Methylol‐functional benzoxazines as precursors for high‐performance thermoset polymers: Unique simultaneous addition and condensation polymerization behavior |
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Authors: | Mohamed Baqar Tarek Agag Hatsuo Ishida Syed Qutubuddin |
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Affiliation: | 1. Department of Chemical Engineering, Case Western Reserve University, Cleveland, Ohio 44106;2. Department of Macromolecular Science and Engineering, Case Western Reserve University, Cleveland, Ohio 44106On leave from Tanta University, Egypt;3. Department of Macromolecular Science and Engineering, Case Western Reserve University, Cleveland, Ohio 44106 |
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Abstract: | A new class of high‐performance resins of combined molecular structure of both traditional phenolics and benzoxazines has been developed. The monomers termed as methylol‐functional benzoxazines were synthesized through Mannich condensation reaction of methylol‐functional phenols and aromatic amines, including methylenedianiline (4,4′‐diaminodiphenylmethane) and oxydianiline (4,4′‐diaminodiphenyl ether), in the presence of paraformaldehyde. For comparison, other series of benzoxazine monomers were prepared from phenol, corresponding aromatic amines, and paraformaldehyde. The as‐synthesized monomers are characterized by their high purity as judged from 1H NMR and Fourier transform infrared spectra. Differential scanning calorimetric thermograms of the novel monomers show two exothermic peaks associated with condensation reaction of methylol groups and ring‐opening polymerization of benzoxazines. The position of methylol group relative to benzoxazine structure plays a significant role in accelerating polymerization. Viscoelastic and thermogravimetric analyses of the crosslinked polymers reveal high Tg (274–343 °C) and excellent thermal stability when compared with the traditional polybenzoxazines. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 |
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Keywords: | benzoxazine resin combined molecular structure crosslinking methylol groups phenols resins resole structure– property relations thermal properties thermogravimetric analysis (TGA) |
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