Material Drying
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Defects caused by insufficient drying before random copolymer polypropylene random copolymer polypropylene processing
Problem Phenomenon
Silver streaks, bubbles and rough surfaces appear on the product surface, and mechanical properties decline.
The consequences of insufficient drying cover multiple defect types and are a common problem in plastics processing.
Cause Analysis
(1) Raw material absorbs moisture (although random copolymer polypropylene has low water absorption, long-term exposure still absorbs water)
(2) Drying temperature is too low or drying time is insufficient
(3) Drying equipment failure or insufficient dehumidification capacity
(4) Dried raw material is left in a humid environment for too long and absorbs moisture again
(5) Regrind is not dried or insufficiently dried
Solution
(1) Use a dehumidifying dryer, drying temperature 60-80°C, time 2-4h
(2) Control moisture content after drying below 0.02% (random copolymer polypropylene)
(3) Seal and store dried raw material, cover the hopper, and limit air exposure to no more than 2h
(4) Dry regrind the same as new material
(5) Control workshop ambient humidity below 60%
Key Takeaway
Insufficient drying is a common root cause of processing defects; a complete drying system and moisture content testing system need to be established.
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