


The tandem extruder at PPI consists of a 34 mm co-rotating intermeshing twin screw extruder (mixing extruder) feeding a 40mm single screw extruder (cooling extruder). Polymer pellets or powders are meter fed into the hopper of the twin screw extruder. The polymer is plasticated in the first section of the extruder. Physical blowing agent is pumped into the next section of the extruder, where it is mixed with the polymer. In the last section of the twin screw, the polymer-blowing agent charge is compressed to high enough pressure to dissolve the blowing agent into the polymer. The single screw extruder or the cooling extruder accepts the polymer at high pressure and cools the melt down at constant pressure. The screw of the cooling extruder is segmented and hence designed to optimize the cooling, mixing and pumping characteristics. There are three barrel sections on the cooling extruder. Heat transfer fluid is circulated through the shell side of the barrel to extract the heat out of the polymer. The die is mounted on the barrel of this cooling extruder. Polystyrene, polyethylene, polypropylene and various copolymers were foamed down to 3 pcf using carbon dioxide gas and to 1 pcf using VOC. Normally closed cell foams were produced in this setup.

For more information please contact

Dr. Niloufar Faridi

(973) 596-5665

faridi@polymers-ppi.org