Choice of the number and placement of the extruder barrel plasticating grooves as the possibility of extrusion process controlling

The results of the studies of the influence of the number and placement of the extruder barrel plasticating grooves, in relation to the hopper and the direction of the screw rotation as well as in relation each to other, on the values characterizing the process of autothermal extrusion of low density polyethylene (PE-LD) were presented. A single-screw extruder of the screw diameter 25 mm and L/D = 18, operating autothermally, was used and screw rotation frequency was fixed. A grooved sleeve with four longitudinal plasticating grooves, placed symmetrically on the circumference, was fixed in the barrel. Their depths could be changed continuously and independently making possible to reach the required configuration of the number (from 0 to 4) and placement of the activated grooves (Table 1). The appropriate direct and indirect resulting factors, variable, constant or disturbing were accepted. The dependence of the following factors: polymer flow rate (Fig. 2), energy efficiency of the extruder (Fig. 3) and plasticating system (Fig. 4), unit energy consumption taken by the extruder (Fig. 5) and plasticating system (Fig. 6) on the number and placement of the activated grooves was found. It was found that these factors, in agreement with the assumptions done, significantly influenced the course of the process investigated. The placement of the activated grooves (not their number) in relation to the hopper and each to other appeared to be of crucial importance.