Extrusion & Post
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Substandard Heat Aging Performance of High-Density Polyethylene PPR Pipes
Problem Phenomenon
After heat aging of PPR/PP-R pipes, the mechanical properties decline significantly, and the oxidation induction time is insufficient.
Substandard heat aging performance shortens the service life of the pipes and is especially critical in hot water systems.
Cause Analysis
（1）The antioxidant content in the raw material is insufficient or the variety is improper
（2）The extrusion temperature is too high, and the antioxidant decomposes and is consumed
（3）Too much regrind is used, and the antioxidant content is low
（4）The pipe use temperature exceeds the design temperature
（5）The amount of heat stabilizer added is insufficient to meet the 110°C test requirement
Solution
（1）Select PPR special material containing sufficient antioxidants
（2）Control the extrusion temperature at 200-220°C to avoid thermal decomposition of antioxidants
（3）Control the regrind ratio to no more than 15%
（4）Ensure the hot water system temperature is within the design range (generally 70°C water supply)
（5）When necessary, add a combination of hindered phenolic and phosphite antioxidants
Key Takeaway
Substandard heat aging performance is caused by an insufficient antioxidant system, and needs to be solved from formulation and processing temperature control.
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