Material Drying
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Brown Amorphous Skin Layer and Annealing Crystallization of PEEK
Fenómeno do problema
[Problem Phenomenon] The surface of PEEK products shows a brown amorphous skin layer, and the strength and chemical resistance do not meet high-temperature service requirements
Análise das causas
Low-mold-temperature molding forms an amorphous skin layer that appears brown; the Victrex guide gives a crystallization-increasing annealing procedure: first dry at 150℃ for 3h, raise to 200℃ at 10℃/h, hold for at least 4h according to wall thickness, then cool to below 140℃ at 10℃/h
Solução
Anneal according to the procedure: 150℃ pre-drying → 10℃/h heating → 200℃ holding ≥4h → 10℃/h slow cooling; thin-wall parts may shorten the holding; after annealing, re-test crystallinity and dimensions
Conclusão principal
Remedy the brown skin layer with the 200℃ procedure annealing, and the heating and cooling rates must be controlled; after confirming effectiveness, solidify the parameters and practices into the work instruction to prevent recurrence
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