Feeding an Extruder of a Modified Feed Zone Design with Poly(vinyl chloride) Pellets of Variable Geometric Properties

The extrusion process is greatly affected by both feed zone geometry and dimensions of pellets fed into the hopper. The paper presents the results of studies undertaken to investigate the effect of both the dimensions of a feed pocket made in the barrel below the feed opening and pellet length on the single-screw extrusion process for plasticized poly(vinyl chloride). The dependencies of the extrudate temperature, extruder screw torque, polymer mass flow rate and unit energy consumption supplied to the extruder on the above mentioned variable factors were determined. It has been found that the most advantageous solution for the investigated screw speed range is to run the extrusion process at the highest screw speeds possible, feed the extruder with pellets whose length is similar to their diameter, and use the feed pocket in the barrel.