Vast improvements in polymer extrusion have been achieved through breakthrough innovations and inventions in fundamental mechanisms, machinery, screw and barrel design, functional operations, monitoring, and control. Discoveries in the fundamental extrusion mechanism played a major role in these inventions. Over the years, these discoveries helped identify the deficiencies existing in the original extruders, screw designs, and compounding processes, and hence initiated a variety of breakthroughs leading to the highly productive processes of today.

The discovery of the melt-pool/solid bed model stimulated breakthrough inventions of a series of barrier screw designs, and the mixing head, which vastly improved melting and mixing capabilities and stability in the single-screw extrusion process.

The discovery of the mixed-melting model and phase-inversion mechanism in twin-screw extrusion significantly enhanced polymer compounding capabilities. Selected examples are given to illustrate these breakthrough inventions. Additionally, the inventions of self-wiping twin-screw elements, kneading discs, modulated designs, and high-production-rate extruders utilizing high-torque, high-speed screw designs made the co-rotating twin-screw extruder the most popular machine in the extrusion world.

Selected innovations in compounding and polymer blends, esp. plastic/rubber blends, are also highlighted in the discussion.

These inventions not only impacted the industry with respect to the demand for extruded products with consistent quality at ever-increasing production rates, but also led to significant advances in the science and technology of the engineering discipline. Stories behind some of these inventions are also presented.

This presentation is based on the ANTEC 2009 paper co-authored by Paul Andersen, Coperion Corp.; Chi-Kai Shih, Chi-Kai Shih LLC; Mark A. Spalding, The Dow Chemical Co.; Mark D. Wetzel, E. I. du Pont de Nemours & Co., Inc.; and Timothy W. Womer, Xaloy, Inc.