ABSTRACT
Counter-rotating, nonintermeshing (CRNI) twin-screw extruders have found wide acceptance in the isolation of polymers from solutions, the isolation of polymers from emulsions or suspensions, and in devolatilization-driven reactive extrusion processes. The full range of screw design technology applicable to single-screw extruders can be adapted to the CRNI twin-screw extruder. The low-rate-mass-transfer regime in a CRNI twin-screw extruder lends itself to a rational analysis without the uncertainties plaguing the analysis of the foam-enhanced, high-mass-transfer-rate devolatilization. CRNI twin-screw extruders have been used with good success as devolatilizers since the 1950s as found in US There are three basic types of twin-screw extruders: counter-rotating, nonintermeshing twin-screw extruders, which are used for compounding, polymer isolation, and for a wide variety of reactive extrusion processes; counter-rotating, fully intermeshing twin-screw extruders, which are principally used for extrusion of polyvinyl chloride pipe and profiles; co-rotating, fully intermeshing twin-screw extruders.
