Surface Defect Geometry/Tensile Failure Relationships of Aminolyzed Poly(ethylene Terephthalate) Fibers

Abstract

Poly(ethylene terephthalate) fibers have been aminolyzed in aqueous n-butylamine and n-butylamine vapor. Aqueous aminolysis causes short cracks to form perpendicular to the fiber axis, whereas vapor aminolysis results in continuous cracks parallel to the fiber axis. At a given treatment time or molecular weight, the breaking load of the vapor aminolyzed fibers is less than that of the fibers aminolyzed in aqueous amine. The differences in strength are considered in light of Prevorsek's model of melt-spun fibers. The amine vapor apparently breaks primarily extended chain tie molecules, and the attack of the aqueous amine is concentrated in unoriented amorphous regions. Scanning electron photomicrographs of fractured fiber ends and fibers stressed to 60, 75, and 90% of their mean breaking load provide further evidence of the different locations of attack.