Process for the preparation of poly-p-phenyleneterephthalamide

A process for making poly-p-phenyleneterephthalamide having an inherent viscosity of at least 2.5 which is suitable for the manufacture of shaped articles by spinning or the like which comprises vigorously mixing and reacting p-phenylene diamine with terephthaloyl chloride in a substantially anhydrous solvent containing N-methyl pyrrolidone and at least 5% by weight of substantially anhydrous calcium chloride based on the weight of the N-methyl pyrrolidone, the weight of calcium chloride in the solvent when the two reactants are mixed together being such that some solid calcium chloride is suspended in the reaction mixture, and separating the resulting poly-p-phenyleneterephthalamide from the solvent, said reaction mixture being free from hexamethylphosphoramide, the inherent viscosity .eta..sub.inh of the poly-p-phenyleneterephthalamide being defined as

• .eta..sub.inh =(ln.sup..eta. rel/0.5)
• where .eta..sub.rel is the ratio of the efflux times of a 0.5 g solution of said poly-p-phenyleneterephthalamide in 100 ml of 96 percent by weight sulphuric acid, and the pure solvent, measured in a capillary viscometer at 25.degree. C.