Closely intermeshing

These two-phase polymers are generated in an optimized single-stage process using a corotating, close-intermeshing, twin-screw extruder. 

K. J. Gadzenveld and L. P. B. M. Janssen, Scale-up of Counter-rotating Closely Intermeshing Twin Screw Extruders without and with Reactions, Polym. Eng. Sci., 30, 1529-1536 (1990). 

Fig. 13.1. Different types of extruders, a) single screw b) co-kneader c) non-intermeshing, mixing mode d) nonintermeshing, transport mode e) counter-rotating, closely intermeshing f) co-rotating, closely intermeshing g) conical counter-rotating h) self-wiping, co-rotating.

Closely intermeshing co-rotating twin screw extruders occupy a dominant position among extruders and are used in a wide variety of applications. They are not only used extensively in the production, compounding, and processing of plastics, but also employed in large numbers in other branches of industry, e.g., the rubber and food processing sectors. 

The first closely intermeshing twin screw extruders were built by Bayer using their own design (Section 2.1) and featured a vertical arrangement of the screws. Figures 1.2 and 1.3 show such a screw arrangement built by Bayer for chemical reactions. 

Screw Elements for Co-rotating, Closely Intermeshing, Twin-Screw Extruders... 

From the time they were first developed, co-rotating, closely intermeshing twin-screw extruders have proven to be highly effective for the continuous treatment of viscous products and they have successfully replaced many discontinuous technologies. They will certainly continue to be successful in other markets in the future, facilitating new production processes. 

The closely intermeshing, self-wiping basic elements, which wipe off each other and also the... 

Fig, 5.25. Geometry cross section for closely intermeshing co-rotating twin screw extruders... 

The necessary ingredients for successful drug discovery are thus close intermeshing of chemistry, pharmacology, and clinical medicine. However, the state of the art in each discipline must be sufficiently advanced to allow the simultaneous convergence of the three disciplines toward the creation of novel therapy. 

To really control the mixture and dispersion of additives, or to do reactive extrusion, a twin-screw extruder is necessary. Twin-screw extruders are available in several different configurations, but for the work of compounding the most often used is a closely intermeshing co-rotating extruder, with a specially designed screw for the particular task. In order to accomplish this with the least amount of machining. 

The machines mainly used for compounding plastics, chemicals and food are co-rotating, closely intermeshing twin-screw extruders. Some 30 000 such extruders are in use worldwide, about 1/3 are ZSK from Coperion Werner Pfleiderer, Stuttgart. In the chemical industry increasingly more and more batch mixers are being replaced by continuous twin-screw knea-ders. 

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