The Mechanical Properties of Plasticized PVC Processed in an Extruder with a Modified Feed Zone

The work presents the results of experimental studies of selected mechanical properties of plasticized poly(vinyl chloride) extruded by a single-screw extruder with a modified feed section. The variable factors were: feed opening width, feed pocket depth in the extruder barrel and the rotational speed of the screw. The following parameters were studied: yield strength ReH (MPa), tensile strength Rm (MPa), percentage total extension at maximum force ∊m (%), Shore hardness H (°ShA). It was found that the increase in the depth of the pocket and the decrease in the width of the feed opening in the studied range increase mechanical properties (besides percentage total extension at maximum force). It was determined that the increase of the screw speed and the simultaneous displacement of both the axis and edge of the feed opening in relation to the plasticizing system axis towards the direction of revolutions of the screw is favorable.

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.