Extrusion & Post
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Thermal aging performance of polyolefin plastomer PPR pipes not up to standard
Problem Phenomenon
The mechanical properties of PPR/PP-R pipes decline 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 particularly critical in hot water systems.
Cause Analysis
（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 pipe use temperature exceeds the design temperature
（5）The heat stabilizer addition is insufficient to meet the 110°C test requirements
Solution
（1）Select PPR special materials containing sufficient antioxidants
（2）Control the extrusion temperature at 200-220°C to avoid thermal decomposition of antioxidants
（3）Control the regrind proportion to no more than 15%
（4）Ensure the hot water system temperature is within the design range (generally 70°C water supply)
（5）Add a combination of hindered phenolic and phosphite antioxidants when necessary
Key Takeaway
Thermal aging performance not up to standard is caused by an insufficient antioxidant system, and needs to be solved from formulation and processing temperature control.
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