Production & Quality
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Yellowing of PVA products after processing
Problembeschreibung
After 1 week of storage, PVA product surface gradually yellows, color difference ΔE>3
Ursachenanalyse
Antioxidant system imperfect, thermo-oxidative degradation produces yellow products; ultraviolet irradiation accelerates photo-oxidation; residual transition metal catalysts catalyze oxidation
Lösung
1) Improve 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 grade
Wichtigste Erkenntnis
Yellowing is caused by thermo-photo-oxidation and metal catalysis; improving the antioxidant system and UV absorber are key
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