Material Drying
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PA6 Hydrolysis Causes Sharp Strength Drop
Fenómeno do problema
The product appearance was normal, but impact and tensile strength dropped significantly, breaking after assembly; appearance inspection is hard to find it, which is a hidden failure.
Análise das causas
Moisture-containing PA6 undergoes hydrolysis at melting temperature, amide bonds break, and molecular weight declines irreversibly; hydrolysis has no obvious appearance features, but mechanical properties have been seriously damaged, and products break in batches during use, which is extremely harmful.
Solução
①Strictly dry to moisture content <0.2%;②verify moisture before startup;③wet material must not be used directly;④use up opened material within 48~72 hours or re-dry it;⑤shorten the residence time of the melt in the barrel to reduce heat accumulation degradation.
Conclusão principal
PA6 hydrolysis = 'irreversible invisible killer': products with normal appearance may already be performance-scrapped; drying is PA6's performance insurance, and directly molding wet material is tantamount to delivering scrap to the customer.
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