Reactive Mixer Offers Lots of Free Volume.
An unusual twin-shaft reactive-extrusion machine can be configured as a batch or continuous process. It is quite different from a
conventional twin-screw extruder. Developed eight years ago by Swiss
machine builder List AG, which has U.S. offices in Acton, Mass., it has
been used primarily by resin makers but also increasingly for reactive compounding. It takes in liquid materials. Because the rotor shafts and
blades are hollow, it can heat or cool very efficiently, promoting
reactions that convert very low-viscosity materials to very
high-viscosity polymers while devolatizing them and mixing in additives.
Of 400-plus installations worldwide and nearly 50 in the U.S., about
half are used in reactive plastic compounding, List says. The
kneader-reactors are custom built from a 1-gal lab model to over