Material Drying
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PC Brittleness Caused by Regrind Use
Problem Phenomenon
After mixing in PC regrind, product impact strength decreases, transparency deteriorates, and melt index rises.
Cause Analysis
PC regrind's molecular weight decreases after thermal history, and regrind absorbs moisture faster; crushed material contains fine powder and plasticizes unevenly; regrind that has undergone hydrolysis aging is even more harmful, with performance dropping off a cliff.
Solution
①Control the regrind ratio to ≤20% and re-dry; ②Remove fine powder; ③Avoid using regrind that has undergone hydrolysis aging; ④Use all-virgin material for critical load-bearing parts and optical parts; ⑤Establish a regrind performance ledger.
Key Takeaway
PC regrind = 'dual deterioration of moisture content and molecular weight': the ratio must be strictly controlled, and it is firmly not used for optical parts and load-bearing parts; PC is sensitive to thermal history and hydrolysis, so regrind management must be stricter than for general-purpose materials.
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