Material Drying
6 مشاهدة
Color darkening in PET extrusion pelletizing
ظاهرة المشكلة
After extrusion pelletizing of PET recycled material, pellet color obviously darkens (yellowing), IV value decreases.
تحليل الأسباب
Extrusion temperature too high or residence time too long causes thermal degradation, residual moisture in recycled material causes hydrolysis, screw shear too strong generates shear heat.
الحل
Control extrusion temperature 260-280°C; fully dry recycled material; use low-shear screws; nitrogen protection in the hopper to prevent oxidation.
الخلاصة الأساسية
PET recycling pelletizing color and IV value control are key indicators of recycling quality.
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