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热老化对恒定内压下PPR管材性能的影响
作者：王英杰，彭效义，杨亚萍，薛书敏，侯云鹏
（江苏省建筑工程质量检测中心有限公司，江苏 南京 210000）
摘要：在95 ℃水浴环境中，对3种不同配方的PPR管材施加长期恒定内压，通过红外光谱分析、冲击强度试验、熔体质量流动速率试验、熔融温度试验和氧化诱导时间试验分析了PPR管材在热老化过程中管材性能和微观结构的变化。实验结果表明，随着老化时间的延长，聚丙烯（PP）分子链中引入乙烯链段，PP分子链的规整性降低，使产品的冲击强度提高；随着老化时间的延长，PPR的结晶度降低，熔体流动速率逐渐降低，管材的熔融温度有所降低；同时管材表面的抗氧剂逐渐被消耗，氧化诱导时间逐渐缩短。微观结构分析表明，经长时间老化后，管材表面的羰基（—C=O）和羟基（—OH）等含氧基团增加。
关键词：PPR管材；恒定内压；热老化；管材性能；微观结构
中图分类号：TU532+.61 文献标识码：A 文章编号：1001-702X（2022）06-0141-04
The effect of thermal aging on the properties of PPR pipes under constant internal pressure
WANG Yingjie，PENG Xiaoyi，YANG Yaping，XUE Shumin，HOU Yunpeng
（Jiangsu Testing Center for Quality of Construction Engineering Co. Ltd.，Nanjing 210000，China）
Abstract：In a 95 ℃ water bath environment，three pipes of different formulations are subjected to long-term constant internal pressure，and they have passed infrared spectroscopy tests，impact strength tests，melt mass flow rate tests，melting temperature tests，and the oxidation induction time tests，analyzed the changes of the pipe performance and microstructure of PPR pipe during the heat aging process. Experiments show that with the extension of aging time，the introduction of ethylene segments into the polypropylene molecular chain reduces the regularity of the PP molecular chain，which increases the impact strength of the product. With the extension of aging time，the crystallinity of PPR decreases and the melt flow rate gradually decreases，and the melting temperature of the pipe decreases，with the extension of the aging time，the antioxidant on the surface of the pipe is gradually consumed，and the oxidation induction time gradually decreases，the microstructure analysis shows that after a long period of aging，the carbonyl group（—C=O） and hydroxyl（—OH） and other oxygen-containing groups on the surface of the piopes increase.
Key words：PPR pipes，constant internal pressure，thermal aging，pipe performance，microstructure