Processing Machinery
2 views
Degradation discoloration of linear low density polyethylene extruded products (Variant: strengthened measures)
Problem Phenomenon
The extrudate turns yellow or darkens, with rough surface and possible odor.
Degradation discoloration indicates the material has undergone thermal oxidative degradation, mechanical properties are severely reduced, and the product is unusable.
In particular, additional attention is needed on the original basis; this problem is more prominent and requires key attention.
Cause Analysis
(1) Barrel temperature too high; material undergoes thermal degradation in the barrel
(2) Screw rotation speed too fast; shear overheating causes degradation
(3) Material residence time in the barrel too long, heat history accumulates
(4) Screw and barrel wear, producing metal-catalyzed degradation
(5) Insufficient or ineffective antioxidants in raw material
(6) On the original basis, additional attention is needed as process parameter fluctuations or equipment status changes have aggravated this problem
Solution
(1) Reduce barrel temperature to a reasonable value within the 190-250°C range
(2) Reduce screw rotation speed, reduce shear heat generation
(3) Check screw and die head flow channels, eliminate dead corners to prevent retention
(4) Regularly check screw and barrel wear, replace in time
(5) Add appropriate antioxidants (0.1-0.5%) or select grades with good thermal stability
(6) And strengthen process monitoring; on the original basis, additional attention is needed, with special attention to parameter stability
Key Takeaway
Degradation discoloration is caused by overheating or excessive shear; it needs to be prevented from three aspects: temperature control, rotation speed, and material selection.
Targeted preventive measures need to be taken in different production scenarios.
Was this helpful?
0 people found this helpful
Thank you for your feedback!