Extrusion & Post
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DSTDP extrusion melt fracture
Problembeschreibung
DSTDP shows severe melt fracture when extrusion rate is too high, the extrudate is spirally twisted
Ursachenanalyse
DSTDP melt elasticity 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 on the low side
Lösung
1) Reduce extrusion rate to 2-3m/min; 2) increase die L/D ratio to 15-20; 3) raise extrusion temperature to 160-200°C; 4) add a small amount of low-elasticity resin to reduce system elasticity; 5) gradually converging die entrance 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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