Influence of Selection of Extruders on the Processing of Recycled PET Flakes

The recycled PET flake was re-processed with various extruders, including single screw extruder, twin-screw extruder, grafting reactive extruder, and poly condensation reactive extruder. The intrinsic viscosity([η] ) of the extrudates was compared. When a single screw or twin-screw extruder was used, the resulted [η] was generally lower than that of the feed. However, when a grafting reactive extruder was employed, the [η] of the extrudate was about 0.83 dL/g. The [η] values between 0.70 and 1.0 dL/g could be obtained using a polycondensation reactive extruder. DSC and WAXD analysis showed that the recycled PET had similar thermal properties and crystal structure as the commercial new one, and thus was suitable for the production of bottles.