Blow Molding
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MP extrusion '2079851475616104457 severe parison sag
Problem Phenomenon
MP extrusion '2079851475616104457 parison sag 20-40mm causes bottle bottom wall thickness of only 0.3-0.4mm
Cause Analysis
MP melt strength low, parison stretched thinner under gravity; parison extrusion speed slow, increasing sag time; parison temperature high, viscosity low, aggravating sag
Solution
1) add slight crosslinking agent 0.3-0.5wt% to increase melt strength; 2) increase parison extrusion speed to shorten sag time; 3) reduce parison temperature 10-15°C to increase viscosity; 4) wall thickness controller to compensate sag
Key Takeaway
parison sag is caused by low melt strength; slight crosslinking and wall thickness control are key
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