Extrusion & Post
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Thermal aging performance of linear low density polyethylene PPR pipes not up to standard (Variant: strengthened measures)
Problembeschreibung
After thermal aging, the mechanical properties of PPR/PP-R pipes decrease significantly, and oxidation induction time is insufficient.
Substandard thermal aging performance shortens pipe service life, especially critical in hot water systems.
In particular, additional attention is needed on the original basis; this problem is more prominent and requires key attention.
Ursachenanalyse
(1) Insufficient antioxidant content in raw material or improper type
(2) Extrusion temperature too high; antioxidants decompose and are consumed
(3) Excessive regrind use, low antioxidant content
(4) Pipe use temperature exceeds design temperature
(5) Heat stabilizer addition insufficient to meet the 110°C test requirement
(6) On the original basis, additional attention is needed as process parameter fluctuations or equipment status changes have aggravated this problem
Lösung
(1) Select PPR dedicated material containing sufficient antioxidants
(2) Control extrusion temperature at 200-220°C, avoid antioxidant thermal decomposition
(3) Control regrind ratio, not exceeding 15%
(4) Ensure hot water system temperature within the design range (generally 70°C water supply)
(5) Add a combination of hindered phenolic and phosphite antioxidants when necessary
(6) And strengthen process monitoring; on the original basis, additional attention is needed, with special attention to parameter stability
Wichtigste Erkenntnis
Substandard thermal aging performance is caused by insufficient antioxidant system; it needs to be solved from formulation and processing temperature control.
Targeted preventive measures need to be taken in different production scenarios.
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