New developments in solid-state extrusion

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Abstract
A few developments have been discussed that extend the range of the solid-state extrusion process for processing polymers and polymer morphologies that were difficult to process by conventional solid-state extrusion. The split billet and the push-pull extrusion techniques proceed at faster rates by comparison to the conventional process. When combined they allow the preparation of extrudates of maximum draw ratio that can be obtained under a load equivalent to the tensile strength of the extrudate at the extrusion temperature. The split billet technique as a coextrusion process eliminates various problems associated with the extrusion process. Thus, by adjusting the dimensions of the components the extrusion pressure and the extent of shear flow may be reduced. In the coextrusion of aliphatic polyamides with HDPE the presence of the ammonia plasticizer reduces significantly the load required to deform the polyamides in the solid state.