A plastic material extruder combines the features of a generally flat rotatable disc and a generally flat opposed stator. At least one of the two is heated by heating elements. The two define a processing gap into which a hopper for feeding a plastic material mixture is discharged. The rotor and the stator develop a high shear force which further heats up the processed mixture in addition to the heating delivered by the heating elements. At the center of the disc/stator assembly, an axial force developing device such as a ram or a feed screw or screws is adapted to further compress and extrude a mixture of the thermoplastic components and thermosetting components, the latter being comprised of crumbled pieces of used tires. The extruder is shown in two embodiments, one injecting the processed alloy into a mold, the other producing pellets of the processed alloy.