Material Drying
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PET injection-grade drying 0.02%
Fenómeno do problema
PET engineering injection molded parts discolor and become brittle, strength tests fail, and the products carry color
Análise das causas
PET molecules contain ester groups and are hydrophilic; when the moisture content exceeds the limit, hydrolysis occurs during '2079851475616104452, molecular weight decreases, and products discolor and become brittle; the moisture red line for injection grade is 0.02%, looser than for sheet but still requiring strict management
Solução
①Dehumidify and dry to moisture <0.02%; ②150℃ × more than 4 hours or 170℃ × 3-4 hours; ③air-shot method inspection: if the shot material strand is smooth and free of bubbles, the drying is qualified
Conclusão principal
PET injection-grade drying can be quickly checked on site with the air-shot method; the 0.02% red line plus air-shot verification is a practical standard executable in the workshop; after confirming effectiveness, solidify the parameters and practices into the work instruction to prevent recurrence
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