Material Drying
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PET drying 100 ppm and IV loss
Problem Phenomenon
Products processed from recycled PET become brittle, and the IV value falls below the usable lower limit of 0.70 dL/g
Cause Analysis
The PET recycling specification requires drying to below 100 ppm with IV loss <0.04 dL/g; excessive hydrolysis reduces the molecular weight, and impact strength, rigidity, and chemical resistance deteriorate across the board, with the products falling out of the usable range
Solution
①Drying temperature 280-320°F (about 138-160℃) with dew point <-20°F; ②dry pellets for 4 hours and recycled material for 5-6 hours; ③monitor IV loss <0.04 dL/g as the release indicator
Key Takeaway
PET drying quality is quantified by IV loss; the dual indicators of 100 ppm plus 0.04 dL/g are the industry benchmark for recycled PET quality control; after confirming effectiveness, solidify the parameters and practices into the work instruction to prevent recurrence
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