Production & Quality
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EVOH product yellowing after processing
Problem Phenomenon
EVOH product surface gradually yellows after 1 week of storage, color difference ΔE>3
Cause Analysis
Incomplete antioxidant system, thermal-oxidative degradation producing yellow products; ultraviolet irradiation accelerating photo-oxidation; residual transition metal catalysts catalyzing 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 thermal-photo oxidation and metal catalysis; improving the antioxidant system and UV absorber is key
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