An extruder for thermoplastics having a directly motor-driven high- speed feed screw which mechanically force-feeds raw plastic pellets, pushing them forward under high pressure into a heat-transfer zone for melting, and finally through a static mixer, to deliver a pressurized homogeneous melt to an extrusion die. Melt pressurization results entirely from the mechanical force-feeding action of the screw rather than through the viscous shear action found in conventional screw extruders.
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