Material Drying
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PET Bottle Body White Haze (Hydrolysis Type)
Problem Phenomenon
The whole bottle presents uniform hazy turbidity, accompanied by brittleness and rough surface, tiny bubbles visible in severe cases, and strength significantly decreased.
Cause Analysis
The preform is damped during storage or insufficiently dried; during blowing heating, moisture triggers hydrolysis, molecular chains break and micropores are produced that scatter light; preforms stored too long in high-humidity environments are a high-incidence scenario.
Solution
①Store preforms sealed and control warehouse humidity; ②re-dry damped preforms or switch to fresh preforms; ③test preform moisture content and IV value; ④first-in first-out to shorten the inventory cycle.
Key Takeaway
Hydrolysis-type white haze is often accompanied by embrittlement and is a material defect rather than a pure process problem; controlling moisture from the preform storage stage is the most economical, and damped preforms are not recommended to go online directly.
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