With the Multi Rotation System (MRS), which was developed for degassing of polymer melts, the active surface of the melt is about 25 times greater than in a twin-screw extruder. The melt stream is fed to a rotating extrusion “drum”. Between eight and ten extruder barrels containing feed screws are arranged around the main axis of rotation. These screws are driven by a ring gear and rotate in the opposite direction. This amplifies the effect of surface exchange within the melt. The outer surface of the barrels in the drum has openings, so that optimum melt access assured and degassing of the melt can take place.
In addition, the temperature of the melt can be carefully controlled, since all surfaces that come in contact with the melt are temperature-controlled. The MRS technology can be incorporated into a single-screw extruder to process, for instance, undried PET bottle flakes quickly and in an uncomplicated manner. In the course of processing, the PET is not only dried; the intrinsic viscosity of the material is increased as well.
Additional applications include removing residual monomers, intentionally increasing the molecular weight through polycondensation or reducing the amount of odor-forming volatiles in the end product, for instance, in resins for automotive components. The MRS system can also be used to incorporate additional substances into the melt, e.g. chemical or physical blowing agents used to create foamed semi-finished goods.
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