Disclosed is a device for processing plastic materials, having a shredding unit, a conveying unit having a screw (7), and an extruder, having at least one extruder screw (11), adjoining the screw, wherein the central longitudinal axis (3) of the screw (7) is oriented at an angle to the central longitudinal axis (10) of the extruder screw (11), in particular at an angle of 80 to 100, preferably 90, and the longitudinal axis (3) of the screw (7) is offset with respect to the longitudinal axis (10) of the extruder screw (11) by an offset (v) in the direction of the direction of rotation (12) of the extruder screw (11) at or in the region of the discharge opening (8) or the intake opening (16) of the conveying unit.

Embodiments of an extruder comprise an extruder housing having an internal wall and a single screw coaxially disposed within the extruder housing, the single screw comprising a shank, wherein the shank and/or a region of the internal wall proximate the shank comprises helical channels. The extruder further comprises a feed channel downstream of the shank, and a visco-seal comprising the helical channels and the annular gap between the shank and the internal wall, wherein the annular gap is variable across its length.

An improved rubber composition having improved extrudate properties and exhibiting superior tolerance to aging when subject to multi-step mixing process and in particular to a mixing process where the rubber composition is mixed in a first mixer, cooled by passing between a pair of cylinders, then mixed in a second mixer, the composition comprised of a disulfide silane.