The following graphic shows measurements with PET at 300°C to determine the processing window. Analogous to the production machine, a 20 mm extruder with online rheometer MBR is used as melt pump. A die L/D = 20 / 1 mm is used with a melt throughput of 1.5 g/min and a spinning length of 1200 mm.
Here, a different target speed is directly approached in each test. The acceleration ramp is also recorded in the force diagram. The tests are stopped after 120 s in each case. While the pull-out at 3000 and 4000 m/min still functions without any problems in steady-state operation, a premature break occurs at 4500 m/min.
At 5000 m/min, the final speed is not reached at all.