Extruder co-rotating

Machine Type single screw extruder, twin screw extruder (co-rotating), twin screw extruder (counter-rotating), multi screw extruder, buss co-kneader, internal mixer, static mixer. 

Counter-rotating extruders Co-rotating extruders Equal screw length Unequal screw length Not used in practice... 

Items Single- Screw Extruder Co-Rotating Twin Screw Extruder Counter- Rotating Twin-Screw Extruder... 

Comparison of single-screw, co-rotating and counter-rotating twin-screw extruders... 

Report 116 Compounding in Co-rotating Twin-Screw Extruders, Y. Wang, Tunghai University. 

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]. 

Fig. 26. Typical mixing elements for a co-rotating intermeshing twin-screw extruder...

Fig. 27. Progressive dispersion of calcium carbonate in polypropylene within a co-rotating intermeshing twin-screw extruder. Filler dispersion is expressed in terms of a mean volume diameter determined by image analysis...

A mixture consisting of powdered polypropylene (59.91 g) and the step 1 product (90 mg) were tumble-mixed in a glass container for 24 hours. Thereafter the mixture (4.5 g) was compounded at 239°C using a small co-rotating twin-screw extruder. The sample required 4 minutes at a screw speed of 40rpm to be prepared. The extruded material only had a slight haze content. 

Fig. 2. Internieshing co-rotating twin-sciew extruder A, motor B, gear box C, feed port D, clam shell barrel E, vent port F, screw shafts G, conveying screws H, kneading paddles I, barrel valve and J, bHster rings. Courtesy of APV Chemical Machinery Inc.

Potente H, Bastian M, Bergemann K, Senge M, Scheel G, Winkelmann T (2001) Morphology of polymer blends in the melting section of co-rotating twin screw extruders. Polym Eng Sci 41 222-231... 

Several studies have been performed to evaluate the mixing capabilities of twin screw extruders. Noteworthy are two studies performed by Lim and White [12,13] that evaluated the morphology development in a 30.7 mm diameter screw co-rotating [28] and a 34 mm diameter screw counter-rotating [3] intermeshing twin screw extruder. In both studies they dry-mixed 75/25 blend of polyethylene and polyamide 6 pellets that were fed into the hopper at 15 kg/h. Small samples were taken along the axis of the extruder and evaluated using optical and electron microscopy. 

Figure 3.38 Number and weight average of polyamide 6 domain sizes along the screws for a co-rotating twin screw extruder with special mixing elements.

Figure 10.39 Pressure distribution on the screw surfaces of a co-rotating double flighted twin screw extruder.

Figure 10.40 Particle tracking inside a co-rotating double flighted twin screw extruder. In order to plot the flow lines, the system is viewed from a coordinate system that moves in the axial direction at a speed of Rftshuj).

Co-rotating, intermeshing twin screw extruder The Banbury... 

H. Potente and U. Melish, Theoretical and Experimental Investigations of the Melting of Pellets in Co-rotating Twin-screw Extruders, Int. Polym. Proc., 11, 101 (1996). 

S. Bawiskar and J. L. White, A Composite Model for Solid Conveying, Melting, Pressure and Fill Factor Profiles in Modular Co-rotating Twin Screw Extruders, Int. Polym. Proc., 12, 1331 (1997). 

B. Vergnes, G. Souveton, M. L. Delacour, and A. Ainser, Experimental and Theoretical Study of Polymer Melting in a Co-rotating Twin Screw Extruder, Int. Polym. Process., 16, 351-362 (2001). 

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