Extrusion & Post
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Thermal aging performance of heat-resistant polyethylene PPR pipes not up to standard (Variant: strengthened measures)
Problembeschreibung
The mechanical properties of PPR/PP-R pipes decrease significantly after thermal aging, and the oxidation induction time is insufficient.
Thermal aging performance not up to standard shortens the service life of the pipes, and is especially critical in hot water systems.
In particular, extra attention is needed on the original basis, this problem is more prominent and needs key attention.
Ursachenanalyse
（1）The antioxidant content of the raw material is insufficient or the variety is improper
（2）The extrusion temperature is too high, and the antioxidant is decomposed and consumed
（3）Too much regrind is used, and the antioxidant content is low
（4）The use temperature of the pipe exceeds the design temperature
（5）The amount of heat stabilizer added is insufficient to meet the 110°C test requirements
（6）On the original basis, extra attention is needed: process parameter fluctuations or equipment status changes have aggravated this problem
Lösung
（1）Select PPR special materials containing sufficient antioxidants
（2）Control the extrusion temperature at 200-220°C to avoid thermal decomposition of the antioxidant
（3）Control the regrind ratio to not exceed 15%
（4）Ensure that the hot water system temperature is within the design range (generally 70°C water supply)
（5）If necessary, add a compound of hindered phenolic and phosphite antioxidants
（6）And strengthen process monitoring; on the original basis, extra attention is needed, with special attention to parameter stability
Wichtigste Erkenntnis
Thermal aging performance not up to standard is caused by insufficient antioxidant system, and needs to be solved from formulation and processing temperature control.
In different production scenarios, targeted preventive measures need to be taken.
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