The influence of construction elements of the screw on the characteristic of blown film extrusion
Polimery 2002, No 6, 435
Experimental results on the effect of various construction element features responsible for intensive shearing and mixing and screw rotation speed (ν) on characteristics of film extrusion with free vertical upward blow are presented. Experiments were performed using an intensive shearing and mixing ring located at the screw feeding zone, allowing to vary the gap (δ) between external surface of the ring active surface and inner surface of the extruder barrel. Dependences of polymer mass flow rate (Ġ), polymer pressure in front of the ahead (ρ), specific energy consumption of the extruder conducted to its power transmission system (EJN) and component energy efficiency of the extruder (ĸ) (coming from its power transmission system) on ν at different δ values were presented. Increase in rotation speed of the screw for all investigated δ values causes increase in Ġ, ρ and ĸ, and reduction of EJN. Visual inspection of the resultant film shows that the changing geometrical factors (δ, intensive shearing and mixing ring active barrel surface — de, channel inclination angle on inflow and outflow from the gap — a) and ν values to not affect homogenization and appearance of the extruded film.
Keywords: blown film extrusion, screw shearing and mixing elements, extrusion characteristics, low-density polyethylene