Phthalonitrile polymers with amide and ortho-, meta-, and para-substituted ether linkages in the backbone were synthesized successfully and their thermal properties were investigated. The monomer building blocks for these polymers were cured without the addition of catalysts due to the self-catalyzing nature of the monomer's amino group. The ether and amide functionalities in the chain enhanced their processability without compromising thermal stability. The resins exhibited a low complex viscosity over a wide processing window between the monomer melting temperature and the polymer cure temperature, with the processing temperature range varying significantly for para-, ortho-, and meta-substituted polymer architectures. All three systems exhibited high thermal and thermo-oxidative stability. The high char yields, which ranged from 66-75% at 900 °C under nitrogen atmosphere, and the high glass transition temperatures of the polymers indicate a high crosslinking density in the network structure.
Some new amino-and imide-containing phthalonitrile compounds with 1:1 molar ratio of amino group to pthalonitrile unit were successfully synthesized. The molecular structures were characterized by spectroscopic techniques. They were thermally polymerized under nitrogen/air, even in the absence of curing additives. The thermal properties of the cured products were characterized by thermogravimetric analysis and differential scanning calorimetry. The 5% weight loss temperatures ranged from 525 to 528 C and 513 to 520 C under nitro-gen and air, respectively. Char yields (900 C) were in the range of 62-70%. Rheometric measurements showed that the rate of the cure reaction differs for all the three monomers. The glass transition temperature advances with increasing extent of cure and disappears on postcure at 375 C. V C 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 5916-5920, 2010
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