Views:4 Author:Site Editor Publish Time: 2017-08-01 Origin:Site
① Technological progress of screw extrusion
The screw extrusion does not develop at once. The history of the screw extrusion is also very tortuous, and each generation of updates has been tested many times. So how does the screw extrusion develop? Read this article to learn more about the history of the screw extrusion.
The first single-screw extruder for polymers was produced in 1951 in Japan for extrusion of wire/cable coating from low density polyethylene. Since then, many kinds of single-screw extruders have been manufactured and used for example, for fiber-spinning of polyamide and polyester and for film-making of poly (vinyl chloride) and polyolefin.
A single-screw extruder is roughly composed of three zones, that is, solid conveying, melting and melt conveying (metering). Theoretical simulation on single-screw extrusion was started for molten polymer flow in the metering section by Carley et al. in 1953. Furthermore the first melting theory was published by Tadmor in 1966
However, practical extrusion behavior is normally more complicated than such theoretical models. Therefore various theories concerning molten polymer flow, melting and solid conveying in single-screw extruder have been reported until now .Thanks to the technological progress in extrusion, a lot of mixing elements for a single-screw extruder have been developed and recent theoretical simulation allows analyzing three-dimensional and non-isothermal flow and mixing behaviors. In addition to recent progress in theoretical simulation techniques, the utilization of extensional flow mixing is becoming popular as well as shears flow mixing.