Poly(p-diphenylmethylterephthalamide) or PMA was synthesized from the reaction between recycled terephthalic acid (TPA) and recycled 4,4'-methylenedianiline (MDA) in the presence of pyridine, triphenyl phosphite, and a solubilizing-aid agent. The reaction conditions used for this polymerization were determined from a model reaction using pure TPA and pure MDA as reactants. It was found that PMA with the highest % yield and molecular weight was obtained when the mixture of lithium chloride (LiCl) and calcium chloride (CaCl2) were used as solubilizing-aid agents with a reaction time of 4 h. Recycled TPA with 92% purity was obtained from acid hydrolysis of waste PET bottles using sulfuric acid as a catalyst at 150degreesC for 5 h. Recycled MDA with 99% purity was obtained from aminolysis of rigid polyurethane foam scrap using diethylenetriamine as a degrading agent at 180degreesC for 70 min. PMAs prepared from recycled monomers exhibited thermal properties, which were comparable to those of PMA prepared from pure monomers. However, due to a possibility of several isomers present in recycled MDA, PMAs prepared from this monomer had lower melting points and thermal decomposition temperatures than those prepared from pure MDA. (C) 2003 Wiley Periodicals, Inc.