N-CYANO-SUBSTITUTED HOMOPOLYAMIDE AND COPOLYAMIDES

Certain biscyanamides were synthesized by reacting aromatic diamines with cyanogen bromide. They were used as starting materials for preparing a new series of N-cyano-substituted homopolyamide and copolyamides. Homopolyamide was prepared from the reaction of terephthaloyl dichloride with 4,4'-biscyanamidediphenylmethane. Various copolyamides were prepared by reacting terephthaloyl dichloride with a mixture of an aromatic diamine and the corresponding biscyanamide. The polycondensations were carried out in solution at low temperature in the presence of acid acceptor. In addition, a model compound was synthesized from the reaction of 4,4'-biscyanamidediphenylmethane with a double molar amount of benzoyl chloride. The polyamides were characterized by FTi.r. and H-1 n.m.r. spectroscopy as well as by inherent viscosity measurements. The modified polyamides showed higher solubility in common solvents than the corresponding unsubstituted polyamide. Crosslinked polymers were obtained by curing the N-cyano-substituted polyamides. Their thermal stability was correlated with the curing conditions as well as the concentration of cyano groups. The cured modified polyamides were stable up to 317-370-degrees-C in N2 or air and afforded anaerobic char yield of 45-58% at 800-degrees-C.