Efficiency of the extrusion process and characteristics of a conical-circular die

The effects of die constructional features (circular channel diameter and length, conical channel length - dies I-IV, Table 1, Fig. 3) on selected properties, characterizing and unequivocally determining the efficiency of the process of low-density polyethylene autothermal extrusion, have been investigated. The following parameters were analyzed: polymer mass flow rate (G, Fig. 4), thermal power conveyed by the polymer (QN, Fig. 7), power supplied to the extruder (Qc, Fig. 5), efficiency of the extrusion process (kp, Fig. 8) and specific consumption of a total energy supplied to the extruder (Ejc, Fig. 6), dependently on a screw rotation frequency (n = 3.7-5.17 s-1). Additionally the distribution of temperature and pressure of a polymer processed along the plasticating unit and extrusion die, dependently on the length/diameter (L/D) ratio of the screw for various dies (I-IV, Fig.9 and 10) were determined. Most advantageous energetic conditions that is best efficiency of autothermal extrusion process were obtained for die IV (kp = 73 %).