Processing Machinery
11 조회수
Random copolymer polypropylene pipe special material (Nordic standard） extruded products degradation discoloration
문제 현상
The extrudate color yellows or darkens, the surface is rough, and there may be an odor.
Degradation discoloration indicates that the material has undergone thermo-oxidative degradation, mechanical properties are severely reduced, and the product is unusable.
원인 분석
（1）Barrel temperature too high, the material undergoes thermal degradation in the barrel\
（2）Screw speed too fast, shear overheating causes degradation\
（3）The material stays in the barrel too long, thermal history accumulates\
（4）Screw and barrel worn, producing metal-catalyzed degradation\
（5）The raw material antioxidant is insufficient or has expired
해결 방법
（1）Lower the barrel temperature to a reasonable value within the 200-220°C range\
（2）Reduce screw speed, reduce shear heating\
（3）Check the screw and die head runners, eliminate dead corners to prevent stagnation\
（4）Regularly check screw and barrel wear, replace in time\
（5）Add an appropriate amount of antioxidant (0.1-0.5%) or select grades with good thermal stability
핵심 요약
Degradation discoloration is caused by overheating or excessive shear, and needs to be prevented from three aspects: temperature control, rotational speed and material selection.
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