Extrusion & Post
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Melt fracture in EAA extrusion
Problembeschreibung
EAA shows severe melt fracture when the extrusion rate is too high, and the extrudate is spirally distorted
Ursachenanalyse
EAA melt elasticity is too high, elastic recovery at the die exit exceeds the critical value; die L/D ratio too short <10, melt not fully relaxed; extrusion temperature too low
Lösung
1) Reduce the extrusion rate to 2-3m/min; 2) Increase the die L/D ratio to 15-20; 3) Raise the extrusion temperature to 180-240°C; 4) Add a small amount of low-elasticity resin to reduce system elasticity; 5) Design a gradually converging die entry
Wichtigste Erkenntnis
Melt fracture is caused by elastic recovery exceeding the critical value; reducing speed and lengthening the die are the core countermeasures
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