Influence of constructional features of the twin-screw plasticizing system
on the characteristic of extrusion process
Polimery 2003, No 6, 443
The research is focused on the constructional improving of twin-screw co-rotating plasticizing systems by changing the screws? configurations. So the effects of constructional features of such systems on the selected parameters characterizing the process of polypropylene (PP) extrusion, especially on a change of a polymer structure, have been determined. The dependence of extruded PP degradation degree [measured as a change of melt flow rate (MFR) value, Table 4] on the configurations of the screws (Table 2, Fig. 4) has also been evaluated. The changes of the structures of PP compositions containing the additives (e.g. light and thermal stabilizers) have been investigated using DSC (Table 3) and FT-IR (Figs. 5 and 6) methods. It has been found that in the process of discussed co-rotating construction system, the necessity of reaching the required temperature of a polymer during its redrawing to the plasticizing zone, as a result of feeding zone elongation, should be taken into account. Next significant requirement concerns the decrease of drive energy scattering in the plasticizing zone by using of kneading segments supporting the transport and minimization of the channels volume reduction. The assessment (evaluation) of the course of the process of a direct extrusion of PP containing chalk as a filler, dependently on various screws configurations and place of feeding a chalk and chalk amounts, has also been presented. Mechanical properties of the pipes obtained (Table 5, Fig. 8) as well as dispersion degree of the filler in a polymer (Fig. 7) were investigated.
Keywords: twin-screw co-rotating plasticizing system, polypropylene extrusion, screw configuration, polymer degradation, mineral filler, direct extrusion of pipes, pipes properties
MeInfluence of constructional features of the twin-screw plasticizing system on the characteristic of extrusion process