Richard L. Ballman

Investigations of Polyester Fiber Process/Structure/Property Relationships Part I

Polyester structure and properties are examined as a function of spinning and texturing processes. Spun fiber tensile and shrinkage properties are related to amorphous orientation and crystallinity. Particularly notable are the observations of textured yarn dyeability dependency on yarn crystallite size and spun yarn crystalline content. Dye path tortuosity is hypothesized to control the disperse dyeing of textured polyester.

Nylon 6,6 Fiber Tensile Properties as a Function of Morphology

Nylon 6,6 amorphous and crystalline orientation and content data are reported herein for a fiber series produced by varying the degree of stretch in conventional spinning and drawing operations. Tensile elongation and tenacity are correlated exponentially with the amorphous orientation function. Crystalline orientation values were observed to be consistently high, varying only slightly with significant tensile property changes. In addition, crystalline and amorphous contents varied by no more than 12% and did not consistently correlate with tensile properties. Extrapolation of the tensile property/amorphous orientation correlations to perfect amorphous chain orientation in the fiber direction implies that, in principle, a nylon 6,6 fiber having 20 gpd (1765 kN.m/kg) tenacity and 5.4% elongation is attainable.

Solution Fracture Barrier in Wet Spinning

The dry jet wet spinning of various molecular weight aromatic polyhydrazide solutions is used to exemplify tenacity and spinnability reduction due to solution fracture, an elastic flow instability initiating in the capillary entrance region. Signif icantly, fiber spun at shear rates an order of magnitude above that required for fracture initiation evidences no tenacity loss. A flow visualization apparatus, used to photo graph the solution orientation changes resulting from fracture, verified reduced in stability amplitude at high shear rates.