Abstract: The present invention is directed to a device for the production of a cellular wood plastic composite material comprised of an orifice that conducts the composite material from the adapter of the extruder to the transition die plate in such a manner that a uniform flow of material reaches the transition die plate; a transition die plate that further directs the flow of material to a flow restriction die plate in a manner ensuring that equal amounts of material are delivered to all areas of the flow restriction die plate; a flow restriction die plate that provides sufficient resistance to material flow to increase the melt pressure of the portion of the material that is upstream in relation to the flow restriction die plate and controls the temperature increase caused by this restriction by dividing the flow into numerous suitably sized and shaped streams; a compression die plate that fuses the separate streams issuing from the flow restriction die plate into a single stream of material and maintains the melt

Abstract: A low-pressure CO2 tank or an air compressor with a refrigerated air dryer is attached either at or after the vent zone of a standard twin-screw extruder. During or after extrusion, the gas is dissolved in the wood-plastic melt. The CO2 expands which foams the wood-plastic material.