Optically anisotropic aromatic polyamide dopes

Claim 1

Optically anisotropic dope consisting essentially of: I. at least about 5 percent by weight of a polymer having an inherent viscosity of at least 0.7 and consisting essentially of at least one type of carbocyclic aromatic homo- or copolyamide having chain extending bonds from each aromatic nucleus which are coaxial or parallel and oppositely directed, and II. at least one liquid medium selected from the group consisting of: A. amides and ureas selected from the group consisting of: N,N-dimethylacetamide, N,N-dimethylpropionamide, N,N-dimethylbutyramide, N,N-dimethylisobutyramide, N,N-dimethylmethoxyacetamide, N,N-diethylacetamide, N-methylpyrrolidone-2, N-methylpiperidone-2, N-methylcaprolactam, N-ethylpyrrolidone-2, .[.N-acetylpyrrolidone.]..Iadd.N-acetylpyrrolidine.Iaddend., N-acetylpiperidine, N,N'-dimethylethyleneurea, N,N'-dimethylpropyleneurea hexamethylphosphoramide, and N,N,N',N'-tetramethylurea and containing a salt from the group consisting of lithium chloride and calcium chloride B. concentrated sulfuric acid, C. hydrofluoric acid, and D. chloro-, fluoro- or methane-sulfonic acids, said polymer being present in the dope in a concentration above the level at which there is a decrease in viscosity with increasing concentration represented by a sharp discontinuity in the slope of the plot of the dope viscosity vs. polymer concentration curve without the formation of a solid phase.