在役埋地聚乙烯给水管道自然老化行为研究

研究了埋地聚乙烯(PE)给水管道在我国台州地区实际服役7～12年过程中的自然老化行为,采用红外光谱仪(FTIR)、差示扫描量热仪(DSC)、扫描电子显微镜(SEM)等分析了管材在服役过程中不饱和基团含量、断链和支化程度、羰基指数、羟基指数等微观结构的变化趋势,考察了不同服役时间管材热稳定性、分子量、氧化诱导时间(OIT...

Study on natural aging behavior of buried polyethylene water supply pipeline in service

This paper reported a study on the natural aging behavior of buried polyethylene(PE)water supply pipelines in service of 7~12 years in Taizhou,China.The variations of unsaturated groups,chain scission and branching,carbonyl index,hydroxyl index of the PE pipelines in service and the thermal stability,molecular weight,oxidation induction time,microscopic morphology,yield strength and tensile modulus of the pipes with different service times were investigated using infrared spectrometer,differential scanning calorimeter,and scanning electron microscope,etc.The results indicated that during the service of buried PE water supply pipelines,the pipes were in the physical aging stage within the first 7 years in service under the protection of antioxidants,and their microstructure and mechanical properties were basically unchanged.After servicing for 7 years,the pipes entered the chemical aging stage,and the content of unsaturated groups and characteristic peaks of chain scission increased gradually.The thermal stability and mechanical properties of the pipes were improved due to a crosslinking reaction.After servicing for 9 years,the degree of oxidation increased sharply,the auto-oxidation reaction was enhanced,the content of the carbonyl increased,the chain scission became the main reaction,the thermal stability and mechanical properties decreased rapidly,and a great number of cracks formed on the surface of the pipes.By nonlinear fitting the antioxidant depletion time curve,the depletion time of antioxidant in the pipes was calculated to be 24.08 years in the service state.