1H-NMR investigation of the thermooxidation degradation of poly(oxymethylene) copolymers

Authors

  • Guangqin Pan,

    1. State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu, Sichuan 610065, People's Republic of China
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  • Huilin Li,

    Corresponding author
    1. State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu, Sichuan 610065, People's Republic of China
    • State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu, Sichuan 610065, People's Republic of China
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  • Ya Cao

    1. State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu, Sichuan 610065, People's Republic of China
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Abstract

The thermooxidative degradation of poly(oxymethylene) copolymer (CPOM-Y) powder was studied in air in 150°C. The effect of the sequence distribution of degraded poly(oxymethylene) (POM) samples on the thermal decomposition behavior was investigated with 1H-NMR and gas chromatography/mass spectrometry. The results showed that the degradation process of CPOM-Y could be divided into three stages with a gradually increasing degradation rate. The change in the sequence molar fractions agreed with the fact that the ethylene oxide (EO) units had higher thermal stability, and the degradation of POM was due to the decomposition of formal units. At the beginning, CPOM-Y tended to split off formaldehyde, starting at the chain ends, some of which were not ended by EO units. In stage 2, the thermooxidation of POM occurred in the amorphous phase. In stage 3, no obvious rules for the changes in the sequence contents were obtained from NMR results, and this indicated further random chain scission and unzipping occurring heavily in the crystalline bulk. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 577–583, 2004

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