Extrusion & Post
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PBAT melt index too high and blown film unstable
Problem Phenomenon
PBAT melt flow index is too high (>15g/10min), the blown film bubble is unstable, and thickness fluctuation is large.
Cause Analysis
PBAT molecular weight is low or degradation causes the melt index to be too high; flowability too good makes the film bubble difficult to shape; melt strength and flowability are unbalanced; recycled material blending reduces molecular weight.
Solution
①Select a grade with moderate melt index; ②chain extender to increase molecular weight and reduce melt index; ③control processing temperature to prevent degradation; ④limit recycled material proportion.; after adjustment, continuously sample to verify the effect, and resume mass production only after confirming stability
Key Takeaway
PBAT melt index management is the prerequisite for blown film stability; chain extender is the adjustment means; degradation prevention starts from the source.; after confirming effectiveness, solidify the parameters and practices into the work instruction to prevent recurrence
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