Extrusion & Post
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EVOH extrusion surface is rough
Problem Phenomenon
EVOH extruded product surface roughness Ra>5μm, exceeding requirements
Cause Analysis
Extrusion temperature too low <190°C with unstable melt flow; die inner wall rough or damaged; EVOH melt elasticity with uneven extrusion swell
Solution
1) Increase extrusion temperature to 190-230°C; 2) Polish die inner wall to Ra<0.4μm; 3) Reduce extrusion rate by 10-15%; 4) Add 0.3-0.5wt% external lubricant
Key Takeaway
Surface roughness is caused by low-temperature extrusion and die defects; increasing temperature and polishing the die are core countermeasures
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