Extrusion & Post
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Thermal aging performance of heat-resistant polyethylene PPR pipes not meeting standard
Problem Phenomenon
The mechanical properties of PPR/PP-R pipes decrease significantly after thermal aging, and the oxidation induction time is insufficient.
Failure of thermal aging performance to meet standards shortens pipe service life and is especially critical in hot water systems.
Cause Analysis
(1) Antioxidant content in raw material insufficient or type improper
(2) Extrusion temperature too high, antioxidant decomposed and consumed
(3) Too much regrind used, antioxidant content low
(4) Pipe use temperature exceeds design temperature
(5) Heat stabilizer addition insufficient to meet 110°C test requirements
Solution
(1) Select PPR special material with sufficient antioxidant
(2) Control extrusion temperature at 200-220°C to avoid thermal decomposition of antioxidant
(3) Control regrind ratio not exceeding 15%
(4) Ensure hot water system temperature is within the design range (generally 70°C water supply)
(5) Add hindered phenolic and phosphite antioxidant combination if necessary
Key Takeaway
Failure of thermal aging performance to meet standards is caused by insufficient antioxidant system, and needs to be solved from formulation and processing temperature control.
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