Abstract: As-spun fiber made from PPD-T with 0.5 to 3.0% sulfur as bound sulfonic acid or sulfonate groups, is disclosed. The fiber and has inherent viscosity greater than 4.5, as-spun yarn tenacity greater than 20 grams per denier, heat-aged strength retention of greater than 90%, and dipped cord strength greater than 18 gram per denier. The process for making the fiber includes PPD-T sulfonation by exposure to high concentration sulfuric acid in dope preparation under carefully controlled temperature and time.

Abstract: Fiber made from PPD-T with 0.5 to 3.0% sulfur as bound sulfonic acid or sulfonate groups, is disclosed. The fiber has inherent viscosity greater than 4.5, yarn tenacity greater than 20 grams per denier, heat-aged strength retention of greater than 90%, and dipped cord strength greater than 18 gram per denier. The process for making the fiber includes PPD-T sulfonation by exposure to high concentration sulfuric acid in dope preparation under carefully controlled temperature and time.

Abstract: A process is disclosed for improving the handling control of a moving, wet, unitary bundle of a plurality of yarns wherein a tension is applied to the yarn between the spinneret and the feed rolls until individual yarns can be separated from the bundle and, then, the tension is removed and the separation is maintained.

Abstract: A process for spinning high-strength high-modulus, aromatic polyamide filaments is disclosed in which an acid solution containing at least 30 g per 100 ml acid of aromatic polyamide having an inherent viscosity of at least 4 and chain-extending bonds which are either coaxial or parallel and oppositely directed is extruded through a layer of inert noncoagulating fluid into a coagulating bath and then through a spin tube along with overflowing coagulating liquid. Additional coagulating liquid is jetted symmetrically about the filaments in a downward direction forming an angle of 0.degree. C. to 85.degree. with respect to the filaments within about 2.0 milliseconds from the time the filaments enter the spin tube. The flow rates of the jetted and the overflowing coagulating liquids are maintained constant. In the process, the mass-flow ratio, i.e.

Abstract: Poly(p-phenyleneterephthalamide) yarn of improved fatigue resistance is prepared.

Abstract: Poly(p-phenyleneterephthalamide) yarn of improved fatigue resistance is prepared by spinning the polymer in sulfuric acid through an air gap into an aqueous coagulating bath to produce a coagulated yarn, maintaining the coagulating bath at a temperature of at least 20.degree. C., washing and neutralizing the yarn while it is under a tension of from 0.2 to 0.4 grams per denier, and drying the yarn at a temperature below 200.degree. C. while it is maintained under a tension of 0.05 to 0.2 grams per denier.