Extrusion & Post
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Thermal aging performance of low density polyethylene PPR pipes not up to standard
Problem Phenomenon
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.
Cause Analysis
(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
Solution
(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
Key Takeaway
Substandard thermal aging performance is caused by insufficient antioxidant system; it needs to be solved from formulation and processing temperature control.
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