Twin Screw Extrusion
Twin-screw extrusion is used extensively for mixing, compounding, or reacting polymeric materials. The flexibility of twin-screw extrusion equipment allows this operation to be designed specifically for the formulation being processed. For example, the two screws may be co-rotating or counter-rotating, intermeshing or nonintermeshing. In addition, the configurations of the screws themselves may be varied using forward conveying elements, reverse conveying elements, kneading blocks, or other designs in order to achieve particular mixing characteristics.
The twin-screw extruder has the same three basic components as the single-screw extruder—the drive section, the process section, and the die/discharge section. The biggest difference between the two is that the twin-screw, as its name indicates, has two screw shafts inside the barrel rather than one. In addition, the twin-screw barrel and screw are usually built with modular components. The principal exception is the counter-rotating extruder used for profile extrusion.(Andersen, 8/7/2010)
More on Twin Screw Extrusion by Paul Andersen
Paul Andersen, Contributor
Recent Journal Articles
1/4/2011
Simulation of screw pumping characteristics for intermeshing counter-rotating twin screw extruders
(37–42)Polymer Engineering & Science 51 #1 (2011)
Jiang, Yang and White of the University of Akron, Ohio developed simulations for intermeshing counter-rotating twin screw extruders and extrusion of profiles and pipe, largely from polyvinyl chloride. Here we extend these efforts to a broader range of screw designs, especially with deeper screw channels where transverse shearing induced by the flights is important. Calculations are done for isothermal power law fluids. (RDC 2/2/2011)
1/7/2010
Influence of crystallinity on the fracture toughness of poly(lactic acid)/montmorillonite nanocomposites prepared by twin-screw extrusion
(896–905)Journal of Applied Polymer Science 120 #2 (2011)
Gamez-Perez et al, Spain prepared samples with two different compositions (0.5 and 2.5% weight OMMT in PLA) by melt mixing in a twin-screw extruder and injection molding. An annealing treatment was applied to increase the percentage of PLA crystallinity. The results show a toughening effect of the nanocomposites on amorphous specimens but embrittlement by annealing. (RDC 1/11/2010).