Molding Process
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Yellowing of CMC Products After Processing
Problem Phenomenon
After CMC products are stored for 1 week, the surface gradually turns yellow with color difference ΔE>3
Cause Analysis
The antioxidant system is imperfect and thermal oxidative degradation produces yellow products; ultraviolet irradiation accelerates photo-oxidation; residual transition metal catalysts catalyze oxidation
Solution
1)Improve the antioxidant system 1010(0.1)+168(0.1)+DSTDP(0.2)wt%; 2)Add UV absorber 0.2-0.5wt%; 3)Add metal deactivator 0.05wt%; 4)Select low-residue raw material grades
Key Takeaway
Yellowing is caused by thermo-photo-oxidation and metal catalysis; improving the antioxidant system and UV absorber is the key
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