Processing Machinery
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Performance decline caused by thermal degradation of high impact polystyrene material
Problem Phenomenon
Thermal degradation occurs during product processing, molecular weight decreases, mechanical properties decrease, color changes.
Cause Analysis
(1) Barrel temperature too high, exceeding the 180-240°C upper limit
(2) Material residence time in the barrel too long
(3) Screw rotation speed too fast, excessive shear generates frictional heat
(4) Material accumulation at the nozzle or non-return ring, long-term high-temperature degradation
(5) Regrind processed multiple times, material molecular weight gradually decreases
Solution
(1) Strictly control barrel temperature within the 180-240°C range
(2) Lower temperature or empty the material in the barrel during shutdown
(3) Appropriately reduce screw rotation speed
(4) Regularly clean accumulated material at the nozzle and non-return ring
(5) Control regrind ratio not exceeding 15-20%
Key Takeaway
Thermal degradation is the main risk in processing; controlling temperature and reducing residence time are key.
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