Abstract: An extruder of the variety including a body having a cylindrical bore therethrough, and a shaft rotatably supported within the bore. The shaft includes at least a first helical flight means defining a main channel. The shaft is divided along its length into a feed section, an intermediate melt section, and at least one metering section. A portion is included in one of the sections which has a plurality of discrete grooves arranged in a discontinuous helix cut into the main channel. There is preferably a plurality of staggered rows of grooves within the main channel, the axis of each row being substantially parallel to the helical axis of the adjacent first helical flight means. The grooves are adapted to so receive the material forced through the extruder that the average shear force exerted against the material, and thus, the average temperature of the material, is reduced while the output of the material is maintained at a predetermined level.

Abstract: An injection molding screw for use in processing heat sensitive polymeric materials and a process for plasticating such materials. The screw has an inlet end, a discharge end, means for mounting a backflow valve on the discharge end, and at least one section which applies high shear and high compression to the polymeric material and controls the material flow rate. A flighted screw section is disposed between the high shear and high compression section and the discharge end; that screw section includes means for decompressing the polymeric material and pumping it to the discharge end of the screw in the decompressed state at a rate at least equal to the pumping rate of the zone of high shear and high compression.

Abstract: An injection molding screw for use in processing heat sensitive polymeric materials and a process for plasticating such materials. The screw has an inlet end, a discharge end, means for mounting a backflow valve on the discharge end, and at least one section which applies high shear and high compression to the polymeric material and controls the material flow rate. A flighted screw section is disposed between the high shear and high compression section and the discharge end; that screw section includes means for decompressing the polymeric material and pumping it to the discharge end of the screw in the decompressed state at a rate at least equal to the pumping rate of the zone of high shear and high compression.