Abstract: An aromatic polyamide comprising (1) a unit of the formula: ##STR1## and (2) a unit of the formula: ##STR2## and being excellent in strength, rigidity and heat resistance and improved in light resistance, flexibility and wear resistance, which can be produced by polycondensation of a diamine component comprising N,N'-bis(p-aminobenzoyl)-ethylenediamine and p-phenylenediamine, the content of the N,N'-bis (p-aminobenzoyl)ethylenediamine being from about 0.6 to 50 mol %, with a dicarboxylic acid component comprising terephthalic acid or its reactive derivative in a substantially equimolar amount to the diamine component in an amide polar solvent.

Abstract: A process for producing novel aromatic polyamides having excellent heat resistance, toughness and chemical resistance and further having improved solubility, molding properties and light resistance, which comprises polycondensing a mixed diamine consisting of piperazine and p-phenylenediamine with a substantially equimolar amount of terephthaloyl dihalide in at least one amide type polar solvent (e.g. hexamethylphosphoramide, N-methyl-2-pyrrolidone, alone or a mixture thereof), wherein said piperazine is contained in a ratio of 10 to 35 % by mol on the basis of the whole mixed diamine component, and fibers produced from the aromatic polyamides having high tenacity, flexing characteristics and wear resistance and further having improved elongation ratio, knot tensile strength, fatigue resistance and fibrillation resistance.