Experimental studies on autothermal extrusion of low density polyethylene (LDPE)
Polimery 1997, No 9, 565
LDPE was autothermally extruded in a conventional T-32 extruder (ZMCh „Metalchem”, Gliwice, PL) equipped with a three-zone screw (L/D = 25), circularhead and a cooling and a receiving system. The total thermal power (QG) generated in, and transferred (QN) by the polymer, total power loss (QQS), polymer mass and volume flow rates (G and W), extruder's energy efficiency (kW) and total energy consumption per unit mass (EJC) are plotted against the rotational speed (v) and angular velocity (ω) of the screw. The distributions of temperatures along the plasticating system and along the extrusion head are described. The temperatures at the surface (tWZ) and at the center (tWS), of the extrudate are plotted against the screw speed. Selected physical properties of the extrudate are discussed in relation to autothermal extrusion conditions. Mass flow rate (MFR), extrudate swelling (corrected Barns effect), and extrudate hardness at various cross-section points were measured.