Production & Quality
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PU repeated processing performance degradation
Problem Phenomenon
After 3-4 times of recycling and reprocessing, the tensile strength of PU decreases by 25-30%
Cause Analysis
Molecular chains break and degrade under repeated high-temperature shearing; antioxidants are consumed up in multiple processing; cumulative effect of thermo-mechanical degradation
Solution
1) Recycled material ratio not exceeding 20-30%; 2) Supplement 0.1-0.2wt% antioxidant at each re-extrusion; 3) Reduce processing temperature by 5-10°C; 4) Reduce screw speed to reduce shearing
Key Takeaway
Multiple processing performance degradation is caused by thermo-mechanical degradation; limiting regrind and supplementing antioxidants are key
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