高温内压环境下聚乙烯燃气管道老化性能评价研究

将一批聚乙烯燃气管道试样置于80 ℃、1.1 MPa水浴环境下进行老化试验，老化时间分别为0、165、500、1 000 h，并通过差示扫描量热法（DSC）、热失重分析（TG）、傅里叶变换红外光谱分析（FTIR）和拉伸试验分别测试各老化试样对应的氧化诱导时间（等温OIT）、热分解温度（T_s）、官能团组成和断裂伸长率（ε），模拟分析高温内压环境下聚乙烯管道的老化性能变化规律。DSC、TG和拉伸试验结果显示，随着老化时间增加，聚乙烯管道的等温OIT、T_s和ε都逐渐降低，老化程度逐渐增加，并且管内壁的老化速率明显大于外壁；FTIR结果显示，随着老化时间增加，聚乙烯管材料的官能团谱图中1 720 cm^-1和3 400 cm^-1处分别出现了C=O和O—H的振荡峰，进一步证实了聚乙烯管材料分子链中引入了氧化反应产物。

Aging evaluation of polyethylene gas pipes under high temperature and inner pressure environment

The polyethylene gas pipe samples were aged in a water bath at 80 ºC and 1.1 MPa for 0， 165， 500， and 1 000 h. The isothermal oxidation induction time （OIT）， thermal decomposition temperature （T_s）， functional group composition， and elongation at break （ε） of each aged specimens were investigated using DSC， TG， FTIR， and tensile measurement. The change rule in the aging performance law of polyethylene gas pipes was analyzed under high temperature and inner pressure environment. The results indicated that the polyethylene gas pipes presented a gradual decrease in isothermal OIT， T_s， and ε with an increase in aging degree. The aging rate of the inner wall was significantly higher than that of the outer wall. FTIR analysis results indicated that there were two characteristic absorption peaks at 1 720 cm^-1 and 3 400 cm^-1 corresponding to C=O and O—H vibration， respectively， in the functional group diagram of polyethylene pipe material with an increase in aging time. This further confirmed the introduction of oxidation reaction products into the molecular chain of polyethylene pipes.