Preparation of high molecular weight polybenzoxazine prepolymers containing siloxane unites and properties of their thermosets

Authors

  • Tsutomu Takeichi,

    Corresponding author
    1. Department of Environmental and Life Sciences, Toyohashi University of Technology, Tempaku-cho, Toyohashi, Aichi 441-8580, Japan
    • Department of Environmental and Life Sciences, Toyohashi University of Technology, Tempaku-cho, Toyohashi, Aichi 441-8580, Japan
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  • Takuya Kano,

    1. Department of Environmental and Life Sciences, Toyohashi University of Technology, Tempaku-cho, Toyohashi, Aichi 441-8580, Japan
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  • Tarek Agag,

    1. Department of Environmental and Life Sciences, Toyohashi University of Technology, Tempaku-cho, Toyohashi, Aichi 441-8580, Japan
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  • Takehiro Kawauchi,

    1. Department of Environmental and Life Sciences, Toyohashi University of Technology, Tempaku-cho, Toyohashi, Aichi 441-8580, Japan
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  • Nobuyuki Furukawa

    1. Chemical and Biological Engineering, Sasebo National College of Technology, Okishin-cho, Sasebo, Nagasaki 857-1193, Japan
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Abstract

High-molecular-weight polybenzoxazine prepolymers containing polydimethylsiloane unit in the main-chain have been synthesized from α,ω-bis(aminopropyl)polydimethylsiloxane (PDMS) (molecular weight = 248, 850, and 1622) and bisphenol-A with formaldehyde. Moreover, another type of prepolymers was prepared using methylenedianiline (MDA) as codiamine with PDMS. The weight average molecular weight of the obtained prepolymers was estimated from size exclusion chromatography to be in the range of 8000–11,000. The chemical structures of the prepolymers were investigated by 1H NMR and IR analyses. The prepolymers gave transparent free standing films by casting their dioxane solution. The prepolymer films after thermally cured up to 240 °C gave brown colored transparent and flexible polybenzoxazine films. Tensile test of the films revealed that the elongation at break increased with increasing the molecular weight of PDMS unit. Dynamic mechanical analysis of the thermosets showed that the Tgs were as high as 238–270 °C. The thermosets also revealed high thermal stability as evidenced by the 5% weight loss temperatures in the range of 324–384 °C from thermogravimetic analysis. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010

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