Extrusion & Post
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EEA extrusion melt fracture
Problembeschreibung
EEA shows severe melt fracture at excessive extrusion rate, extrudate twisted in a spiral shape
Ursachenanalyse
EEA melt elasticity too high, elastic recovery at the die exit exceeding the critical value; die L/D ratio too short <10, melt not fully relaxed; extrusion temperature too low
Lösung
1) Reduce extrusion rate to 2-3m/min; 2) Increase die length-to-diameter ratio to 15-20; 3) Increase extrusion temperature to 160-210°C; 4) Add a small amount of low-elasticity resin to reduce system elasticity; 5) Gradually converging die inlet design
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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