Synthesis and properties of polyterephthalamides with ester pendent groups

Abstract

3,5-Dinitrobenzoyl chloride reacted with various alcohols such as phenol, biphenyl-4-ol, 1-naphthol, or diphenylmethanol to afford the 3,5-dinitrobenzoic acid ester derivatives which were catalytically hydrogenated to the corresponding diamines. The latter reacted with terephthaloyl dichloride to yield a new series of modified polyterephthalamides bearing pendent groups connected to the polymer backbone with ester linkages. The analogous unsubstituted polyterephthalamide were also prepared to compare the properties of the two series of aromatic polyamides. The polyamides were characterized by FT-IR, 1H-NMR, inherent viscosity, and water-absorption measurements, x-ray, DTA, TMA, TGA, and isothermal gravimetric analysis. The modified polyamides exhibited better solubility in certain organic solvents and higher hydrophilicity than the corresponding unmodified one. They were amorphous and softened at about 230°C. The glass transition temperatures ranged from 178 to 217°C. After an appropriate thermal treatment, crosslinking of modified polyamides was achieved and their thermal stability was slightly lower than that of parent unsubstituted polyamide. They were stable up to 354–370°C in N2 or air and afforded anaerobic char yields of 50–60% at 800°C. © 1996 John Wiley & Sons, Inc.