Mixing in single screw extruders

Fig. 23. Screw sections for enhancing distributive mixing in single-screw extruders (a) Dul-madge mixer, (b) Saxton mixer, (c) pin mixer, (d) pineapple mixer, (e) cavity transfer mixer, (f) slotted screw flight, (g) Kenics and Ross ISG static mixers [148]...

Mixing in single screw extruders. Mixing caused by the cross-channel flow component can be further enhanced by introducing pins in the flow channel. These pins can either sit on the screw as shown in Fig. 3.29 [9] or on the barrel as shown in Fig. 3.30 [15]. 

Erwin [8] developed the theoretical background to assess the effect orientation has on the distributive mixing in single screw extruders. His starting point was the equation that relates the growth of an interface between fluids undergoing shear flow (Fig. 6.43), and described... 

Fig. 6.11 Vector field of the cross-channel flow of an incompressible isothermal Newtonian fluid in a channel with an aspect ratio of 5. [Reprinted by the permission from M. Kaufman, Advection and Mixing in Single Screw Extruder—An Analytic Model, The AIChE Annu. Tech. Conf. Meeting Proc., San Francisco (2003).]...

M. Kaufman, Advection and Mixing in Single Screw Extruder—An Analytic Model, The AIChE Annual. Techn. Conf. Meeting Proc., San Francisco (2003). 

C. Rauwendaal, Mixing in Single Screw Extruders, in Mixing and Compounding of Polymers, I. Manas-Zloczower and Z. Tadmor, Eds., Hanser, Munich, 1994. 

Figure 2. Schematic diagram of mixing in single screw extruder.

C Rauwendaal. Mixing in single screw extruder. In I Manas-Zloczower and Z Tadmor, eds. Mixing and Compounding of Polymers. New York Hanser, 1994, pp 251-329. 

The mixing in single screw extruders was also studied by Tadmor and Klein [103] who used the mean strain to evaluate the mixing performance of the extruder their result is shown in Fig. 7.133. 

Mixing in single screw extruders is determined mostly by the two main velocity components in the screw channel. These are the velocity in the direction of the channel (z-direction) and the velocity in the cross-channel direction (x-direction) (see Fig. 45). 

Striation formation is an essential part of the distributive mixing process. In Chapter 2 it was shown diagrammatically how an individual pellet was transformed into a striation in a simple laminar shear field - the mechanism available for mixing in single screw extruders. 

Houston, Tx., 25th-28th Feb. 2001, p.411-30 ELONGATIONAL MIXING IN SINGLE SCREW EXTRUDERS LukerK... 

---