高等学校化学学报 ›› 2020, Vol. 41 ›› Issue (12): 2838-2844.doi: 10.7503/cjcu20200350

• 高分子化学 • 上一篇    下一篇

有机小分子对聚丙烯光氧老化的传染作用

刘璇, 刘昊雨, 李一枫, 赵皎宏, 杨睿()   

  1. 清华大学化学工程系高分子研究所, 北京 100084
  • 收稿日期:2020-06-15 出版日期:2020-12-10 发布日期:2020-12-09
  • 通讯作者: 杨睿 E-mail:yangr@mail.tsinghua.edu.cn
  • 基金资助:
    国家自然科学基金(51673111)

Infectious Effect of Organic Small Molecules on Photo-oxidative Aging of Polypropylene

LIU Xuan, LIU Haoyu, LI Yifeng, ZHAO Jiaohong, YANG Rui()   

  1. Polymer Research Institute,Department of Chemical Engineering,Tsinghua University,Beijing 100084,China
  • Received:2020-06-15 Online:2020-12-10 Published:2020-12-09
  • Contact: YANG Rui E-mail:yangr@mail.tsinghua.edu.cn
  • Supported by:
    ? Supported by the National Natural Science Foundation of China(51673111)

摘要:

以聚丙烯(PP)为研究对象, 选择代表典型小分子降解产物结构的酸、 酯、 醛、 酮和醇类共18种模型小分子, 研究有机小分子对PP光氧老化的传染作用. 研究发现, 所有的小分子都能不同程度地加速PP的光氧老化. 其中, 酸类、 醛类和酮类小分子的加速作用较强, 酯类和醇类小分子的加速作用较弱. 进一步研究了丙酮和乙酸对PP光氧老化的作用机理. 结果表明, 丙酮易光解产生甲基自由基, 通过引发PP氧化的方式加速其老化进程; 乙酸不具备引发能力, 通过催化氢过氧化物分解的方式促进PP中氧化产物的产生和积累.

关键词: 聚丙烯, 光氧老化, 有机小分子, 传染

Abstract:

Aging of a polymer is generally affected by adjacent polymers, known as infectious behavior of aging. Organic small molecules generated during aging are considered to be infection agents. However, the way they influence aging process and the difference among various infection agents are still unknown. In this paper, the influence of 18 representative organic small molecules on photo-oxidative aging of polypropylene(PP) was studied. The small molecules included acids, esters, aldehydes, ketones and alcohols, correspon-ding to typical photo-oxidative degradation products of polymers. When they were placed near PP during aging, the carbonyl index(CI) of PP was higher compared to the case when PP was aged individually. It was demonstrated that photo-oxidative aging of PP was accelerated by all the small molecules. The acceleration effects of acids, aldehydes and ketones were outstanding. Especially for propanoic acid, isobutyric acid, me- thacrylic acid, formaldehyde, acetaldehyde and butanone, CI was increased by more than 700% when PP was aged with them. Further, infection mechanism of acetone and acetic acid was investigated, since they had been identified as typical infection agents. CI and concentrations of gaseous degradation products of PP with and without acetone or acetic acid were measured with aging time. When PP was aged with acetone, CI was increased from as early as 24 h at an extremely high rate. With acetic acid, CI was increased after an obvious induction period and the increasing rate was lower than that with acetone. Similar phenomenon was observed in gaseous degradation products. The results showed that acetone acted as an initiator, photolyzed to generate CH3· that could initiate the oxidation of PP; while acetic acid acted as a catalyzer, facilitating the decomposition of hydroperoxides and the accumulation of oxidation products.

Key words: Polypropylene, Photo-oxidative aging, Organic small molecule, Infection

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