Material Analysis
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PET regrind contamination introducing impurities
Problem Phenomenon
The preforms show black specks, white haze, and mechanical property fluctuations, and tracing finds that other plastics and contaminated material have been mixed into the regrind.
Cause Analysis
Regrind sources are complex, with incompatible plastics such as PVC mixed in or contamination by oil, water, and vapor; the regrind itself has experienced thermal history and has low IV, and its incorporation pulls down the overall performance.
Solution
①Strictly control regrind sources and classified management; ②reduce the regrind blending ratio; ③re-dry the regrind and sieve it to remove impurities; ④test the IV and AA after blending regrind.
Key Takeaway
Regrind management is an important variable for preform quality; source control, ratio limits, and re-drying are all indispensable, and food-grade applications require even more compliance evaluation.; after confirming effectiveness, solidify the parameters and practices into the work instruction to prevent recurrence
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