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Characteristics of the degradation and improvement of the thermal stability of poly(siloxane urethane) copolymers

Authors

  • Jeh-Taut Yeh,

    Corresponding author
    1. Graduate School of Polymer Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan, Republic of China
    • Graduate School of Polymer Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan, Republic of China
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  • Yao-Chi Shu

    1. Department of Polymer Materials, Vanung University, Chung-Li, Tao-Yuan 320, Taiwan, Republic of China
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Abstract

This work investigates the characteristics of the thermal degradation of poly(ether urethane) (E-PU) and poly(siloxane urethane) (S-PU) copolymers by thermogravimetric analysis (TGA) and thermogravimetric analysis/Fourier transform infrared spectroscopy (TG–FTIR). The stage of initial degradation for E-PU was demonstrated as a urethane-B segment consisting of 4,4′-diphenylmethane diisocyanate (MDI) and 1,4-butanediol. Moreover, the urethane-B segment in the copolymers had the lowest temperature of degradation (ca. 200°C). The degradation of E-PU was determined by TGA and TG–FTIR analyses and had three stages including seven steps. Although the soft segment of S-PU possessed the thermal stability of polydimethylsiloxane (PDMS), the unstable urethane-B segment existed in S-PU. Therefore, the initial degradation of S-PU appeared around 210°C. The four stages of degradation of S-PU involved eight steps, as revealed by TG–FTIR, which identified the main decomposition products: CO2, tetrahydrofuran, and siloxane decomposition products. The imide group with high thermal stability was to replace the urethane-B segment of S-PU, which had the lowest thermal stability herein. The poly(siloxane urethane imide) (I-PU) copolymer around 285°C exhibited a high initial temperature of degradation, and the initial degradation occurred at the urethane-S segment consisting of MDI and PDMS. The degradation of I-PU was similar to that of S-PU and had four stages including six steps. Moreover, the degradation region of the imide group between 468 and 625°C was merged into the degradation stage of the siloxane decomposed products. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

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