Material Analysis
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Fast UV aging of PU
Problem Phenomenon
After 48h of UV irradiation, PU mechanical properties decrease >20%, yellowing
Cause Analysis
PU molecular chains degrade rapidly by photo-oxidation under UV; surface molecular chains break forming micro-cracks
Solution
1) Add UV absorber 0.3-0.5wt% to block UV; 2) Add HALS 0.2wt% for free radical scavenging; 3) Carbon black 2wt% to physically shield UV
Key Takeaway
Fast UV aging is caused by photo-oxidation; UV absorber and HALS are key
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