Intermeshed co-rotating

PC PC/15% MWNT masterbatch 2 wt.% 105 2-cm Melt mixing in intermeshing co-rotating twin screw extruder... 

The industrial use of twin-screw extruders for this purpose revolves extensively, but not exclusively, around intermeshing co-rotating variants. Closely in-termeshing counter-rotating designs are widely used for profile extrusion of UPVC dry-blends since they permit close temperature control and exhibit a high conveying efficiency due to the positive displacement of material where the screws intermesh [150]. 

A. C. Y. Wong, F. Zhu, and T. Liu, Qualitative Study on Intermeshing Co-rotating Twin Screw Extrusion Using Novel Visual Technique, Plast. Rubber Comps. Proc. Appl., 26, 271 (1997). 

L. Zhu and X. Geng, Visual Research of Melting Mechanism of Polymer Pellets in Intermeshing Co-rotating Twin-screw Extrusion, SPE ANTEC Tech. Papers, 55, 3684 (1997). 

Fig. 10.1 Photograph and schematic representation of the modular screw-element sequences and barrel sections of an intermeshing, co-rotating TSE. [Courtesy of Coperion Werner and Pfleiderer Corp.]...

The fully intermeshing, co-rotating TSEs shown in Fig. 10.1 are by far the most widely used twin screw-based processing equipment. They were developed in the 1940s by... 

Fig. 10.8 Fully intermeshing, co-rotating elements in configurations matching square-pitch screws, (a) Forward screw conveying elements with different numbers of lobes (b) forward staggered kneading paddles (a.k.a., disk elements) representing leaky screw elements, and (c) neutral configuration. [Reprinted by permission from D. B. Todd, APV (Baker Perkins) Systems, in Plastics Compounding—Equipment and Processing, D. B. Todd, Ed., Hanser, Munich, 1998.]...

Fig. 10.11 Snapshots of the repetitive expansion/contraction of each of the cross-sectional area pockets between a pair of kneading disks and the barrel of fully intermeshing, co-rotating extruders. The evolution of the expansion/contraction is followed for one of the three pockets, ...

B. Qian and C. G. Gogos, The Importance of Plastic Energy Dissipation (PED) to the Heating and Melting of Polymer Particulates in Intermeshing Co-rotating Twin Screw Extruders, Adv. Polym. Tech., 19, 287-299 (2000). 

Y. Wang, J. L. White, and W. Szydlowski, Flow in a Modular Intermeshing Co-rotating Twin Screw Extruder, Int. Polym. Process., 4, 262-269 (1989). 

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 desired self-cleaning function led to the development of the intermeshing twin screw. The counter-rotating screw was discarded, because it tended to get blocked by solids and was a poor mixer attention focused instead on the intermeshing, co-rotating extruder. 

Material transport in intermeshing, co-rotating twin-screw extruders is generally dependent on drag flow. The screws pick up the material as they rotate and, where the two screws meet, a complete transfer of the material from one screw to the other takes place, see Fig, 4. The tip of one screw wipes the flanks and roots of the other screw, resulting in a self-wiping action. As the material is transferred from one screw to the other, the direction of material flow is changed and new material surfaces are created with each screw revolution. 

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

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 concept of a self-wiping co-rotating twin-screw extruder dates to the beginning of the twentieth century (Figure 1.14) [77, 78]. However, an intermeshing co-rotating t vin-screw extruder was not commercialized until 1939. This was initiated by Roberto Colombo [79] and Lavorazione Materie Plastische (LMP) in Turin, Italy. 

Figure 3.7 Fully Intermeshing, co-rotating twin-screw extruder. BP Process Equipment Systems, Saginaw, Ml, USA.

These two books and others considered that an intermeshing co-rotating twin-screw extruder is the preferred choice among many pieces of equipment that have been used for manufacturing polymer compounds of various compositions. This chapter will highlight the key features of each type of equipment described in these two books and add current developments in the design of each equipment area that... 

Intermeshing Co-rotating (or Co-rotating Intermeshing) Twin-Screw Extruder ... 

Figure 5.13 shows a schematic representation of the modular screw-element sequences, barrel sections, and overall assembly of an intermeshing co-rotating twin-screw extruder. 

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