Intermeshing co-rotating extruders

Good feeding, can handle pellets, powder, liquids 

Good melting dispersed solids melting mechanism 

Good distributive mixing with effective mixing elements 

Fair feeding, slippery additives tend to give problems 

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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, ...

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. 

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. 

These openings are considerably smaller than in intermeshing co-rotating extruders see also Figs. 10.3 and 10.4. As a result, CICT extruders can achieve relatively positive conveying characteristics. 

The first known twin screw device was an intermeshing co-rotating extruder invented in 1939, and patented in 1949 [66]. Developments in twin screw extruders have come a long way since then. The mechanisms of different types of twin screw extruders shown in Figure 5.13 make a distinction between axially open machines, where there is a... 

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]. 

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. 

Figure 2.8 Multiple shaft co-rotating extruder system with full intermeshing and mutual cleaning of the shafts. There is a continuous connection between A, B, C, and D etc. The possible material movements in principle are as follows ...

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... 

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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