Extrusion & Post
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Thermal aging performance of linear low-density polyethylene PPR pipes not meeting standards
Problem Phenomenon
After thermal aging, the mechanical properties of PPR/PP-R pipes decline significantly, and oxidation induction time is insufficient.
Thermal aging performance not meeting standards shortens pipe service life and is especially critical in hot water systems.
Cause Analysis
(1) Raw material antioxidant content is insufficient or the type is improper
(2) Extrusion temperature is too high, and antioxidants are decomposed and consumed
(3) Too much regrind is used, and antioxidant content is low
(4) Pipe service temperature exceeds the design temperature
(5) Heat stabilizer addition is insufficient to meet the 110°C test requirement
Solution
(1) Select PPR special material containing sufficient antioxidants
(2) Control extrusion temperature at 200-220°C to avoid thermal decomposition of antioxidants
(3) Control the regrind proportion to no more than 15%
(4) Ensure hot water system temperature is within the design range (generally 70°C water supply)
(5) If necessary, add a combination of hindered phenolic and phosphite antioxidants
Key Takeaway
Thermal aging performance not meeting standards is caused by an insufficient antioxidant system and needs to be solved from formulation and processing temperature control.
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