There is a trend to perform compounding and devolatilization in a twin screw extruder and to produce TPE sheet or profile in one-step, bypassing pelletizing. Coextruded and foamed products also benefit from twin screw technology. Advantages associated with direct extrusion from a twin screw compounder include: the materials having one less heat history, the elimination of paying a toll compounder's conversion costs, and the ability to fine tune a formulation on-line. Significant machine system, control and formulation developments in recent years make direct extrusion preferable for many applications that formerly used two process steps. Notwithstanding the technical successes of direct extrusion, the product mix and anticipated volumes need to be assessed to determine which process sequence is preferred- pelletizing or direct extrusion.
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