Abstract: Certain fiber-forming aromatic polyamides having a high solubility in organic solvents used in their preparation are provided. The polyamides are prepared from diacid chlorides and from diamines containing sulfonate linkages by the low temperature solution polymerization technique. Fibers of the polyamides have a high modulus to tenacity ratio.

Abstract: An acrylic fiber having improved basic dyeability and the method for making the same wherein an acrylic polymer containing a sulfonated vinyl monomer as a part thereof is dissolved in a suitable solvent to form a spinning dope and a solution of a second or additive polymer dissolved in the same solvent is added to the dope which is then spun to form fibers. The second polymer is selected from the group consisting of cellulose triacetate, polymethyl methacrylate, polyvinyl chloride, a polyamide of hexamethylenediamine with 1,1,3-trimethyl-5-carboxy-3-(p-carboxyphenyl) indane and a polyamide of hexamethylene diamine with isophthalic acid. The spin dope will contain 10 to 35 weight percent of polymer solids, with the amount of the second or additive polymer being 0.5 to 25 weight percent of the total polymer solids. Fibers spun from the dope have enhanced basic dyeability. The method is effective only when the acrylic polymer contains a sulfonated vinyl monomer as part of the acrylic polymer backbone.

Abstract: Disclosed is an acrylic fiber having improved basic dyeability. The fiber is made by a process wherein a copolymer of an acrylic monomer and a sulfonated vinyl monomer is dissolved in a solvent to form a spinning dope and a solution of polystyrene in the same solvent is added to the dope prior to spinning the dope to form fibers. The polystyrene will be in the form of a separate phase dispersed throughout the spinning dope and the fibers formed from the dope. Fibers formed from this polystyrene-containing dope have improved basic dyeability.