Processing Machinery
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Performance decline caused by thermal degradation of styrene-acrylonitrile copolymer material
Problem Phenomenon
The product undergoes thermal degradation during processing, with molecular weight decline, mechanical property reduction and color change.
Cause Analysis
(1) Barrel temperature is too high, exceeding the 200-260°C upper limit
(2) Material residence time in the barrel is too long
(3) Screw speed is too fast, and excessive shear generates frictional heat
(4) Material accumulates at the nozzle or check ring, degrading under long-term high temperature
(5) Regrind is processed multiple times, and material molecular weight gradually decreases
Solution
(1) Strictly control barrel temperature within the 200-260°C range
(2) Lower the temperature or empty the material in the barrel at shutdown
(3) Appropriately reduce screw speed
(4) Regularly clean accumulated material at the nozzle and check ring
(5) Control the regrind proportion to no more than 15-20%
Key Takeaway
Thermal degradation is the main risk in processing; controlling temperature and reducing residence time is key.
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