Material Drying
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Decreased Transparency/Yellowing of acrylonitrile-butadiene-styrene copolymer SAN/AS Products
Problem Phenomenon
The transparency of SAN/AS products is lower than the standard or yellowing appears.
SAN is known for its transparency and heat resistance.
Cause Analysis
（1）The processing temperature is too high, and the material thermally degrades and yellows
（2）The raw material moisture content is high, and micro-bubbles form in the product
（3）The regrind is used multiple times, and the material ages and yellows
（4）The additives are poorly dispersed, affecting the transparency
（5）The mold temperature is improper, and the surface replication effect is poor
Solution
（1）Control the processing temperature within the 220-260°C range
（2）Fully dry the raw material, with moisture content ≤0.02%
（3）Control the regrind ratio to no more than 10%
（4）Use additives with good dispersibility
（5）Optimize the mold temperature to a higher value within the 50-90°C range
Key Takeaway
The decrease in SAN transparency is caused by thermal degradation or micro-bubbles.
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