Extrusion & Post
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Thermal Aging Performance of Polypropylene PPR Pipe Not Up to Standard
Problem Phenomenon
After thermal aging, the mechanical properties of PPR/PP-R pipes decline significantly, and the oxidation induction time is insufficient.
Thermal aging performance not up to standard shortens the service life of the pipe, and is especially critical in hot water systems.
Cause Analysis
(1) The antioxidant content of the raw material is insufficient or the type 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 service temperature of the pipe exceeds the design temperature
(5) The amount of heat stabilizer added is insufficient to meet the 110°C test requirement
Solution
(1) Select a 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 not exceed 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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