Material Drying
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PEEK Pellets Absorbing 0.5% Moisture and the Drying Red Line
Problem Phenomenon
[Problem Phenomenon] Silver streaks and water splash marks appear on the surface of PEEK products, molecular weight decreases in mechanical property testing, and strength fluctuates between batches
Cause Analysis
PEEK pellets can absorb about 0.5% moisture in air; when processed at 350-400℃, the water vaporizes and triggers hydrolytic degradation and molecular chain scission; Victrex requires drying to a moisture content below 0.02% (dew point -40℃), 150℃×3h or 120℃×5h
Solution
Dry with a dehumidifying dryer at 150℃×3h or 160℃×2h, spreading the material in a 2.5cm thin layer to ensure moisture permeation; after drying, release only after actual measurement below 0.02% with a moisture meter; do not release based on timing alone — when the desiccant fails, no matter how long the time, it will not meet the standard
Key Takeaway
0.02% moisture content is the life-and-death line of PEEK, and actual measurement with a moisture meter is more reliable than drying timing; after confirming effectiveness, solidify the parameters and practices into the work instruction to prevent recurrence
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